JP4938480B2 - Radiation imaging apparatus, radiation imaging method, and program - Google Patents

Description

  The present invention relates to a radiation imaging apparatus, a radiation imaging method, and a program. In particular, the present invention relates to a radiation imaging apparatus and a radiation imaging method for capturing a radiation image, and a program for the radiation imaging apparatus.

A radiographic image that recognizes a predetermined anatomical region in a chest radiographic image that constitutes a chest dynamic image indicating the respiratory dynamics of the subject's chest and aligns and displays the chest radiographic image based on the recognized anatomical region A processing apparatus is known (for example, refer to Patent Document 1). In addition, an image processing apparatus that performs independent component analysis processing after aligning two images and outputs a main component image and a temporal change detection image is known (see, for example, Patent Document 2). . A radiation image processing apparatus that extracts a change with time by obtaining a difference image from an image captured in the previous year is known for each mode of inhalation mode and expiration mode (see, for example, Patent Document 3).
JP 2003-290193 A JP 2005-197792 A JP 2005-151099 A

  In order to capture an X-ray image having sufficient contrast with an imaging apparatus having a low X-ray intensity, it is necessary to increase the exposure time of X-rays. However, if the exposure time is lengthened, the X-ray image is blurred due to the influence of the subject's heart movement, respiratory movement, body movement, and the like. If the captured image is blurred, the images cannot be properly aligned as in the devices described in Patent Documents 1 to 3, and an appropriate difference image may not be obtained.

  Then, an object of this invention is to provide the radiation imaging device, the radiation imaging method, and program which can solve the said subject. This object is achieved by a combination of features described in the independent claims. The dependent claims define further advantageous specific examples of the present invention.

  In order to solve the above problem, the radiation imaging apparatus according to the first embodiment of the present invention includes a radiation generation unit that irradiates a subject with radiation, and radiation that is irradiated from the radiation generation unit and transmitted through the subject. At least one radiographic image in a plurality of radiographic images captured by the radiographic image capturing unit, a radiological image capturing unit that continuously captures a plurality of radiographic images of the subject, a motion detection unit that detects the motion of the subject A motion correction unit that corrects changes in the plurality of radiographic images due to the movement of the subject detected by the motion detection unit and a radiographic image that includes the radiographic image corrected by the motion correction unit and superimposes a plurality of radiographic images to form a composite image. And a composite image generation unit for generating.

  In the radiation imaging method according to the second aspect of the present invention, a plurality of radiation images of a subject are continuously captured by radiation irradiated by a radiation generation unit that irradiates the subject and transmitted through the subject. A radiographic image capturing stage, a motion detection stage for detecting a motion of the subject, and a subject detected in the motion detection stage in at least one radiographic image in a plurality of radiographic images captured in the radiographic image capturing stage A motion correction stage that corrects changes in a plurality of radiographic images due to movement of the image, and a composite image generation stage that generates a composite image by superimposing a plurality of radiographic images including the radiographic image corrected in the motion correction stage.

  According to a third aspect of the present invention, there is provided a program for a radiation imaging apparatus, wherein the radiation imaging apparatus is irradiated from a radiation generation unit that irradiates the subject with radiation, and is transmitted from the radiation generation unit and transmitted through the subject. At least one radiation in the plurality of radiation images captured by the radiation image capturing unit that continuously captures a plurality of radiation images of the subject by radiation, a motion detection unit that detects the motion of the subject, and the radiation image capturing unit. In the image, a motion correction unit that corrects changes in the plurality of radiographic images due to the motion of the subject detected by the motion detection unit, and a radiographic image corrected by the motion correction unit are overlaid on each other to superimpose a plurality of radiographic images. It is made to function as a synthetic image generation unit to be generated.

  The above summary of the invention does not enumerate all the necessary features of the present invention, and sub-combinations of these feature groups can also be the invention.

  ADVANTAGE OF THE INVENTION According to this invention, the radiographic imaging apparatus which can reduce the blurring amount in a radiographic image can be provided.

  Hereinafter, the present invention will be described through embodiments of the invention. However, the following embodiments do not limit the invention according to the scope of claims, and all combinations of features described in the embodiments are included. It is not necessarily essential for the solution of the invention.

  FIG. 1 shows an example of a usage environment of a radiation imaging system 100 according to an embodiment. The radiation imaging system 100 includes a radiation imaging device 110, a communication path 150, a wireless communication device 152, diagnostic devices 115 a and 115 b (hereinafter collectively referred to as a diagnostic device 115), a server 170, and a database 172. The radiation imaging apparatus 110 includes a radiation detector 120 and a control device 130. The control device 130 includes a monitor 140, an input device 142, a radiation source 132, a visible light camera 134, and a heartbeat signal detector 136. The diagnostic device 115a has a monitor 160a. Hereinafter, the monitors 160a and 160b are collectively referred to as the monitor 160.

