JP2020131019A - Image processing device, image processing method, and program - Google Patents

Abstract

To provide an image processing device capable of easily and accurately extracting the contour of a desired region from a tomographic image.SOLUTION: The device comprises: an image storage unit 101 which stores a tomographic image; an operation receiving unit 102 which receives a specifying operation for specifying a reference pixel which becomes reference, among first pixels showing a first tissue included in the tomographic image; a contour extraction unit 103 which extracts a contour having a border between a first pixel continuous to the reference pixel specified by the specifying operation and a second pixel showing a second tissue different from the first tissue; and an output unit 104 which performs outputting the contour extracted by the contour extraction unit 103.SELECTED DRAWING: Figure 1

Description

The present invention relates to an apparatus or the like for processing a tomographic image.

Conventionally, it has been known that a map image for displaying the contour of a blood vessel portion in an identifiable manner is generated by extracting the contour of the blood vessel portion in a contrast image (see, for example, Patent Document 1). Further, it has been known that the aortic axis is automatically extracted and the inner diameter of the blood vessel is automatically extracted based on the blood vessel axis (see, for example, Non-Patent Document 1).

Japanese Unexamined Patent Publication No. 2018-469922 (Page 1, Fig. 1, etc.)

Tetsuo Hongo, 4 outsiders, "Usefulness of analysis software for macrovascular disease", [online], [Search on January 25, 2007], Internet <URL: http://www.innervision.co.jp/suite_ws /aze/jisedai/127.html>

Conventionally, as an automatic contour extraction of a blood vessel or the like, for example, a contrast medium is rapidly administered to a patient, the blood vessel lumen is filled with the contrast medium, an X-ray CT (computed tomography) image is taken, and then contrast is obtained in this CT image. It was done by detecting the high part of. However, it was not possible to use contrast media in cases of decreased renal function or allergies to contrast media. In addition, it was difficult to evaluate the outer contour when there was a wall thrombus in the aneurysm or when there was stenosis / occlusion due to some disease in the blood vessel. Furthermore, structures such as multiple muscles and lymph nodes that show a soft tissue concentration structure with almost the same CT value are difficult to separate, and require an interactive and time-consuming operation by a skilled radiologist or radiologist. In such a case, the reproducibility becomes lower as the part that depends on the manual operation increases, and there is also a problem that objective and scientific evaluation is difficult.

If no contrast agent is available, a plain X-ray CT image is taken without the contrast agent. As an image analysis method for general contour extraction, as an edge detection algorithm, for example, the documents listed in the following URL ("http://ishidate.my.coocan.jp/opencv_7/opencv_7.htm") Laplacian filters, Sobel filters, etc., as described in, have been devised, but the purpose is to simply apply these algorithms to simple X-ray CT images of living organisms because of their low contrast. The success rate of organ contour extraction is low.

Algorithms that use Hough transforms (see, for example, "https://ja.wikipedia.org/wiki/Hough transforms") are also known, but they take a considerable amount of time to calculate and are targeted. It is necessary to determine the figure in advance.

As described above, in the conventional technique, it is not easy to accurately extract a desired region, for example, a region of a desired organ, a contour of a region such as a blood vessel, or a contour of a hematoma or the like from a tomographic image of a living body. There was a problem.

The present invention has been made to solve the above problems, and provides an image processing device or the like capable of easily and accurately extracting the contour of a desired region from a tomographic image of a living body. The purpose.

The image processing apparatus of the present invention performs a specific operation of specifying a reference reference pixel among an image storage unit in which a tomographic image is stored and a first pixel indicating a first structure included in the tomographic image. It is provided with an operation reception unit that accepts an operation, a contour extraction unit that extracts a contour related to a first pixel continuous with a reference pixel specified by a specific operation, and an output unit that outputs the contour extracted by the contour extraction unit. It is an image processing device.

With such a configuration, the contour of a desired region can be easily and accurately extracted from a tomographic image of a living body.

In addition, as a result of diligent research by the inventor of the present application, in living organisms, specific tissues such as fat are often present around tissues such as blood vessels and organs, which is a characteristic of tissue distribution. Therefore, it was found that the contour of the region composed of the desired tissue can be appropriately extracted from the tomographic image by utilizing such a difference in the tissue distribution. That is, in the present invention, in the image processing apparatus, the contour extraction unit shows a first pixel continuous with a reference pixel specified by a specific operation and a second structure different from the first structure. The outline having a boundary with the pixel of the above may be extracted.

With such a configuration, the contour of a desired region can be easily and accurately extracted from a tomographic image of a living body.

In addition, as a result of diligent research by the inventor of the present application, it has been found that organs and the like of living organisms have morphological features such as no extremely protruding parts and no sharply pointed parts. It was found that the contours of organs and the like can be estimated with high reproducibility by using these features. That is, in the image processing apparatus of the present invention, the contour extraction unit determines in advance the distance between the reference pixel and the boundary between the first pixel and the second pixel continuous with the reference pixel. A contour having a boundary excluding the boundary satisfying the condition may be extracted.

With such a configuration, the contour of a desired region can be accurately extracted by deleting the boundary satisfying the condition from the boundary between the first pixel and the second pixel continuous with the reference pixel.

Further, in the image processing apparatus of the present invention, in the image processing apparatus, the contour extraction unit determines the distance between each of the boundaries between the first pixel and the second pixel continuous with the reference pixel and the reference pixel. Statistical processing may be performed, and the contour may be extracted by excluding the boundary where the distance from the reference pixel is an outlier.

With this configuration, by removing the boundary where the distance from the boundary between the first pixel and the second pixel continuous with the reference pixel is an outlier by statistical processing, the contour of the desired region can be accurately obtained. Can be extracted.

Further, in the image processing apparatus of the present invention, in the image processing apparatus, the contour extraction unit detects a portion where the detected boundary is discontinuous, and the boundary is interpolated for the detected portion to extract the contour. Good.

With such a configuration, the contour can be extracted with high accuracy.

Further, in the image processing apparatus of the present invention, in the image processing apparatus, the contour extraction unit detects a plurality of boundaries having the same direction with respect to the reference pixel from the detected boundaries, and one of the detected plurality of boundaries. It may be reduced to.

With such a configuration, the contour can be extracted with high accuracy.

Further, in the image processing apparatus of the present invention, in the image processing apparatus, the first pixel and the second pixel are pixels that can be identified by the values corresponding to the respective pixels, and the contour extraction unit is the first. The boundary between the pixel and the second pixel may be detected by using the value corresponding to each pixel.

With such a configuration, the boundary of a desired region can be detected without using the relative relationship of the values corresponding to the pixels such as the density difference and the contrast difference between the pixels, and the contour and the extraction can be performed with high accuracy. can do.

Further, in the image processing apparatus of the present invention, in the image processing apparatus, the specific operation received by the operation receiving unit is an operation of designating a desired region with respect to the tomographic image, and the contour extraction unit is an operation of specifying a desired region. An image processing device that extracts contours by using a pixel located at the center as a reference pixel may be used.

With such a configuration, the contour of a desired region can be easily and accurately extracted by using the region designated by the user.

Further, in the image processing apparatus of the present invention, the tomographic image is an X-ray CT image in the image processing apparatus, and the value corresponding to the pixel used by the contour extraction unit for contour extraction may be a CT value.

With such a configuration, the contour can be extracted with high accuracy by using the CT value of the pixel.

Further, in the image processing apparatus of the present invention, the tomographic image may be a tomographic image of a living body in the image processing apparatus.

With such a configuration, the contour of a desired region can be accurately and easily extracted in a living body.

Further, in the image processing apparatus of the present invention, in the image processing apparatus, the first tissue may be adipose tissue and the second tissue may be soft tissue.

With this configuration, by detecting the boundary between the soft tissue and the adipose tissue, it is possible to accurately extract the contour of an organ or the like composed of the soft tissue surrounded by the adipose tissue.

In addition, the image processing device of the present invention includes an area designation receiving unit that accepts an operation of designating a first pixel area composed of one or more first pixels in the image processing device, and one in the first pixel area. The contour extraction unit further includes an acquisition unit that acquires a range of values corresponding to the first pixel by using the values corresponding to the first pixels, and the contour extraction unit is the first pixel acquired by the acquisition unit. The contour related to the first pixel continuous with the reference pixel may be extracted by using the range of values corresponding to.

With such a configuration, it is possible to obtain a range of values corresponding to an appropriate first pixel from the pixels in the tomographic image.

Further, in the image processing apparatus of the present invention, in the image processing apparatus, the acquisition unit uses representative values of values corresponding to each of the plurality of first pixels, and the lower limit of the range of values corresponding to the first pixels. You may want to get the value.

With such a configuration, it is possible to obtain a lower limit value in a range of values corresponding to an appropriate first pixel.

Further, in the image processing apparatus of the present invention, in the image processing apparatus, the operation of designating the first pixel region is an operation of designating the region in the blood vessel of the tomographic image as the first pixel region, and there are a plurality of acquisition units. A value larger than the representative value of the value corresponding to each of the first pixels of 1 may be acquired as the lower limit value of the range of values corresponding to the first pixel.

With such a configuration, it is possible to obtain an appropriate lower limit value in the corresponding value range for the first pixel corresponding to blood.

Further, the image processing apparatus of the present invention displays the first pixel in the tomographic image in a mode that can be distinguished from other pixels by using the range of values acquired by the acquisition unit in the image processing apparatus. A display unit may be further provided.

With such a configuration, it is possible to easily identify the first pixel in the tomographic image.

Further, in the image processing device of the present invention, the specific operation received by the operation receiving unit in the image processing device may be an operation of designating one of the first pixels in the tomographic image displayed by the display unit.

With such a configuration, the operation of specifying the first pixel can be easily performed.

Further, in the image processing apparatus of the present invention, in the image processing apparatus, the contour extraction unit relates the contour of the region composed of the first pixel continuous with the reference pixel to the first pixel continuous with the reference pixel. It may be extracted as a contour to be processed.

With such a configuration, the contour associated with the appropriate first pixel can be extracted.

Further, in the image processing apparatus of the present invention, in the image processing apparatus, the contour extraction unit includes a contour of a region composed of a first pixel continuous with a reference pixel and an extended region set around the contour. Therefore, it is composed of the first pixels detected in the expansion region in which the amount of expansion in the upward direction is larger than the amount of expansion in the downward direction and the amount of expansion in the lateral direction decreases from the upward direction to the downward direction. The contour of the region may be extracted as the contour related to the first pixel continuous with the reference pixel.

With such a configuration, the contour of the first pixel can be appropriately extracted according to the distribution of the detection target in the living body of the first pixel.

Further, in the image processing apparatus of the present invention, in the image processing apparatus, the acquisition unit has a lower limit value that is larger than a representative value of a value corresponding to one or more first pixels in the first pixel region. The first range, which is the range of values corresponding to the first pixel, and the value equal to or more than the representative value of the values corresponding to one or more first pixels in the first pixel region, respectively, and the first range. The second range, which is the range of values corresponding to the first pixel having a value smaller than the minimum value of, as the lower limit value, is acquired, and the contour extraction unit is the first one continuous with the reference pixel. The contour of the area composed of pixels is extracted using the values in the first range, and the expansion area is set around this contour, and the amount of expansion in the upward direction is the amount of expansion in the downward direction. The contour of the region composed of the first pixel detected in the expansion region, which is larger and the lateral expansion amount decreases from the upper direction to the lower direction, is extracted using the second range. You may.

With this configuration, the lower limit of the range of values used when detecting the first pixel is lowered, and the first pixel that could not be detected as the first pixel continuous with the reference pixel is detected in the extended region. And the contour related to the first pixel continuous with the reference pixel can be extracted accurately.

Further, in the image processing apparatus of the present invention, in the image processing apparatus, the contour extraction unit determines as a range of values used when determining whether or not the pixel continuous with the reference pixel is the first pixel. The outline of the area composed of the first pixel continuous with the reference pixel is extracted using the range of the value obtained by correcting the lower limit value so that the vertical position of the target pixel becomes lower as it goes up. You may try to do it.

With such a configuration, the contour of the first pixel can be appropriately extracted by utilizing the difference in the value corresponding to the first pixel depending on the position in the living body.

Further, in the image processing apparatus of the present invention, the first tissue may be blood in the image processing apparatus.

With such a configuration, the contour of the first pixel can be appropriately extracted by utilizing the difference in the value corresponding to the first pixel depending on the position in the living body due to the change in blood density.

Further, the image processing apparatus of the present invention further includes an exclusion designation reception unit that accepts an exclusion designation operation for designating the contour of the exclusion region to be excluded from the contour extracted by the contour extraction unit for the tomographic image in the image processing apparatus. The contour extraction unit may extract the contour excluding the contour specified by the exclusion specification operation.

With such a configuration, the process of excluding the exclusion region from the contour can be easily performed.

Further, in the image processing apparatus of the present invention, in the image processing apparatus, a plurality of tomographic images taken at different positions in the same living body are stored in the image storage unit, and the contour extraction unit is among the plurality of tomographic images. Using the contour extracted from one tomographic image, reference pixels are specified for different tomographic images taken at different positions in the same living body, and the first pixel continuous with the specified reference pixel and the first tissue May detect a boundary with a second pixel indicating a different second structure in the different tomographic image and extract a contour having the detected boundary.

With such a configuration, in different tomographic images, the contour corresponding to the contour extracted for one tomographic image can be automatically extracted without designating the reference pixel or the like.

Further, in the image processing apparatus of the present invention, in the image processing apparatus, a plurality of tomographic images taken at different positions in the same living body are stored in the image storage unit, and the contour extraction unit is among the plurality of tomographic images. Using the contour extracted for one tomographic image, the contour corresponding to the contour extracted for the one tomographic image may be extracted for different tomographic images taken at different positions of the same living body.

With such a configuration, in different tomographic images, the contour corresponding to the contour extracted for one tomographic image can be automatically extracted.

Further, in the image processing apparatus of the present invention, in the image processing apparatus, a plurality of tomographic images taken at different M locations (M is an integer of 3 or more) in the same living body are stored in the image storage unit. , The contour extraction unit is continuous with the reference pixel extracted for the tomographic image (N is an integer of 2 or more and less than M) whose imaging position is the Nth tomographic image in which the reference pixel is specified among the plurality of tomographic images. Using the contour related to the first pixel to be imaged, the N-1th tomographic image is used in order from the N-1st tomographic image to the Kth tomographic image (K <N, K is an integer) whose shooting position is one or more before the Nth. After extracting the contour related to the first pixel that is continuous with the first pixel in the same contour as the contour extracted in the tomographic image immediately after, the Lth (L) that is one or more behind this Kth tomographic image. Up to the tom image (> K and L are integers), the contours related to the first pixel continuous with the first pixel in the same contour as the contour extracted in the immediately preceding tom image are extracted in order from the K + 1th tom image. Then, for one or more tomographic images from the Kth to the Lth, the contour corresponding to the contour extracted for the Nth tomographic image may be extracted.

With such a configuration, it is possible to accurately extract the contour corresponding to the contour extracted for the Nth tomographic image.

Further, in the image processing apparatus of the present invention, in the image processing apparatus, a plurality of tomographic images taken at different M locations (M is an integer of 3 or more) in the same living body are stored in the image storage unit. , The contour extraction unit is continuous with the reference pixel extracted for the Nth tomographic image (N is an integer of 2 or more and less than M), which is a tomographic image in which the reference pixel of the plurality of tomographic images is specified. Using the contour associated with the first pixel, up to the P-th (P> N, P is an integer) tomographic image whose imaging position is one or more later than the N-th, in order from the N + 1th tomographic image, the immediately preceding fault. After extracting the contour related to the first pixel that is continuous with the first pixel in the same contour as the contour extracted in the image, the Qth (P> Q,) which is one or more before this Pth tomographic image. Up to the tomographic image (Q is an integer), the contours related to the first pixel continuous with the first pixel within the same contour as the contour extracted in the immediately following tomographic image are extracted in order from the P-1st tomographic image. Then, for one or more tomographic images from the Qth to the Pth, the contour corresponding to the contour extracted for the Nth tomographic image may be extracted.

With such a configuration, it is possible to accurately extract the contour corresponding to the contour extracted for the Nth tomographic image.

Further, in the image processing apparatus of the present invention, in the image processing apparatus, a plurality of tomographic images taken at different M locations (M is an integer of 3 or more) in the same living body are stored in the image storage unit. The contour extraction unit is continuous with the reference pixel extracted for the N-th tomographic image (N is an integer of 2 or more and less than M), which is a tomographic image in which the reference pixel of the plurality of tomographic images is specified. Immediately after the N-1st tomographic image, up to the Kth tomographic image (K <N, K is an integer) whose shooting position is one or more before the Nth, using the contour related to the first pixel. After extracting the contour related to the first pixel that is continuous with the first pixel in the same contour as the contour extracted in the tomographic image of, the tomographic image immediately before is in order from the K + 1th tomographic image to the Nth tomographic image. The imaging position is N, which is a tomographic image in which a contour related to the first pixel continuous with the first pixel in the same contour as the contour extracted in the image is extracted and a reference pixel among a plurality of tomographic images is specified. Using the contour related to the first pixel continuous with the extracted reference pixel for the second tomographic image, up to the Pth (P> N, P is an integer) tomographic image whose imaging position is one or more later than the Nth. , N + 1 In order from the 1st tomographic image, after extracting the contour related to the 1st pixel continuous with the 1st pixel in the same contour as the contour extracted in the immediately following tomographic image, until the Nth tomographic image, P -In order from the 1st tomographic image, the contour related to the 1st pixel continuous with the 1st pixel in the same contour as the contour extracted in the immediately preceding tomographic image is extracted, and the region acquired for the Nth tomographic image. The region in which the reference pixels are combined may be extracted as the contour related to the first pixel continuous with the reference pixel in the Nth tomographic image in which the reference pixel is specified.

With such a configuration, the contour related to the contour continuous with the reference pixel of the tomographic image in which the reference pixel is specified can be extracted with high accuracy.

Further, in the image processing apparatus of the present invention, in the image processing apparatus, the contour extraction unit extracts the tomographic image whose imaging position is before the Nth in the tomographic image immediately after the N-1st tomographic image in order. Extract the contour related to the first pixel that is continuous with the first pixel in the same contour as the contour, and for the tomographic image whose shooting position is later than the Nth, the immediately preceding fault in order from the N + 1th tomographic image. The contour related to the first pixel continuous with the first pixel in the same contour as the contour extracted in the image may be extracted.

With such a configuration, in a tomographic image other than the tomographic image in which the reference pixel is specified, a contour corresponding to the contour extracted in the tomographic image in which the reference pixel is specified can be accurately extracted.

Further, the image processing apparatus of the present invention accepts an exclusion designation operation for designating the contour of the exclusion region to be excluded from the contour extracted by the contour extraction unit for each of two or more tomographic images in the image processing device. The contour extraction unit extracts the contour excluding the contour of the specified exclusion area for the tomographic image in which the exclusion area is specified by the exclusion specification operation, and the contour extraction unit extracts the contour of the tomographic image in which the exclusion area is not specified. For, the contour excluding the region obtained by interpolating a plurality of excluded regions may be extracted.

With this configuration, it is possible to extract the contour excluding the excluded area even in the tomographic image in which the excluded area is not specified.

Further, in the image processing apparatus of the present invention, in the image processing apparatus, the contour extraction unit extracts contours from a plurality of tomographic images taken at different positions in the same living body, and the contour extraction units are different in the same living body. A three-dimensional acquisition unit that acquires information on the three-dimensional shape using the contours extracted from each of the plurality of tomographic images taken at the position is further provided, and the output unit extracts the information on the three-dimensional shape acquired by the three-dimensional acquisition unit. It may be output as the information about the contour extracted by the part.

With such a configuration, it is possible to acquire information on the three-dimensional shape corresponding to the extracted contour.

Further, in the image processing apparatus of the present invention, in the image processing apparatus, the contour extraction unit may extract the contour obtained by further performing morphology conversion on the extracted contour.
With such a configuration, a more appropriate contour can be extracted.

According to the image processing apparatus or the like according to the present invention, the contour of a desired region can be easily and accurately extracted from a tomographic image of a living body.

Block diagram of the image processing apparatus according to the first embodiment of the present invention A flowchart illustrating an example of the operation of the image processing device. Diagrams showing tomographic images for explaining the image processing apparatus (FIGS. 3 (a) to 3 (d)). Schematic diagrams of tomographic images for explaining the image processing apparatus (FIGS. 4 (a) to 4 (e)). Schematic diagram showing an example of the appearance of a computer that realizes the image processing apparatus according to the embodiment of the present invention. Diagram showing the internal configuration of the computer Block diagram of the image processing apparatus according to the second embodiment of the present invention The figure which shows the experimental result for explaining the image processing apparatus. The figure which shows the experimental result for explaining the image processing apparatus. Schematic diagram for explaining the image processing apparatus Schematic diagrams for explaining the image processing apparatus (FIGS. 11 (a) and 11 (b)). Flow chart for explaining the operation of the image processing device Flow chart for explaining the operation of the image processing device Figures showing tomographic images for explaining the image processing apparatus (FIGS. 14 (a) to 14 (d)). Schematic diagram for explaining the operation of the image processing device The figure which shows the display example of the image processing apparatus

Hereinafter, embodiments of the image processing apparatus and the like will be described with reference to the drawings. In the embodiment, the components with the same reference numerals perform the same operation, and thus the description may be omitted again.

(Embodiment 1)
FIG. 1 is a block diagram of the image processing device 1 of the present embodiment.

The image processing device 1 includes an image storage unit 101, an operation reception unit 102, a contour extraction unit 103, and an output unit 104.

A tomographic image is stored in the image storage unit 101. A tomographic image is an image acquired by tomography. A tomographic image is a tomographic image of a living body such as a human body or an animal. The tomographic image is, for example, a medical image. The image storage unit 101 may store tomographic images taken at different positions of one living body. The different positions of the living body are, for example, different positions in the longitudinal direction of the living body. Further, the image storage unit 101 may store tomographic images of different living bodies. Here, a case where the tomographic image is an X-ray CT image taken by X-ray CT (Computed Tomography) will be described as an example. Further, a case where the tomographic image is a tomographic image of a living body will be described as an example. The resolution of the tomographic image does not matter.

The tomographic image is an image to be processed by the image processing device 1. The image here may be considered as image data. A tomographic image is, for example, an image composed of a plurality of pixels. The tomographic image is, for example, a bitmap image composed of a plurality of pixels arranged in a grid pattern. Bitmap images are also called raster images. Each pixel of the tomographic image, which is an X-ray CT image, is associated with a value called a CT value acquired at a position corresponding to each pixel of an imaging target such as a living body. For example, when a tomographic image is displayed by the output unit 104 or the like, an image in which each pixel is represented by a density corresponding to a CT value corresponding to each pixel (for example, a gray scale image or the like, a single color shade or light / darkness). It is displayed as (the image represented by). The density of the pixel may be considered as the brightness of the pixel, the brightness, or the like. Each pixel of the tomographic image may be, for example, a pixel having a higher corresponding CT value value and a pixel whose color indicating the density of the pixel is closer to white, and a pixel having a higher corresponding CT value value is a pixel. It may be a pixel in which the color indicating the density of is close to white. However, when displaying the tomographic image, each pixel may be displayed as an image of a plurality of colors converted into different colors according to the CT value corresponding to each pixel. The CT value corresponding to the pixel may be, for example, possessed by the tomographic image, or may be associated with the tomographic image and stored in the image storage unit 101. Further, the CT value may be a pixel value. The file format and data structure of the tomographic image do not matter. Since the tomographic image and the technique for displaying the tomographic image are known techniques, detailed description thereof will be omitted here.

