JP5634539B2 - X-ray imaging device - Google Patents

Description

  The present invention relates to an X-ray imaging apparatus that captures an X-ray image of a breast of a subject by X-ray irradiation.

  Various improvements have been proposed for mammography apparatuses that take X-ray fluoroscopic images of breasts and breasts.

  For example, Patent Document 1 discloses a technique for acquiring three-dimensional data and calculating volume data for the purpose of increasing the amount of diagnostic information.

  Patent Document 2 discloses a technique for obtaining an image including three-dimensional data without compressing the subject's chest and calculating volume data and the like.

JP 2003-116825 A JP 2004-105729 A

  It is well known that the incidence of breast cancer near the axilla is high. This is why the medio-lateral oblique (MLO) is adopted as the imaging direction in X-ray mammography. If a whole body CT scanner that can take a tomographic image of the entire torso of a subject can be used, the axilla can also be imaged. However, there is a drawback in that it exposes a part unnecessary for diagnosis and the reconstruction area is large. As a result, the resolution of the image is insufficient. That is, it is required for the mammographic CT imaging apparatus to appropriately scan a portion close to the axilla. However, the conventional technology does not satisfy the requirement.

  In addition, when performing an operation for removing a breast cancer portion while referring to a photographed CT image, a CT image having the same posture as the posture of the patient at the time of surgery (that is, the supine position) is required. However, except for whole body CT, there was no technique for X-ray mammography in the supine position.

  An object of the present invention is to provide an X-ray imaging apparatus that solves at least one of these problems.

According to one aspect of the present invention, an X-ray imaging apparatus that captures an X-ray image of a subject 's breast has a space for accommodating the subject 's breast, and sandwiches the space. A scan frame that holds an X-ray generation unit and an X-ray detection unit provided at opposite positions, and the X-ray generation unit and the X-ray detection unit swivel around the breast to rotate the breast. to perform a scan to collect transmission data from the direction, and the angular distance adjusting unit for adjusting the distance between the inclination angle and the scan frame and the object of the scan frame, the scan frame through the angular distance adjuster the has a support frame for supporting lifting, and the angular distance adjusting unit, based on the transmission data including the subject of the breast obtained by prescanning for collecting transmission data without rotating the scan frame , X-rays imaging apparatus and adjusting the inclination angle and the distance is provided.

  According to the X-ray imaging apparatus of the present invention, a portion close to the axilla can be appropriately scanned. In addition, X-ray mammography can be performed in the supine position.

1 is an overall configuration diagram of an X-ray imaging apparatus in an embodiment. , It is a figure which shows the detailed structure of the scan frame in embodiment. It is a figure which shows the reconstruction area which the scan frame in embodiment forms. 3D image of the reconstructed breast It is a figure explaining the process of the transmission data collected from the scan frame in embodiment. It is a figure explaining scan frame position adjustment based on transmission data in an embodiment. It is a figure explaining the scan frame position adjustment using the histogram analysis of the transmission data in an embodiment. It is a figure explaining the scanning plan based on whole body CT data in an embodiment. It is a figure which shows the structural example in the case of having further having a whole body CT scanner apparatus. It is a figure explaining the example of the setting of the milestone in the scan plan in embodiment, and the image produced | generated. It is a figure explaining the prescan by step movement and spiral movement. It is a figure explaining the example which divides | segments an inspection part and scans in multiple times. It is a figure explaining the example which provided the X-ray bundle change part for reducing a reconstruction area | region. FIG. 3 is a conceptual diagram in which a standard reconstruction area is divided into reduced reconstruction areas and three scans are performed. It is a whole block diagram of the X-ray image imaging device which concerns on a modification.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited to the following embodiment, It shows only the specific example advantageous for implementation of this invention. In addition, not all combinations of features described in the following embodiments are indispensable as means for solving the problems of the present invention.