  The radiation imaging apparatus 110 captures a radiation image of the subject by the operation of the radiologist 180. The radiation imaging apparatus 110 may be a mobile radiation imaging apparatus, and may image a subject by operating the radiation technician 180 in a hospital room where the subject is present or in the subject's home. The radiation imaging apparatus 110 has a plurality of imaging modes including a first imaging mode and a second imaging mode. Hereinafter, an imaging operation of the radiation imaging apparatus 110 in the first imaging mode will be described.

  The radiation imaging apparatus 110 acquires the imaging order of the subject from the server 170 through the communication path 150 and the wireless communication device 152 in the vicinity of the radiation imaging apparatus 110 before imaging the subject. The monitor 140 displays the subject ID, the subject's name, age, sex, weight, imaging location, imaging direction, and doctor ID included in the imaging order.

  The radiologist 180 determines imaging conditions based on the age, sex, weight, and imaging region displayed on the monitor 140, and inputs the determined imaging conditions from the input device 142. The imaging conditions include tube current, tube voltage, aperture diameter of the radiation source 132, and irradiation time. The radiation imaging apparatus 110 may receive imaging conditions from the server 170. The radiation source 132 intermittently irradiates the subject with radiation with an irradiation time shorter than the irradiation time input as the imaging condition. The radiation source 132 irradiates the radiation until the total irradiation time during which the radiation is irradiated becomes substantially the same as the irradiation time input as the imaging condition.

  The radiation detector 120 detects the radiation dose detected from the radiation source 132, and each time radiation is emitted from the radiation source 132, generates a radiation image based on the detected radiation dose and stores it in the memory. The control device 130 wirelessly acquires the radiation image stored in the radiation detector 120 from the radiation detector 120 when radiation irradiation ends. And the control apparatus 130 produces | generates one synthetic | combination image by aligning, after aligning the several radiographic image obtained by intermittent irradiation.

  The visible light camera 134 images the subject's body with light from the subject over a period in which the radiation source 132 emits radiation. Then, the control device 130 calculates the respiratory phase of the subject at the time of capturing the radiation image based on the image of the subject captured by the visible light camera 134, and based on the calculated respiratory phase, The position and size of the person's lung may be corrected. The heartbeat signal detector 136 detects a heartbeat signal of the subject's heart and supplies it to the control device 130. The control device 130 calculates a heartbeat phase at the time of capturing a radiographic image from the heartbeat signal supplied from the heartbeat signal detector 136, and corrects the position and size of the subject's heart based on the calculated heartbeat phase. It's okay.

  Then, the control device 130 transmits the generated composite image to the server 170 through the wireless communication device 152 and the communication path 150. Then, the server 170 stores the composite image received from the radiation imaging apparatus 110 in the database 172.

  As described above, the control device 130 irradiates the radiation intermittently with a time width shorter than the irradiation time capable of obtaining a desired contrast. Thereby, according to the radiation imaging device 110, a plurality of radiation images with a small amount of blur due to the movement of the subject can be obtained. A composite image having a desired contrast can be obtained by aligning and superimposing the obtained radiographic images. Therefore, according to the radiation imaging apparatus 110, even if it has only a low intensity of radiation compared to a stationary imaging apparatus, such as a mobile imaging apparatus, and it is necessary to image with a long exposure time, The blur amount of the radiation image due to the movement of the subject can be reduced.

  The diagnostic device 115 acquires the composite image from the database 172 and displays it on the monitor 160. Doctors 190 a and 190 b (hereinafter collectively referred to as doctor 190) make a diagnosis by looking at the composite image displayed on monitor 160. Although only one radiation imaging apparatus 110 is shown for convenience of drawing, the radiation imaging system 100 may include a plurality of radiation imaging apparatuses 110. Further, the recording of the image data and the series of communication control in the above may be performed according to the DICOM standard. Further, the radiation detector 120 that captures a radiation image of the subject may be a solid radiation detector such as an FPD. The radiation in the present embodiment may be electromagnetic radiation such as X-rays and γ rays, or particle beams such as alpha rays.

  Next, the imaging operation of the radiation imaging apparatus 110 in the second imaging mode will be described. The imaging operation of the radiation imaging apparatus 110 in the second imaging mode is substantially the same as the imaging operation of the radiation imaging apparatus 110 in the first imaging mode, except that the timing at which the radiation detector 120 is exposed to radiation is different from the first imaging mode. Since it is the same, description is abbreviate | omitted except a difference. Also in the second imaging mode, the radiation source 132 intermittently irradiates the subject with radiation with an irradiation time shorter than the irradiation time input as the imaging condition. In the second imaging mode, the radiation source 132 calculates the respiration phase of the subject from the image content of the subject imaged by the visible light camera 134 and emits X-rays at the timing when the calculated respiration phase becomes a predetermined phase. Irradiate. The radiation detector 120 is exposed to radiation in synchronization with the timing at which the radiation source 132 emits X-rays. Whenever the radiation detector 120 exposes the radiation, the control device 130 acquires the dose detected by the radiation detector 120 and generates a radiation image based on the acquired dose. Thereafter, the radiation imaging apparatus 110 generates a composite image by superimposing a plurality of captured radiation images in the same manner as the imaging operation in the first imaging mode.