The tomographic image may be an image obtained by converting the CT value corresponding to each pixel into the density value of each pixel having a predetermined number of gradations. In this case, the density of each pixel of the tomographic image is a converted value of the CT value corresponding to each pixel. In this case, a value indicating the density of each pixel may be used as a CT value corresponding to each pixel. The value indicating the density of the pixel may be the brightness value or the brightness value of the pixel. When converting the CT value of each pixel to the density of each pixel, the number of gradations may be reduced. Further, the tomographic image may be an image obtained by converting each pixel into a color having a hue, saturation, or the like corresponding to the CT value or the range of the CT value corresponding to each pixel.

The image storage unit 101 may store a plurality of tomographic images taken at different positions of one living body in association with each other. For example, the image storage unit 101 may store a plurality of tomographic images taken at different positions of one living body in the same folder. Further, for example, a file having a plurality of tomographic images taken at different positions of one living body may be stored in the image storage unit 101. Further, the image storage unit 101 may store management information such as a list of a plurality of tomographic images taken at different positions of one living body in addition to the tomographic images. Further, the plurality of tomographic images taken at different positions of one living body stored in the image storage unit 101 may include the identifier of the living body or the like in the file name or the like.

The image storage unit 101 is preferably a non-volatile recording medium, but can also be realized by a volatile recording medium. In addition, the storage here is a concept including temporary storage. The same applies to the following other storage units.

The operation reception unit 102 receives a specific operation for the tomographic image. The operation reception unit 102 receives, for example, a specific operation for the tomographic image stored in the image storage unit 101. The operation reception unit 102 receives, for example, a specific operation from the user. The specific operation is an operation of specifying a reference reference pixel among the first pixels indicating the first structure included in the tomographic image. The first tissue is a tissue in the living body for which a tomographic image is taken. The first tissue is, for example, a tissue constituting a site (for example, an organ) whose contour is to be detected in a tomographic image. The organ here may be a blood vessel or the like. The first tissue is, for example, a soft tissue in vivo. The soft tissue is, for example, the tissue of the portion of the living body excluding the skeleton and the adipose tissue. The soft tissue is, for example, a tissue such as an organ, a muscle, or a blood vessel. The tissue may be a special connective tissue such as blood or cartilage. The first organization may be composed of a plurality of different organizations. The first pixel is the pixel corresponding to the first tissue in the tomographic image. The reference pixel is, for example, a pixel used as a reference when extracting a contour. The reference pixel is usually one first pixel, but may be a plurality of adjacent first pixels or the like. In this case, the center positions of the plurality of reference pixels may be considered as the positions of the reference pixels.

The operation reception unit 102 identifies, for example, a tomographic image output (for example, displayed) by the output unit 104 to a monitor (not shown) or the like via an input device such as a keyboard, a mouse, a touch panel, or a stylus pen. The operation may be accepted. It should be noted that the processing and configuration for accepting an operation of designating an area or a pixel of an image output to a monitor or the like via an input device or the like is a known technique as a technique such as GUI (Graphical User Interface). Therefore, detailed description thereof will be omitted here.

The operation reception unit 102 may further accept an operation for designating a tomographic image to be a specific operation. Then, a specific operation may be accepted for this designated tomographic image. In addition, the operation reception unit 102 may accept an operation for displaying a tomographic image that is a target of a specific operation.

The specific operation accepted by the operation reception unit may be any operation as long as the reference pixel in the tomographic image can be specified as a result. For example, as will be described later, the contour extraction unit 103 has a pixel specified in a region, such as a pixel located in the center of this region, from a region designated for one tomographic image by an operation received by the operation reception unit 102. Is specified as a reference pixel, the specifying operation may be, for example, an operation of designating a region in one tomographic image. The specific operation for designating the area is, for example, an operation of moving the pointer or the like along the contour portion of the tomographic image region, or an operation of tracing the contour portion of the tomographic image region with a finger or a stylus pen. .. The operation of designating the area may be an operation of arranging an image having a desired shape and size on the tomographic image, an operation of tapping the position of the apex of the polygon with a finger or a stylus pen, or the like. .. The operation of specifying the area is not limited to the above operation. The area designated by the operation needs to be an area in which the position specified as the reference pixel in the designated area, such as the center of the designated area, becomes the first pixel. For example, in the region designated by the specific operation, it is preferable that the vicinity of the center is the first pixel.

Further, for example, the specific operation may be an operation of designating a reference pixel in one tomographic image. For example, in one tomographic image, a specific operation is an operation of moving a pointer (not shown) or the like on a pixel designated as a reference pixel and then performing a mouse click specified in advance, or an operation on a pixel designated as a reference pixel. May be an operation of tapping with a finger, a stylus pen, or the like. In this case, the pixel specified by the above operation is designated as the reference pixel. The specific operation may be an operation of designating a pixel designated as a reference pixel by coordinates or the like. The pixel designated as the reference pixel here needs to be the first pixel.

In the following, a case where the specific operation is an operation for designating an area will be described as an example.

The operation reception unit 102 may accept operations from users other than the above. The acceptance of operations here includes acceptance of operation information input from an input device such as a keyboard, mouse, touch panel, and stylus pen, and reception of information transmitted via a wired or wireless communication line. It is a concept. The input means for the operation may be any, such as a keyboard, a mouse, a touch panel, or a menu screen. The operation reception unit 102 can be realized by a device driver for input means such as a mouse or a touch panel, control software for a menu screen, or the like.

The contour extraction unit 103 extracts the contour of the tomographic image. The contour extraction unit 103 extracts the contour related to the first pixel continuous with the reference pixel specified by the specific operation received by the operation reception unit 102. The contour associated with the first pixel is, for example, a contour composed of pixels having a value having a predetermined relationship with respect to the value corresponding to the first pixel. The contour extraction unit 103 includes, for example, a first pixel continuous with a reference pixel specified by a specific operation received by the operation reception unit 102, and a second pixel indicating a second structure different from the first structure. Extract the contour with the boundary of. The contour extraction unit 103 includes, for example, a first pixel continuous with a reference pixel specified by a specific operation received by the operation reception unit 102, and a second pixel indicating a second structure different from the first structure. Boundary is detected in the tomographic image that is the target of the specific operation. Then, the contour having the detected boundary is extracted. The second tissue is the tissue in vivo. The second organization is, for example, an organization similar to the first organization except that it differs from the first organization. The contour extracted by the contour extraction unit 103 is, for example, the contour of a portion composed of the first tissue in the tomographic image. The contour of one area is composed of, for example, the boundary of the boundary between the pixels in one area and the pixels outside one area in contact with the pixels in one area. The contour extracted by the contour extraction unit 103 is, for example, the contour of a region including a reference pixel. The contour may be considered as a contour line. The contour extracted by the contour extraction unit 103 is, for example, the contour of a region having a first pixel continuous with the reference pixel. However, the region indicated by this contour may eventually include pixels other than the first pixel.

Extracting the contour here means, for example, acquiring information indicating the contour. As the information indicating the contour, for example, information indicating the contour used for ordinary image processing or the like can be used. For example, the information indicating the contour is to acquire the position information (for example, a coordinate group) of a plurality of pixels forming the pixel group showing the contour and the identifier of each pixel forming the pixel group showing the contour. The pixel group showing the contour is, for example, a pixel group adjacent to the inside or the outside of the contour. For example, the inside of the contour may be considered here as the side containing the reference pixel with respect to the contour, and the outside of the contour may be considered as the side opposite to the reference pixel with respect to the contour, for example. Further, the inside of the contour may be considered as the inside of the area surrounded by the contour. Here, a case where the contour extraction unit 103 detects the position information of the pixel group adjacent to the outside of the contour as the information indicating the contour will be described as an example. A group of pixels showing such a contour may be considered as a contour for convenience. For example, the contour of one area may be considered as a group of pixels in contact with the outside of one area or a group of pixels located on the outermost peripheral side in one area.

The contour extraction unit 103 determines, for example, whether the pixels constituting the tomographic image are the first pixel or the second pixel based on the values corresponding to the pixels, and determines whether the pixels are continuous with the reference pixel. The boundary between the pixel and the second pixel is detected. When the value corresponding to one pixel constituting the tomographic image is a value indicating that it is the first pixel, the contour extraction unit 103 determines this one pixel as the first pixel and determines the tomographic image. When the value corresponding to one pixel constituting the above is a value indicating that it is the second pixel, this one pixel is determined to be the second pixel. The value corresponding to the pixel is, for example, a CT value corresponding to the pixel. The second tissue is, for example, adipose tissue in vivo. When the first tissue is a soft tissue as described above, the range of CT values corresponding to the first pixel in the X-ray CT image which is a tomographic image is 1 to 1499, and the second tissue is adipose tissue. In some cases, the range of CT values corresponding to the second pixel is −200 to 0. Therefore, if the CT value corresponding to the pixel of the tomographic image falls within the range of the CT value corresponding to the first pixel, the contour extraction unit 103 determines this pixel as the first pixel and determines that the pixel is the first pixel of the tomographic image. If the CT value corresponding to the pixel falls within the range of the CT value corresponding to the second pixel, this pixel is determined to be the second pixel. The first pixel and the second pixel are preferably pixels that can be identified by a value corresponding to each pixel, and more preferably a pixel that can be identified only by a value corresponding to each pixel. Is preferable. The tomographic image is preferably an image in which the first pixel and the second pixel are such pixels. Hereinafter, in the present embodiment, a case where the first tissue is a soft tissue and the second tissue is an adipose tissue will be described as an example.

The process of extracting the contour by the contour extraction unit 103 will be described. The contour extraction unit 103 first specifies the reference pixel according to the specific operation received by the operation reception unit 102. Specifying the reference pixel may be considered to acquire information (for example, coordinates) indicating the position of the reference pixel. For example, when the specific operation is an operation for designating a reference pixel, the contour extraction unit 103 specifies the pixel designated by this operation as the reference pixel. When the specific operation is an operation for designating an area, the contour extraction unit 103 specifies a pixel located at the center of the area designated by this operation as a reference pixel. The pixel near the center may be used as a reference pixel. The center of gravity of the region may be used as the center of the region here. The center of the area may be obtained in any way. Since the process of determining the center of the region is a known technique, detailed description thereof will be omitted here. As the center of the region, the center of the smallest rectangle or the like including the region may be used.

The contour extraction unit 103 detects the first pixel continuous with the reference pixel in the entire circumferential direction of the reference pixel specified above, and determines the boundary between the first pixel continuous with the reference pixel and the second pixel. To detect. For example, the contour extraction unit 103 detects the first pixel continuous with the reference pixel in all directions with the reference pixel as the reference point, and the first pixel continuous with the reference pixel and the second pixel Detect boundaries. The contour extraction unit 103 detects, for example, the boundary between the first pixel and the second pixel that are continuous with the reference pixel both inside and outside the desired region indicated by the specific operation received by the operation reception unit 102. .. The first pixel continuous with the reference pixel is, for example, a first pixel adjacent to the reference pixel or connected to the reference pixel via one or more first pixels. The boundary between the first pixel and the second pixel is the boundary where the first pixel and the second pixel are adjacent to each other. Boundaries can be thought of as boundaries. Each of the boundaries adjacent to each pixel may be considered as one boundary, and continuous boundaries may be considered as one boundary. In the former case, multiple boundaries are usually detected. The contour extraction unit 103 acquires information indicating the boundary between the detected first pixel and the second pixel. As the information indicating the boundary, information indicating the boundary used in ordinary image processing or the like can be used. The information indicating the boundary may be, for example, the position information of at least one of the first pixel and the second pixel adjacent to each other across the boundary, and the first pixel and the first pixel having the boundary as at least a part of the outer circumference. It may be the position information of at least one of the two pixels, and may be the identifier of these pixels instead of the position information of these pixels. Here, as the information indicating the boundary, a case where the position information of the pixels adjacent to the boundary is acquired will be described as an example. Further, the pixels arranged at the positions indicated by the information indicating the boundary are hereinafter referred to as pixels indicating the boundary. Boundary detection may be considered, for example, detection of pixels indicating boundaries. The pixel indicating the boundary between the first pixel continuous with the reference pixel detected by the contour extraction unit 103 and the second pixel is usually the second pixel adjacent to the boundary.

The contour extraction unit 103 may not detect the boundary between the first pixel and the pixels other than the second pixel. For example, in an X-ray CT image of a living body, it is preferable not to detect the boundary between the first pixel corresponding to the soft tissue and the pixel corresponding to the metal in the living body. The metal in the living body is, for example, a stent, a bolt, a bone plate, or the like. For example, in an X-ray CT image, the CT value of air is -201 or less and the CT value of metal is 1500 or more. Therefore, if the first tissue is a soft tissue having a CT value of 1 or more and 1499 or less. , The boundary between the first pixel and the pixel corresponding to metal, and the boundary between the first pixel and the pixel corresponding to air can also be detected. However, since the vicinity of the metal placed in the living body is affected by the metal artifact, the boundary becomes unclear in the vicinity of the position corresponding to the metal in the tomographic image. Therefore, it is preferable not to detect the boundary between the pixel whose CT value is in the metal range and the first pixel. In order not to detect such a boundary with the metal, for example, when detecting the boundary as described above, it is preferable to treat the pixel showing the CT value of the metal as the first pixel. Further, in particular, since a metal artifact having a fat concentration appears around the metal even if there is no fat, the first pixel without determining the CT value for the pixels around the pixel showing the CT value of the metal. It is preferable to treat as. Therefore, when the contour extraction unit 103 detects the boundary as described above, the pixel indicating the CT value of the metal and the pixel located within a predetermined distance around the pixel (for example, a pixel within 10 pixels) ) Is more preferably determined as the first pixel. The predetermined distance (for example, the number of pixels) here is appropriately set according to, for example, the resolution of the tomographic image.

The contour extraction unit 103 extracts, for example, a contour having the boundary detected above. The contour extraction unit 103 may extract a contour having all the boundaries detected above as a contour having a boundary, or may extract a contour having a contour having a part of the detected contour. For example, the contour extraction unit 103 may use a part of the boundary detected above as a contour having a boundary, excluding the boundary excluded according to the distance from the reference pixel or the like by a process or the like described later. You may extract the contour having all. The information indicating the contour having a boundary is, for example, information having information indicating the boundary as information indicating at least a part of the contour. For example, the information indicating the contour having a boundary has, for example, the position information of one or more pixels indicating the boundary as at least a part of the position information of one or two or more pixels (for example, a pixel group) indicating the boundary. Information. Extracting the contour may be considered to acquire the position information of one or more pixels showing the contour, and one or two or more pixels showing the contour are the one or two or more pixels indicated by the position information. You may think. The outline-indicating pixel is, for example, a pixel having a pixel indicating the boundary detected above.

The contour extraction unit 103 defines, for example, a boundary among the boundaries between the first pixel and the second pixel that are continuous with the reference pixel, excluding the boundary that satisfies the condition that the distance between the reference pixels is predetermined. The contour to have may be extracted. The boundary here may be considered as a pixel indicating the boundary. The distance to the boundary is, for example, the distance between the pixel showing the boundary as described above and the reference pixel. Boundary exclusion is, for example, exclusion of information indicating a boundary. Boundary exclusion can be thought of as the exclusion of pixels that indicate the boundary.

The predetermined condition is, for example, a condition for detecting at least one of a boundary where the distance to the reference pixel is long and a boundary near the reference pixel, and is determined according to, for example, a general organ shape or the like. The boundary that satisfies the predetermined condition is, for example, at least one of a boundary that is far enough to satisfy the condition of the distance to the reference pixel and a boundary that is close enough to satisfy the condition of the distance to the reference pixel. The boundaries that satisfy the predetermined conditions are, for example, a boundary in which the distance to the reference pixel is equal to or greater than the predetermined first threshold value and a boundary in which the distance to the reference pixel is equal to or less than the second threshold value (first threshold value> second threshold value). It may be the boundary of either one of them. For example, this threshold value may be set in advance from the maximum value or the minimum value of the size of the portion to be detected in the tomographic image.

Further, the boundary satisfying the predetermined condition is, for example, 1 or 2 in which the distance to the reference pixel becomes an outlier as a result of statistically processing the distances between the plurality of boundaries detected by the above processing and the reference pixel. It may be the above boundary. That is, the contour extraction unit 103 performs statistical processing on each of the boundaries between the first pixel and the second pixel continuous with the reference pixel and the distance between the reference pixel, and by this statistical processing, the reference pixel and the reference pixel are obtained. Contours may be extracted by excluding boundaries where the distance between them is an outlier. For example, a boundary having such an outlier may be considered as a boundary satisfying a predetermined condition.

The statistical processing here may be any statistical processing, and any value may be an outlier. For example, the distance between the boundary and the reference pixel longer than the average value of the distance between the boundary and the reference pixel and the distance between the boundary and the reference pixel shorter than the threshold value may be set as outliers. Further, the outliers may be detected by, for example, a process used for a normal test or the like. For example, the contour extraction unit 103 may detect outliers by performing a Smirnov-Grabs test or the like on the distance between the boundary and the reference pixel.

In the present embodiment, as an example, a case where a boundary in which the distance to the reference pixel is an outlier is detected and excluded by the following statistical processing will be described. However, the process of detecting the boundary that becomes the outlier is not limited to the one using the following formula.

First, the contour extraction unit 103 acquires the distances from the reference pixels for each of the plurality of boundaries detected above, and calculates the value R _max for the following equation (1). The distance between the plurality of boundaries and the reference pixel here may be considered as the distance between the plurality of pixels indicating the boundary and the reference pixel, and this distance may be used. Then, the boundary where the distance to the reference pixel is longer than this value R _max is detected as a pixel whose distance to the reference pixel is an outlier, and the detected boundary is excluded from the boundary detected above. .. Further, the contour extraction unit 103 calculates the value R _min for the following equation (2). Then, a boundary in which the distance to the reference pixel is shorter than this value R _min is also detected as a boundary in which the distance to the reference pixel is an outlier, and the detected boundary is excluded from the boundary detected above. ..

R _max = (R _{3 / 4t −} R _{1 / 2t} ) * 1.5 + R _{1 / 2t}・ ・ ・ Equation (1)

R _min = R _{1 / 2t} − (R _{1 / 2t −} R _{1 / 4t} ) * 1.5 ・ ・ ・ Equation (2)

In addition, in equations (1) and (2), R _{3 / 4t} is the total distance between each of the plurality of boundaries detected above and the reference pixel, counting from the shortest one. The 3/4th distance, R _{1 / 2t} is the distance that is the _{1 /} 2nd length of the whole counting from the shortest, and R _{1 / 4t} is the same. , The length is the distance that is the 1 / 4th length of the whole counting from the shortest one.

Many parts such as organs composed of soft tissue, which is the first tissue in the living body, usually do not have a part having an extremely protruding cross-sectional shape. Therefore, the distance from the reference pixel is increased. The longer boundary is likely to be the boundary between a different site composed of the first tissue and the second tissue. Therefore, as described above, by excluding the boundary where the distance from the reference pixel does not satisfy the predetermined condition, it is possible to prevent the detection of the contours of different parts and perform high-quality contour extraction. It will be possible.

For example, the contour extraction unit 103 excludes a boundary in which the distance between the reference pixels satisfies a predetermined condition from the boundary between the first pixel and the second pixel continuous with the reference pixel as described above. If so, extract contours with boundaries that remain unexcluded.

The contour extraction unit 103 may detect a discontinuous portion in the boundary detected as described above, interpolate the boundary with respect to the detected portion, and extract the contour. The contour extraction unit 103 detects, for example, a discontinuous portion at the boundary between the first pixel and the second pixel that are continuous with the reference pixel, and extracts the contour by interpolating the boundary for the detected portion. You may. Further, the contour extraction unit 103 appropriately interpolates the boundary obtained by excluding the boundary where the distance from the reference pixel meets the predetermined condition, and generates a new boundary between the boundaries. Then, the contour having the boundary obtained above and the boundary obtained by interpolation may be extracted. In the process of interpolating the following boundaries, the process related to the boundary may be considered as the process for the pixel indicating the boundary, and the description of the following boundary may be appropriately read as the pixel indicating the boundary.

The detection of the interpolation point of the boundary and the interpolation of the boundary may be performed in any way. Boundary interpolation is preferably performed so that, for example, the portions where the boundaries are not connected are connected. The portion where the boundary is not connected may be considered as, for example, the portion where the boundary is missing. For example, the contour extraction unit 103 detects a portion in the tomographic image in which the boundaries are not continuous, that is, a discontinuous portion, and for this discontinuous portion, between the boundaries located on both sides of the discontinuous portion. In addition, a new boundary may be set so as to connect discontinuous parts.

For example, the contour extraction unit 103 may set one or more boundaries so as to linearly interpolate between the boundaries. Specifically, interpolation may be performed by setting one or more boundaries on a straight line connecting the boundaries. Setting a new boundary may be considered to set a pixel in contact with the new boundary (for example, a second pixel, etc.) as a pixel of the boundary.

Further, for example, when there is no boundary in one direction centered on the reference pixel, the angle formed with respect to the reference direction is close to the angle formed by this one direction with respect to the reference direction. The above boundary is detected from the boundary detected as described above, and the distance from the reference pixel is a boundary that is a representative value such as an average value or an intermediate value of the distance between the detected one or more boundary and the reference pixel. It may be set in the direction of. Alternatively, the contour extraction unit 103 may detect two boundaries closest to the straight line with a straight line extending in one direction in between, linearly interpolate the two boundaries, and set a new boundary in one direction. ..

Further, in the above, an example of interpolation using linear interpolation is shown, but interpolation other than linear interpolation may be used. For example, when a part where a boundary is missing is detected, a plurality of boundaries close to the missing part are detected on both sides of the missing part, and both sides are used by using these position information and the like. In each of the above, a straight line passing through a plurality of detected boundaries or a line approximating a plurality of boundaries may be acquired, and a new boundary may be set at a position where the acquired lines intersect. In addition, when a part where a boundary is missing is detected in one direction, three or more boundaries close to the straight line indicating this one direction are detected, and a line that approximates the detected boundary is acquired. A new boundary may be set at the intersection of this line and a straight line indicating one direction.

As the process of interpolating the boundary, any process used for normal image processing or the like other than the above may be used.

If it is not necessary to interpolate the boundary, or if there is no boundary excluded by the distance from the reference pixel, the contour may be extracted using the detected boundary without performing the interpolation.

Further, the contour extraction unit 103 may detect a plurality of boundaries having the same direction as the reference pixel as the base point in the detected boundaries as described above, and reduce the detected plurality of boundaries to one boundary. Good. A boundary having the same direction with respect to the reference pixel is a boundary where the straight line connecting the boundary and the reference pixel has the same angle with respect to the reference direction, or a boundary where the straight line connecting the boundary and the reference pixel overlaps. is there. However, even when the difference in angles is equal to or less than a predetermined threshold value, it may be considered that the angles are the same here. Further, even when the angle formed by the straight lines is equal to or less than the threshold value, it may be considered that the straight lines overlap here. The threshold value here is preferably an angle smaller than the angle between the directions for detecting the presence or absence of the boundary when interpolating the boundary described above. In the following processing for reducing boundaries, the processing related to boundaries may be considered as processing for pixels indicating boundaries, and the following description of boundaries may be appropriately read as pixels indicating boundaries.

