JP6274484B2 - X-ray computed tomography system - Google Patents

Description

  Embodiments described herein relate generally to an X-ray computed tomography apparatus.

  In general, an X-ray computed tomography apparatus (hereinafter referred to as an X-ray CT apparatus) is an apparatus that can take a tomographic image (diagnosis image) of a subject by scanning the subject with X-rays. is there.

  By the way, when starting tomography of a subject in an X-ray CT apparatus, it is necessary to make a scan plan. In this scan plan, various scan conditions such as a scan start position and a stop position are set using a scanogram. The scanogram is obtained by scanography performed by moving the top plate on which the subject is placed in the direction of the body axis of the subject while the rotation of the X-ray tube and the X-ray detector is stopped. It is a plane transmission image of a specimen.

  Further, at the time of the scan planning described above, in order to appropriately set the scan conditions described above, for example, scan images from the front and side surfaces of the subject are generally presented to the user as three-dimensional information.

JP 2004-298247 A

  However, when presenting a scano image from the front and side in the above scan plan, two scans (scano imaging) are required. Performing two scans in this way is not efficient because the examination time is long, and is not preferable in that the exposure dose of the subject is easily affected by body movement.

  Therefore, the problem to be solved by the present invention is to provide an X-ray computed tomography apparatus capable of efficiently obtaining a scanogram required for setting scan conditions.

  According to the embodiment, an X-ray computed tomography apparatus that performs scanography in order to obtain scanograms necessary for setting various scan conditions is provided.

An X-ray computed tomography apparatus according to an embodiment includes an X-ray tube that generates X-rays irradiated on a subject, and a plurality of detections that detect X-rays generated from the X-ray tube and transmitted through the subject An X-ray detector in which element rows are arranged along the body axis direction of the subject, and a line-of-sight angle with respect to the body axis direction of the subject specified by the user among the plurality of detection element rows Specifying means for specifying at least two detector element rows adjacent to a position on the X-ray detector;
Generating means for generating a scanogram relating to the subject according to the angle of the line of sight based on the output data from the specified at least two detection element arrays .

The figure which shows the structure of the X-ray computed tomography apparatus which concerns on embodiment. The figure for demonstrating schematically the structure of the X-ray detector 12 shown in FIG. The figure for demonstrating the positional relationship of an X-ray tube and the X-ray detector 12. FIG. The flowchart which shows the process sequence at the time of the scanography in the X-ray CT apparatus which concerns on this embodiment. The figure for demonstrating the position on the X-ray detector 12 corresponding to the angle | corner (theta) of the gaze calculated in step S2 of FIG. 4, and two detection element rows specified in step S3.

  Hereinafter, embodiments will be described with reference to the drawings.

  FIG. 1 shows a configuration of an X-ray computed tomography apparatus (hereinafter referred to as an X-ray CT apparatus) according to the present embodiment.

  As shown in FIG. 1, the X-ray CT apparatus is required for a gantry 1 configured to collect projection data relating to a subject, and for various signal processing such as control of the gantry 1 and image reconstruction. It has a console 2 that houses a plurality of modules.

  The gantry 1 includes an X-ray tube device 11, an X-ray detector 12, a data acquisition device (DAS: Data Acquisition System) 13, and an X-ray control / high voltage generator 14.

  The X-ray tube device 11 and the X-ray detector 12 are mounted on a ring-shaped frame (hereinafter referred to as a rotating frame) that is rotationally driven. That is, the X-ray tube device 11 and the X-ray detector 12 are rotatably supported on the gantry 1. Further, the X-ray tube device 11 and the X-ray detector 12 are opposed to each other with an imaging region S into which the subject is inserted at the time of imaging.

  The X-ray tube apparatus 11 has an X-ray tube (sphere) that generates X-rays. This X-ray tube has, for example, a cathode and an anode, a tube voltage is applied between the cathode and the anode of the X-ray tube, and a filament current is supplied to the cathode filament of the X-ray tube. By such tube voltage application and filament current supply, X-rays are generated from a target such as tungsten at the anode of the X-ray tube.