  FIG. 1 is a diagram showing an overall configuration of an X-ray imaging apparatus 100 in the present embodiment. The subject 1 is placed on the table 2 in a supine position. The table support portion 3 that supports the table 2 has a slide mechanism (not shown). The subject 1 is inserted into the through-hole portion formed in the gantry 4 by the slide of the table 2. A support frame 5 is arranged in an arc shape on the gantry 4. In FIG. 1, the support frame 5 has 360 degrees, but it only needs to extend in the shoulder width direction of the subject 1 placed on the table 2 in the supine position, and may be, for example, only the upper circle portion. A scan frame 6 is attached to the support frame 5 toward the subject 1. A space for accommodating the breast, which is the examination portion 9 of the subject 1, is formed at the tip of the scan frame 6, and the X-ray generator 7 and the two-dimensional X-ray detection that face each other across the space Part 8 is held. Inspection is performed by rotating the scan frame 6 so that the X-ray generation unit 7 and the two-dimensional X-ray detection unit 8 rotate around the breast that is the inspection part 9 during the X-ray exposure from the X-ray generation unit 7. X-ray transmission data from the multi-direction (360-degree direction) of the portion 9 is collected (scanning). The computer 50 connected to the gantry 4 and functioning as an operation console and an image processing apparatus can reconstruct the cross section of the inspection portion 9 by performing reverse radon conversion on the transmission data and display it on the monitor 51.

  2 and 3 are detailed views of the scan frame 6. FIG. FIG. 2 shows the case where the scan frame 6 is mounted perpendicular to the support frame 5. The scan frame 6 is covered with a cover 10 so that the rotating part does not directly touch the subject 1. The X-ray bundle 11 from the X-ray generator 7 is shaped so as to enter only the two-dimensional X-ray detector 8 by a collimator (not shown).

  FIG. 4 is a diagram showing the reconstruction area 12 formed by the scan frame 6. As shown, the reconstruction area 12 is determined by the fan angle 13. The scan frame 6 is slidably supported on the support frame 5, and as shown in FIG. 2, the slide position on the support frame 5 can be changed by the scan frame moving unit 14 (arrow A). However, the movement of the scan frame 6 can also be realized by rotating the support frame 5 itself.

  A rotation rod 17 serving as a rotation axis of the scan frame 6 is attached to the upper portion of the scan frame 6, and the rotation rod 17 is supported by the support frame 5. The rotation rod 17 is rotationally driven by the scan frame rotation drive unit 15, whereby the scan frame 6 is rotated by CT scan (arrow B).

  The rotating rod 17 is provided with a known feed amount adjusting mechanism or expansion / contraction mechanism (not shown). Further, at the end of the rotating rod 17, a scan frame angular distance adjustment for adjusting the slide position of the scan frame 6 on the support frame 5, the mounting angle with respect to the support frame 5, and the feed amount (or the amount of expansion / contraction) of the rotary rod 17 is adjusted. Part 16 is attached. FIG. 3 shows a case where the scan frame 6 is inclined at an attachment angle with respect to the support frame 5. The scan frame angle distance adjustment unit 16 adjusts the inclination angle of the rotating rod 17 and the feed amount (arrow C) of the rotating rod 17. Thereby, the distance between the scan frame 6 and the subject 1 can be adjusted.

  The transmission data captured from the two-dimensional X-ray detection unit 8 is subjected to reconstruction processing by the computer 50 and converted into a plurality of cross sections, so-called three-dimensional images 18. The reconstruction process can be performed by inverse Radon transform. The inverse Radon transform is realized by filtering the transmission data and backprojecting it toward the X-ray focus. The angle and position of back projection are determined from the slide position and angle of the scan frame 6 on the support frame 5 when the transmission data is collected, the feed length of the rotating rod 17, and the scan angle. As an example of the inverse Radon transform, the Feldkamp algorithm can be used. References include "Practical Cone Beam Algorithm" by Feldkamp et al., J. Opt. Soc. Am. A1, 612-619, 1984. An example of the reconstructed three-dimensional image 18 of the breast 30 is shown in FIG.