Normally, the contours of organs and the like composed of soft tissues in a living body often do not have a complicated intricate shape, and in particular, when a pixel corresponding to the soft tissue is used as the first pixel, they overlap in one direction. Since any of the boundaries is considered to be a contour other than the contour originally desired to be detected, it is possible to extract an appropriate contour by reducing the number of boundaries overlapping in one direction to one.

When a plurality of boundaries having the same direction with respect to the reference pixel as the base point are detected, the contour extraction unit 103 may reduce the plurality of boundaries to one boundary. For example, two or more boundaries in which the angle formed by the virtual straight line connecting the reference pixels with respect to the reference direction is close to the angle formed by the virtual straight line connecting the plurality of boundaries with respect to the reference direction. Preferably, two boundaries located across a virtual straight line in which the plurality of boundaries are located are detected, and the distance to the reference pixel is the closest to the average value of the distances between the two or more detected boundaries and the reference pixel. The boundary may be detected from among a plurality of boundaries having the same direction with respect to the reference pixel, and the other boundaries may be deleted. Further, for example, the boundary other than the boundary closest to the reference pixel among the plurality of boundaries may be deleted. Further, a new boundary may be generated instead of the plurality of boundaries at a position intermediate between the plurality of boundaries.

Hereinafter, an example of the process of interpolating the boundary performed by the contour extraction unit 103 and the process of excluding the boundary in the same direction will be described.

The contour extraction unit 103 calculates the distance to the reference pixel and the angle of the boundary for each boundary detected as described above. Each boundary here is preferably a boundary excluding a boundary satisfying a predetermined distance, for example, but may not be excluded. The angle of the boundary is, for example, an angle formed by a straight line connecting the reference pixel and the boundary and a predetermined reference direction. Then, using the angle calculated for each boundary, the contour extraction unit 103 determines whether the boundary exists in each of the directions rotated by a predetermined angle with respect to the above-mentioned reference direction about the reference pixel. Judge whether or not. For example, when it is determined whether or not there is an angle calculated for each boundary that matches one direction obtained by rotating by a predetermined angle, and there is one that matches. , Judge that the boundary exists in this one direction. Further, when a plurality of matching objects exist, the plurality of boundaries are detected as boundaries located in this one direction. If there is no match, it is determined that there is no boundary in this one direction. The angle in one direction obtained by rotating by a predetermined angle is, for example, an angle formed by this one direction with respect to the above-mentioned reference direction. The predetermined angle is usually a constant angle such as 1 ° (degree), but this angle does not have to be constant. For example, the smaller the predetermined angle, the finer the interpolation can be performed, but the processing time becomes longer. The predetermined angle is preferably determined according to the resolution of the tomographic image. For example, when the boundaries are interpolated at a predetermined angle, it is preferable that the angles are such that all the boundaries are connected and a contour is formed. When the reference direction is different between the boundary angle and the angle formed by the direction rotated by a predetermined angle, at least one of the angles may be corrected so that the reference directions match. Further, the direction rotated by a predetermined angle may be considered to include a direction in which the predetermined angle is not rotated from the reference direction, that is, a reference direction.

When the contour extraction unit 103 determines that there is no boundary in one direction rotated by a predetermined angle, the contour extraction unit 103 approaches one of the boundaries whose angle is smaller than the angle in this one direction. One boundary (for example, the boundary with the largest angle) and one boundary close to one direction (for example, the boundary with the smallest angle) among the boundaries having an angle larger than the angle in this one direction. Detect and linearly interpolate between these boundaries to set the boundaries in one direction. For example, a boundary is set at the intersection of a straight line connecting the boundaries and a straight line extending in one direction from the reference pixel. This process may be, for example, linearly interpolating the pixels indicating the boundary to set the pixels indicating a new boundary in one direction. The contour extraction unit 103 detects the two boundaries closest to the straight line by sandwiching a straight line extending in one direction using the position information of the boundary, and linearly interpolates the boundary to the boundary in one direction. A pixel indicating the above may be newly set. Further, although linear interpolation is used here, interpolation other than linear interpolation may be used.

When two or more boundaries are detected in one direction rotated by a predetermined angle, the contour extraction unit 103 has two or more boundaries close to the angle in this one direction from the boundaries other than the detected boundaries. Detect the boundaries of. For example, two or more boundaries whose angles with respect to the reference direction are close to the angle in this one direction are detected. For example, as two or more boundaries, among the boundaries whose angle is smaller than the angle in one direction, the boundary close to one direction (for example, the boundary having the largest angle) and the angle in this one direction Also, among the boundaries with a large angle, the boundary close to one direction (for example, the boundary with the smallest angle) is detected. The average value of the distances between each of the detected boundaries and the reference pixel is calculated, and the distance to the reference pixel among the two or more boundaries located in one of the detected directions is close to the calculated average (for example, the average). By detecting the boundary (closest to the value), deleting the boundary other than the detected boundary, and leaving the detected boundary as the boundary in this one direction, the boundary in this one direction is reduced to one.

When only one boundary is detected in one direction, the contour extraction unit 103 does not perform the above interpolation or reduction processing.

Further, the order of the processing directions of the processing of interpolating the boundary and the processing of reducing the boundary performed in a plurality of directions with the reference pixel as the base point does not matter. For example, processing such as interpolation may be performed for each direction in which a desired angle is rotated. In addition, a plurality of directions obtained by rotating a desired angle are set in advance, and directions are sequentially selected from these plurality of directions in a random order or a predetermined order, and a boundary is formed for the selected direction. You may perform a process of interpolating or a process of reducing.

Then, the contour extraction unit 103 extracts a contour having an interpolated boundary and a boundary that remains unreduced. Preferably, a contour with all the interpolated boundaries and the unreduced remaining boundaries is extracted. For example, it obtains information indicating contours including the interpolated boundaries and the boundaries that remain unreduced.

In addition, as described above, when the process of excluding the boundary according to the distance is performed, and after this process, the boundary remaining by this process is subjected to the above-mentioned interpolation and reduction processing to extract the contour. The extracted contour is used as information for designating an area for specifying the reference pixel as described above, a new reference pixel is detected for the same tomographic image, and the reference pixel is used to construct the extracted contour. For the boundary to be processed, the process of excluding the boundary according to the distance is performed, and the boundary remaining by this process is subjected to the above-mentioned interpolation and reduction processing, and then the process of acquiring the contour is performed once or twice. The above may be repeated. By performing such a process once or more, the accuracy of detecting the contour is improved. However, since it takes time if the number of times the process is repeated is large, it is usually sufficient to extract the contour once and then perform the above process once using the extracted contour.

Further, as the distance between each boundary used for interpolation and reduction and the like and the reference pixel, the distance acquired for each boundary may be used when excluding the boundary according to the distance. In addition, when excluding the boundary according to the distance or before that, the distance between each boundary and the reference pixel and the angle of each boundary are acquired, and the acquired distance is used for excluding the boundary, and the acquired distance is obtained. And angles may be used for boundary interpolation and reduction.

Further, when a plurality of tomographic images taken at different positions in the same living body are stored in the image storage unit 101, the contour extraction unit 103 extracts the contour of one tomographic image and then the one fault. When extracting contours at the same positions for different tomographic images taken at different positions of the same living body as the imaged living body, the contour extraction unit 103 identifies the reference pixels for the contours extracted in one tomographic image. A reference pixel is specified by using it as information indicating an area to be used, and similarly to the above, a first pixel continuous with the specified reference pixel and a second structure indicating a second structure different from the first structure are shown. The boundary with the pixel may be detected in the different tomographic image, and the contour having the detected boundary may be extracted. In this case as well, the process of excluding the boundary, interpolating the boundary, or reducing the boundary may be performed in the same manner as described above depending on the distance between the boundary and the reference pixel. When the contours extracted from one tomographic image are used to extract the contours of tomographic images taken at different positions of the same living body, these tomographic images may be tomographic images taken at the same time. preferable.

When the contour already extracted for one tomographic image is used for contour extraction from the tomographic images acquired at different positions of the same living body, the output unit 104 uses, for example, the contour extracted by the contour extraction unit 103 as a tomographic fault. It is preferable to store the image in a storage unit (not shown) in association with the image identifier or the identifier of the living body to which the tomographic image is to be captured. Further, it is preferable that a plurality of tomographic images taken at different positions in the same living body are stored in the image storage unit 101 in association with an identifier of the living body so that the same living body can be identified. By doing so, the contour extracted in the same tomographic image as the tomographic image for which the contour is to be extracted can be detected by using the biometric identifier or the like associated with each.

For example, when the contour extraction unit 103 starts extracting the contour of one tomographic image, the contour extraction unit 103 immediately acquires the information indicating the extracted contours of different tomographic images taken for the same living body as the one tomographic image. It may be determined whether or not the image has been stored or whether or not it is stored in a storage unit (not shown), and if it is stored, information indicating this contour may be read from the storage unit to perform contour extraction. Whether the tomographic image whose contour was extracted immediately before is a tomographic image to be newly contoured (for example, a tomographic image designated as a contour extraction target) and a tomographic image taken from the same living body. Whether or not it may be determined in any way. For example, when the tomographic image whose contour was extracted immediately before and the tomographic image to be newly contoured are stored in the same folder, or when the file name or the like has the same identifier of the living body, or each file. When the names and the like are stored in the same list, it may be determined that they are tomographic images acquired for the same living body.

The user may specify whether or not to use the contour already extracted for one tomographic image for contour extraction from the tomographic image acquired for different positions of the same living body. In this case, when the operation receiving unit 102 receives an operation for specifying to use the contour acquired in the past when extracting the contour of the tomographic image, the contour extracting unit 103 is designated by this operation. The information indicating the contour may be read out from a storage unit (not shown) or the like, and the reference pixel may be specified in the tomographic image by using the information indicating the contour.

The output unit 104 outputs the contour extracted by the contour extraction unit 103. The output related to the contour may be to output information indicating the contour, and an image in which the contour is drawn by a line or the like, an image showing an area surrounded by the contour, or the like is combined with a tomographic image and combined. It may be to output the tomographic image. The output related to the contour is not limited to that described here.

The output unit 104 may appropriately output an output other than the output related to the contour. As described above, the output unit 104 monitors (as described above) a tomographic image used by the operation receiving unit 102 to receive a specific operation, an image showing a region designated by the specific operation on the tomographic image, and the like. (Not shown) or the like. The output unit 104 appropriately outputs, for example, according to the operation received by the operation reception unit 102.

The output here means display on a monitor, projection using a projector, printing to a printer, transmission to an external device, storage on a recording medium, and processing results to other processing devices or programs. It is a concept that includes delivery. The output unit 104 may or may not include an output device such as a monitor. The output unit 104 can be realized by the driver software of the output device, the driver software of the output device, the output device, or the like.

Next, an example of the operation of the image processing device 1 will be described with reference to the flowchart of FIG.

(Step S101) It is determined whether or not the operation reception unit 102 has accepted the operation for designating the tomographic image stored in the image storage unit 101. This designation is, for example, the designation of a tomographic image for which the contour is to be acquired. If the specified operation is accepted, the process proceeds to step 102, and if not, the process returns to step S101.

(Step S102) The output unit 102 reads out the tomographic image specified by the operation received in step S101 from the image storage unit 101 and displays it.

(Step S103) The operation reception unit 102 determines whether or not a specific operation has been accepted for the tomographic image displayed in step S102. The specific operation is, for example, an operation of designating a region having the first pixel near the center. If accepted, the process proceeds to step S104, and if not accepted, the process returns to step S103.

(Step S104) The contour extraction unit 103 specifies a reference pixel according to the specific operation received in step S103. For example, the contour extraction unit 103 sets the pixel at the center of the region designated by the operation of designating the region, which is a specific operation, as the reference pixel.

(Step S105) The contour extraction unit 103 substitutes 1 for the counter m.

(Step S106) The contour extraction unit 103 detects the boundary between the first pixel and the second pixel continuous with the reference pixel by using the value (for example, CT value) corresponding to the pixel of the tomographic image. The detected contour information is stored in, for example, a storage medium (not shown). The accumulation here may be temporary memory.

(Step S107) For each boundary detected in step S106, the contour extraction unit 103 calculates and acquires the distance from the reference pixel and the angle with respect to the reference direction in the direction from the reference pixel to each boundary.

(Step S108) The contour extraction unit 103 performs statistical processing using the distance acquired for each boundary in step S107, and excludes the boundary whose distance is an outlier.

(Step S109) The contour extraction unit 103 substitutes 1 for the counter n.

(Step S110) The contour extraction unit 103 is a direction with the reference pixel as a base point, and is a value indicating n × θ (θ is a predetermined angle larger than 0) with respect to a predetermined reference direction. ), It is determined whether or not there is a boundary that remains undeleted in step S107. If there is, the process proceeds to step S114, and if not, the process proceeds to step S112.

(Step S111) The contour extraction unit 103 interpolates the boundary in the direction shown in step S110. For example, the contour extraction unit 103 detects boundaries located close to the straight line on both sides of a virtual straight line extending in a direction forming an angle of n × θ with the reference pixel as the base point, and linearly interpolates the detected boundaries. Then, a new boundary is set in the direction forming an angle of n × θ with the reference pixel as the base point.

(Step S112) The contour extraction unit 103 increments the value of the counter n by 1.

(Step S113) The contour extraction unit 103 determines whether or not n × θ is 360 ° or more. If it is 360 ° or more, the process proceeds to step S114, and if it is less than 360 °, the process proceeds to step S110.

(Step S114) The contour extraction unit 103 determines whether or not the boundary detected in step S110 is 2 or more. If it is two or more, the process proceeds to step S115, and if it is one, the process proceeds to step S112.

(Step S115) The contour extraction unit 103 performs a process of reducing the boundary detected in step S110 to one. For example, the contour extraction unit 103 detects boundaries located close to the straight line on both sides of a virtual straight line extending in a direction forming an angle of n × θ with the reference pixel as the base point, and the detected boundary and the reference pixel are used. The average value of the distances of the above is calculated, and the boundary other than the boundary whose distance to the reference pixel is closest to the calculated average value from the plurality of boundaries detected in step S110 is deleted. Then, the process returns to step S112.

(Step S116) The contour extraction unit 103 extracts a contour having a boundary. For example, the contour extraction unit 103 extracts a contour that is a boundary that remains without being excluded in step S108 and has a boundary that remains without being deleted in step S115 and a boundary that is interpolated in step S111. Specifically, information indicating the outline is acquired.

(Step S117) The contour extraction unit 103 determines whether or not the value of the counter m is larger than p (p is a predetermined integer of 1 or more). If it is large, the process proceeds to step S118, and if it is not large, the process proceeds to step S123.

(Step S118) The output unit 104 outputs the contour extracted in step S116. For example, a tomographic image in which an image showing an outline is superimposed on the tomographic image displayed in step S102 is displayed on a monitor (not shown) or the like.

(Step S119) The operation reception unit 102 determines whether or not an operation for designating another tomographic image has been accepted. If accepted, the process proceeds to step S120, and if not accepted, the process returns to step S119.

(Step S120) The output unit 104 reads the tomographic image specified by the operation received in step S119 from the image storage unit 101 and displays it.

(Step S121) The contour extraction unit 103 determines whether or not the tomographic image specified by the operation received in step S119 is a tomographic image acquired at a different position of the same living body as the tomographic image whose contour was extracted immediately before. To do. For example, the contour extraction unit 103 uses the identifier of the living body associated with the tomographic image, the identifier of the living body accumulated in association with the contour information, and the like to determine whether or not the tomographic image is the same living body. to decide. If it is a tomographic image of the same living body, the process proceeds to step S122, and if it is not the same living body, the process returns to step S103.

(Step S122) The contour extraction unit 103 reads out information indicating the contour extracted from the tomographic image of the same living body (for example, contour information extracted in the immediately preceding step S116) from a storage unit (not shown) or the like, and extracts the extracted contour. The reference pixel is specified in the tomographic image read out and displayed in step S120.

(Step S123) The contour extraction unit 103 increments the value of the counter m by 1.

(Step S124) The contour extraction unit 103 specifies a reference pixel for the tomographic image specified by the operation received in step S101 by using the contour extracted in the immediately preceding step S116. Then, the process returns to step S106. In the processing after step S106 after this, the processing is performed using the newly specified reference pixel.

In the flowchart of FIG. 2, the process ends when the power is turned off or an interrupt for the end of the process occurs.

Hereinafter, the specific operation of the image processing device 1 according to the present embodiment will be described with reference to an example. Here, the tomographic image is an X-ray CT image taken in the body of the human body, the first pixel is the pixel corresponding to the soft tissue which is the first tissue, and the second pixel is the second. The case where the pixel corresponds to the adipose tissue which is a tissue will be described.

3 (a) to 3 (d) are diagrams showing tomographic images to be contour extracted. This tomographic image is a tomographic image of the abdominal cavity of the subject in the case of ruptured aortic aneurysm, and shows a view seen from the foot side of the subject. 3 (a) to 3 (d) are tomographic images of the same human body, and FIGS. 3 (a) to 3 (c) are tomographic images taken at the same position in the cranio-caudal direction. 3 (d) is a tomographic image taken at a position different from that of FIGS. 3 (a) to 3 (c). In FIG. 3, the white portion 35 shows a metal archfect (disorder image) due to a metal stent placed in the descending aorta. Further, the white part along the wall of the aorta on the dorsal side (lower part of the figure) of the part 35 indicates a calcified part as a result of the atherosclerotic change of the arterial wall, and further, the white part on the dorsal side thereof. The part shows the spine (lumbar vertebral body and vertebral arch). Further, FIG. 3 is an image in which the corresponding CT value becomes higher as the pixel density becomes lighter. In FIG. 3, the light gray region 37 is a soft tissue region and the dark gray region 38 is an adipose tissue. Area of.

4 (a) to 4 (c) are schematic views of tomographic images for explaining the process of extracting the contour, and FIGS. 4 (d) and 4 (e) are the processes of extracting the contour. It is a schematic diagram which shows a part of the tomographic image for demonstrating. In FIGS. 4A to 4C, it is assumed that the pixel represented by the diagonal line is the first pixel 41 and the white pixel is the second pixel 42. Further, in FIGS. 4 (d) and 4 (e), the pixels 60a to 60f shown by diagonal lines are pixels indicating a boundary, and the pixel 61 surrounded by the dotted line is an interpolated pixel, and the pixel 50. Is a reference pixel. In FIGS. 4 (d) and 4 (e), it is assumed that the white pixel is an arbitrary pixel. It is assumed that a CT value is associated with each pixel. Actually, the first pixel and the second pixel have different densities depending on the CT value, but here, for the sake of explanation, the first pixel and the second pixel are divided into two. It is represented by a value. Further, each image in FIG. 4 is for illustration purposes only, and is not an actual tomographic image, and the resolution and the like do not always match the actual ones and the like.

First, the user specifies and displays a tomographic image as shown in FIG. 4A, and then uses a mouse or the like to specify an area including the first pixel 41 as shown by the dotted line 40 in the vicinity of the center. Assuming that the operation is performed, the operation reception unit 102 accepts an operation for designating this area. Since the area designation in this case is an area designation for specifying the reference pixel, the contour does not need to accurately specify the extraction area, and may be a rough designation.

As shown in FIG. 4B, the contour extraction unit 103 specifies the pixel located at the center of the area indicated by the dotted line 40 indicated by this operation as the reference pixel 50 in response to the operation received by the operation reception unit 102. To do. Here, as the pixel located at the center of the region, the pixel located at the center of gravity of the region is detected. Then, the position information of the detected pixel of the center of gravity is acquired as the position information of the reference pixel 50.

The contour extraction unit 103 detects the first pixel 41 continuous with the acquired reference pixel 50 in all directions centering on the reference pixel 50 by using the CT value associated with the pixel. As shown in 4 (c), all the boundaries 43 between the first pixel 41 continuous with the reference pixel 50 and the second pixel 42 adjacent thereto are detected. The boundary 43 is shown by a dotted line in FIG. 4 (c). If the CT value corresponding to one pixel in the tomographic image is a value between 1 and 1499, this one pixel is determined to be the first pixel 41, and the CT value corresponding to one pixel is If the value is between −200 and 0, this one pixel is determined to be the second pixel 42. Further, here, the boundary between the first pixel 41 and the pixel corresponding to the metal is not detected. Specifically, a pixel showing a CT value of metal (that is, a pixel having a CT value of 1500 or more) and a predetermined number of pixels around it (for example, 10 pixels) are determined as the first pixel. Here, it is assumed that the information indicating the detected boundary 43 is the position information (for example, coordinates) of the pixels adjacent to the outside of the boundary 43. Here, for example, a pixel adjacent to the outside of the boundary is a pixel indicating the boundary.

Next, the contour extraction unit 103 directs the distance to the reference pixel 50 and the straight line connecting the reference pixel 50 and each pixel toward the upper side of the tomographic image with the reference pixel 50 as the base point for each pixel indicating the detected boundary 43. Calculate the angle formed with respect to the direction of vertical extension.

The contour extraction unit 103 calculates a range of distances that are outliers from the above equations (1) and (2) using the distances calculated for each pixel indicating the boundary 43, and the calculated distances are outliers. The pixel of the boundary 43 that becomes is excluded. For example, a pixel whose distance to the reference pixel 50 is larger than that of a pixel showing another boundary, such as pixel 44 in FIG. 4C, has a distance to the reference pixel 50 within the range of the outlier value. Since there is a high possibility, by excluding the pixels that have outliers, the pixels that show the boundary where the distance to the reference pixel 50 changes sharply with respect to the pixels that show other boundaries will be the target of the contour. Exclude from the pixels showing the boundary, and acquire the most accurate contour for extracting the contour of living organs, etc. as the contour of the part composed of soft tissue with few sharply protruding parts and sharp parts. It becomes possible.

Next, the contour extraction unit 103 performs outliers in the above processing in each of the directions in which the angles formed with respect to the direction extending vertically toward the upper side of the tomographic image with the reference pixel 50 as the base point are increased by predetermined angles. It is determined whether or not the pixel indicating the boundary excluding is located. For example, when the angle calculated above for the pixel indicating one boundary matches the angle in the direction obtained by increasing the predetermined angle, the contour extraction unit 103 sets this one boundary as a predetermined angle. It is detected as a pixel existing in the direction obtained by increasing the angle. As a result, it is determined whether or not the pixel indicating the boundary is located in the direction in which the pixel is increased by a predetermined angle. The predetermined angle is 1 ° here. This predetermined angle can be increased, for example, as the size of the contour detection target becomes smaller. For example, when the direction extending vertically toward the upper side of the tomographic image from the reference pixel 50 as the base point is set to 0 °, the contour extraction unit 103 first determines whether or not there is a pixel indicating a boundary in the direction of 0 °. If there is only one pixel indicating the boundary, the pixel indicating the boundary is not interpolated or reduced in this direction, and if there is a pixel indicating two or more boundaries, one pixel is used. If there is no pixel indicating the boundary, the pixel indicating the boundary is set by interpolation. After that, the same processing is performed for each direction in which the angle is increased by 1 °, such as the direction of 1 ° and the direction of 2 °. This process is performed until just before the angle reaches 360 °.