  The X-ray detector 12 detects X-rays generated from the X-ray tube and transmitted through the subject inserted in the imaging region S. The X-ray detector 12 has a plurality of detection elements arranged in a two-dimensional manner. For example, the plurality of detection elements are arranged along an arc centered on the rotation axis of the rotation frame described above. The arrangement direction of the detection elements along this arc is called a channel direction. A plurality of detection elements arranged along the channel direction is called a detection element array. Further, the plurality of detection element rows are arranged along the row direction along the rotation axis of the rotation frame (that is, the body axis direction of the subject). Each of these detection elements detects X-rays generated from the X-ray tube, and supplies output data including a count of the detected X-rays to the data acquisition device 13.

  The data collection device 13 collects output data from the X-ray detector 12. Data (projection data) collected by the data collection device 13 is supplied to the console 2.

  The X-ray control / high voltage generator 14 includes a high voltage generator and an X-ray controller (not shown). The high voltage generation unit generates a tube voltage applied to the X-ray tube in order to generate X-rays from the X-ray tube.

  The X-ray control unit controls the generation of X-rays by controlling the high voltage generation unit according to, for example, a scanning condition set by a user (operator).

  The console 2 includes an operation unit 21 for an operator to input scan conditions and the like, a control unit 22 for controlling the entire apparatus in accordance with the scan conditions set by the operator, and a data collection device. And a reconstruction unit 23 for reconstructing an image (tomographic image) relating to the cross section of the subject based on the data collected by the computer 13.

  In the X-ray CT apparatus according to the present embodiment, for example, when the user sets various scan conditions (that is, at the time of scan planning), scanography is performed to obtain a scanogram (scanogram). In the scanography, the top plate (not shown) on which the subject is placed in a state where the rotation of the X-ray tube device 11 (X-ray tube) and the X-ray detector 12 is stopped is the body axis of the subject. It is done while moving in the direction. The scano image obtained by performing this scano imaging is a plane transmission image of the subject. The user can set various scanning conditions based on such a scanogram.

  The reconstructing unit 23 provided in the console 2 described above is used by the user among the plurality of detection element arrays arranged along the body axis direction of the subject in the X-ray detector 12 at the time of such scanography. Based on the output of the detection element array corresponding to the angle of the line of sight with respect to the body axis direction of the specified subject, a scan image relating to the subject corresponding to the angle of the line of sight is generated.

  Hereinafter, an operation at the time of scanography in the X-ray CT apparatus according to the present embodiment will be described. Here, as the X-ray detector 12 described above, an X-ray detector of SW (mm) × Nseg (column), Mch (channel) is used as shown in FIG. That is, the X-ray detector 12 has a plurality of detection elements 100 mounted thereon, and a plurality of detection element arrays 110 made up of a plurality of detection elements arrayed along the channel direction are arranged in the body axis direction (here, N arrays). ) It shall be arranged. SW is the width (element width) of the detection element in the body axis direction. Here, for convenience of explanation, it is assumed that the X-ray detector 12 as shown in FIG. 2 is used, but the X-ray detector 12 having another configuration (structure) may be used.

  The positional relationship between the X-ray tube (X-ray tube device 11) and the X-ray detector 12 is as shown in FIG. 3, and the distance between the X-ray tube and the X-ray detector 12 is FDD. It shall be.

  Note that the information about the configuration of the above-described X-ray detector 12 (detection elements and the like mounted thereon) and the distance between the X-ray tube and the X-ray detector 12 and the like are included in the reconfiguration unit 23 provided on the console 2 ( ) It is assumed that it is held in advance inside.

  Here, FIG. 4 is a flowchart showing a processing procedure at the time of scanography in the X-ray CT apparatus according to the present embodiment.

