JP2014061232A - Breast x-ray photographing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a breast X-ray photographing device capable of suppressing an X-ray exposure dose in breast X-ray photographing as much as possible, and reducing an impact of the exposure on a human body by a medical examination.SOLUTION: A breast X-ray photographing device that includes an X-ray tube and a squeezer, and photographs an analyte from a plurality of different photographing directions including first and second photographing directions is provided with a shielding member for shielding the irradiation of X-rays, a calculation part for calculating an amount of movement of the shielding member so that the shielding member shields the irradiation of X-rays in an area other than the area corresponding to a blind area when the analyte is photographed from the first photographing direction, and a movement control part for controlling the movement of the shielding member based on the result of the calculation. When photographing from the first photographing direction is performed without the shielding member being inserted between the breast of the analyte and the squeezer, and the shielding member is inserted in the photographing from the second photographing direction, the movement of the shielding member is controlled by the movement control part.

Description

  This embodiment of the present invention relates to a mammography apparatus.

  Breast cancer incidence is increasing year by year, but breast cancer is the only cancer capable of self-diagnosis, and if it can be detected early, the disease itself is easy to cure. Have.

  Therefore, in order to diagnose breast cancer and other abnormal conditions in breast tissue, a mammography apparatus (X-ray mammography apparatus) using X-rays is used in many hospitals and screening centers. Then, the doctor interprets the image obtained by the mammography apparatus and confirms whether there is breast cancer or the like.

  This mammography apparatus can provide an image capable of finding “calcification” and “tumor”, which are typical findings when breast cancer is strongly suspected.

  The mammography apparatus performs x-ray imaging of the breast while pulling and compressing the breast with a breast compression plate. Specifically, the mammography apparatus, for example, MLO (media-later-bliquie; inner-outer oblique direction) or CC (cranial-caudal; head-to-caudal direction) while pulling the breast with a breast compression plate and compressing it. X-ray photography from the above. However, in the case of X-ray imaging from the MLO, a blind area (that is, a region that is not drawn as an X-ray image in the entire breast) is likely to occur inside the breast, while in the case of X-ray imaging from the CC, the breast Blind areas are likely to occur outside

  Therefore, in order to reduce the blind area of the breast as much as possible, the X-ray imaging of the breast in the screening is not an X-ray imaging of the breast only from one direction in many facilities, but usually in two directions (for example, MLO and CC). X-ray imaging of the breast is performed (see, for example, Patent Document 1). By doing this, we strive to draw the entire breast as much as possible.

Japanese Patent Application Laid-Open No. 2011-10848

  As described above, since the breast is X-rayed from the two directions of MLO and CC, the blind area in the breast can be reduced as much as possible, and a wide area of the breast can be depicted as an image. However, there is an area that is not a blind area in both X-ray imaging from MLO and X-ray imaging from CC. In this area, X-rays are irradiated in duplicate from two directions. It will be. As a result, the exposure dose of X-rays irradiated to the subject increases.

  Accordingly, there is a demand for a mammography apparatus that can suppress the X-ray exposure dose in the X-ray imaging of the breast as much as possible and reduce the influence on the human body due to the exposure by the examination.

  The mammography apparatus according to the present embodiment includes an X-ray tube that irradiates a subject with X-rays, and a diaphragm that limits the irradiation range of the X-rays. In a mammography apparatus that images the subject from a plurality of different imaging directions including the imaging direction and the second imaging direction, the apparatus moves so as to be inserted between the breast of the subject and the X-ray tube A shielding member configured to shield the X-ray irradiation on the subject in a part of the irradiation range at the time of insertion, and the first imaging direction in the X-ray irradiation range. A calculation unit for calculating a movement amount when moving the shielding member so that the shielding member shields the X-ray irradiation in a region other than a region corresponding to a blind area when imaging the subject from In the calculation result by the calculation unit And a movement control unit for controlling the movement of the shielding member, and the movement control unit, when imaging the subject from the first imaging direction, the breast of the subject and the X-ray Inserting the shielding member between the breast of the subject and the X-ray tube when imaging the subject from the second imaging direction without inserting the shielding member between the tube and the X-ray tube; It is characterized by that.