For example, as shown in FIG. 4D, in the direction rotated by 90 ° from the reference pixel 50, that is, in the left direction indicated by the arrow in the figure, the contour extraction unit 103 has the pixel 60b and the pixel 60c indicating the boundary. Is detected, the contour extraction unit 103 detects the pixels 60a and the pixels 60d showing the contours located in the directions close to this direction by using the angles and the like calculated for each pixel showing the contours above. The average value of the distances between the pixels 60a and 60d and the reference pixel 50 is calculated, and the distance between the pixel 60b and the pixel 60c indicating the boundary detected above and the reference pixel 50 is the average value. Pixels 60c, which are the remaining pixels, are deleted, leaving the closest pixels 60c. This reduces the number of boundaries located in this direction to one.

Further, for example, as shown in FIG. 4E, the contour extraction unit 103 detects the pixel indicating the boundary in the direction rotated by 90 ° from the reference pixel 50, that is, in the left direction indicated by the arrow in the figure. If not, the contour extraction unit 103 uses the pixels 60e and the pixels 60f indicating the contours located in the directions close to this direction with this direction in between, and the angles calculated for each pixel showing the contours above. The pixel 60e and the pixel 60f are linearly interpolated to set the pixel 61 indicating the boundary indicated by the dotted line in the direction rotated by 90 ° from the reference pixel 50. As a result, the boundaries are interpolated in this direction.

As described above, the contour extraction unit 103 extracts the contour having the pixels indicating the boundary obtained after performing the processing of interpolating the pixels indicating the boundary and the processing of reducing the number of pixels.

Further, the contour extraction unit 103 uses the region indicated by the extracted contour in place of the region indicated by the dotted line 40 specified by the above specific operation, sets the center of this region as the reference pixel, and sets the same fault. The contour of the image is extracted by performing the same processing as the subsequent processing for setting the reference pixel. The contour extraction unit 103 acquires information indicating the contour.

Then, the output unit 104 uses the information indicating the contour acquired by the contour extraction unit 103 to generate a tomographic image in which the contour is drawn by a line on the tomographic image from which the contour is extracted, and is monitored (shown). Display in). Further, the output unit 104 stores the information indicating the extracted contour in a storage unit or the like (not shown).

Here, it is assumed that the tomographic images taken at different positions of the same living body are stored in the same folder in the image storage unit 101, and the same folder as the folder in which the tomographic images whose contours are extracted above are stored. , It is assumed that a tomographic image taken at a different position for the same living body as the above tomographic image is stored. Then, as described above, the user performs an operation of extracting a contour from one tomographic image and then designating a tomographic image to newly extract a contour in the same folder as the folder in which this one tomographic image is stored. Suppose you went.

When the operation reception unit 102 receives an operation for designating this new tomographic image, the output unit 104 displays the designated tomographic image on a monitor (not shown), and the contour extraction unit 103 displays the new tomographic image. It is determined that the image is a tomographic image read from the same folder as the tomographic image whose contour was extracted immediately before, and information indicating the contour extracted immediately before is read from a storage unit (not shown) to show the read contour. Using the information, the central pixel of the region indicated by this contour of the new tomographic image is set as the reference pixel. Then, the same processing as above is performed to extract the contour of the new tomographic image, and the output unit 104 superimposes the image drawn by the line on the new tomographic image and displays it on the monitor (not shown). To do. In addition, information indicating this contour is stored in a storage unit (not shown).

Here, a case where the above-mentioned contour extraction process is performed on the tomographic image shown in FIG. 3A will be described below.

From FIG. 3A, it is observed that the adipose tissue 38 is present around the soft tissue 37 so as to surround it. In FIG. 3A, blood leaks from the ruptured aorta and a hematoma is formed in the right abdominal cavity. In such a case, the contour of the aorta in the tomographic image is partially discontinuous.

It is assumed that a region as shown by line 31 in FIG. 3B is designated for this tomographic image by a specific operation received from the user by the operation reception unit 102. This region is a roughly designated region of the aorta. Upon receiving such a specific operation, the contour extraction unit 103 performs a process of extracting the contour as described above for this tomographic image. Then, the tomographic image in which the contour extracted by the contour extraction unit 103 is drawn by the output unit 104 with the line 32 and displayed is as shown in FIG. 3C.

The contour shown in FIG. 3 (c) was used as information of the region for identifying the reference pixel, and the same subject as the tomographic image shown in FIG. 3 (a) approached in the head-to-caud direction. When the contour of the tomographic image taken at the position is automatically extracted, the tomographic image in which the extracted contour is drawn by the line 33 is as shown in FIG. 3 (d).

As described above, according to the present embodiment, the boundary between the first pixel and the second pixel continuous with the reference pixel is detected and the contour having the boundary is extracted, so that it is easy from the tomographic image. It is possible to extract the outline of a desired region with high accuracy. For example, unlike the case where the contour is extracted by the difference in the values corresponding to the pixels between adjacent pixels (for example, the contrast difference such as the density difference of the pixels), it is composed of the first pixel corresponding to the desired structure. The area can be extracted accurately. Further, for example, the user only needs to perform a specific operation for specifying a reference pixel on the tomographic image, so that the operation is easy. Further, for example, by extracting the contour from the reference pixel, it is expected that highly reproducible evaluation that does not depend on the subjectivity of an image interpreting doctor or the like becomes possible.

In the above embodiment, the case where the tomographic image is an X-ray CT image has been described, but the tomographic image is not limited to the X-ray CT image. The tomographic image is, for example, an image in which pixels corresponding to a desired tissue or organ in a living body can be distinguished by a value corresponding to a pixel such as a CT value, for example, MRI (magnetic resonance imaging), PET. It may be an image acquired by (positron emission tomography), SPECT (single photon emission computed tomography), or the like. When the tomographic image is an image other than the X-ray CT image, for example, the description corresponding to the CT value of the above embodiment appropriately obtains the magnetic field strength for the position corresponding to each pixel when the tomographic image is taken. It may be read as the explanation about the detected value, the signal value, and the like. Even when such a tomographic image is used, the first pixel and the second pixel are based on the values corresponding to the respective pixels, specifically, only the values corresponding to the respective pixels. It is preferable to use identifiable pixels. Further, the tomographic image is preferably an image in which the first pixel and the second pixel can be distinguished.

(Embodiment 2)
FIG. 7 is a block diagram of the image processing device 2 of the present embodiment.

The image processing device 2 includes an image storage unit 101, an area designation reception unit 211, an acquisition unit 212, a display unit 213, an exclusion designation reception unit 214, a three-dimensional acquisition unit 215, an operation reception unit 202, a contour extraction unit 203, and an output unit 204. I have.

Hereinafter, in the present embodiment, the region extracted by the image processing apparatus 2 in the biological image is the region of the hematoma in the living body, and the first pixel is the pixel corresponding to the blood which is the first tissue. , The case where the tomographic image is an X-ray CT image will be described as an example. A hematoma is, for example, a state in which blood is accumulated in a living body due to bleeding to form a mass, or a portion in which the state has become.

Since the image storage unit 101 is the same as the image storage unit 101 of the first embodiment, the description thereof will be omitted here. In the following, a case where the tomographic image is an X-ray CT image of a living body will be described as an example. Further, the tomographic image stored in the image storage unit 101 is a tomographic image obtained by taking the living body in the supine position, and in this tomographic image, the lower part (that is, the dorsal side) of the living body is located below. It is assumed that it is a tomographic image. However, the tomographic image stored in the image storage unit 101 may be a tomographic image other than such a tomographic image.

In this embodiment, it is assumed that the top and bottom of the tomographic image correspond to the top and bottom of the living body at the time of photographing. Specifically, the side of the tomographic image that shows the upper part of the living body at the time of shooting is considered to be the upper side of the tomographic image, and the side that shows the lower part of the living body at the time of shooting is the tomographic image. Think of it as the bottom of the image. For example, in a tomographic image of a living body in the supine position, the side where the ventral side is shown is the upper side, and the side where the dorsal side is shown is the lower side.

The area designation reception unit 211 accepts an operation of designating the first pixel area for one or more tomographic images stored in the image storage unit 101. The first pixel region is a region composed of one or more first pixels in the tomographic image. The first pixel region is preferably an region composed of a plurality of first pixels. The first pixel region is preferably an region composed of only a plurality of consecutive first pixels. The first pixel region is more preferably a region within a blood vessel such as a large blood vessel. The area designation reception unit 211 accepts, for example, an operation of designating a first pixel area for a tomographic image displayed on a monitor (not shown) or the like by a display unit 213 or the like described later. As an operation for designating the first pixel area accepted by the area designation reception unit 211, for example, the same operation as the specific operation for designating the area accepted by the operation reception unit 102 can be used except that the designated area is different. Is. However, the operation of designating the first pixel area is not limited to these operations. For example, the operation of designating the first pixel area composed of one first pixel may be, for example, an operation of designating one first pixel by a mouse click, a tap, or the like. It may be an operation of inputting the coordinates of one pixel or the like. The area designation reception unit 211 can be realized by, for example, the same configuration as the operation reception unit 102.

The acquisition unit 212 uses values corresponding to one or a plurality of first pixels in the area designated by the operation of designating the first pixel area received by the area designation reception unit 211 in the tomographic image. Acquires the range of values corresponding to the first pixel. The tomographic image here is, for example, a tomographic image that has received an operation of designating the first pixel region. For example, the acquisition unit 212 acquires representative values of values corresponding to one or more first pixels in the area designated by the operation of designating the first pixel area, and uses the acquired representative values. , Acquired as the lower limit of the range of values corresponding to the first pixel. The acquisition unit 212 preferably acquires representative values of values corresponding to each of the three or more first pixels in the designated region.

As described above, the case where the value corresponding to the first pixel is the CT value corresponding to the first pixel will be described. The range corresponding to the value of the first pixel is, for example, the range of the value corresponding to the first pixel used when the display unit 213 described later detects the first pixel. It is a range of CT values corresponding to the first pixel. However, the range of values corresponding to the first pixel is particularly preferably the range of CT values corresponding to extravascular blood such as blood leaked into the living body.

The representative value is, for example, preferably an average value, a median value, or an intermediate value corresponding to a plurality of, preferably three or more first pixels, but may be a maximum value or a minimum value. The acquisition unit 212 does not care how to determine a plurality of first pixels in the region used for acquiring the representative value. For example, a plurality of pixels may be randomly determined from within the region, or a plurality of pixels located at the center of the region may be determined as pixels used for acquiring a representative value. Further, a plurality of pixels may be determined according to a predetermined rule or the like, for example, a pair of a central pixel and a pixel at a position separated from the pixel by a predetermined distance to the left and right. When the operation of designating the first pixel area is the operation of designating the first pixel area composed of one first pixel, the acquisition unit 212 may, for example, perform one of the operations designated by this operation. The value corresponding to one pixel may be acquired as the representative value as described above. In the following, a case where the operation of designating the first pixel area is an operation of designating the first pixel area composed of a plurality of first pixels will be mainly described.

For example, the acquisition unit 212 may use the acquired representative value as it is as the lower limit value of the range of values corresponding to the first pixel, and multiplys the acquired representative value by a predetermined value. , May be used as the lower limit. For example, when the operation of designating the first pixel region is an operation of designating the pixel region corresponding to blood in a blood vessel such as a large blood vessel in a tomographic image, a predetermined value is set as the acquired representative value. The multiplied value is preferably used as the lower limit of the range of values (eg, CT values) corresponding to the first pixel used to detect extravascular blood such as hematoma. This is because the density of blood rapidly increases when it comes out of the blood vessel, and the CT value rises. The value corresponding to the pixel is the CT value, the first tissue is blood (that is, the first pixel is the pixel corresponding to blood), and the operation of specifying the first pixel region is in the blood vessel. In the case of an operation of designating a pixel region corresponding to blood, the predetermined value to be multiplied by the representative value is preferably 1 or more, and 1.2 or more and 1.6 or less. It is preferably present, and more preferably 1.4. For example, it is preferable to use a value obtained by multiplying the average value, which is a representative value, by 1.4 as the lower limit value. The acquisition unit 212 may use a value obtained by adding a predetermined value to the acquired representative value as the lower limit value.

When the value corresponding to the pixel is the CT value, the first tissue is blood, and the representative value is the average value, and the representative value acquired by the acquisition unit 212 is less than 38 HU, the representative value is Instead, 38HU is preferably used to set the lower limit of the range of values corresponding to the first pixel. For example, 38HU may be used as the lower limit value as it is, or a value obtained by multiplying 38HU by a predetermined value may be used as the lower limit value. 38HU is a general average of CT values for blood flowing through large blood vessels. The reason for using 38HU instead of the representative value as the value used to set the lower limit is that when the average HU of blood is less than 38, the average CT value of blood and the CT value of hematoma deviate from each other. This is to avoid unexpected results. The case where the average HU of blood is less than 38 is, for example, data with a large amount of anemia.

The upper limit of the range of values corresponding to the first pixel is preferably a value sufficiently higher than the lower limit value, and is a value sufficiently higher than the upper limit value of the value corresponding to the normal first pixel. Is more preferable. The upper limit value may be a predetermined value or a value determined according to the lower limit value. However, this upper limit value is preferably a value sufficiently lower than the value of the pixel corresponding to the tissue other than the first structure. For example, this upper limit is preferably 100 HU or less, and more preferably 90 HU or less. The upper limit value described here is an example, and is appropriately changed according to the conditions of the camera and the equipment used for taking a tomographic image such as tube pressure, the position to be taken, the living body to be photographed, and the like. You may. Similarly, the above lower limit value of 38HU may be appropriately changed according to the conditions of the device used for photographing the tomographic image, the position to be photographed, the living body to be imaged, and the like.

The acquisition unit 212 corresponds to one or more first pixels in the first pixel region as a range of values corresponding to the first pixel used when the contour extraction unit 203 described later extracts the contour. The first range, which is the range of values corresponding to the first pixel having a value larger than the representative value of the value to be used as the lower limit value, and the value corresponding to one or more first pixels in the first pixel region, respectively. The second range, which is a range of values corresponding to the first pixel having a value equal to or more than the representative value of the above-mentioned first range and smaller than the minimum value of the first range as the lower limit value. You may try to get it.

The display unit 213 displays the first pixel in the tomographic image in a manner identifiable with respect to the other pixels by using the range of the values of the first pixel acquired by the acquisition unit 212. The tomographic image here is, for example, a tomographic image that has received an operation of designating the first pixel region. For example, in the display unit 213, in the tomographic image, the value corresponding to the pixel is within the range of the value corresponding to the first pixel acquired by the acquisition unit 212, that is, the first pixel acquired by the acquisition unit 212. A pixel between the lower limit value and the upper limit value of the value corresponding to the pixel of is detected as the first pixel, and the detected pixel is displayed in an identifiable manner with respect to other pixels in the tomographic image. .. The display unit 213 has, for example, a first lower limit value having a value larger than a representative value of one or more, preferably a plurality of first pixels, in the first pixel region acquired by the acquisition unit 212. It is preferable to display the first pixel in the tomographic image in a manner that can be distinguished from other pixels by using the range of values corresponding to the pixels. The range of values corresponding to the first pixel here may be the first range described above. The first pixel in the tomographic image is preferably all the first pixels using the range of values of the first pixel acquired by the acquisition unit 212, but some may be appropriately excluded. good. Displaying in an identifiable manner means displaying a tomographic image in which the detected first pixel is processed so that it can be visually identified with respect to other pixels. For example, displaying in an identifiable manner may be, for example, overlaying a predetermined color on the detected first pixel in the tomographic image, and the detected first pixel may be displayed. It may be displayed by coloring it with a predetermined color, and the outline of one or more regions composed of the detected first pixels is surrounded by a predetermined color line, a dotted line, or the like. It may be to display.

The display unit 213 can switch between displaying a tomographic image in which the first pixel in the tomographic image is displayed in an identifiable manner with respect to other pixels and a tomographic image not being displayed in the identifiable manner. It may be possible to display them side by side. The tomographic image that is not displayed in an identifiable manner is, for example, to display the tomographic image stored in the image storage unit 101 as it is.

In the display unit 213, the corresponding CT value falls within the standard value range of the first tissue in the tomographic image before the area designation reception unit 211 accepts the operation of designating the first pixel area. By detecting a pixel and displaying the detected pixel in a mode different from that of other pixels, visual support for accepting an operation of designating a first pixel region may be provided.

The display unit 213 uses, for example, a monitor (not shown) to perform the above-mentioned display. It should be noted that the display unit 213 may also consider that the display unit 213 transmits image data for display to an external device having a monitor or the like and causes the device to display the image data. The display unit 213 may or may not include a display device such as a monitor. The display unit 213 has a processor such as an MPU or GPU, a memory, or the like for generating image data for displaying the first pixel in the tomographic image in an identifiable manner with respect to other pixels. Is also good. These processing procedures are usually implemented in software. The display unit 213 is realized by the driver software of the display device, the driver software of the display device, the display device, or the like.

The exclusion designation reception unit 214 accepts the exclusion designation operation. The exclusion specification operation is an operation of specifying the outline of the exclusion area. The exclusion area is an area excluded from the contour extracted by the contour extraction unit 203. The area designation reception unit 211 receives, for example, an exclusion designation operation for a tomographic image displayed on a monitor (not shown) or the like by a display unit 213 or the like described later. The process by which the contour extraction unit 203 extracts the contour in the tomographic image will be described later. The exclusion region is, for example, a region in the tomographic image composed of pixels corresponding to one or more specific tissues other than the first tissue, or a specific target area. For example, when the first tissue is blood, the specific one or more tissues are the tissues constituting the specific one or more organs such as the liver. Further, the specific target is, for example, a substance other than those composed of the first tissue such as hematoma, such as the liver and the pancreas.

The exclusion specification operation may be any operation as long as the contour of the exclusion area can be specified. For example, the contour to be accepted by the operation reception unit 102 is specified except that the designated area is different. The same operation as the specific operation can be used. For example, the exclusion designation operation may be an operation of tracing the contour of the outside area with a mouse, a finger, or the like. In addition, since most of the liver usually has a substantially triangular shape in the tomographic image perpendicular to the longitudinal direction of the living body, when the region of the image corresponding to the liver in the tomographic image is excluded, the tomographic image In order to simplify the operation, it is preferable that the operation specified by clicking the three vertices of the substantially triangle of the image corresponding to the liver with the mouse or tapping on the touch panel is an exclusion specification operation. By increasing the number of vertices of the outline of the exclusion area specified by the exclusion specification operation to more than 3, it is possible to specify a more complicated exclusion area or more accurately specify the exclusion area.

When a plurality of tomographic images taken at three or more different positions in the same living body are stored in the image storage unit 101, the same exclusion is applied to two or more tomographic images among the plurality of tomographic images. An exclusion specification operation that specifies an exclusion area corresponding to the target may be accepted. In the operation of designating the exclusion area in the plurality of tomographic images, the same exclusion operation as described above may be accepted for each tomographic image. For example, this exclusion operation is an operation of designating an exclusion region corresponding to the liver to be excluded, and is an operation of designating three vertices of the liver having a substantially triangular shape in each of two or more tomographic images. There may be.

Information indicating the exclusion designation area received by the exclusion designation operation is stored in a storage unit (not shown) by, for example, the exclusion designation reception unit 214, and is appropriately read out. The information indicating the exclusion designation area is stored in a storage unit (not shown) in association with the tomographic image that has received the exclusion designation operation, for example. The exclusion designation reception unit 214 can be realized by, for example, the same configuration as the operation reception unit 102.

The operation reception unit 202 receives a specific operation for specifying a reference reference pixel among the first pixels indicating the first structure included in the tomographic image. Then, the operation reception unit 202 acquires information indicating the reference pixel specified by this specific operation, for example, information such as the coordinates of the reference pixel. The specific operation received by the operation reception unit 202 is, for example, an operation of designating one of the first pixels in the tomographic image displayed by the display unit 213. The operation of designating one of the first pixels is, for example, an operation of clicking one of the first pixels in the tomographic image with a mouse, an operation of clicking with a stylus pen, or a touch panel. It is an operation such as tapping using. Further, the operation of designating one of the first pixels may be, for example, an operation of inputting the coordinates of one of the first pixels in the tomographic image. The tomographic image displayed by the display unit 213 is, for example, a tomographic image in which the first pixel is displayed in a manner identifiable with respect to other pixels. For example, the operation of designating one of the first pixels is one of the first pixels identifiablely displayed in the tomographic image in which the first pixel is displayed in an identifiable manner with respect to the other pixels. It is an operation to specify. The first pixel specified here is, for example, the first pixel in the first pixel group for which contours are to be extracted, and in the present embodiment, one of the pixels in the region considered to be a hematoma region. Is.

In addition, instead of the operation of designating one of the first pixels in the tomographic image displayed by the display unit 213, the operation reception unit 202 uses, for example, the first pixel displayed by the display unit 213 as another pixel. On the other hand, in the tomographic image displayed in an identifiable manner, the same operation as the specific operation received by the operation reception unit 102 of the first embodiment may be accepted. For example, the operation reception unit 202 may accept an operation for designating a region composed of a plurality of first pixels in the tomographic image displayed by the display unit 213.

Since the operation reception unit 202 is the same as the operation reception unit 102 except for the above points, detailed description thereof will be omitted here.

The contour extraction unit 203 extracts the contour related to the first pixel continuous with the reference pixel specified by the specific operation received by the operation reception unit 202. The contour associated with the first pixel is, for example, a contour composed of pixels having a value having a predetermined relationship with respect to the value corresponding to the first pixel. Here, the contour extraction unit 203 is mainly set to the contour of the region composed of the first pixel continuous with the reference pixel specified by the specific operation received by the operation reception unit 202, and around the contour. The first pixel detected in an expansion region in which the amount of expansion in the upward direction is larger than the amount of expansion in the downward direction and the amount of expansion in the lateral direction decreases from the upward direction to the downward direction. The case where the contour of the region composed of is extracted as the contour related to the first pixel continuous with the reference pixel will be described. Further, a case where the first pixel continuous with the reference pixel here is a pixel indicating extravascular blood such as blood in the hematoma region will be described.

First, the contour extraction unit 203 specifies the reference pixel according to the specific operation received by the operation reception unit 202. For example, when the specific operation is an operation for designating one pixel, this pixel is specified as a reference pixel. Further, when the specific operation is the same operation as the specific operation of the first embodiment, for example, the same process as the first embodiment is performed to specify the reference pixel corresponding to the specific operation.