  FIG. 16 shows a modification of the X-ray imaging apparatus 100 shown in FIG. The support frame 5 includes a C arm 19, and the scan frame 6 is supported by the C arm 19. The scan frame 6 can be slid on the C arm 19 to change its position. Instead, the scan frame 6 may be fixed to the C arm 19 and the position of the scan frame 6 may be changed by changing the feed amount of the C arm 19. In addition, the angle adjustment of the scan frame 6 is performed by tilting the C arm 19 itself by receiving the drive of the C arm up-and-down rotation unit 162 by the control command of the control unit 161 instead of adjusting the mounting angle of the C arm 19 and the scan frame 6. You may make it adjust by doing.

  According to the configuration shown in FIG. 1 and FIG. 16 described above, it is possible to flexibly cope with a breast having a curved surface shape or a size different depending on a subject, and an examination can be performed efficiently. In addition, the configuration as described above places the subject in a supine position, hangs both arms in the direction of gravity, facilitates exposure of the curved surface formed by the ribcage near the breast, and is important in breast examination Facilitates inspection of parts. Also, with this configuration, by providing a breast examination with the subject placed in the supine position, images in the same posture as during surgery can be collected.

  In the front view of FIG. 1, the vicinity of the breast of the subject 1 is shown. The breast 30 is attached to the pectoral muscle 20, and the pectoral muscle 20 covers the rib 21. In the X-ray imaging apparatus 100 in the present embodiment, the breast part including the pectoral muscle 20 is used as the examination part 9. If scanning is performed including the rib 21, not only unnecessary exposure is given to the subject 1, but also the signal value of the transmission data is lowered, and the S / N of the reconstructed image is lowered. Therefore, in the present embodiment, the transmission data from the two-dimensional X-ray detection unit 8 is analyzed, and the angle of the scan frame 6 and the feed amount of the rotating rod 17 are adjusted.

  6A is a cross-sectional view when the scan frame 6 is scanned too close to the breast 30 and includes the rib 21, FIG. 6B is the transmission data, and FIG. 6C is the binarization of the transmission data. Data are shown. If the X-ray passes through the rib 21 which is a high attenuation portion, the transmission data value becomes extremely small. Therefore, whether the transmission data is scanned including the rib 21 by binarizing the transmission data with a predetermined threshold value. And the area of the rib 21 can be known.

  FIG. 7 shows an example of the result of adjusting the angle of the scan frame 6 and the feed amount of the rotating rod 17 based on the binarized data of FIG. The analysis of the transmission data and the adjustment of the angle of the scan frame 6 and the feed amount of the rotating rod 17 are performed in real time during the rotation scan of the scan frame 6. By adjusting the feed amount and rotating the scan frame 6 simultaneously, the time required for X-ray imaging can be shortened.

  In FIG. 6 and FIG. 7, the transmission data is controlled so as not to include the ribs 21, but the subject 1 may have a thick pectoral muscle 20. In this case, it is necessary to control the scan frame 6 so that the pectoral muscle 20 that greatly attenuates X-rays is scanned thinly. In this case, as shown in FIG. 8, the threshold value 22 of the predetermined binarization process may be changed to the threshold value 23 by histogram analysis.

  The cross section of the breast CT image is required to be as close as possible to the chest wall. If a contact detector or the like is used when bringing the scan frame 6 and the chest wall as close as possible, a burden is placed on the human body. On the other hand, according to the example of adjusting the angle of the scan frame 6 and the feed amount of the rotating rod 17 based on the transmission data described above, there is no need to use a contact detector or the like.