  FIG. 2 shows an example of a block configuration of the radiation imaging apparatus 110. The radiation imaging system 100 includes a radiation image imaging unit 200, an object extraction unit 210, a motion detection unit 220, a motion correction unit 230, an optical image imaging unit 240, an imaging control unit 250, a composite image generation unit 260, an output unit 270, and radiation. A generator 290 is provided. The radiation image capturing unit 200 includes a radiation detection unit 202. The composite image generation unit 260 includes a signal acquisition unit 262. The radiation source 132 and the radiation detector 120 are examples of the radiation generation unit 290 and the radiation detection unit 202, respectively. The visible light camera 134 and the heartbeat signal detector 136 are examples of the motion detection unit 220. The motion detection unit 220 may be an infrared camera that captures an image of a subject using infrared light. The operation of each component of the radiation imaging apparatus 110 in the first imaging mode will be described below.

  The radiation generating unit 290 irradiates the subject with radiation. The radiographic image capturing unit 200 continuously captures a plurality of radiographic images of the subject using the radiation irradiated from the radiation generating unit 290 and transmitted through the subject. Specifically, the radiation detection unit 202 detects radiation irradiated from the radiation generation unit 290 and transmitted through the subject. The radiographic image capturing unit 200 captures a radiographic image of the subject based on the radiation dose detected by the radiation detection unit 202. More specifically, the radiation generator 290 irradiates the subject with X-rays. Then, the radiographic image capturing unit 200 continuously captures a plurality of radiographic images of the subject by X-rays irradiated from the radiation generating unit 290 and transmitted through the subject.

  The imaging control unit 250 controls the timing and time width at which the radiation generation unit 290 irradiates the subject with radiation and the timing and time width at which the radiation detection unit 202 detects radiation. Specifically, the imaging control unit 250 uses the radiation detection unit to emit radiation irradiated by the radiation generation unit 290 only during a time width in which the amount of blur generated in the radiation image due to the movement of the subject is equal to or less than a predetermined value. 202 to expose. For example, the imaging control unit 250 exposes the radiation detected by the radiation generation unit 290 to the radiation detection unit 202 for a time period sufficiently shorter than the heartbeat cycle of the subject's heart or the breathing cycle of the subject. More specifically, the imaging control unit 250 causes the radiation generation unit 290 to detect the amount of blur generated in the radiographic image due to the periodic movement of the subject at the timing when the radiographic image capturing unit 200 captures a plurality of radiographic images. The subject is irradiated with radiation for a period of time width that is equal to or less than a predetermined value.

  The motion detector 220 detects the motion of the subject. The motion correction unit 230 corrects a change in the plurality of radiographic images due to the motion of the subject detected by the motion detection unit 220 in at least one radiographic image of the plurality of radiographic images captured by the radiographic image capturing unit 200. . Then, the composite image generation unit 260 generates a composite image by superimposing a plurality of radiographic images including the radiographic image corrected by the motion correction unit 230. Then, the output unit 270 outputs the composite image generated by the composite image generation unit 260. For example, the output unit 270 displays the composite image generated by the composite image generation unit 260 on the monitors 140 and 160 or records it in the database 172. Further, the output unit 270 may print the composite image generated by the composite image generation unit 260.

  Specifically, the motion detection unit 220 detects the heartbeat phase of the subject's heart at the timing when the radiographic image capturing unit 200 captures a plurality of radiographic images. Then, the motion correction unit 230 corrects changes in the plurality of radiation images due to the motion of the subject corresponding to the heartbeat phase of the subject detected by the motion detection unit 220.

  In addition, the motion detection unit 220 may detect the respiratory phase of the subject at the timing when the radiographic image capturing unit 200 captures a plurality of radiographic images. Then, the motion correction unit 230 may correct changes in a plurality of radiation images due to the movement of the subject corresponding to the respiratory phase of the subject detected by the motion detection unit 220. Specifically, the optical image capturing unit 240 receives light from the subject's body and continuously captures the optical image of the subject. Then, the motion detection unit 220 detects the respiratory phase of the subject based on the change in the image content of the optical image captured by the optical image capturing unit 240.

The object extraction unit 210 extracts an object from a plurality of radiographic images captured by the radiographic image capturing unit 200. Then, the motion detection unit 220 detects a change in the position of the object extracted by the object extraction unit 210 in a plurality of radiation images. The motion correction unit 230 corrects the change in the position of the object detected by the motion detection unit 220 by correcting the position of the object included in at least one of the plurality of radiation images. Note that the motion detection unit 220 may detect a change in the size of the object extracted by the object extraction unit 210 in a plurality of radiation images. The motion correction unit 230 may correct the change in the size of the object detected by the motion detection unit 220 by correcting the size of the object included in at least one of the plurality of radiation images.