  First, the data collection device 13 collects output data (X-ray count) from each detection element mounted on the X-ray detector 12 in scanography (step S1). The scanography is performed while moving the top plate on which the subject is placed in the direction of the body axis of the subject in a state where the rotation of the X-ray tube apparatus 11 and the X-ray detector 12 is stopped as described above. Is called. Data collected by the data collection device 13 (hereinafter referred to as collected data) is supplied to the reconstruction unit 23 provided in the console 2. The reconstruction unit 23 generates a scanogram based on the collected data.

  Thus, when a scanogram is generated based on the collected data supplied from the data collection device 13, the user can view the subject's line of sight in the body axis direction via the operation unit 21 provided in the console 2. You can specify the angle. In the following description, the line-of-sight angle designated by the user is referred to as the line-of-sight angle θ. The range of values that can be specified as the line-of-sight angle θ is determined in advance by the configuration of the X-ray detector 12 described above, the distance FDD between the X-ray tube and the X-ray detector 12, and the like.

  Here, the reconstruction unit 23 calculates a position SegPos on the X-ray detector 12 corresponding to the line-of-sight angle θ (step S2). This position SegPos is calculated by SegPos = FDD * sin θ / SW.

  Next, the reconstruction unit 23 identifies at least two detection element arrays adjacent to the calculated position SegPos among the plurality of detection element arrays arranged in the body axis direction of the subject in the X-ray detector 12. (Step S3).

  If at least two detection element arrays adjacent to the calculated SegPos are Seg1 and Seg2, Seg1 is specified by Seg1 = ceil (SegPos), and Seg2 is specified by Seg2 = floor (SegPos).

  Next, the reconstruction unit 23 calculates the X-ray count 203 at the calculated position SegPos (step S4).

Here, the count of the X-rays at the position SegPos (that is, the position on the X-ray detector 12 corresponding to the line-of-sight angle θ) is, as shown in FIG. 5, two detection element arrays adjacent to the position SegPos. That is, it is calculated by performing a complementary operation based on output data (X-ray count) 201 and 202 from (Seg1 and Seg2 specified in step S3). Specifically, the X-ray count at the position SegPos is calculated from the following equation (1).

  In this equation (1), Ray_InterP represents the X-ray count at the position SegPos. Ray (Seg, z) represents the count of X-rays detected by the detection element array Seg at the couch (bed) position z. This Ray (Seg, z) can be acquired from the collected data described above.

  This Ray_InterP is calculated for each Ch. Thereby, data corresponding to the output data from the detection element array at the position SegPos can be obtained. Ray_InterP is calculated for each position of the top board.

  Next, the reconstruction unit 23 is based on Ray_InterP calculated as described above (that is, the X-ray count at the position SegPos on the X-ray detector 12 corresponding to the line-of-sight angle θ designated by the user). Thus, data for the scano image projected at the angle θ of the line of sight is generated (step S5).

  Based on the generated scano image data, the reconstruction unit 23 displays a scano image related to the subject in accordance with the line-of-sight angle θ (step S6). The user can set various scanning conditions with reference to the scanogram displayed in this way.

  Here, if the scan condition cannot be appropriately set only by the scanogram displayed in step S6, the user gives an instruction to change the above-described line-of-sight angle θ via the operation unit 21, for example. can do.

  As described above, when the user gives an instruction to change the line-of-sight angle θ (YES in step S7), the process returns to the above-described step S2 and is repeated. In other words, in this case, for example, the processes in steps S2 to S6 described above are executed based on the changed line-of-sight angle θ ′ designated by the user.

  On the other hand, when the setting of the scan condition is completed and the user does not give an instruction to change the line-of-sight angle θ (NO in step S7), the process is terminated.

  If one detection element array can be specified by the position SegPos calculated in step S3, the process in step S4 is omitted, and scano image data is generated based on the output data of the detection element array. It doesn't matter.