  Next, based on the whole body CT data related to the tomogram of the entire thorax including the breast of the subject, the adjustment of the slide position of the scan frame 6 on the support frame 5, the mounting angle, and the feed amount of the rotating rod 17 is planned. This will be explained. FIG. 9 shows an example of a tomographic image of the entire thorax including the breast 30 photographed by a whole body CT scanner apparatus or a whole body MRI apparatus capable of capturing a tomographic image of the entire thorax including the breast of the subject. By binarizing the tomographic image based on the whole body CT with a predetermined threshold, the volume of the breast portion can be determined three-dimensionally. As shown in FIG. 4, an area that can be imaged by one scan is also determined three-dimensionally. Therefore, when the breast 30 is large, a scan is planned for a plurality of times for the breast 30 on one side. The position of the scan frame 6 can be planned by displaying the binarized image (inspection portion 9) on the monitor 51 of the computer 50 and overlaying the reconstruction area 12 by the operator.

  This process can also be automated by the computer 50. When automating with the computer 50, the volume is calculated for each of the left and right breasts 30, and it is determined whether the volume, height, and area of each breast 30 are less than or equal to the reconstruction area 12 by one scan. . If it does not fit in a single scan, calculate how many times the breast volume corresponds to the reconstructed region 12 from a single scan. When the number of scans is determined in this way, the breast volume is divided by the number of scans, and a scan plan is made so that the scan center matches the center of gravity of the divided area (see FIG. 13). The plan for scanning with whole body CT data and the adjustment of the reference position of the scan frame 6 for CT imaging by the X-ray imaging apparatus 100 according to the present embodiment are performed by the radiographer at the first predetermined scan position. Done by placing six. Note that the whole body CT data in this case only needs to be scanned with a low dose since it is sufficient to know the approximate shape of the rib cage for the scan plan.

  FIG. 10 is a diagram illustrating a configuration example in the case of further including the whole body CT scanner device 200. The whole body CT scanner device 200 includes a gantry 40 having a cavity 41 for inserting the subject 1 lying on the table 2. The gantry 40 is provided with an X-ray generation unit 70 and an X-ray detection unit 80 provided at a position facing the X-ray generation unit 70 with the cavity 41 interposed therebetween. The whole body scan is performed by the X-ray generation unit 70 and the X-ray detection unit 80 orbiting the cavity 41. The merit in this case is that the positional relationship between the CT data collected by the X-ray imaging apparatus 100 and the whole body CT data collected by the whole body CT scanner apparatus 200 is clear. For this reason, it is not necessary to perform a scan plan based on the whole body CT data and to adjust the reference position of the scan frame 6 for CT imaging by the X-ray imaging apparatus 100.

  Next, based on the two-dimensional or three-dimensional fluoroscopic image obtained by pre-scanning using the two-dimensional X-ray detector 8, the slide position of the scan frame 6, the mounting angle, and the rotation rod 17 are sent out. Explain the planning of volume adjustment.

  FIG. 11 shows a prescan method. As shown in FIG. 11 (a), with the subject 1 lying on the table 2 in the supine position, the engineer switches a plurality of milestones 24 along the curved surface of the chest of the subject 1 (not shown). Register with etc. The computer 50 calculates a curve that passes through the registered milestone 24 and controls the scan frame 6 to continuously move while emitting a low dose of X-rays. During this movement, the computer 50 adjusts the position and angle of the scan frame 6 on the support frame 5 and the feed amount of the rotating rod 17.

  In pre-scanning, the scan frame 6 may or may not be rotated. When the scan frame 6 is not rotated, the slide position of the scan frame 6 on the support frame 5 is fixed and transmission data is collected at a plurality of slide positions (for example, the positions of the milestones 24) on the support frame 5. Such movement of the scan frame 6 is called “step movement”. According to the prescan by this step movement, a two-dimensional perspective image as shown in FIG. 11B is obtained. On the other hand, when the scan frame 6 is rotated, the following pre-scan is specifically performed. That is, transmission data is collected while rotating the scan frame 6 and continuously moving the scan frame 6 along the support frame 5 in synchronization with the rotation. In this case, since the X-ray generation unit 7 and the two-dimensional X-ray detection unit 8 draw a spiral trajectory, such movement is called “spiral movement”, and transmission data collected at that time is Also called “spiral data”.