  Note that the radiation generation unit 290 may irradiate radiation having an intensity smaller than a predetermined intensity. For example, the radiation generation unit 290 irradiates the subject with radiation having an intensity smaller than the intensity of the radiation to be irradiated when capturing one radiographic image at each timing when the radiographic image capturing unit 200 captures a plurality of radiographic images. You can do it. More specifically, the radiation generation unit 290 captures radiation with a dose rate smaller than the dose rate of radiation to be irradiated when capturing one radiation image, and the radiation image capturing unit 200 captures a plurality of radiation images. The subject may be irradiated at the timing.

  As described above, according to the radiation imaging apparatus 110, even when it is necessary to image a subject by irradiating radiation at a low dose rate for a long period, the image of the subject due to heartbeat, breathing, etc. The amount of blur can be reduced.

  FIG. 3 shows an example of an imaging flow by the radiation imaging apparatus 110 in the first imaging mode. The radiation generation unit 290 intermittently irradiates X-rays with a predetermined short irradiation time, and the radiation detection unit 202 exposes X-rays in synchronization with the timing at which the radiation generation unit 290 irradiates X-rays. (S302). Thereby, the radiographic image capturing unit 200 captures a plurality of X-ray images of the subject. Note that the optical image capturing unit 240 captures a moving image of the subject including a plurality of visible light images of the subject by receiving visible light from the subject.

  Then, the imaging control unit 250 determines whether a predetermined number of X-ray images have been captured (S304). Specifically, the imaging control unit 250 has captured the number of X-ray images determined by the X-ray irradiation time included in the imaging order and the time width during which the radiation generation unit 290 intermittently irradiates X-rays. Determine whether. For example, when the irradiation time of X-rays included in the imaging order is T and the time width during which the radiation generation unit 290 intermittently irradiates X-rays is t, the imaging control unit 250 includes the radiation image capturing unit 200. It is determined whether or not a number of X-ray images greater than or equal to T / t has been captured.

  In S304, when it is determined that the imaging control unit 250 has captured a predetermined number of X-ray images, the motion detection unit 220 captures a plurality of visible light images captured by the optical image imaging unit 240 at each irradiation timing. The line of the examiner's body is specified (S306). Then, the motion correction unit 230 calculates the shift amounts in the X direction and the Y direction of the image that can match the body lines of the subject in the plurality of visible light images based on the detected positions of the body lines. calculate. Then, the motion correction unit 230 performs correction by shifting the plurality of radiographic images captured by the radiographic image capturing unit 200 by the calculated shift amount, thereby matching the body lines of the subject between the plurality of radiographic images. (S308).

  Further, the object extraction unit 210 extracts the outline of the object from a plurality of radiation images by edge extraction or the like. Then, the motion detection unit 220 identifies lung fields in a plurality of radiographic images by pattern matching between the contour of the object extracted by the object extraction unit 210 and a predetermined lung shape pattern (S310). . Then, the motion correction unit 230 performs correction to match the position and size of the lung field (S312). Then, the composite image generation unit 260 generates one composite image by superimposing the radiographic images subjected to the correction of S312 (S314). Then, the output unit 270 records the composite image generated in S314 in the database 172 or the like.

  In the above explanation, in order to prevent the explanation from becoming complicated, the imaging flow in the case of correcting the overall movement of the subject's body and the movement of the subject due to breathing has been explained. Needless to say, in addition to the correction, a process for correcting the movement of the subject's heart can be added.

  FIG. 4 shows an example of phase information stored in the motion detector 220 in a table format. The motion detection unit 220 stores respiratory phase information in which a ratio of a lung field area in each respiratory phase to a lung field area in a predetermined respiratory phase is associated with the respiratory phase. The motion detection unit 220 compares the time change of the lung field area value in the plurality of radiographic images of the subject with the area ratio-breathing phase data indicated by the respiratory phase information stored in advance. The respiration phase of the subject at each timing when the radiographic image is taken is calculated.

  Further, the motion detection unit 220 stores heart rate phase information in which the ratio of the area of the heart field in each heartbeat phase of the heart field to the area of the heart field in a predetermined heartbeat phase is associated with the heartbeat phase. Yes. Then, the motion detection unit 220 compares the time change of the area value of the heart field in the plurality of radiographic images of the subject with the area ratio-heart rate phase data indicated by the previously stored heart rate phase information. The heartbeat phase of the subject at each timing when the radiographic image is taken is calculated.