Next, the contour extraction unit 203 extracts the contour of the region composed of the first pixel continuous with the reference pixel specified by the specific operation received by the operation reception unit 202. For example, the contour extraction unit 203 detects the first pixel continuous with the reference pixel and acquires the contour of the region composed of the detected first pixel. Extracting the contour can be thought of as extracting the area surrounded by the contour. The contour extraction unit 203 determines, for example, whether the pixel continuous with the reference pixel is the first pixel by using the range of values corresponding to the first pixel acquired by the acquisition unit 212 described above. For example, if the value corresponding to the pixel continuous with the reference pixel is within the range of the value, it is determined that this pixel is the first pixel continuous with the reference pixel, and if it is outside the range of the value, the reference pixel. It is determined that the first pixel is not continuous with. The range of values corresponding to the first pixel is the range of CT values corresponding to blood. The range of values corresponding to the first pixel here may be considered to be the range of CT values corresponding to blood outside the blood vessel, such as blood leaked from the blood vessel in the living body. Here, the range of values corresponding to the first pixel used by the contour extraction unit 203 when determining whether the pixel continuous with the reference pixel is the first pixel is the first range as described above. Is preferable. Further, the first range in this case is a range of values having a value larger than a representative value of a value corresponding to each of two or more first pixels in the first pixel region having a plurality of pixels as a lower limit value. It is more preferable to have. This first range is the same value range as the value range of the first pixel used when the display unit 213 displays the first pixel in the tomographic image in a manner that can be identified with respect to other pixels. May be.

The contour extraction unit 203 of the present embodiment further surrounds the contour (hereinafter, referred to as a reference contour) of the region composed of the first pixel continuous with the reference pixel extracted above in the tomographic image. In the set extended region, one or more regions composed of pixels indicating the first structure are detected. Then, a contour having the above-mentioned reference contour and the contour of the region detected in the extended region is extracted. For example, the contour obtained by combining the above reference contour and the contour of the region detected in the extended region is extracted. The extended area is a band-shaped area set around the reference contour. The extended region is, for example, an region in which the region of the first pixel that is not continuous with the region indicated by the reference contour is detected. The extended area here is an area that does not include the area surrounded by the reference contour. The expansion region is a region in which the amount of expansion in the upward direction is larger than the amount of expansion in the downward direction, and the amount of expansion in the lateral direction decreases from the upward direction to the downward direction.

The contour detected by the contour extraction unit 203 in the extended region is, for example, a contour formed by a boundary between a region composed of the first pixel and pixels other than the first pixel. The range of values corresponding to the first pixel used when detecting the region of the first pixel from the extended region is preferably the above-mentioned second range acquired by the acquisition unit 212. The second range in this case is a value equal to or more than a representative value of a value corresponding to each of two or more first pixels in the first pixel region having a plurality of pixels, and is the minimum of the above first range. It is more preferable that the range of values has a value smaller than the value as the lower limit value. The lower limit of the second range is more preferably a representative value of a value corresponding to one or more first pixels in the first pixel region. A range of values corresponding to the first pixel other than the second range, such as the first range, may be used when detecting the region of the first pixel from the extended region. For example, the contour extraction unit 203 sets an expansion region, detects one or more regions composed of one or two or more consecutive first pixels in the expansion region, and determines the contour of each of the detected regions. To detect.

The extended area will be described below. As a result of diligent research by the inventor of the present application, blood leaked from a blood vessel or the like in the living body rapidly becomes denser than blood flowing in the blood vessel, and in the living body, the density in the blood is high. It was found that the part that became sunk tended to sink downward with the passage of time.

FIG. 8 is a diagram showing the results of experiments conducted to investigate changes in blood density over time. In this experiment, a blood-filled and plugged test tube was allowed to stand horizontally in the longitudinal direction. Then, after a plurality of predetermined times had elapsed, the blood filled in the test tube was subjected to CT tomography so as to be perpendicular to the longitudinal direction in a state where the longitudinal direction of the test tube was horizontal. FIG. 8 shows tomographic images taken at each time, and the upper part of the tomographic image shows the elapsed time from filling with blood to taking a picture.

The CT value obtained by CT imaging is a value that changes according to the density of each part in the living body, and usually, the higher the density, the higher the CT value. Further, in the tomographic image obtained by CT imaging, the portion having a high CT value is displayed whiter than the portion having a low CT value.

In the tomographic image of FIG. 8, since the white part is concentrated in the lower part of the container with the passage of time, it can be seen that the part having a high density in the blood sinks downward with the passage of time.

FIG. 9 is a diagram showing the results of experiments conducted to investigate changes in CT values of blood over time. In this experiment, the blood filled in the container was subjected to CT imaging after a plurality of predetermined times had elapsed, and the maximum value of the CT value obtained by the CT imaging was obtained. FIG. 9 is a graph showing the relationship between the maximum value of the CT value acquired in this way and the elapsed time.
From the graph of FIG. 9, it can be seen that the CT value rapidly increases with the passage of time.

From the above findings, the blood inside the blood vessel has a higher density than the blood outside the blood vessel, and after a long period of time in the same posture to take a tomographic image, the density of the leaked blood is on the lower side of the living body. It is thought that high blood will sink. Since the CT value obtained by CT imaging as described above increases as the density of each part in the living body increases, the CT value of blood on the lower side of the tomographic image becomes higher than the CT value of blood on the upper side. .. For example, in a tomographic image of a living body taken in a supine position, the CT value of the dorsal blood of the leaked blood is higher than the CT value of the ventral blood, and the dense dorsal blood. Appears whiter than the ventral blood.

When the lower limit of the CT value range used to detect the first pixel indicating extravascular blood in one tomographic image is set to a constant value, as the above findings show, the tomographic image Since the blood located on the upper side has a low density and a low CT value, the proportion of blood having a CT value before and after the lower limit value is higher in the upper side of the tomographic image than in the lower side (for example, the dorsal side). It is considered expensive. Therefore, on the upper side of the tomographic image, even if the pixel actually indicates blood, its CT value is lower than the lower limit of the range of CT values corresponding to the first pixel indicating blood. It is considered that there are many cases where it is not judged to be the first pixel indicating. On the other hand, the CT value of the lower blood of the living body is higher than that of the upper blood, and it is considered that the proportion of blood below the lower limit of the CT value range is low, so it corresponds to the first pixel indicating blood. It is considered that there are few blood pixels that are not detected in the range of CT values. For this reason, in the part located on the upper side at the time of photographing the living body in which blood is difficult to be detected, the range in which the first pixel is detected with respect to the reference contour detected first is expanded widely, and in the lower side, The range in which the first pixel is detected is narrowed (or the range becomes 0) with respect to the initially detected reference contour, and in these expanded regions, is it discontinuous with the region within the reference contour? Regardless of whether or not, the first pixel is detected. Further, here, the first pixel is detected in the extended region using the second range in which the lower limit value is smaller than the first range used when detecting the reference contour. The range of CT values of pixels is expanded to detect the first pixel that could not be detected when the reference contour is detected. Even when the water concentration is high due to old-fashioned hematoma, the lower limit of the CT value for detecting hematoma in the dilated area is the lower limit of the CT value from the viewpoint that it is preferable to consider it as the part that was previously hematoma and include it as the area of hematoma. , A value smaller than the lower limit of the first range, preferably a value close to the representative value of the first pixel in the first pixel region, and more preferably the same value as this representative value. For example, by using such a second range, when the hematoma does not increase or decrease in the closed cavity, the hematoma becomes edematous over time, and the edematous part becomes a hematoma. It is possible to prevent the volume of the detected hematoma from becoming different from the actual volume of the hematoma because it is no longer detected. Therefore, by detecting the first pixel from the extended region as described above, the difference in the detection accuracy of the blood due to the difference in the CT value of the extravascular blood in the vertical direction of the tomographic image is compensated as a result, and the accuracy is corrected. It is possible to detect the hematoma area well.

From the above viewpoint, the expansion region is defined as, for example, a region in which the amount of expansion in the upward direction is larger than the amount of expansion in the downward direction, and the amount of expansion in the lateral direction decreases from the upward direction to the downward direction. Is preferable. For example, the vertical width of the portion of the extended region located above the reference contour is set to be longer than the vertical width of the portion located below the reference contour. Further, the lateral width of the extension area located on the left and right of the reference contour is set to decrease from the top to the bottom. Here, the upward and downward directions are the upward and downward directions of the tomographic image.

The expansion amount is, for example, the distance from the reference contour to the contour outside the expansion region. The unit of the width and the length may be expressed in the unit of the length such as millimeters, and may be expressed in the number of pixels. The upward expansion amount is, for example, the upward distance from the reference contour to the outer contour of the expansion region. The downward expansion amount is, for example, the downward distance from the reference contour to the outer contour of the expansion region. The amount of expansion in the lateral direction is, for example, the distance in the lateral direction (for example, the left-right direction) from the reference contour to the contour outside the expansion area.

The fact that the amount of lateral expansion decreases from upward to downward means that even if the amount of lateral expansion decreases continuously from upward to downward, it gradually decreases. It may be to decrease. When setting the expansion region so that the expansion amount in the lateral direction continuously decreases from the upward direction to the downward direction, the position of the expansion region in the height direction and the expansion amount in the lateral direction (for example, from the reference contour) The relationship with the lateral distance to the contour outside the extended region) may be in direct proportion or may be other than in direct proportion. Further, if the amount of expansion in the upward direction is larger than the amount of expansion in the downward direction, the amount of expansion in the upward direction may decrease continuously or stepwise toward the lower side of the reference contour. Further, if the amount of expansion in the upward direction is larger than the amount of expansion in the downward direction, the amount of expansion in the downward direction may decrease continuously or stepwise toward the lower side of the reference contour.

The contour of the region composed of pixels corresponding to the discontinuous blood detected from the expanded region is combined with the reference contour first detected by, for example, morphology processing as described later. It is preferable to do so.

FIG. 10 is a diagram for explaining an example of an expansion region set by the above processing with respect to the reference contour. Here, in order to simplify the explanation, a case where the shape of the reference contour 70 is rectangular will be described. The extended area 71 indicates an area indicated by a diagonal line.

The contour extraction unit 203 moves the upper portion of the reference contour above the tomographic image by a distance k (k> 0). Further, the lower portion of the reference contour is moved below the tomographic image by a distance l (k> l ≧ 0). The upper portion of the reference contour here is a portion of the reference contour in which no other portion of the reference contour exists above. Further, the lower portion of the reference contour is a portion of the reference contour in which no other portion of the reference contour exists below. It does not matter which of the upper and lower contours is temporarily set first.

Further, the left side portion of the reference contour is moved to the left side so that the amount of movement increases in proportion to the upward distance from the portion located at the lowest position of the reference contour. The upward distance is a distance that considers the upward distance to be positive. Here, as an example, the lowermost part of the reference contour moves to the left by a distance p (p ≧ 0), and the uppermost part of the reference contour moves to the left by a distance q (q> p). In addition, each part on the left side of the reference contour is moved so that the relationship between the upward distance from the lowermost portion of the reference contour and the amount of movement to the left side becomes a direct proportional increase function. For example, if the height of the reference contour is r (r> 0), the vertical distance from the lowermost portion of the reference contour in the left portion of the reference contour is t (t ≧ 0). The leftward movement amount u of the portion where) is u = t × (q−p) / r.

Similarly, the right portion of the reference contour is moved to the right so that the amount of movement increases in proportion to the upward distance from the portion located at the lowest position of the reference contour. Here, as an example, similarly to the above, the lowermost portion of the reference contour moves to the right by a distance p, and the uppermost portion of the reference contour moves to the right by a distance q. Each part on the right side is moved so that the relationship between the upward distance from the part to be positioned at the lowest position of the reference contour and the amount of movement to the right side is a directly proportional increasing function.

The portion on the left side of the reference contour here is a portion of the reference contour in which no other portion of the reference contour exists on the right side. The right side portion of the reference contour is a portion of the reference contour in which no other portion of the reference contour exists on the left side. The order in which the upper portion, the lower portion, the left portion, and the right portion of the reference contour are moved does not matter.

Then, the area sandwiched between the upper part of the reference contour moved above and the upper part of the reference contour before movement, the lower part of the reference contour moved above, and the reference contour before movement. The area sandwiched between the lower part, the left part of the reference contour moved above, the area sandwiched between the left part of the reference contour before movement, and the reference contour moved above. The area sandwiched between the right part and the right part of the reference contour before movement is set as the extended area. The overlapping portions of these regions are combined.

The unit of the above distance does not matter. For example, the above distance may be expressed by the International System of Units such as mm or inch or the international imperial system, or may be expressed by the number of pixels such as pixels.

The value of the distance p is preferably 0 or more and 1 mm or less, and most preferably 0. The value of the distance q is preferably 3 mm or more and 7 mm or less, and most preferably 5 mm. The value of the distance k is preferably 5 mm or more and 7 mm or less, and most preferably 6 mm. The value of the distance l is preferably 2 mm or more and 4 mm or less, and most preferably 3 mm. For example, it is one of the most preferable examples that the value of k is 6 mm, the value of l is 3 mm, the value of p is 0, and the value of q is 5 mm. The extended distances such as p, q, k, and l described above are examples, and the conditions of the equipment used for capturing the tomographic image, the imaging position, the living body to be imaged, and the CT value inside the hematoma. It may be changed as appropriate according to the above. Further, the extending distances of the above p, q, k, l and the like may be appropriately changed according to the size of the reference contour and the like. For example, as the size of the reference contour increases, the extending distances such as p, q, k, and l may be continuously or gradually increased.

The process of setting the extended area with respect to the reference contour is not limited to the process described above, and the extended area may be set by a process other than the above. Further, for example, the expansion region may not be provided below the reference contour in the tomographic image or in the vicinity thereof.

Further, when setting the extended region, the region composed of pixels whose corresponding values (for example, the corresponding CT values) are clearly different from the values corresponding to the first pixel indicating blood as described above. , It may not be included in the extension area. For example, pixels having a CT value of more than 100 HU, pixels showing fat having a CT value in the range of −200 to -1HU, and the like described in the first embodiment are excluded from the expansion region. May be good.

Here, the first pixel acquired by the acquisition unit 212 is defined as a range of values corresponding to the first pixel continuous with the reference pixel and the first pixel used for detecting the first pixel in the extended region. The first range, the second range, etc., which are the range of values corresponding to the pixels, are used, but the range of the values corresponding to the first pixel corresponds to the predetermined first pixel. A range of values (for example, a range of CT values corresponding to extravascular blood such as blood leaked into a living body) may be used. For example, when the area designation reception unit 211, the acquisition unit 212, or the like is omitted, the same value as the range of values corresponding to the first pixel used for detecting the first pixel in the first embodiment. The range of may be used.

When a plurality of tomographic images taken at different positions in the same living body are stored in the image storage unit 101, the contour extraction unit 203 extracts the tomographic image of one of the plurality of tomographic images by the above-described processing. The contour may be used to extract the contour corresponding to the contour extracted for one tomographic image from a plurality of tomographic images taken at different positions of the same living body. The contour corresponding to the contour extracted for one tomographic image is the contour of the same object as the target indicated by the contour extracted for one tomographic image. The target here is, for example, the target of contour extraction. The subject here is, for example, a hematoma. However, the target may be other than hematoma, for example, an organ or a tumor. The contour corresponding to the contour extracted for one tomographic image is, for example, a contour that at least partially overlaps the contour extracted for one tomographic image and is a region related to a continuous first pixel. .. The region related to the continuous first pixel may be a region having a continuous first pixel, and the region having the continuous first pixel may be used to extend an extended region or the like as described above. It may be an area having a first pixel acquired by using it.

For example, the contour extraction unit 203 may use the contour of the region related to the first pixel continuous with the reference pixel extracted in one tomographic image and extract the contour corresponding to this contour in different tomographic images. Good. For example, when a plurality of tomographic images of a living body taken at different positions on the same straight line so as to be perpendicular to the straight line are stored in the image storage unit 101, the contour extraction unit 203 may be used. Using the contour extracted by the above-described processing for one tomographic image, the contour corresponding to the contour extracted above is extracted from one or more of the tomographic images taken at two or more different positions of the living body.

Hereinafter, one or more of the tomographic images taken at two or more different positions of the same living body using the contour of the region related to the first pixel continuous with the reference pixel extracted in one tomographic image. An example of the process of extracting the contour corresponding to this contour will be described.

In FIGS. 11A and 11B, a plurality of tomographic images taken at consecutive different positions (hereinafter, may be referred to as imaging positions) in the hematoma region in the living body are cut perpendicular to the tomographic image. It is a schematic diagram. In the figure, each cell shows a pixel of a tomographic image. The horizontal rows show each tomographic image, and the vertical columns show pixels located at the same coordinates in different tomographic images. In the figure, the vertical direction indicates the cranio-caudal direction, and it is assumed that the imaging position of the upper tomographic image has a smaller arrangement order value than the imaging position of the lower tomographic image. The shaded cells indicate the first pixel.

As shown in FIG. 11A, when the reference pixel 1102 shown by the double frame in the tomographic image 1101a is specified, the area of the first pixel continuous with the reference pixel is used. , The contour with the region of the first pixel included in the extended region of this region is detected in the tomographic image 1101a. It is assumed that the detected contour is the contour 1103. In the tomographic image 1101b immediately before the tomographic image 1101a, all the first pixels in the same contour as the contour 1103 are detected, and the region of the first pixel which is continuous with all the first pixels and this The contour with the region of the first pixel included in the extended region of the region is extracted in the tomographic image 1101b. The same contour here is, for example, a contour having the same planar shape and position in a tomographic image. The same contour may be considered as, for example, a contour in which a plurality of coordinates indicating the contour (for example, the coordinates of the pixels of the contour and the coordinates of the pixels adjacent to the contour) are the same. The same applies to the following. Further, the extended area here is assumed to be an extended area similar to the extended area set for the contour of the area of the first pixel continuous with the reference pixel. The same applies to the following extended regions set to contours other than the contours of the first pixel continuous with the reference pixel. Further, in a tomographic image taken at a position different from the tomographic image having a reference pixel, the range of values corresponding to the first pixel used when detecting the first pixel from the extended region includes, for example, the above. It is preferable to use the same second range, and when detecting the other first pixel, for example, it is preferable to use the same first range as described above. This also applies when detecting the first pixel in the tomographic images taken at different positions described below.

Further, the same processing is sequentially performed on the tomographic images at the imaging positions prior to the tomographic image 1101b. Further, in the tomographic image 1101c immediately after the tomographic image 1101a, all the first pixels in the same contour as the contour 1103 are detected, and a region continuous with all the first pixels and an extended region of this region are detected. The contour with the region of the first pixel included in is extracted, and the same processing is sequentially performed on the tomographic image whose imaging position is later than the tomographic image 1101c. The region indicated by the contour extracted in this way is as shown in region 1104 of FIG. 11B, and it can be seen that the contours of region 1105 and region 1106, which are a part of the hematoma region, cannot be extracted. ..

On the other hand, in the tomographic image 1101b immediately before the tomographic image 1101a, all the first pixels in the same contour as the contour 1103 are detected, and the region of the first pixel that is continuous with all the first pixels. And the contour with the region of the first pixel included in the extended region of this region is extracted in the tomographic image 1101b. Further, using the contour detected in the tomographic image 1101b, the same as above in the tomographic image after the tomographic image 1101b, that is, the tomographic image 1101a and the tomographic image 1101b including the tomographic image 1101c. By sequentially performing the above processes, the contour of a part of the hematoma region 1105 that could not be detected above can be extracted.

Similarly, in the tomographic image 1101c immediately behind the tomographic image 1101a, all the first pixels in the same contour as the contour 1103 are detected, and the region of the first pixel that is continuous with all the first pixels is used. , The contour with the region of the first pixel included in the extended region of this region is extracted in the tomographic image 1101c. Further, using the contour detected in the tomographic image 1101c, the same as above is applied to the tomographic image whose imaging position is earlier than the tomographic image 1101c, that is, the tomographic image 1101c or earlier including the tomographic image 1101a and the tomographic image 1101b. By sequentially performing the treatment, the contour of a part of the hematoma region 1106 that could not be detected above can be extracted.

Therefore, in consideration of such a point, the contour extraction unit 203 uses, for example, the contour of the region related to the first pixel continuous with the reference pixel extracted in one tomographic image as follows. Contours are extracted for multiple tomographic images.

A plurality of tomographic images taken at different M locations (M is an integer of 3 or more) on the same straight line in the same living body are stored in the image storage unit 101 in association with, for example, the arrangement order of the imaging positions. The contour extraction unit 203 extracts the contour related to the first pixel continuous with the reference pixel from the tomographic image in which the reference pixel is specified among the plurality of tomographic images by performing the above processing. Suppose you did. Here, it is assumed that the tomographic image in which the reference pixel is specified is the tomographic image at the Nth imaging position (N is an integer of 2 or more and less than M).

The contour extraction unit 203 uses the contour related to the first pixel continuous with the reference pixel extracted for the Nth tomographic image to make the first pixel continuous with the first pixel in the same contour as this contour. The relevant contour is obtained from the pixels in the N-1st tomographic image. The contour related to the first pixel here is, for example, the contour of a continuous first pixel and the contour of the region of the first pixel detected in the extended region set around the contour. .. The same applies to the following. In this expansion region, for example, similar to the expansion region described above, the amount of expansion in the upward direction is larger than the amount of expansion in the downward direction, and the amount of expansion in the lateral direction increases from the upward direction to the downward direction. It is an extended area that becomes smaller. Here, the contour of the region in the N-1st tomographic image, which is composed of the first pixels continuous with all the first pixels in the same contour as the contour extracted for the Nth tomographic image, and The outline of the region composed of the first pixels detected from the same expansion region set for this region is extracted. The overlapping region and the adjacent region among the plurality of regions detected in the N-1th tomographic image are appropriately combined into one region to form a contour before setting the expansion region, for example. Extract. The same applies to the following.

Next, for the N-1st tomographic image, the contour related to the first pixel continuous with the first pixel in the same contour as the contour extracted above is acquired for the Nth tomographic image. Here, in the Nth tomographic image, the contour of the region composed of the first pixels continuous with all the first pixels in the same contour as the contour extracted for the N-1st tomographic image, and The contour of the region composed of the first pixel detected from the same expansion region set for this region as described above is extracted as the contour related to the first pixel. The overlapping region and the adjacent region among the plurality of regions detected in the Nth tomographic image are appropriately combined with one region and the contour is extracted before setting the expansion region, for example. ..

Similarly, the contour extraction unit 203 uses the contour related to the first pixel continuous with the reference pixel extracted for the Nth tomographic image, and the first pixel continuous with the first pixel within the same contour as this contour. The contour associated with the pixel of is obtained from the pixel in the N + 1th tomographic image. Here, the contour of the region in the N + 1th tomographic image, which is composed of the first pixels continuous with all the first pixels in the same contour as the contour extracted for the Nth tomographic image, and this region. The outline of the region composed of the first pixel detected from the same expansion region as described above set in is extracted.

Next, for the N + 1th tomographic image, the contour related to the first pixel continuous with the first pixel in the same contour as the contour extracted above is acquired for the Nth tomographic image. Here, the contour of the region in the Nth tomographic image, which is composed of the first pixels continuous with all the first pixels in the same contour as the contour extracted for the N + 1th tomographic image, and this region. The outline of the region composed of the first pixel detected from the same expansion region as described above set in is extracted.

Then, the region of the Nth tomographic image extracted by using the N-1st tomographic image and the region of the Nth tomographic image extracted by using the N + 1th tomographic image are combined. The contour is newly extracted as the contour related to the first pixel continuous with the reference pixel of the Nth tomographic image.
In the above, the order in which the N-1st tomographic image and the N + 1st tomographic image are used does not matter.