  FIG. 12A is a diagram for explaining pre-scanning by step movement and spiral movement. A broken line 25 indicates an example of a locus by spiral movement, and a broken line 26 indicates an example of a locus by step movement. In any case, when the scan frame 6 is rotated, a three-dimensional image 18 of the breast 30 attached to the chest wall as shown in FIG. 5 is obtained. Note that the purpose of the pre-scan is to plan the main scan, and it is sufficient if the contour of the inspection portion 9 can be specified. Therefore, the pre-scan may be a scan with a lower dose than the main scan.

  When the scan frame 6 is not rotated, the directions of the X-ray generation unit 7 and the two-dimensional X-ray detection unit 8 are set so that the breast region is imaged in the body axis direction of the subject 1 (the traveling direction of the table 2). . FIG. 12B shows an example of a two-dimensional perspective image generated by pre-scanning by step movement without rotating the scan frame 6.

  Based on the transmission data obtained by the pre-scan as described above, it is possible to plan the adjustment of the position and angle of the scan frame 6 on the support frame 5 and the feed amount of the rotating rod 17. This includes a method in which the operator determines as described above and an automatic method by the computer 50. An image reconstruction process of transmission data by spiral movement is also performed by inverse Radon transformation. The angle and position of back projection of the inverse Radon transform are determined from the position and angle of the scan frame 6 on the support frame 5 when the transmission data is collected, the amount of rotation of the rotating rod 17 and the scan angle.

  Also in the main scan, it is possible to select whether to execute the first main scan by the step movement or the second main scan by the spiral movement. The merit of the second main scan by the spiral movement is that the scan time is shorter than the first main scan by the step movement because the scan frame 6 does not move up and down. The selection of whether to perform the first main scan by step movement or the second main scan by spiral movement may be performed by the operator or automatically depending on the size of the breast 30 by image processing. You may make it perform. For example, it is determined whether the volume, height, and plane area of the breast 30 are less than or equal to the reconstruction area 12 by one scan. If it is determined that the breast 30 may touch the cover 10 of the scan frame 6 and the breast 30 may be deformed when the spiral movement is performed based on the volume, height, and plane area of the breast 30, step movement is performed. The first main scan by is selected. Specifically, when the breast height exceeds the height of the reconstruction area 12, the first main scan by step movement is selected when the breast area exceeds the scan diameter of the scan frame 6.

  By the way, when the examination part 9 is smaller than the reconstruction area 12, or when the divided examination part 9 is smaller than the reconstruction area 12 when performing a plurality of scans, for the patient (subject) It can be said that an unnecessary exposure area has occurred. It is desirable to eliminate such unnecessary exposure as much as possible.

  Therefore, as shown in FIG. 14, an X-ray bundle changing unit 27 that changes the irradiation range of the X-rays from the X-ray generating unit 7 may be provided in front of the X-ray generating unit 7. Thereby, the reconstruction area | region 29 which deform | transformed the X-ray beam and made the reconstruction area | region 12 small can be formed. For example, if it is determined that such an unnecessary exposure area has occurred at the time of a scan plan, the X-ray bundle changing unit 27 is instructed to narrow the X-ray irradiation range from the X-ray generation unit 7. be able to. FIG. 15 is a conceptual diagram in which the standard reconstruction area 12 is divided into reduced reconstruction areas 29 and three scans are performed.