  FIG. 5 shows an example of a composite image generated by the composite image generation unit 260. The radiation generation unit 290 repeats X-ray irradiation for a period of time T1 at a predetermined time interval. For example, the radiation generation unit 290 irradiates the subject with X-rays between times t0 and t1. The radiation detection unit 202 detects the X-ray dose irradiated by the radiation generation unit 290 over the period from time t0 to time t1. And the radiographic imaging part 200 reads the signal which shows the dose which the radiation detection part 202 detected in the period of the time t1-t2 with the time length of T2. As described above, the radiographic image capturing unit 200 captures one radiographic image 500 in a period of T1 + T2. By repeating such an imaging operation continuously, the radiographic image capturing unit 200 captures the radiographic image 510 and the radiographic image 520. Although not shown for convenience of drawing, a plurality of radiographic images are also captured between time t2 and time t10 and between time t12 and time t20.

  Then, the motion correction unit 230 performs image processing for correcting the motion of the subject on the radiation images 500, 510, and 520. Here, the motion correction unit 230 performs image processing for correcting the radiographic images 500 and 520, thereby determining the position of the subject, the position of the lung field, and the size of the lung field in the radiographic image 510. , The position of the lung field, and the size of the lung field. Specifically, as described with reference to FIG. 3, the positions of the subject are matched by shifting the radiation images 500 and 520.

  The motion correction unit 230 matches the area and position of the lung field in the radiation image 510 by enlarging or reducing the lung field and the surrounding area of the lung field in the radiation images 500 and 520. In addition, the motion correction unit 230 matches the positions of the lung apexes 501 and 521 with the position of the lung apex 511. In this way, the motion correction unit 230 generates corrected images 501 and 521 in which the movement of the subject in the radiation images 500 and 520 is corrected. Then, the composite image generation unit 260 generates a composite image 550 by superimposing the correction images 501, 510, and 521.

  FIG. 6 shows an example of lung field correction performed by the motion correction unit 230. In this figure, a contour 600 shows the contour of the lung in the first respiratory phase, and a contour 610 shows the contour of the lung in the second respiratory phase. The motion correction unit 230 corrects the movement of the subject due to respiration by enlarging the lung field in the second respiration phase. Note that the motion correction unit 230 may enlarge the lung field at different magnifications in the X direction and the Y direction. Furthermore, the motion correction unit 230 reduces the area around the lung field as the lung field expands. Note that the motion correction unit 230 may store in advance the enlargement ratio for enlarging the lung field and the reduction ratio for the area other than the lung field in association with the first respiratory phase and the second respiratory phase. Further, the motion correction unit 230 may match the position of the reference point such as the lung apex 601 between the plurality of radiation images by adjusting the enlargement ratio and the reduction ratio.

  Further, the motion correction unit 230 may store in advance the movement vector for moving each part in the radiation image together with the enlargement ratio and the reduction ratio in association with the first respiratory phase and the second respiratory phase. Then, the motion correction unit 230 corrects the radiation image of the subject using the enlargement rate or reduction rate stored in advance in association with the respiratory phase and the movement vector. As described above, the motion correction unit 230 corrects the motion of the subject in the plurality of radiographic images by changing the radiographic image according to the change amount determined in advance in association with the respiratory phase.

  In FIGS. 5 and 6, an example of a correction method for correcting the movement of the subject by deforming the radiation image according to the respiratory phase has been described. By deforming the radiographic image, it is possible to correct the movement of the subject's heart.

  Next, the operation of the radiation imaging apparatus 110 in the second imaging mode will be described. In the following description, the description of the operation that is substantially the same as the operation of each component in the first imaging mode is omitted, and the difference from the operation of each component in the first imaging mode is mainly described.

  The motion detector 220 detects a periodic motion of the subject. The radiographic image capturing unit 200 includes a plurality of radiographic images of the subject at the timing at which the motion phases detected by the motion detecting unit 220 are substantially the same as the radiation irradiated from the radiation generating unit 290 and transmitted through the subject. Image. Specifically, the radiographic image capturing unit 200 detects the subject's phase at the timing when the phase of the motion detected by the motion detection unit 220 is approximately the same by the X-rays emitted from the radiation generation unit 290 and transmitted through the subject. A plurality of radiographic images are taken.

  Note that, at the timing when the motion phases detected by the motion detection unit 220 are substantially the same, the imaging control unit 250 causes the amount of blur generated in the radiographic image due to the periodic motion of the subject to be a predetermined value or less. The radiation detection unit 202 is exposed to the radiation emitted by the radiation generation unit 290 for the time width. Note that the imaging control unit 250 determines in advance the amount of blur generated in the radiation image due to the periodic motion of the subject at the timing when the phase of the motion detected by the motion detection unit 220 is substantially the same. Radiation may be irradiated for a time width that is less than or equal to the given value.

  Then, the composite image generation unit 260 generates a composite image by superimposing a plurality of radiation images continuously captured by the radiation image capturing unit 200. The motion detector 220 detects the heartbeat phase of the subject's heart. Then, the radiographic image capturing unit 200 receives a plurality of radiographic images of the subject at a timing at which the heartbeat phases detected by the motion detecting unit 220 are substantially the same by the radiation irradiated from the radiation generating unit 290 and transmitted through the subject. Take an image.