Then, for the tomographic image whose imaging position is before the Nth, for example, in order from the N-1th tomographic image, the first pixel continuous with the first pixel in the same contour as the contour extracted in the immediately following tomographic image. For the tomographic images whose imaging position is after the Nth, the contours related to the pixels of the Extract the contour associated with the first pixel.

The order of performing the process of extracting the contour of the tomographic image whose imaging position is later than the Nth position and the process of extracting the contour of the tomographic image whose imaging position is earlier than the Nth position does not matter.

The process of extracting the contour corresponding to the extracted contour from the tomographic images taken at different positions of the same living body by the contour extraction unit 203 using the contour extracted from one tomographic image is the above-mentioned process. It is not limited.
Further, here, when extracting the contour related to the first pixel in different tomographic images, the extended region is used, but the extended region may not be used.

In addition, the region of the Nth tomographic image extracted by using the N-1st tomographic image and the region of the Nth tomographic image extracted by using the N + 1th tomographic image are combined. The contour may be used as a contour related to the first pixel continuous with the reference pixel extracted by the contour extraction unit 203.

When the exclusion designation reception unit 214 accepts the exclusion designation operation for the tomographic image for which the reference pixel is specified, the contour extraction unit 203 excludes the tomographic image specified by the exclusion designation operation from the above contour extracted for the tomographic image. The contour excluding the contour of the region may be extracted. For example, when the exclusion specification operation is an operation of designating three vertices of the image corresponding to the liver, the contour extraction unit 203 sets the contour of the triangle connecting the three vertices specified by this operation for this tomographic image. Acquire the contour excluded from the above extracted contour. By increasing the number of vertices of the contour of the exclusion area specified by the exclusion specification operation from 3, more complicated exclusion areas such as organs other than the liver can be specified, or the exclusion area can be specified more accurately. Can be done. Further, for example, when the exclusion designation operation is an operation of tracing the contour of the image corresponding to the exclusion target, the contour extracted by this operation is extracted by the contour extraction unit 203 for this tomographic image. Get the contour excluded from the contour.

As described above, the image storage unit 101 stores tomographic images taken at three or more different positions in the same living body, and the contour extraction unit 203 stores two of the stored tomographic images. In the case of extracting the contour related to the first pixel for the above tomographic image as described above, the exclusion designation reception unit 214 for each of the two or more tomographic images stored in the image storage unit 101. When the contour extraction unit 203 is accepting the exclusion specification operation for specifying the outline of the exclusion area to be excluded from the contour to be extracted, the contour extraction unit 203 receives the tomographic image in which the exclusion area is specified by the exclusion specification operation. The contour excluding the contour of the specified exclusion area is extracted, and for the tomographic image in which the exclusion area is not specified, the contour excluding the area obtained by interpolating the acceptance exclusion area for each of two or more tomographic images is extracted. You may do so. The interpolation here may be linear interpolation or other interpolation.

For example, the exclusion designation reception unit 214 receives a region designation operation for designating three vertices for excluding the liver region for each of the two tomographic images, and excludes the two tomographic images as information for designating the exclusion region. Two sets of information, the coordinates of the three vertices of the region and the information that specifies the tomographic image for which the exclusion region is specified (for example, the information that specifies the shooting position, etc.), are stored in a storage unit (not shown). In this case, the contour extraction unit 203 reads out the coordinates of the three vertices of the exclusion region and the information on the imaging position of the tomographic image corresponding to each of the two sets of information. Then, using the value of the shooting position of the tomographic image corresponding to the coordinates of each vertex as the coordinates in the longitudinal direction of each vertex, three straight lines connecting the vertices having a short distance between the two sets of three vertices. Calculate the formula for. Then, for the tomographic image that does not accept this exclusion designation operation, the exclusion areas set in the above two tomographic images are interpolated by substituting the values indicating the shooting positions of the tomographic images into the three mathematical formulas. The coordinates of the three vertices of the excluded area can be obtained. The exclusion area represented by these three vertices is an exclusion area obtained by interpolating the exclusion areas set in the above two tomographic images. Then, the contour connecting the three vertices with a straight line or the like may be excluded from the contour extracted by the contour extraction unit 203 above to obtain the contour excluding the contour of the exclusion region. Since the technique for acquiring a region obtained by interpolating two or more regions is a known technique, detailed description thereof will be omitted here.

In the above, when the first tissue is blood, the contour extraction unit 203 sets an expansion region and further detects the contour from this expansion region. However, the contour is defined from the expansion region. Instead of detecting, the range of values (for example, the range of CT values) used when determining whether or not the pixel continuous with the reference pixel is the first pixel corresponding to blood is to be determined. A region composed of the first pixel continuous with the reference pixel may be detected and the outline of this region may be extracted by changing the position according to the vertical position of the pixel. By doing so, it is possible to correct the difference in blood density due to the difference in the position in the height direction and accurately detect the pixel corresponding to the blood outside the blood vessel, and the first pixel continuous with the reference pixel can be detected. The contour related to the pixel can be extracted with high accuracy. For example, as the position of the pixel to be determined in the height direction in the tomographic image increases, the range of values used when determining whether or not this pixel is the first pixel corresponding to blood ( For example, the lower limit of the CT value range) may be set to be low. Since the density of extravascular blood located on the upper side at the time of taking a tomographic image is low, by lowering the lower limit value, it is possible to accurately detect blood outside the blood vessel having a low density by reducing detection omission. For example, the lower limit value may be continuously lowered according to the change in height, or the lower limit value may be lowered stepwise. For example, the lower limit may be lowered in proportion to the height. For example, as the height position in the tomographic image of the position of the pixel to be determined becomes higher (for example, in proportion to the height position becoming higher), in the area specified by the operation of specifying the first pixel area. From the values obtained from the values corresponding to each of the plurality of first pixels, the value to be multiplied when obtaining the lower limit of the range of values used when determining whether or not the first pixel is used is small. You may. Further, from the value associated with the height position of the pixel to be judged prepared in advance and increasing continuously or stepwise as the height position becomes higher, the pixel to be judged is determined. A value corresponding to the height position is acquired, and it is determined whether or not this value is the first pixel acquired as described above for the area specified by the operation for specifying the first pixel area by the acquisition unit 212. The lower limit value corresponding to the height position of the pixel to be determined may be obtained by subtracting from the lower limit value of the range of values used at the time. Here, an example in which the lower limit value is changed according to the height position of the pixel to be determined has been mainly described, but whether or not the pixel is the first pixel depending on the height position of the pixel to be cut. The upper limit of the value for determining whether or not may be changed. The range of values used when determining whether or not the pixel is the first pixel that changes depending on the height may be acquired by, for example, the acquisition unit 212.

The contour extraction unit 203 may perform one or more morphological conversions on a contour having a reference contour and a contour detected from the extended region acquired for the tomographic image that has received the specific operation. Further, the contour extraction unit 203 performs once or more with respect to the contour corresponding to the contour related to the first pixel continuous with the reference pixel acquired as described above for the tomographic image other than the tomographic image that has received the specific operation. The morphology conversion of may be performed. Then, the contour after the morphology conversion may be extracted.

The morphology conversion is one of the processes of expanding or contracting a region in an image. For example, the contour extraction unit 203 performs at least one of a morphological conversion that expands the region and a morphological conversion that contracts the region with respect to the region indicated by the contour. For example, the contour extraction unit 203 performs a process of expanding the region once or twice or more with respect to the region indicated by the contour, and then performs a process of contracting the region once or twice or more. By appropriately combining the morphology conversion that expands the region one or more times and the morphology conversion that contracts one or more times, for example, noise in the region surrounded by the above contour (for example, other than the first pixel). (Pixel area), noise outside the area surrounded by the above contour, or a non-contiguous area within the reference contour and an area within one or more contours detected from the extended area. Can be connected so as to form a continuous region.

When the contour extraction unit 203 performs a morphology conversion that expands the region and a morphology conversion that contracts the region on one tomographic image from which the contour has been extracted, the contour extraction unit 203 determines the region with respect to the number of times the morphology transformation that expands the region is performed. It is preferable to reduce the number of times of performing the morphological conversion for contracting the same or one time. For example, it is preferable that the morphology conversion for expanding the region is repeated three or more times, and then the morphology conversion for contracting the region for the same number of times or one time less than this number of times is repeated. As the lower limit of the range of values corresponding to the first pixel used when extracting the contour, a predetermined value is set with respect to the representative value of the values of the plurality of first pixels acquired from the first pixel area. When using the multiplied value, when a value larger than 1.3, for example, 1.4, etc. is used as the predetermined value to be multiplied, the number of times the morphology conversion for contracting the region is performed is increased. It is preferable to reduce the number of times by 1 time.

In the present embodiment, the contour extraction unit 203 performs a morphology conversion that expands the region three times or more with respect to the region indicated by the contour, and then contracts the region one less than this number of times. The case of performing morphology conversion will be described as an example.

The contour extraction unit 203 describes the contour obtained by excluding the contour of the exclusion region specified by the exclusion designation operation received by the exclusion designation reception unit 214 from the contour extracted from the tomographic image as described above. It is preferable to perform the morphology conversion as described above, but after performing the morphology conversion as described above from the contour related to the first pixel extracted as described above, the exclusion region specified by the exclusion specification operation The contour may be excluded.

The three-dimensional acquisition unit 215 acquires information on the three-dimensional shape by using the contours corresponding to each other (for example, the contours extracted for the same object) extracted by the contour extraction unit 203 in a plurality of tomographic images as described above. The three-dimensional shape is, for example, a three-dimensional shape of an object indicated by a plurality of contours corresponding to each other extracted in a plurality of tomographic images. The subject may be a hematoma, an organ, fat, bone, or the like. Since the information about the three-dimensional shape is acquired by using the contour, it may be considered as the information about the contour. The information about the three-dimensional shape is, for example, the three-dimensional shape data of the three-dimensional shape or the volume of the three-dimensional shape. For example, the three-dimensional acquisition unit 215 uses information such as a plurality of contours extracted by the contour extraction unit 203 in each of the plurality of tomographic images and information indicating the distance between the tomographic images from which each contour is extracted. The three-dimensional shape data of the three-dimensional shape composed of the first structure corresponding to one pixel and the information such as the volume of the three-dimensional shape are acquired. For example, when each contour is a contour of a hematoma region composed of the first pixel corresponding to blood, the acquired three-dimensional shape is the three-dimensional shape of the hematoma to be indicated by the contour, and the acquired volume. Is the volume of the hematoma. When the contour information extracted from each of the multiple tomographic images taken at equal intervals is used as the information of the plurality of contours, the distance between the positions where the tomographic images are taken is used as the distance between the tomographic images. May be good. It should be noted that the process of acquiring the three-dimensional shape data of the three-dimensional shape of one object, the volume, etc. by using a plurality of contours of one object detected in each of a plurality of tomographic images is a known technique. , Detailed description is omitted here. When the contour extraction unit 203 does not extract the contour of the region composed of the first pixel in the plurality of tomographic images in the plurality of tomographic images, or when the contour extraction unit 203 does not acquire the information on the three-dimensional shape, the three-dimensional acquisition unit 215 It may be omitted.

The output unit 204 outputs the contour extracted by the contour extraction unit 203. The output related to the contour may be, for example, an output of contour information extracted by the contour extraction unit 203 or an output indicating the contour, and an output of information or the like acquired by the contour extraction unit 203 or the like using the extracted contour. It may be. The contour extracted by the contour extraction unit 203 may be, for example, a contour having a reference contour and a contour detected in the extended region, or may be a contour obtained by performing the above-mentioned morphology conversion on this contour. ..

The output related to the contour performed by the output unit 204 is, for example, an output related to the contour similar to the output unit 104 of the first embodiment. For example, the output unit 204 may output a tomographic image showing the extracted contour in an identifiable manner with respect to other regions, similarly to the display unit 213 described above. Further, the output unit 204 may output a tomographic image showing the extracted contour in a manner identifiable with respect to another region and the same tomographic image not showing the extracted contour side by side, and switch between them. It may be possible to output. Further, when the contour extraction unit 203 extracts contours for each of the plurality of tomographic images, a plurality of tomographic images showing the extracted contours in a manner that can be identified with respect to other regions may be output side by side. It may be possible to switch and output a plurality of tomographic images.

Further, the output unit 204 uses information about the three-dimensional shape composed of the first structure acquired by the three-dimensional acquisition unit 215 using the contours extracted by the contour extraction unit 203 for a plurality of tomographic images (for example, the three-dimensional shape 3). Dimensional shape data, volume of three-dimensional shape, etc.) may be output as output related to the contour extracted by the contour extraction unit 203.

Since the same output unit 204 as the output unit 104 can be used, detailed description thereof will be omitted here.

In the first embodiment, the same three-dimensional acquisition unit 215 as in the present embodiment is further provided, and the output unit 104 outputs information on the three-dimensional shape acquired by the three-dimensional acquisition unit 215 as information on the contour. You may do so.

Next, an example of the operation of the image processing apparatus of the present embodiment will be described with reference to the flowchart shown in FIG. Here, an example is taken in the case where a plurality of tomographic images obtained by photographing one living body at a plurality of positions arranged on the same straight line perpendicular to the arrangement direction are stored in the image storage unit 101. I will explain. It is assumed that the plurality of tomographic images are, for example, CT images. Further, it is assumed that the first pixel detected here is, for example, a pixel corresponding to blood outside the blood vessel, and the contour detected is the contour of a hematoma. In addition, the order of arrangement of the positions where each tomographic image is taken in a plurality of tomographic images is hereinafter considered as the order of arrangement of each tomographic image.

(Step S201) Whether or not the display unit 213 has received the operation of displaying the N (N is an integer of 1 or more) th tomographic image stored in the image storage unit 101 via a reception unit (not shown) or the like. to decide. The Nth tomographic image is, for example, an arbitrary tomographic image specified by the user. If accepted, the process proceeds to step S202, and if not accepted, the process returns to step S201. For example, when only one tomographic image taken for one living body is stored in the image storage unit 101, it may be determined in this step whether or not the instruction to display this tomographic image has been accepted. ..

(Step S202) The display unit 213 displays the tomographic image indicated by the instruction received in step S201 on a monitor (not shown) or the like.

(Step S203) The area designation reception unit 211 determines whether or not the operation for designating the first pixel area has been accepted for the tomographic image displayed in step S202. The operation for designating the first pixel region here is, for example, the designation of a region having a plurality of pixels corresponding to blood in the blood vessel. The operation of designating the first pixel region here is an operation of designating the contour of a region in a blood vessel such as a large blood vessel. If accepted, the process proceeds to step S204, and if not accepted, the process returns to step S203.

(Step S204) The acquisition unit 212 acquires representative values of corresponding values for a plurality of pixels included in the area received in step S203. For example, the acquisition unit 212 calculates an average value of values such as CT values corresponding to a plurality of pixels.

(Step S205) The acquisition unit 212 acquires a range of values corresponding to the first pixel by using the representative value acquired in step S204. The range of values corresponding to the first pixel here is, for example, a value (for example, a CT value) corresponding to the first pixel used when detecting the first pixel. For example, the acquisition unit 212 acquires a first range and a second range as a range of values corresponding to the first pixel. For example, when the representative value is 38 HU or less, the lower limit of the first range is set to a value obtained by multiplying 38 HU by a predetermined value. If it is not 38 HU or less, a value obtained by multiplying this representative value by a predetermined value is set as the lower limit value of the first range. The predetermined value is, for example, a value of 1.2 to 1.6, preferably 1.4. As the lower limit value of the second range, for example, 38HU is used when the representative value is 38HU or less, and the representative value is used when the representative value is not 38HU or less. Further, as the upper limit values of the first range and the second range, a predetermined value (for example, 100 HU or the like) is used. Here, the upper limit values of the first range and the second range are set to the same value, but different values may be used.

(Step S206) The display unit 213 detects the first pixel in the Nth tomographic image using the range of values acquired in step S205, and transmits the detected first pixel to other pixels. Display in an identifiable manner. Here, the first pixel is detected using the first range. For example, in the Nth tomographic image, the display unit 213 detects a pixel whose value range corresponding to the pixel is within the range of the value acquired in step S205, and can identify the detected pixel. Display the tomographic image shown.

(Step S207) The exclusion designation reception unit 211 determines whether or not the exclusion designation operation has been accepted. If accepted, the process proceeds to step S208, and if not accepted, the process proceeds to step S209. The acceptance of the exclusion designation operation here may be the reception of the exclusion designation operation for a plurality of tomographic images. In this case, for example, for a tomographic image other than the currently displayed tomographic image, an operation for displaying a tomographic image similar to the above steps S201 and S202 is further accepted, and an exclusion designation operation is also performed for the displayed tomographic image. Should be accepted.

(Step S208) The exclusion designation receiving unit 214 stores information on the outline of the exclusion area indicated by the exclusion designation operation received in step S207 in a storage unit (not shown). Then, the process proceeds to step S209.

(Step S209) The operation reception unit 202 determines whether or not an operation for designating a reference pixel has been accepted. The operation of designating the reference pixel here is an operation of designating one of the first pixels designated as the reference pixel in the tomographic image displayed in step S206 by mouse clicking, tapping, or the like. The first pixel is a pixel displayed in a manner identifiable with respect to other pixels in step S206. If accepted, the process proceeds to step S210, and if not accepted, the process returns to step S207.

(Step S210) The contour extraction unit 203 detects the first pixel continuous with the reference pixel specified by the operation received in step S209, and extracts the contour of the region composed of the continuous first pixel. .. The contour extracted here is the reference contour described above. Here, the first pixel is detected using the first range.

(Step S211) The contour extraction unit 203 sets an extended region around the reference contour detected in step 210. This expansion region is, for example, an expansion region in which the amount of expansion in the upward direction is larger than the amount of expansion in the downward direction, and the amount of expansion in the lateral direction decreases from the upward direction to the downward direction.

(Step S212) The contour extraction unit 203 detects the first pixel in the extended region set in step S211 and extracts the contour of the region composed of the first pixel. Here, the first pixel is detected using the second range.

(Step S213) The contour extraction unit 203 performs a process of extracting contours corresponding to the contours extracted in steps S210 and S212 for a plurality of tomographic images. The details of this process will be described later.

(Step S214) The contour extraction unit 203 excludes the contour indicated by the exclusion designation operation accumulated in step S208 from the contour extracted for each tomographic image in step S213. For example, for a tomographic image for which an exclusion designation operation has been performed, the exclusion area specified by this operation is excluded from the contour. For tomographic images for which the exclusion designation operation has not been performed, the contour of the exclusion region obtained by interpolating the plurality of exclusion regions specified by the exclusion designation operation performed on the other plurality of tomographic images is used as the above contour. Exclude from. If the exclusion designation is not accepted in step S207, the process proceeds to step S215 as it is.

(Step S215) The contour extraction unit 203 performs morphology processing on the contour acquired in step S214. For example, in each tomographic image, a morphology process for expanding a region a plurality of times is continuously performed, and then a morphology process for contracting a region once less than this number of times is continuously performed. Then, the contour information obtained by this process is stored in a storage unit (not shown) or the like. For example, the information of the ring is stored in association with the tomographic image, the arrangement order of the tomographic images, and the like.

(Step S216) The three-dimensional acquisition unit 215 acquires information on the three-dimensional shape using the contours acquired for each of the plurality of tomographic images in step S215.

(Step S217) The output unit 204 outputs information regarding the contour acquired in steps S215 and S216. The information regarding the contour here may be the information regarding the three-dimensional shape acquired in step S216. The output unit 204 may output information on the contour according to the instruction received by the reception unit or the like (not shown), or may appropriately change the information on the contour to be output according to the received instruction.

(Step S218) The output unit 204 determines whether or not to end the output of information regarding the contour. For example, when a reception unit or the like (not shown) receives an instruction to end the output, it is determined to end the output related to the contour. When the output of the information regarding the contour is finished, the output is finished and the process returns to step S201. If the output is not finished, the process returns to step S218.

In the flowchart of FIG. 12, the process ends when the power is turned off or an interrupt for the end of the process occurs.

Next, a process in which the image processing device 2 extracts a contour corresponding to a contour related to the first pixel continuous with the reference pixel extracted in the tomographic image in which the reference pixel is specified for a plurality of tomographic images will be described. .. This process corresponds to the process of step S213 in FIG. Here, a case where the tomographic image in which the reference pixel is specified is the Nth tomographic image among the tomographic images of 3 or more will be described as an example.

(Step S301) The contour extraction unit 203 determines whether or not the tomographic image whose imaging position is N-1 is stored in the image storage unit 101. If it is stored, the process proceeds to step 302, and if it is not stored, the process proceeds to step S304.

(Step S302) The contour extraction unit 203 reads out a tomographic image whose imaging position is N-1st, and uses the contour extracted for the Nth tomographic image to obtain a contour related to the first pixel. Extract. Specifically, the contour of the region in the N-1st tomographic image composed of the first pixel continuous with the first pixel in the same contour as the contour extracted in the Nth tomographic image, and this contour. The outline of the area composed of the first pixel in the extended area set in is extracted. Here, as in step S211 of FIG. 12, the amount of expansion in the upward direction is larger than the amount of expansion in the downward direction around the contour of the former, and the amount of expansion in the lateral direction is from the upward direction to the downward direction. An expansion region that becomes smaller toward the direction is set, and in this expansion region, the outline of one or more regions composed of one or two or more consecutive first pixels is extracted. In this step, for the detection of the first pixel from the extended region, for example, the second range acquired in step S205 is used, and for the detection of the other first pixels, for example, the acquisition in step S205. Use the first range. This also applies to the detection of the first pixel in the steps after step S303.

(Step S303) The contour extraction unit 203 extracts the contour related to the first pixel by using the contour extracted from the N-1st tomographic image extracted in step S302 with respect to the tomographic image whose imaging position is Nth. To do. Specifically, the contour of the region in the Nth tomographic image composed of the first pixel continuous with the first pixel in the same contour as the contour extracted in the N-1st tomographic image, and this contour. The outline of the area composed of the first pixel in the extended area set in is extracted. Here, as in step S211 of FIG. 12, the amount of expansion in the upward direction is larger than the amount of expansion in the downward direction around the contour of the former, and the amount of expansion in the lateral direction is from the upward direction to the downward direction. An expansion region that becomes smaller toward the direction is set, and in this expansion region, the outline of one or more regions composed of one or two or more consecutive first pixels is extracted.

(Step S304) The contour extraction unit 203 determines whether or not the tomographic image whose imaging position is N + 1 is stored in the image storage unit 101. If it is stored, the process proceeds to step 305, and if it is not stored, the process proceeds to step S307.

(Step S305) The contour extraction unit 203 reads out the tomographic image at the N + 1th imaging position, and extracts the contour related to the first pixel from the tomographic image using the contour extracted from the Nth tomographic image. .. This process is the same as the process in which the N-1st tomographic image is replaced with the N + 1th tomographic image in the process of step S302.

(Step S306) The contour extraction unit 203 extracts the contour related to the first pixel by using the contour extracted from the N + 1th tomographic image extracted in step S305 with respect to the tomographic image whose imaging position is Nth. This process is the same as the process in which the N-1st tomographic image is replaced with the N + 1th tomographic image in the process of step S303.