DESCRIPTION OF SYMBOLS 1 Subject 2 Table 3 Table support part 4 Gantry 5 Support frame 6 Scan frame 7 X-ray generation part 8 Two-dimensional X-ray detection part 9 Inspection part 10 Cover 12 Reconstruction area 13 Fan angle 14 Scan frame moving part 15 Scan frame rotation Drive unit 16 Scan frame angular distance adjustment unit

Claims (12)

An X-ray imaging apparatus for imaging an X-ray image of a breast of a subject,
A scan frame having a space for accommodating the breast of the subject , and holding an X-ray generation unit and an X-ray detection unit provided at positions facing each other across the space;
To perform a scan to collect transmission data from multiple directions of the breast by the X-ray generation unit and the X-ray detection unit to pivot around the breast, the inclination angle and the scan frame of the gantry An angular distance adjustment unit for adjusting the distance to the subject ;
A support frame for supporting lifting the gantry through the angular distance adjusting unit,
Have
The angular distance adjustment unit adjusts the inclination angle and the distance based on transmission data including a breast of a subject obtained by pre-scanning that collects transmission data without rotating the scan frame. X-ray imaging apparatus. A binarization processing unit that binarizes the transparent data with a predetermined threshold;
A determination unit that determines whether or not scanning is performed including a high attenuation portion of the subject based on the binarized data obtained by the binarization processing;
The X-ray imaging apparatus according to claim 1, comprising: A binarization processing unit for binarizing the transparent data with a predetermined threshold;
The X-ray imaging apparatus according to claim 1, wherein the angular distance adjustment unit adjusts the tilt angle and the distance based on binarized data obtained by the binarization processing. 4. The X-ray imaging apparatus according to claim 1, wherein the pre-scan is performed with a lower dose than the scan. 5. The X-ray imaging apparatus according to claim 1, wherein the angular distance adjustment unit adjusts the inclination angle and the distance based on a tomographic image of the entire thorax including a breast of a subject. Further comprising a whole body CT scanner device or a whole body MRI device capable of taking a tomographic image of the entire thorax including the breast of the subject;
The angular distance adjustment unit adjusts the inclination angle and the distance based on a tomographic image of the entire thorax including the breast of the subject imaged by the whole-body CT scanner device or the whole-body MRI device. The X-ray imaging apparatus according to claim 1. Characterized in that said pre-scanning, it is performed to collect transmission data to fix the sliding position of the support frame of the gantry without rotating the scan frame in a plurality of slide positions in the support frame The X-ray imaging apparatus according to claim 1. An X-ray imaging apparatus for imaging an X-ray image of a breast of a subject,
A scan frame having a space for accommodating the breast of the subject, and holding an X-ray generation unit and an X-ray detection unit provided at positions facing each other across the space;
In order to perform a scan in which the X-ray generator and the X-ray detector rotate around the breast to collect transmission data from multiple directions of the breast, the scan frame tilt angle and the scan frame An angular distance adjustment unit for adjusting the distance to the subject;
A support frame that supports the scan frame via the angular distance adjustment unit;
Have
The angular distance adjustment unit adjusts the inclination angle and the distance based on transmission data including a breast of a subject obtained by pre-scanning that collects transmission data while rotating the scan frame. X-ray imaging apparatus. The prescan, while rotating the scan frame, and wherein the synchronization with the rotation is to collect transmission data while continuously moving along the gantry to the support frame The X-ray imaging apparatus according to claim 8 .   A first main scan for collecting transmission data by fixing the slide position of the scan frame on the support frame and rotating the scan frame at a plurality of slide positions on the support frame; and rotating the scan frame And a selection means for selecting which of the second main scans to collect transmission data while continuously moving the scan frame along the support frame in synchronization with the rotation. The X-ray imaging apparatus according to claim 1, comprising: Said selection means, X-rays imaging apparatus according to claim 10, characterized in that the selection based on the tomographic image of the entire thorax including the image or subject of the breast obtained by the prescan. The scan frame, X-rays imaging apparatus according to any one of claims 1 to 11, further comprising an X-ray flux changing unit for changing an irradiation range of the X-ray from the X-ray generator .

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