  Further, the motion detection unit 220 may detect the respiratory phase of the subject. The radiation image capturing unit 200 includes a plurality of lungs including the lungs of the subject at the timing at which the respiratory phases detected by the motion detection unit 220 are substantially the same as the radiation irradiated from the radiation generation unit 290 and transmitted through the subject. A radiographic image is taken.

  The radiation detection unit 202 generates a signal that is generated according to the amount of radiation emitted from the radiation generation unit 290 and transmitted through the subject at a plurality of timings when the motion phases detected by the motion detection unit 220 are substantially the same. May accumulate. And the signal detection part 262 acquires the signal which the radiation detection part 202 accumulate | stored, and produces | generates a synthesized image from the acquired signal. The radiation detection unit 202 accumulates the amount of charge generated according to the amount of radiation emitted from the radiation generation unit 290 and transmitted through the subject at a plurality of timings when the motion phases detected by the motion detection unit 220 are substantially the same. You can do it. The signal detection unit 262 may acquire the charge amount accumulated by the radiation detection unit 202 and generate a composite image from the acquired charge amount. Since the radiation imaging apparatus 110 does not need to read image data at each timing in the second imaging mode, the radiation detection unit 202 uses an imaging plate that uses a radiation film or a photostimulable phosphor that is sensitive to radiation. Can be used. Of course, the radiation detection unit 202 may be an FPD.

  As described above, according to the radiation imaging apparatus 110, imaging can be performed in substantially the same respiratory phase and heartbeat phase, so that the amount of blur can be reduced.

  FIG. 7 shows an example of an imaging flow by the radiation imaging apparatus 110 in the second imaging mode. The optical image capturing unit 240 captures a visible light image of at least one cycle of breathing while causing the subject to breathe (S702). Further, the imaging control unit 250 identifies the breathing cycle of the subject based on the image captured by the optical image imaging unit 240 (S704). For example, the imaging control unit 250 may specify the length of a period in which the thickness of the chest or abdomen of the subject is a maximum as the respiratory cycle. In addition, the imaging control unit 250 may allow the subject to breathe through the bellows and specify the breathing cycle based on the length of the bellows. In addition, the imaging control unit 250 does not necessarily specify the respiratory cycle from the visible light image, and may specify the respiratory cycle by a respirometer or the like that measures exhalation and inspiratory flow.

  The motion detector 220 detects the respiratory phase of the subject. Then, the imaging control unit 250 predicts the timing at which the lung size is maximized based on the respiratory phase of the subject detected by the motion detection unit 220 (S706). The imaging control unit 250 causes the radiation generation unit 290 to irradiate X-rays at the timing predicted in S <b> 706, and causes the radiation detection unit 202 to X in synchronization with the timing at which the radiation generation unit 290 irradiates X-rays. The line is exposed (S708). The radiographic image capturing unit 200 captures one X-ray image from the X-ray dose obtained by exposure and stores it in the memory (S710).

  Then, the imaging control unit 250 determines whether or not a predetermined number of X-ray images have been captured (S712). Note that the determination method in S712 is the same as the determination method in S304 of FIG. In S712, when the imaging control unit 250 determines that a predetermined number of X-ray images have not been captured, the process waits until the timing when the lung size becomes maximum (S714). Here, the weighting may be performed for one respiratory cycle specified in S704, or may be performed until the thickness of the chest or abdomen by the optical image capturing unit 240 is maximized. Then, after waiting, the process proceeds to S708. By repeating this operation, the radiographic image capturing unit 200 can capture a plurality of radiographic images in substantially the same respiratory phase.

  When the imaging control unit 250 determines that a predetermined number of X-ray images have been captured in S712, the composite image generation unit 260 generates a composite image by superimposing a plurality of radiographic images captured in S708, The output unit 270 records the generated composite image in the database 172 or the like (S716), and ends the process. When the radiation detection unit 202 is an imaging plate using a radiation film or a photostimulable phosphor that is sensitive to radiation, it is only necessary to expose the radiation detection unit 202 to X-rays in S708. In step S716, the output unit 270 may output a radiation image obtained by reading the exposed X-ray dose as a composite image.

  In the above description, in order to prevent the description from becoming complicated, the imaging flow in the case of capturing a radiographic image at a timing at which the subject's respiratory phase is substantially the same has been described. It goes without saying that a radiographic image can be taken at a timing at which the heartbeat phases of the hearts are substantially the same. The radiographic image capturing unit 200 can also capture a plurality of radiographic images at the timing when both the respiratory phase and the heartbeat phase are substantially the same.