(Step S307) The contour extraction unit 203 merges, that is, combines the contour extracted for the Nth tomographic image in step S303 and the contour extracted for the Nth tomographic image in step S306. For example, two or more regions in which partially overlap each other are combined into continuous regions and their contours are extracted. This contour is the contour associated with the first pixel continuous with the reference pixel of the newly extracted Nth tomographic image. The extracted contour information is stored in a storage unit (not shown) in association with the Nth tomographic image. If the contour is extracted only in step S303 or step S306, the above merging process is omitted, and the acquired contour information is associated with the Nth tomographic image and is not shown. Accumulate in.

(Step S308) The contour extraction unit 203 substitutes 1 for the value of the counter m.

(Step S309) The contour extraction unit 203 determines whether or not the N + mth tomographic image is stored in the image storage unit 101. If it is stored, the process proceeds to step S310, and if it is not stored, the process proceeds to step S313.

(Step S310) The contour extraction unit 203 reads out the N + m th tomographic image, and uses the contour acquired in the N + m-1st tomographic image for the read tomographic image to obtain the contour of the first pixel corresponding to this contour. Performs the process of extracting the contour. Specifically, the contour of the region composed of the first pixel continuous with the first pixel in the same contour as the contour extracted in the N + m-1st tomographic image in the N + mth tomographic image is extracted. Further, around the extracted contour, the amount of upward expansion is larger than the amount of downward expansion, as in step S211 of FIG. 12, and the amount of lateral expansion is from upward to downward. An expansion region that becomes smaller according to is set, and in the expansion region, the contour of one or more regions composed of one or two or more consecutive first pixels is extracted. The extracted contour information is stored in a storage unit (not shown) in association with the N + mth tomographic image. Then, the process proceeds to step S311. Even if the contour cannot be extracted, the process proceeds to step S311 as it is. When using the contour of the Nth tomographic image, for example, the contour of the Nth tomographic image accumulated in step S307 is used. The same applies to step S315.

(Step S311) The contour extraction unit 203 determines in step S278 whether the contour can be extracted. If it can be done, the process proceeds to step S312, and if it cannot be done, the process proceeds to step S313.

(Step S312) The contour extraction unit 203 increments the value of the counter m by 1. Then, the process returns to step S309.

(Step S313) The contour extraction unit 203 substitutes 1 for the value of the counter m.

(Step S314) The contour extraction unit 203 determines whether or not the Nmth tomographic image is stored in the image storage unit 101. If it is stored, the process proceeds to step S315, and if it is not stored, the process returns to a higher-level process.

(Step S315) The contour extraction unit 203 reads out the Nmth tomographic image, and uses the contour acquired in the Nm + 1th tomographic image for the read tomographic image to correspond to the first tomographic image. The process of extracting the outline of the pixel is performed. This process is the same as the process in which the N + mth tomographic image is read as the Nmth tomographic image and the N + m-1st tomographic image is read as the Nm + 1th tomographic image in the process of step S310. is there. Then, the process proceeds to step S316. Even if the contour cannot be extracted, the process proceeds to step S316 as it is.

(Step S316) The contour extraction unit 203 determines whether the contour can be extracted in step S315. If it can be done, the process proceeds to step S317, and if it cannot be done, the process returns to a higher-level process.

(Step S317) The contour extraction unit 203 increments the value of the counter m by 1. Then, the process returns to step S314.

In the flowchart of FIG. 13, the process ends when the power is turned off or an interrupt for the end of the process occurs.

Next, a specific example of the operation of the image processing device 2 of the present embodiment will be described. Here, when the torso image is an X-ray CT cross-sectional image perpendicular to the height direction taken in the body of the human body, and the first pixel is a pixel corresponding to the leaked blood which is the first tissue. Will be described. Further, it is assumed that the image storage unit 101 stores a plurality of tomographic images taken at equal intervals at different positions in the height direction of the same subject.

FIG. 14 is a tomographic image for explaining the operation of the image processing device 2, and is a tomographic image of the abdominal cavity of a subject in a case of ruptured aortic aneurysm similar to FIG. 3, which is a view seen from the foot side of the subject. Is shown. 14 (a) to 14 (d) all show the same tomographic image. However, the part of the tomographic image shown and the enlargement ratio are different.

First, when the user performs an operation of displaying one tomographic image stored in the image storage unit 101 to a reception unit or the like (not shown), the display unit 213 images the tomographic image in response to this operation. It is read from the storage unit 101 and displayed on the monitor. It is assumed that the tomographic image displayed by the display unit 213 is a tomographic image as shown in FIG. 14A.

In the tomographic image shown in FIG. 14A, the user visually determines the aorta, operates a mouse or the like (not shown) to move the cursor, and surrounds an arbitrary circular area in the aorta with a circle 1301. Assuming that the operation of designating the pixel area is performed, the area designation receiving unit 211 accepts this operation. Since the circle 1301 is designated in the aorta, the pixels in the circle 1301 are the pixels of blood in the blood vessel.

The acquisition unit 212 randomly selects three pixels from the area in the circle 1301 designated by the operation of designating the first pixel area, acquires a CT value which is a value corresponding to each pixel, and obtains the CT value thereof. Calculate the average value. Although three pixels are selected here, the number of pixels is not limited to three.

The acquisition unit 212 determines whether or not the acquired average value is 38 HU or less, and if it is 38 HU or less, the lower limit is 38 HU multiplied by 1.4, and the upper limit is 100 HU which is predetermined. The range of values is obtained as a value indicating the first range of CT values corresponding to the leaked blood. If it is not 38 HU or less, the lower limit is a value obtained by multiplying the representative value by 1.4, and the upper limit is a predetermined range of 100 HU, which is the first CT value corresponding to the leaked blood. Obtained as a value indicating the range. Further, when the acquired average value is 38 HU or less, the lower limit value is 38 HU and the upper limit value is a predetermined 100 HU value range, which indicates the second range of the CT value corresponding to the leaked blood. Get as a value. If it is not 38 HU or less, the representative value is the lower limit value, and the upper limit value is a predetermined range of 100 HU, which is acquired as a value indicating the second range of the CT value corresponding to the leaked blood. Here, for example, the representative value is larger than 38 HU, and the acquisition unit 212 sets a value indicating the first range of the CT value corresponding to the leaked blood from a value 1.4 times the representative value to 100 HU. It is assumed that the value in the range of 100 HU is obtained from the representative value as the value indicating the second range.

In the tomographic image shown in FIG. 14A, the display unit 213 uses as the first pixel a pixel whose CT value, which is a value corresponding to a pixel, is included in the first range acquired by the acquisition unit 212. By superimposing a predetermined color on the detected pixels, a tomographic image in which the first pixel can be identified is constructed and displayed on a monitor (not shown). FIG. 14B is a diagram showing a display example of a tomographic image in which the first pixel is shown as an overlay. In the figure, the shaded area 1302 is the area where the first pixel shown by the overlay is arranged.

Here, it is assumed that the user has performed an exclusion designation operation for designating the exclusion region in the two tomographic images. The information indicating the excluded area is stored in a storage unit (not shown) in association with the information indicating the imaging position of the tomographic image.

Next, in the tomographic image shown in FIG. 14 (b), the user visually refers to the arrangement of the first pixel corresponding to the leaked blood shown in the overlay, and one point 1303 of the portion considered to be a hematoma. Is clicked by operating the mouse.

The operation reception unit 202 receives a specific operation for specifying a pixel located at one point 1303 clicked in response to this operation as a reference pixel.

The contour extraction unit 203 detects the first pixel continuous with the reference pixel specified by the specific operation. Specifically, a pixel that is continuous with the reference pixel and whose value corresponding to the pixel falls within the first range that is the range of the CT value corresponding to the leaked blood acquired by the acquisition unit 212 above. To detect. Then, the contours of the detected continuous pixels are extracted. The contour extracted here is the reference contour described above.

Further, the contour extraction unit 203 sets an extended region around the reference contour extracted here by performing the same processing as the processing described with reference to FIG. 10 above. Here, the above-mentioned value of K used when setting the expansion region is 6 mm, the value of L is 3 mm, the value of P is 0, and the value of Q is 5 mm. Further, the expansion area is set so that the width in the lateral direction of the expansion area decreases in direct proportion from the top to the bottom.

Then, the contour extraction unit 203 detects pixels that fall within the second range, which is the range of the CT value corresponding to the leaked blood acquired by the acquisition unit 212, even within the extended region set in this way. , Extract the contour of one or more regions composed of one or more first pixels that are not continuous with the reference contour. The contour extracted in this way becomes the contour 1304 as shown in FIG. 14 (c). Here, the inside of the contour 1304 is indicated by diagonal lines.

After that, the contour extraction unit 203 uses one or more tomographic images before and after the tomographic image shown in FIG. 14A, and uses the first tomographic images corresponding to the contour 1305 detected above for these tomographic images. The contours related to the pixels are sequentially detected. The contours detected in the tomographic images before and after these are considered to be cross sections of the hematoma shown by the contour 1305 at different positions in the continuous portion in the height direction of the living body. The one or more tomographic images before and after are, for example, a tomographic image taken on the head side and a tomographic image taken on the foot side of the tomographic image shown in FIG. 14A.

FIG. 15 is a schematic view showing tomographic images taken at the shooting positions before and after the tomographic image shown in FIG. 14A, and is a perspective view in which a plurality of tomographic images are arranged in the order of shooting. However, FIG. 15 is prepared for explanation, and is not a tomographic image that accurately corresponds to FIG. 14 and the like. Hereinafter, the process of sequentially detecting the contours related to the first pixel corresponding to the contours 1305 will be specifically described with reference to FIG.

The contour extraction unit 203 uses the contour related to the first pixel continuous with the reference pixel extracted for the Nth tomographic image to make the first pixel continuous with the first pixel in the same contour as this contour. The relevant contour is extracted in the N-1th tomographic image. Here, the contour of the region composed of the first pixels continuous with all the first pixels in the same contour as the contour 1305 extracted for the Nth tomographic image in the N-1st tomographic image. , The contour of the region composed of the first pixels detected from the same expansion region set for this region as described above is extracted as the contour. The overlapping region and the adjacent region among the plurality of regions detected in the N-1th tomographic image are appropriately combined into one region to form a contour before setting the expansion region, for example. Extract. It is assumed that the contour extracted here is the contour 1501. In the extended region in the N-1th tomographic image, the CT value range corresponding to the first pixel used when detecting the first pixel is the same second range as described above. For the detection of the first pixel other than this, the same first range as described above is used. This also applies to the process of detecting the first pixel in the subsequent tomographic images.

Next, for the N-1st tomographic image, the contour related to the first pixel continuous with the first pixel in the same contour as the contour 1501 extracted above is acquired for the Nth tomographic image. Here, similarly to the above, the Nth tomographic image is composed of first pixels that are continuous with all the first pixels in the same contour as the contour 1501 extracted for the N-1st tomographic image. The contour of the region and the contour of the region composed of the first pixels detected from the same expansion region set for this region are extracted. The same applies to the following. It is assumed that the contours extracted here are the contour 1305 and the contour 1502.

Similarly, the contour extraction unit 203 uses the contour 1305 related to the first pixel continuous with the reference pixel extracted for the Nth tomographic image and continues to the first pixel in the same contour as the contour 1305. The contour associated with the first pixel is obtained from the pixels in the N + 1th tomographic image. It is assumed that the contour extracted here is the contour 1503.

Next, for the N + 1th tomographic image, the contour related to the first pixel continuous with the first pixel in the same contour as the contour 1503 extracted above is acquired for the Nth tomographic image. It is assumed that the contours extracted here are the contour 1305 and the contour 1504.

Then, the contour 1305 and the contour 1502 of the Nth tomographic image extracted by using the N-1st tomographic image above, and the contour 1305 and the contour 1305 of the Nth tomographic image extracted by using the N + 1th tomographic image. The contour of the region in which the contour 1504 is combined is newly extracted as the contour of the Nth tomographic image related to the first pixel continuous with the reference pixel.

Next, the contour extraction unit 203 sets the first pixel in the same contour as the contour extracted in the immediately following tomographic image in order from the N-1st tomographic image for the tomographic image whose imaging position is before the Nth. Extract the contour associated with the first consecutive pixel.

Specifically, the contour extraction unit 203 uses the contour 1305, the contour 1502, and the contour 1504 related to the first pixel continuous with the reference pixel newly extracted above for the Nth tomographic image, and the above Similarly, contours related to the first pixel continuous with the first pixel in the same contour as these contours are extracted from the N-1th tomographic image. Here, it is assumed that the contour 1501 and the contour 1505 are extracted.

For the N-2nd tomographic image, the contours 1501 and 1505 extracted from the N-1st tomographic image are used to make the first pixel continuous with the first pixel in the same contour as the contour. The relevant contour is obtained from within the N-2nd tomographic image. Here, it is assumed that the contour 1506 and the contour 1507 are extracted.

Similarly for the N-3rd and earlier tomographic images, the contours extracted for the immediately following tomographic image (eg, contour 1501 and contour 1505) are used in the same manner as for the first in the same contour as this contour. The contour associated with the first pixel consecutive to the pixel is extracted. This process is performed, for example, until the contour related to the first pixel is no longer extracted or the tomographic image to be extracted disappears. However, it does not matter when the contour extraction is terminated. For example, when contours are extracted for a predetermined number of tomographic images, contour extraction for earlier tomographic images may be completed.

Next, the contour extraction unit 203 is continuous with the first pixel in the same contour as the contour extracted in the immediately preceding tomographic image in order from the N + 1th tomographic image for the tomographic image whose imaging position is later than the Nth. Extract the contour associated with the first pixel.

Specifically, the contour extraction unit 203 uses the contour 1305, the contour 1502, and the contour 1504 extracted above for the Nth tomographic image to be continuous with the first pixel in the same contour as these contours. The contour associated with one pixel is extracted in the N + 1th tomographic image. Here, it is assumed that the contour 1503 and the contour 1508 are extracted.

Further, for the N + 2nd tomographic image, the contour 1503 and the contour 1508 extracted from the N + 1th tomographic image are used to obtain a contour related to the first pixel continuous with the first pixel in the same contour as this contour. Extracted in the N + 2nd tomographic image. Here, it is assumed that the contour 1509 and the contour 1510 are extracted.

Similarly, for the N + 3rd and subsequent tomographic images, the contours extracted for the immediately preceding tomographic image (for example, contour 1509 and contour 1510) are used continuously for the first pixel in the same contour as this contour. Extract the contour associated with the first pixel. This process is performed, for example, until the contour related to the first pixel is no longer extracted or the tomographic image to be extracted disappears. However, it does not matter when the contour extraction is terminated. For example, when contours are extracted for a predetermined number of tomographic images, contour extraction for later tomographic images may be completed.

Further, here, the information of the three vertices for designating the exclusion region 1511 of the triangle is associated with the Nth tomographic image of FIG. 15 as the information indicating the exclusion region by the exclusion designation operation, and similarly. , N + It is assumed that the information of the three vertices for designating the exclusion region 1512 of the triangle is associated with the information indicating the exclusion region by the exclusion designation operation also in the second tomographic image.

For the contour extracted for the Nth tomographic image, the contour extraction unit 203 acquires the contour excluding the overlapping portion if there is a portion overlapping the contour of the exclusion region 1511. Similarly, for the contour extracted for the N + 1th tomographic image, if there is a portion that overlaps with the contour of the exclusion region 1512, the contour excluding the overlapping portion is acquired.

Further, for example, for the N + 1th tomographic image, an exclusion region 1513 is generated by interpolating the exclusion region 1511 and the exclusion region 1512, and if there is a portion that overlaps the extracted contour and the generated exclusion region, the overlapping portion Get the contour excluding.

Further, for example, for the N-1st tomographic image, an exclusion region 1514 is generated by interpolating the exclusion region 1511 and the exclusion region 1512, and if there is a portion that overlaps the extracted contour and the generated exclusion region, Get the contour excluding the overlapping part. The process of excluding the exclusion region is similarly performed on the tomographic image from which other contours have been extracted.

Further, the contour extraction unit 203 performs morphological conversion on the contours extracted in each tomographic image above. Here, as an example, in each tomographic image, the morphology conversion for expanding the contour is performed 5 times in a row, and then the morphology conversion for contracting the contour is performed 4 times. Then, the contour extraction unit 203 extracts the contour obtained by the morphology transformation as the contour for each tomographic image. For example, if the contour 1305 as shown in FIG. 14 (c) is extracted in the Nth tomographic image, the contour 1305 as shown in FIG. 14 (d) is performed by performing the morphology conversion as described above. Is converted to. Here, the inside of the contour 1305 is indicated by diagonal lines. For example, when FIG. 14 (c) and FIG. 14 (d) are compared, in FIG. 14 (c), the region composed of the first pixel existing inside the contour 1304 and the pixel not determined to be determined is , In FIG. 14D, it is the region of the first pixel.

The three-dimensional acquisition unit 215 acquires three-dimensional shape data of the three-dimensional shape of the hematoma by using the contours extracted in each of the plurality of tomographic images as described above. Then, using this three-dimensional shape data, the volume of the three-dimensional shape, that is, the volume of the hematoma region is calculated.

FIG. 16 is a diagram showing an output example (here, a display example) relating to the contour by the output unit 204.

The output unit 204 outputs the contour extracted by the contour extraction unit 203. For example, the output unit 204 is predetermined with respect to the region in the contour 1305 extracted by the contour extraction unit 203 of the tomographic image that has received the above-mentioned specific operation as shown in FIG. 14 (d). The tomographic image 2042 with the color overlay is displayed on the monitor 2041. In addition, a tomographic image in which a predetermined color is overlaid on the region in the contour extracted by the contour extraction unit 203 of the tomographic image taken at the shooting position before and after the tomographic image that has received the specific operation is displayed. It may be displayed on the monitor 2041 included in the output unit 204. Further, the tomographic images without overlay may be displayed side by side at the same time, or the tomographic images without overlay may be displayed by switching to the overlaid image.

Further, the output unit 204 uses a tomographic image that has received the specific operation and a plurality of contours corresponding to the specific operation acquired for the tomographic images before and after the specific operation, and three-dimensional shape data of the three-dimensional shape of the hematoma corresponding to the contour. 2043 is displayed on the monitor as a three-dimensional image of the hematoma (here, a three-dimensional wire frame image) corresponding to the contour acquired by rendering or the like using the three-dimensional shape data.

Further, the output unit 204 calculates the volume of the three-dimensional shape of the hematoma using the three-dimensional data of the three-dimensional shape of the hematoma corresponding to the contour, and displays the calculated volume as the volume 2044 of the hematoma on the monitor 2041.

The hematoma region shown as an overlay on the tomographic image shown in FIG. 16, the three-dimensional shape and volume of the hematoma, etc. are schematic for explanation, and the above processing is not necessarily performed. It was not obtained in a row.

The output unit 204 may output the display or the like as described above according to the operation received from the user by the reception unit (not shown), or may change the tomographic image or the like to be output.

As described above, according to the present embodiment, the first pixel acquired by using the representative value of the value corresponding to one or a plurality of first pixels included in the area designated by the operation of designating the first pixel area. By extracting the contour of the first pixel using the range of values corresponding to, the contour of the first pixel corresponding to the reference pixel can be extracted with high accuracy.

Further, according to the present embodiment, the contour of the region composed of the first pixel continuous with the reference pixel and the expansion region set around the contour, the amount of expansion in the upward direction is determined. The contour of the region composed of the first pixel detected in the expansion region, which is larger than the downward expansion amount and the lateral expansion amount decreases from the upward direction to the downward direction, is continuous with the reference pixel. By extracting as the contour related to the first pixel, the blood pixel can be detected accurately from the tomographic image in consideration of the distribution of blood with different densities in the body, and the hematoma region etc. can be accurately detected. Can be extracted.

Further, the lower limit value of the second range, which is the range of values corresponding to the first pixel used when detecting the first pixel in the extended region, is used as the first pixel used when detecting the reference contour. By setting the value smaller than the lower limit of the first range, which is the range of values corresponding to, the first pixel that was not detected when the reference contour was detected can be detected in the extended region, and the reference pixel can be detected. The contour related to the first pixel consecutive to the first pixel can be extracted with high accuracy. Thereby, for example, a portion of the hematoma whose concentration has decreased with time, such as an edematous portion, can be detected, and the hematoma can be detected accurately.

In the second embodiment, the case where the tomographic image is an X-ray CT image has been described, but the tomographic image is not limited to the X-ray CT image. The tomographic image is, for example, an image acquired by MRI, PET, SPECT, etc., if the value corresponding to the pixel is a different value depending on the tissue density or the like, such as a CT value. You may. When the tomographic image is an image other than the X-ray CT image, for example, the description corresponding to the CT value of the above embodiment appropriately obtains the magnetic field strength for the position corresponding to each pixel when the tomographic image is taken. It may be read as the explanation about the detected value, the signal value, and the like.

Further, in the above embodiment, the case where the first pixel is blood which is the first tissue and the tomographic image is an X-ray CT image has been described as an example, but in the present invention, the first pixel The first tissue corresponding to one pixel is not limited to blood. Further, in the present invention, the extracted contour is not limited to the contour of the hematoma region.

In particular, for configurations other than the configuration in which the contour is extracted using the extended region, the types of tomographic images such as X-ray CT images and MRI images, the first structure corresponding to the first pixel, and the extracted contour are The objects to be shown are not limited to the above.

In the above embodiment, the operation reception unit 202 may receive the same specific operation as in the first embodiment in the first image displayed by the output unit 204 or the like, as in the first embodiment. good.

Further, the operation receiving unit 202 may accept a specific operation in the first image displayed by the output unit 204 or the like, as in the first embodiment.

In the above embodiment, the first pixel of the tomographic image is used by using the range of values corresponding to the first pixel acquired by using the first pixel area designated by the operation of designating the first pixel area. If is not displayed in a different manner with respect to other pixels, the area designation reception unit 211, the acquisition unit 212, and the display unit 213 may be omitted.

Further, the operation receiving unit 202 may accept the same specific operation as in the first embodiment, for example, an operation of specifying a reference pixel by designating an area composed of the first pixel.

Further, the acquisition unit 212 described in the above embodiment acquires a representative value according to the operation of designating the first pixel area received by the area designation reception unit 211, and the value corresponding to the first pixel. The configuration in which the display unit displays the first pixel in the tomographic image in a manner that can be identified with respect to other pixels by acquiring the range and using the range of values corresponding to the acquired first pixel is described above. It may be used in the first embodiment. In this case, the first tissue corresponding to the first pixel is not limited to blood.

Further, in the above embodiment, the contour extraction unit 203 uses the contour extracted in the Nth tomographic image in which the reference pixel is specified, and is related to the first image in the N-1st tomographic image. The case where the contour to be extracted is extracted and the contour related to the first pixel is extracted in the tomographic image taken at the Nth and later shooting positions using this contour has been described. For example, using the contour extracted in the Nth tomographic image, the contour corresponding to the first pixel is extracted in order up to the tomographic image in which the imaging position is earlier than the N-1th, and this contour is used. Therefore, in the tomographic image whose imaging position is later than the tomographic image from which this contour is extracted, the contour related to the first pixel may be extracted.