  As described above, in the present embodiment, the angle of the line of sight with respect to the body axis direction of the subject designated by the user among the plurality of detection element arrays arranged along the body axis direction of the subject in the X-ray detector 12. Based on the output data from the detection element array corresponding to, the scan image related to the subject according to the angle of the line of sight is generated, so that the scan image necessary for setting the scan condition can be efficiently obtained. Become.

  Further, in the present embodiment, the subject according to the angle of the line of sight is changed based on the output data from the detection element array corresponding to the angle of the line of sight specified by the user. Since the scanogram is updated every time the gaze angle is changed, the scanogram (scanogram) can be observed as if the user is moving the gaze up and down. . According to this, for example, it is possible to grasp the overlap of organs and the like inside the subject without observing a scanogram from the side surface, and therefore it is possible to set appropriate scanning conditions.

  That is, in the present embodiment, scan images (three-dimensional information) at various angles in the body axis direction of the subject can be efficiently referred to by one scan scan without performing multiple scan scans. It becomes possible to make a scan plan more efficiently.

  In the present embodiment, it is also possible to display the scanogram as a three-dimensional image by simultaneously generating a scanogram for each of a plurality of different viewpoints (gaze angles). That is, according to such a configuration, the user can observe a scanogram on a 3D display, for example. Note that it is also possible to adopt a configuration in which a scan image is automatically generated for each of a plurality of different gaze angles and the three-dimensional display is performed even if the gaze angle is not specified by the user.

  In this embodiment, a scan image (data) is generated based on output data from two detection element arrays adjacent to a position on the X-ray detector 12 corresponding to the line-of-sight angle designated by the user. However, for example, scan image data corresponding to the line-of-sight angle designated by the user may be generated by performing a complementary operation using output data from four detection element arrays as sources. Absent.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1 ... Base, 2 ... Console, 11 ... X-ray tube apparatus, 12 ... X-ray detector, 13 ... Data acquisition device, 14 ... X-ray control and high voltage generator, 21 ... Operation part, 22 ... Control part, 23: Reconstruction unit.

Claims (5)

In an X-ray computed tomography apparatus that performs scanography to obtain a scanogram necessary for setting various scan conditions,
An X-ray tube for generating X-rays irradiated on the subject;
An X-ray detector in which a plurality of detection element arrays that detect X-rays generated from the X-ray tube and transmitted through the subject are arranged along the body axis direction of the subject;
Specification that specifies at least two detection element rows adjacent to positions on the X-ray detector according to the angle of the line of sight with respect to the body axis direction of the subject specified by the user among the plurality of detection element rows Means,
On the basis of the output data from the identified at least two row of detecting elements, and generating means for generating a scanogram related to the subject according to the angle of the line of sight,
Comprising an X-ray computed tomography apparatus. Said specifying means, the angle of the visual line, based on the distance and the body axis direction of the element width of the plurality of detection element arrays between the X-ray detector and the X-ray tube, the angle of the pre-Symbol vision line wherein that identifies the position on the X-ray detector, X-rays computed tomography system according to claim 1, wherein in response to. A calculation means,
The output data of the detection element array includes an X-ray count ,
The calculating means, the specific location on the X-ray detector, before Kitoku constant has been at least 2 that is at least two counts and before Kitoku constant of the X-rays included in the output data from the detector element array One of the basis of the position of the detecting element array, to calculate the count of the X-ray at the position on the front Kitoku constant X-ray detector,
The generating means generates the scanogram based on the calculated X-ray count .
X-ray computed tomography apparatus 請 Motomeko 2 wherein. Further comprising display means,
The generating means generates the scanano image for each of a plurality of different gaze angles,
The display means displays the scanogram generated for each of the plurality of different gaze angles as a three-dimensional image ;
X-ray computed tomography apparatus 請 Motomeko 1 wherein. Further comprising changing means for changing the angle of the pre-Symbol vision line,
The generation unit, based on the output data from the detector element rows corresponding to the angle of the altered line of sight, to generate the scanogram image according to the angle of the line of sight,
X-ray computed tomography apparatus 請 Motomeko 1 wherein.

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