  FIG. 8 shows an example of a composite image generated by the composite image generation unit 260. As described with reference to FIG. 5, the radiation detection unit 202 is exposed to X-rays having an exposure time T0, and the X-ray dose is read from the radiation detection unit 202 by the radiation detection unit 202 at a readout time T1. Thereby, radiation images 820, 821, and 823 are obtained. Then, the composite image generation unit 260 generates a composite image 850 by superimposing the captured radiographic images 820, 821, and 823.

  FIG. 9 shows an exemplary hardware configuration of the radiation imaging apparatus 110. The radiation imaging apparatus 110 includes a CPU peripheral unit having a CPU 1505, a RAM 1520, a graphic controller 1575, and a display device 1580 connected to each other by a host controller 1582, and communication connected to the host controller 1582 by an input / output controller 1584. An input / output unit having an interface 1530, a hard disk drive 1540, and a CD-ROM drive 1560, and a legacy input / output unit having a ROM 1510, a flexible disk drive 1550, and an input / output chip 1570 connected to the input / output controller 1584. .

  The host controller 1582 connects the RAM 1520, the CPU 1505 that accesses the RAM 1520 at a high transfer rate, and the graphic controller 1575. The CPU 1505 operates based on programs stored in the ROM 1510 and the RAM 1520 and controls each unit. The graphic controller 1575 acquires image data generated by the CPU 1505 and the like on a frame buffer provided in the RAM 1520 and displays the image data on the display device 1580. Alternatively, the graphic controller 1575 may include a frame buffer that stores image data generated by the CPU 1505 or the like.

  The input / output controller 1584 connects the host controller 1582 to the hard disk drive 1540, the communication interface 1530, and the CD-ROM drive 1560, which are relatively high-speed input / output devices. The hard disk drive 1540 stores programs and data used by the CPU 1505. The communication interface 1530 is connected to the network communication device 1598 to transmit / receive programs or data. The CD-ROM drive 1560 reads a program or data from the CD-ROM 1595 and provides it to the hard disk drive 1540 and the communication interface 1530 via the RAM 1520.

  The input / output controller 1584 is connected to the ROM 1510, the flexible disk drive 1550, and the relatively low-speed input / output device of the input / output chip 1570. The ROM 1510 stores a boot program executed when the radiation imaging apparatus 110 is started, a program depending on the hardware of the radiation imaging apparatus 110, and the like. The flexible disk drive 1550 reads a program or data from the flexible disk 1590 and provides it to the hard disk drive 1540 and the communication interface 1530 via the RAM 1520. The input / output chip 1570 connects various input / output devices via a flexible disk drive 1550 and, for example, a parallel port, a serial port, a keyboard port, a mouse port, and the like.

  A program executed by the CPU 1505 is stored in a recording medium such as the flexible disk 1590, the CD-ROM 1595, or an IC card and provided by the user. The program stored in the recording medium may be compressed or uncompressed. The program is installed in the hard disk drive 1540 from the recording medium, read into the RAM 1520, and executed by the CPU 1505.

  The program executed by the CPU 1505 causes the radiation imaging apparatus 110 to perform the radiation image capturing unit 200, the object extraction unit 210, the motion detection unit 220, the motion correction unit 230, and the optical image capturing unit 240 described with reference to FIGS. The imaging control unit 250, the composite image generation unit 260, the output unit 270, the radiation generation unit 290, the radiation detection unit 202, and the signal acquisition unit 262 function.

  The program shown above may be stored in an external storage medium. As the storage medium, in addition to the flexible disk 1590 and the CD-ROM 1595, an optical recording medium such as a DVD or PD, a magneto-optical recording medium such as an MD, a tape medium, a semiconductor memory such as an IC card, or the like can be used. Further, a storage device such as a hard disk or a RAM provided in a server system connected to a dedicated communication network or the Internet may be used as a recording medium, and the program may be provided to the radiation imaging apparatus 110 via the network.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

1 is a diagram illustrating an example of a usage environment of a radiation imaging system 100. FIG. 1 is a diagram illustrating an example of a block configuration of a radiation imaging system 100. FIG. It is a figure which shows an example of the imaging flow by the radiation imaging device 110 in 1st imaging mode. It is a figure which shows an example of the phase information which the motion detection part 220 has stored in the table format. It is a figure which shows an example of the synthesized image which the synthesized image production | generation part 260 produces | generates. It is a figure which shows the example of correction | amendment of the lung field by the motion correction part. It is a figure which shows an example of the imaging flow in 2nd imaging mode. It is a figure which shows an example of the synthesized image which the synthesized image production | generation part 260 produces | generates. It is a figure which shows an example of the hardware constitutions of the radiation imaging device.