For example, when a plurality of tomographic images taken at different M locations (M is an integer of 3 or more) in the same living body are stored in the image storage unit 101, the contour extraction unit 203 uses the plurality of tomographic images. The contour related to the first pixel continuous with the reference pixel extracted for the Nth tomographic image (N is an integer of 2 or more and less than M), which is the tomographic image in which the reference pixel is specified. It is the same as the contour extracted in the immediately following tomographic image in order from the N-1st tomographic image up to the Kth tomographic image (K <N, K is an integer) whose imaging position is one or more before the Nth tomographic image. After extracting the contour related to the first pixel continuous with the first pixel in the contour, the L-th (L> K, L is an integer) tomographic image that is one or more behind this K-th tomographic image. From the K + 1th tomographic image, the contours related to the first pixel continuous with the first pixel in the same contour as the contour extracted in the immediately preceding tomographic image are extracted, and the contours from the Kth to the Lth are extracted. For one or more tomographic images, the contour corresponding to the contour extracted for the Nth tomographic image may be detected. The contour corresponding to the contour extracted for the Nth tomographic image is a contour extracted for the same extraction target, for example, the same hematoma. The same applies to the following.

Further, in the above embodiment, the contour extraction unit 203 uses the contour extracted in the Nth tomographic image in which the reference pixel is specified to obtain the contour related to the first image in the N + 1th tomographic image. The case where the contour related to the first pixel is extracted in the tomographic image taken at the Nth and earlier shooting positions by extracting and using this contour has been described, but the contour extraction unit 203 has, for example, , Using the contour extracted in the Nth tomographic image, the contour corresponding to the first pixel is extracted in order up to the tomographic image whose shooting position is later than the N + 1th, and this contour is used to obtain this contour. In the tomographic image whose imaging position is earlier than the extracted tomographic image, the contour corresponding to the contour extracted for the Nth tomographic image may be extracted.

For example, when a plurality of tomographic images taken at different M locations (M is an integer of 3 or more) in the same living body are stored in the image storage unit 101, the contour extraction unit 203 uses the plurality of tomographic images. The contour associated with the first pixel continuous with the reference pixel extracted for the Nth tomographic image (N is an integer of 2 or more and less than M), which is the tomographic image in which the reference pixel is specified, is used. Then, up to the P-th (P> N, P is an integer) tomographic image whose shooting position is one or more later than the N-th tomographic image, in order from the N + 1th tomographic image, within the same contour as the contour extracted in the immediately preceding tomographic image. After extracting the contour related to the first pixel continuous with the first pixel, P up to the Qth tomographic image (P> Q, Q is an integer) which is one or more before this Pth tomographic image. -In order from the 1st tomographic image, the contours related to the 1st pixel continuous with the 1st pixel in the same contour as the contour extracted in the immediately following tomographic image are extracted, and the 1st from the Qth to the Pth. In the above tomographic image, the contour corresponding to the contour extracted for the Nth tomographic image may be detected.

Further, when a plurality of tomographic images taken at different M locations (M is an integer of 3 or more) in the same living body are stored in the image storage unit 101, the contour extraction unit 203 uses the plurality of tomographic images. Of the tomographic images in which the reference pixel is specified, the contour related to the first pixel continuous with the reference pixel extracted for the Nth tomographic image (N is an integer of 2 or more and less than M) is used. The same contour as the contour extracted in the immediately following tomographic image, up to the Kth tomographic image (K <N, K is an integer) whose imaging position is one or more before the Nth, in order from the N-1st tomographic image. After extracting the contour related to the first pixel that is continuous with the first pixel in, up to the Nth tomographic image, in order from the K + 1st tomographic image, within the same contour as the contour extracted in the immediately preceding tomographic image. The contour related to the first pixel continuous with the first pixel is extracted, and the reference pixel of the plurality of tomographic images is the reference pixel extracted for the Nth tomographic image, which is the tomographic image in which the reference pixel is specified. Using the contour related to the first continuous pixel, up to the P-th (P> N, P is an integer) tomographic image whose shooting position is one or more later than the N-th, in order from the N + 1th tomographic image, immediately before After extracting the contour related to the first pixel that is continuous with the first pixel in the same contour as the contour extracted in the tomographic image of, the Nth tomographic image, P-1st tomographic image, and immediately after The reference pixel identifies the region in which the contours related to the first pixel continuous with the first pixel in the same contour as the contour extracted in the tomographic image of No. 1 are extracted and the regions acquired for the Nth tomographic image are combined. The N-th tomographic image may be extracted as a contour related to the first pixel continuous with the reference pixel.

When a plurality of tomographic images taken at different positions in the same living body are stored in the image storage unit 101, the contour extraction unit 203 performs a process other than the process described above to perform a plurality of tomographic images. Using the contour extracted for the tomographic image of one of the images, the contour corresponding to this contour may be extracted in different tomographic images taken at different positions of the same living body.

For example, the contour extraction unit 203 sets the contour extraction unit 203 to be more than the tomographic image from which the contour is extracted for one or more tomographic images whose imaging position is earlier than the tomographic image from which the contour related to the first pixel continuous with the reference pixel is extracted. It is also possible to extract contours related to the first pixel continuous with the first pixel in the same contour as the contour extracted in the tomographic image immediately after that in order from the tomographic image immediately before the imaging position. Further, the contour extraction unit 203 uses the contour extraction unit 203 for one or more tomographic images whose imaging position is behind the tomographic image from which the contour related to the first pixel continuous with the reference pixel is extracted, as compared with the tomographic image from which the contour is extracted. The contour related to the first pixel continuous with the first pixel in the same contour as the contour extracted in the tomographic image immediately before the tomographic image may be extracted in order from the tomographic image one image behind.

Further, in the above embodiment, as contours related to the first pixel continuous with the reference pixel, the contour of the first pixel continuous with the reference pixel and the extension region set around the contour are acquired. The case where the contour extraction unit 203 extracts the contour of the region of the first pixel has been described, but the contour extraction unit 203 uses the contour extraction unit 203 as the contour related to the first pixel continuous with the reference pixel in the above-described first embodiment. The contour having a boundary between the first pixel continuous with the reference pixel and the second pixel indicating the second structure different from the first structure may be extracted as described in the above. In this case, as the second tissue corresponding to the second pixel, for example, a tissue other than blood such as bone and fat may be used.

Further, the contour extraction unit 203 may use, for example, the contour of the first pixel continuous with the reference pixel as the contour related to the first pixel continuous with the reference pixel. Similarly, the contour extraction unit 203 sets the boundary between the first pixel and the second pixel instead of the contour corresponding to the first pixel extracted from the tomographic image other than the tomographic image having the reference pixel. The contour to have or the contour of the first continuous pixel may be extracted.

For example, as described above, in the case of extracting a contour using a plurality of different tomographic images of the same living body, for one tomographic image, the first one within the same contour as the contour extracted in the immediately preceding or immediately following tomographic image. Instead of the process of acquiring the contour of the first pixel that is continuous with the pixel and the contour of the first pixel in the extended area around this contour, the same contour as the contour extracted in the tomographic image immediately before or after. Only the contour of the first pixel that is continuous with the first pixel in the image may be used.

In each of the above embodiments, each process (each function) may be realized by centralized processing by a single device (system), or by distributed processing by a plurality of devices. May be done.

Further, in each of the above embodiments, the case where the image processing device is stand-alone has been described, but the image processing device may be a stand-alone device or a server device in a server / client system. In the latter case, the output unit and the reception unit receive input via the communication line and output the screen.

Further, in each of the above embodiments, each component may be configured by dedicated hardware, or a component that can be realized by software may be realized by executing a program. For example, each component can be realized by a program execution unit such as a CPU reading and executing a software program recorded on a recording medium such as a hard disk or a semiconductor memory. At the time of execution, the program execution unit may execute the program while accessing the storage unit (for example, a recording medium such as a hard disk or memory).

The software that realizes the image processing device in each of the above embodiments is the following program. That is, this program identifies a reference pixel among the first pixels indicating the first structure contained in the tomographic image by a computer that can access the image storage unit in which the tomographic image is stored. As an operation reception unit that accepts a specific operation, a contour extraction unit that extracts a contour related to the first pixel continuous with the reference pixel specified by the specific operation, and an output unit that outputs the contour extracted by the contour extraction unit. It is a program to make it work.

In the above program, in the transmission step for transmitting information and the reception step for receiving information, processing performed by hardware, for example, processing performed by a modem or interface card in the transmission step (only performed by hardware). Processing that is not done) is not included.

Further, the number of computers that execute this program may be singular or plural. That is, centralized processing may be performed, or distributed processing may be performed.

FIG. 5 is a schematic view showing an example of the appearance of a computer that executes the above program and realizes the image processing apparatus according to the above embodiment. The above embodiment can be realized by computer hardware and a computer program executed on the computer hardware.

In FIG. 5, the computer system 900 includes a computer 901 including a CD-ROM (Compact Disk Read Only Memory) drive 905, a keyboard 902, a mouse 903, and a monitor 904.

FIG. 6 is a diagram showing an internal configuration of the computer system 900. In FIG. 6, the computer 901 is connected to the MPU (Micro Processing Unit) 911, the ROM 912 for storing a program such as a bootup program, and the MPU 911 in addition to the CD-ROM drive 905, and issues an instruction of the application program. A RAM (Random Access Memory) 913 that temporarily stores and provides a temporary storage space, a hard disk 914 that stores application programs, system programs, and data, and a bus 915 that interconnects MPU 911, ROM 912, etc. Be prepared. The computer 901 may include a network card (not shown) that provides a connection to the LAN.

A program for causing the computer system 900 to execute a function such as an image processing device according to the above embodiment may be stored in the CD-ROM 921, inserted into the CD-ROM drive 905, and transferred to the hard disk 914. Alternatively, the program may be transmitted to the computer 901 via a network (not shown) and stored on the hard disk 914. The program is loaded into RAM 913 at run time. The program may be loaded directly from the CD-ROM921 or the network.

The program does not necessarily have to include an operating system (OS), a third-party program, or the like that causes the computer 901 to execute the functions of the image processing apparatus according to the above embodiment. The program may include only a portion of the instruction that calls the appropriate function (module) in a controlled manner to obtain the desired result. It is well known how the computer system 900 works, and detailed description thereof will be omitted.

It goes without saying that the present invention is not limited to the above embodiments, and various modifications can be made, and these are also included in the scope of the present invention.

As described above, the image processing apparatus or the like according to the present invention is suitable as an apparatus or the like for processing a tomographic image of a living body, and is particularly useful as an apparatus or the like for extracting contours in a tomographic image.

1, 2 Image processing device 101 Image storage unit 102, 202 Operation reception unit 103, 203 Contour extraction unit 104, 204 Output unit 211 Area designation reception unit 212 Acquisition unit 213 Display unit 214 Exclusion designation reception unit 215 Solid acquisition unit 215

Claims (33)

An image storage unit that stores tomographic images and
An operation reception unit that accepts a specific operation for specifying a reference reference pixel among the first pixels indicating the first structure included in the tomographic image.
A contour extraction unit that extracts contours related to the first pixel continuous with the reference pixel specified by the specific operation, and
An image processing device including an output unit that outputs the contour extracted by the contour extraction unit. The contour extraction unit extracts a contour having a boundary between a first pixel continuous with the reference pixel specified by the specific operation and a second pixel indicating a second structure different from the first structure. Image processing device. The contour extraction unit excludes the boundary between the first pixel and the second pixel that are continuous with the reference pixel and excludes the boundary that satisfies the condition that the distance between the reference pixel and the reference pixel is predetermined. The image processing apparatus according to claim 2, wherein the contour is extracted. The contour extraction unit performs statistical processing on each of the boundaries between the first pixel and the second pixel continuous with the reference pixel and the distance between the reference pixel, and the reference pixel is subjected to the statistical processing. The image processing apparatus according to claim 3, wherein the contour is extracted by excluding the boundary where the distance between the image and the pixel is an outlier. The image processing apparatus according to any one of claims 2 to 4, wherein the contour extraction unit detects a portion where the detected boundary is discontinuous, interpolates the boundary with respect to the detected portion, and extracts a contour. The contour extraction unit detects a plurality of boundaries having the same direction with respect to the reference pixel from the detected boundaries, and reduces the detected plurality of boundaries to one, any one of claims 2 to 5. The image processing apparatus according to the item. The first pixel and the second pixel are pixels that can be identified by the values corresponding to the respective pixels.
The image processing apparatus according to any one of claims 2 to 6, wherein the contour extraction unit detects a boundary between a first pixel and a second pixel using a value corresponding to each pixel. The specific operation received by the operation reception unit is an operation of designating a desired region composed of the first pixel with respect to the tomographic image.
The image processing apparatus according to any one of claims 1 to 7, wherein the contour extraction unit uses a pixel located at the center of the desired region as a reference pixel to extract the contour. The tomographic image is an X-ray CT image and is
The image processing apparatus according to any one of claims 1 to 8, wherein the value corresponding to the pixel used by the contour extraction unit for contour extraction is a CT value. The image processing apparatus according to any one of claims 1 to 9, wherein the tomographic image is a tomographic image of a living body. The first tissue is adipose tissue
The image processing apparatus according to any one of claims 2 to 7, wherein the second structure is a soft tissue. An area designation reception unit that accepts an operation for designating a first pixel area composed of one or more first pixels in the tomographic image.
Further, an acquisition unit for acquiring a range of values corresponding to the first pixel by using a value corresponding to one or more first pixels in the first pixel region is further provided.
Claims 1 to 11 that the contour extraction unit extracts a contour related to the first pixel continuous with the reference pixel by using a range of values corresponding to the first pixel acquired by the acquisition unit. The image processing apparatus according to any one of the above. The image processing apparatus according to claim 12, wherein the acquisition unit acquires a lower limit value in a range of values corresponding to the first pixel by using a representative value of a value corresponding to each of the plurality of first pixels. The operation of designating the first pixel region is an operation of designating the region in the blood vessel of the tomographic image as the first pixel region.
The image processing according to claim 13, wherein the acquisition unit acquires a value larger than a representative value of a value corresponding to each of the plurality of first pixels as a lower limit value of a range of values corresponding to the first pixel. apparatus. Claims 12 to 14 further include a display unit that displays the first pixel in the tomographic image in an identifiable manner with respect to other pixels by using the range of values acquired by the acquisition unit. The image processing apparatus according to the first paragraph. The image processing apparatus according to claim 12, wherein the specific operation received by the operation receiving unit is an operation for designating one of the first pixels in the tomographic image displayed by the display unit. The 12th to 16th claims, wherein the contour extraction unit extracts the contour of a region composed of the first pixel continuous with the reference pixel as a contour related to the first pixel continuous with the reference pixel. Image processing device. The contour extraction unit is a contour of a region composed of a first pixel continuous with the reference pixel and an expansion region set around the contour, and the amount of expansion in the upward direction is downward. The contour of the region composed of the first pixel detected in the expansion region, which is larger than the expansion amount of the The image processing apparatus according to claim 1 to 16, wherein the contour is extracted as a contour related to the pixel. The acquisition unit is a range of values corresponding to the first pixel having a value larger than a representative value of a value corresponding to one or more first pixels in the first pixel region as a lower limit value. A value that is equal to or greater than a representative value of a value corresponding to one range and one or more first pixels in the first pixel region, and is smaller than the minimum value of the first range. A second range, which is a range of values corresponding to the first pixel, which is held as a lower limit value, is acquired.
The contour extraction unit is an expansion region set around the contour by extracting the contour of a region composed of the first pixel continuous with the reference pixel using the value of the first range. Therefore, it is composed of the first pixels detected in the expansion region in which the amount of expansion in the upward direction is larger than the amount of expansion in the downward direction and the amount of expansion in the lateral direction decreases from the upward direction to the downward direction. The image processing apparatus according to claim 18, wherein the contour of the region is extracted using the second range. The contour extraction unit sets the range of values used when determining whether or not the pixel continuous with the reference pixel is the first pixel, as the vertical position of the pixel to be determined becomes higher. The image processing apparatus according to claim 1 to 16, wherein the contour of a region composed of a first pixel continuous with a reference pixel is extracted using a range of values obtained by correcting a lower limit value so that the value becomes lower. The image processing apparatus according to any one of claims 18 to 20, wherein the first tissue is blood. The tomographic image is further provided with an exclusion designation reception unit that accepts an exclusion designation operation that specifies the contour of the exclusion region to be excluded from the contour extracted by the contour extraction unit.
The image processing apparatus according to any one of claims 1 to 21, wherein the contour extraction unit extracts a contour excluding the contour specified by the exclusion designation operation. A plurality of tomographic images taken at different positions in the same living body are stored in the image storage unit.
The contour extraction unit identifies reference pixels for different tomographic images taken at different positions of the same living body by using the contour extracted for one of the plurality of tomographic images, and sets the specified reference pixels. Claim 1 to detect a boundary between a continuous first pixel and a second pixel indicating a second structure different from the first structure in the different tomographic image, and extract a contour having the detected boundary. 11. The image processing apparatus according to any one of claims 11. A plurality of tomographic images taken at different positions in the same living body are stored in the image storage unit.
The contour extraction unit uses the contour extracted for one of the plurality of tomographic images to obtain the contour extracted for the one tomographic image for different tomographic images taken at different positions of the same living body. The image processing apparatus according to any one of claims 1 to 21, which extracts a corresponding contour. A plurality of tomographic images taken at different M locations (M is an integer of 3 or more) in the same living body are stored in the image storage unit.
The contour extraction unit
The first toll image continuous with the reference pixel extracted for the tomographic image (N is an integer of 2 or more and less than M) whose imaging position is the Nth tomographic image in which the reference pixel of the plurality of tomographic images is specified. Using the contour related to the pixel, the tomographic image immediately after the Kth tomographic image (K <N, K is an integer) whose shooting position is one or more before the Nth tomographic image is in order from the N-1st tomographic image. After extracting the contour related to the first pixel continuous with the first pixel in the same contour as the contour extracted in, the Lth (L> K, L) which is one or more behind this Kth tomographic image. Is an integer), in order from the K + 1th tomographic image, the contours related to the first pixel continuous with the first pixel in the same contour as the contour extracted in the previous tomographic image are extracted, and K The image processing apparatus according to any one of claims 1 to 21, wherein the contour corresponding to the contour extracted from the N-th tom image is extracted from one or more tomographic images from the th to the Lth. A plurality of tomographic images taken at different M locations (M is an integer of 3 or more) in the same living body are stored in the image storage unit.
The contour extraction unit
The first pixel continuous with the reference pixel extracted for the tomographic image (N is an integer of 2 or more and less than M) whose imaging position is the Nth tomographic image in which the reference pixel of the plurality of tomographic images is specified. Using the contours related to, the tomographic images of the Pth (P> N, P are integers) whose imaging position is one or more later than the Nth tomographic image are extracted in the immediately preceding tomographic image in order from the N + 1th tomographic image. After extracting the contour related to the first pixel that is continuous with the first pixel in the same contour as the contour, the Qth (P> Q, Q is an integer) that is one or more before this Pth tomographic image. Up to the tomographic image of P-1, in order from the 1st tomographic image, the contour related to the 1st pixel continuous with the 1st pixel in the same contour as the contour extracted in the immediately following tomographic image is extracted, and the Qth The first to the Pth to one or more tomographic images, the contour corresponding to the contour extracted from the Nth tomographic image is extracted. One of claims 1 to 21, 24 and 25. Image processing device. A plurality of tomographic images taken at different M locations (M is an integer of 3 or more) in the same living body are stored in the image storage unit.
The contour extraction unit
The first pixel continuous with the reference pixel extracted for the tomographic image (N is an integer of 2 or more and less than M) whose imaging position is the Nth tomographic image in which the reference pixel of the plurality of tomographic images is specified. In the tomographic image immediately after the N-1st tomographic image, up to the Kth tomographic image (K <N, K is an integer) whose imaging position is one or more before the Nth, using the contour related to. After extracting the contour related to the first pixel that is continuous with the first pixel in the same contour as the extracted contour, the K + 1st tomographic image was extracted in the immediately preceding tomographic image up to the Nth tomographic image. Extract the contour related to the first pixel that is continuous with the first pixel in the same contour as the contour,
The imaging position is determined by using the contour related to the first pixel continuous with the reference pixel extracted for the Nth tomographic image, which is the tomographic image in which the reference pixel of the plurality of tomographic images is specified. Up to the Pth (P> N, P is an integer) tomographic image that is one or more later than the Nth tomographic image, in order from the N + 1th tomographic image, to the first pixel in the same contour as the contour extracted in the immediately following tomographic image. After extracting the contours related to the continuous first pixel, the first pixel in the same contour as the contour extracted in the immediately preceding tomographic image is displayed in order from the P-1st tomographic image up to the Nth tomographic image. Extract the contours associated with the first consecutive pixel
From claim 1, the region in which the regions acquired for the N-th tomographic image are combined is extracted as the contour related to the first pixel continuous with the reference pixel of the N-th tomographic image in which the reference pixel is specified. The image processing apparatus according to any one of claims 21, 24, 25 and 26. The contour extraction unit
For tomographic images whose imaging position is before the Nth, it is related to the first pixel continuous with the first pixel in the same contour as the contour extracted in the immediately following tomographic image in order from the N-1st tomographic image. Extract the contour,
For tomographic images whose imaging position is later than the Nth, in order from the N + 1th tomographic image, contours related to the first pixel continuous with the first pixel in the same contour as the contour extracted in the immediately preceding tomographic image are obtained. The image processing apparatus according to claim 27 for extraction. For each of the two or more tomographic images, an exclusion designation reception unit that accepts an exclusion designation operation that specifies the contour of the exclusion region to be excluded from the contour extracted by the contour extraction unit is further provided.
The contour extraction unit extracts the contour excluding the contour of the designated exclusion region for the tomographic image in which the exclusion region is designated by the exclusion designation operation, and for the tomographic image in which the exclusion region is not designated, the contour extraction unit extracts the contour excluding the contour of the designated exclusion region. The image processing apparatus according to any one of claims 23 to 28, wherein the contour excluding the region obtained by interpolating the plurality of exclusion regions is extracted. The contour extraction unit extracts contours from a plurality of tomographic images taken at different positions in the same living body.
The contour extraction unit further includes a stereoscopic acquisition unit that acquires information on the three-dimensional shape by using the contours extracted from each of a plurality of tomographic images taken at different positions in the same living body.
The image processing apparatus according to any one of claims 23 to 29, wherein the output unit outputs information on a three-dimensional shape acquired by the three-dimensional acquisition unit as information on a contour extracted by the contour extraction unit. The aspect according to any one of claims 1 to 30, wherein the contour extraction unit extracts a contour obtained by further performing a morphology conversion on the extracted contour as a contour related to the first pixel. Image processing device. It is an image processing method performed by using an image storage unit for storing a tomographic image, an operation reception unit, a contour extraction unit, and an output unit.
An operation reception step in which the operation reception unit receives a specific operation for specifying a reference reference pixel among the first pixels indicating the first structure included in the tomographic image.
A contour extraction step in which the contour extraction unit extracts a contour related to a first pixel continuous with a reference pixel specified by the specific operation.
An image processing method including an output step in which the output unit outputs the contour extracted in the contour extraction step. A computer that can access the image storage area where the tomographic image is stored
An operation reception unit that accepts a specific operation for specifying a reference reference pixel among the first pixels indicating the first structure included in the tomographic image.
A contour extraction unit that extracts contours related to the first pixel continuous with the reference pixel specified by the specific operation, and
A program for functioning as an output unit that outputs the contour extracted by the contour extraction unit.