Explanation of symbols

100 Radiation Imaging System 110 Radiation Imaging Device 115 Diagnostic Device 120 Radiation Detector 130 Control Device 132 Radiation Source 134 Visible Light Camera 136 Heartbeat Signal Detector 140 Monitor 142 Input Device 150 Communication Path 152 Wireless Communication Device 160 Monitor 162 Input Device 170 Server 172 Database 180 Radiologist 190 Doctor 200 Radiation imaging unit 202 Radiation detection unit 210 Object extraction unit 220 Motion detection unit 230 Motion correction unit 240 Optical image imaging unit 250 Imaging control unit 260 Composite image generation unit 262 Signal acquisition unit 270 Output unit 290 Radiation Generator

Claims (11)

A radiation generator for irradiating the subject with radiation;
A radiation image capturing unit that continuously captures a plurality of radiation images of the subject by a radiation detection unit that detects radiation irradiated from the radiation generation unit and transmitted through the subject;
A motion detector for detecting the motion of the subject;
At the timing when the radiographic image capturing unit captures the plurality of radiographic images, the amount of blur generated in the plurality of radiographic images due to the periodic movement of the subject in the radiation generating unit is equal to or less than a predetermined value. An imaging control unit that irradiates the subject with radiation only for a period of time width, and exposes the radiation irradiated by the radiation generation unit only for the period of time width to the radiation detection unit,
A motion correction unit that corrects a change in the plurality of radiographic images due to movement of the subject detected by the motion detection unit in at least one radiographic image captured by the radiographic image capturing unit;
A radiation imaging apparatus comprising: a composite image generation unit that generates a composite image by superimposing the plurality of radiation images, including the radiation image corrected by the motion correction unit. An object extraction unit for extracting an object from the plurality of radiation images;
The motion detection unit detects a change in the position of the object extracted by the object extraction unit in the plurality of radiation images;
The radiation imaging according to claim 1, wherein the motion correction unit corrects a change in the position of the object detected by the motion detection unit by correcting a position of an object included in at least one of the plurality of radiation images. apparatus. An object extraction unit for extracting an object from the plurality of radiation images;
The motion detection unit detects a change in size of the object extracted by the object extraction unit in the plurality of radiation images;
The said movement correction | amendment part correct | amends the change of the magnitude | size of the object which the said movement detection part detected by correct | amending the magnitude | size of the object contained in at least 1 in these radiation images. Radiation imaging device. The motion detection unit detects a heartbeat phase of a subject's heart at a timing when the radiographic image capturing unit captures the plurality of radiographic images;
The motion compensation unit, according to any one of claims 1 to 3, compensate for changes in the plurality of radiographic images due to the movement of the subject in which the motion detection unit corresponding to the cardiac phase of the subject detected Radiation imaging device. The motion detection unit detects a respiratory phase of the subject at a timing when the radiographic image capturing unit captures the plurality of radiographic images;
The motion compensation unit, according to any one of claims 1 to 3, compensate for changes in the plurality of radiographic images due to the movement of the subject in which the motion detection unit corresponding to the respiratory phase of the subject detected Radiation imaging device. A light image capturing unit that receives light from the subject body and continuously captures a light image of the subject;
The radiation imaging apparatus according to claim 5, wherein the motion detection unit detects a respiratory phase of the subject based on a change in image content of the optical image captured by the optical image imaging unit.   The imaging control unit is shorter than the irradiation time of radiation input as the imaging condition to the radiation generation unit until the total irradiation time of radiation irradiation is substantially the same as the irradiation time input as the imaging condition. Subject is exposed to radiation intermittently over a period of time
The radiation imaging apparatus according to any one of claims 1 to 6. The radiation generator irradiates the subject with X-rays,
The radiographic image capturing unit, the X-rays transmitted through the being irradiated subject from the radiation generating unit, to any one of claims 1 to continuously capture a plurality of radiation images of the subject 7 The radiation imaging apparatus described. A program for causing a computer to function as the radiation imaging apparatus according to any one of claims 1 to 8. An irradiation stage for irradiating the subject with radiation from the radiation generation unit; and
The radiation detecting section for detecting radiation the radiation generating unit is transmitted through the subject is irradiated, a radiation imaging step for continuously taking a plurality of radiographic images of the subject,
A motion detection stage for detecting the motion of the subject;
At the timing of capturing the plurality of radiation images, the radiation generation unit emits radiation for a period of time width in which the amount of blur generated in the plurality of radiation images due to the periodic movement of the subject is equal to or less than a predetermined value. An imaging control step of exposing the radiation to the subject and exposing the radiation emitted by the radiation generation unit only for a period of the time width,
A motion correction step of correcting a change in the plurality of radiation images due to the movement of the subject detected in the motion detection step in at least one radiation image in the plurality of radiation images captured in the radiation image capturing step;
A radiation imaging method comprising: a composite image generation step of generating a composite image by superimposing the plurality of radiation images including the radiation image corrected in the motion correction step.   The imaging control step is shorter than the irradiation time of radiation input as the imaging condition in the radiation generation unit until the total irradiation time of radiation irradiation is substantially the same as the irradiation time input as the imaging condition. Subject is exposed to radiation intermittently over a period of time
The radiation imaging method according to claim 10.

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