1 is an external perspective view showing an overall external configuration of a mammography apparatus in the present embodiment. FIG. 2 is an external perspective view showing a partial external configuration of the mammography apparatus in the present embodiment shown in FIG. 1. The other external appearance perspective view which shows the one part external appearance structure of the mammography apparatus in this embodiment shown in FIG. The figure which shows the area | region which becomes a blind area or a blind area easily in the case of the mammography from MLO. The figure which shows the area | region which tends to become a blind area or a blind area at the time of the mammography from CC. The figure explaining the cause which the exposure dose of the X-ray irradiated to a subject increases in the conventional mammography. 1 is a block diagram showing an internal configuration of a mammography apparatus according to a first embodiment. FIG. 2 is a block diagram showing functions of the mammography apparatus in the first embodiment. The 1st flowchart which shows the process example of the mammography apparatus of 1st Embodiment. FIG. 6 is a second flowchart showing a processing example of the mammography apparatus of the first embodiment. The figure which shows an example of the imaging condition calculation table previously memorize | stored in the memory or memory | storage device of a system control part. The figure which shows the image of the average breast in the breast group image | photographed from CC in the past. The figure for demonstrating the method of calculating | requiring the area | region which cannot be drawn as an image in the case of the breast X-ray imaging from MLO based on the projection data obtained by imaging | photography by this Pre exposure. The figure explaining the method of calculating the movement amount of a shielding board from the positional relationship of a breast and an irradiation field restriction mask. The figure for demonstrating the method of calculating | requiring the coordinate of point R 'on an irradiation field restriction | limiting mask from the ratio of length C and D which is the distance from the point R to the both ends of an image area. Explanatory drawing of the Example shielded only by an irradiation field restriction mask. The block diagram which shows the internal structure of the mammography apparatus in 2nd Embodiment. The block diagram which shows the function of the mammography apparatus in 2nd Embodiment. 9 is a flowchart illustrating a processing example of a mammography apparatus according to a second embodiment. The block diagram which shows the functional structure inside the mammography apparatus in 4th Embodiment. The 1st flowchart which shows the process example of the mammography apparatus of 4th Embodiment. The 2nd flowchart which shows the processing example of the mammography apparatus of 4th Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

(1) Configuration and general operation (first embodiment)
FIG. 1 is an external perspective view showing an overall external configuration of a mammography apparatus 1 according to the present embodiment.

  As shown in FIG. 1, the mammography apparatus 1 includes an imaging table apparatus 11 and an image processing apparatus 12. This mammography apparatus 1 can radiograph a breast of a patient P as a subject.

  The imaging table device 11 includes an arm unit 15, a stand unit 16, a connection unit 17, and an operation unit 18. The arm portion 15 is supported by the stand portion 16 so as to be rotatable via the connection portion 17.

  The arm unit 15 of the imaging table device 11 has an X-ray tube 20 above the inside thereof. Details of the internal configuration of the imaging platform 11 will be described later with reference to FIG. Further, the arm unit 15 of the imaging table device 11 includes a face guard 23, a breast compression plate 24, a bucky device 25, an imaging table 26, a compression foot pedal 27, an information display panel 28, a C-arm vertical / rotation fine adjustment switch 29, and A side panel 30 is provided. The operation unit 18 includes an imaging condition setting panel 31 and a high voltage supply device 32 therein.

  The X-ray tube 20 of the arm unit 15 is a vacuum tube for receiving a high voltage from the high voltage supply device 32 of the operation unit 18 and irradiating the imaging table 26 with X-rays through the breast of the patient P. is there.

  The face guard 23 is a protective device for protecting the head of the patient P from X-ray exposure during imaging.

  The breast compression plate 24 is a compression device provided above the imaging table 26 in order to compress the breast of the patient P with the imaging table 26 during imaging. The breast compression plate 24 is formed of a transparent resin, and is supported so as to be able to contact and separate from the imaging table 26. Then, the breast of the patient P can be compressed by moving the breast compression plate 24 toward the imaging table 26, and the thickness of the breast can be made thin and substantially uniform. When the compression foot pedal 27 is operated by an operator such as a doctor or an engineer, the breast compression plate 24 is a drive mechanism (see FIG. 1) composed of a motor for moving the breast compression plate 24 in the vertical direction (the arrow direction in FIG. 1). 7 breast compression plate drive mechanism 57) is driven to move in the vertical direction.

  The Bucky device 25 is an instrument for removing scattered X-rays from the subject in X-ray imaging and transmitting X-rays (direct X-rays) that are not scattered by the subject, which are made of a grid or the like.

  The imaging table 26 is a table in which an FPD (flat panel detector) 26a for detecting X-rays transmitted through the breast of the patient P is provided. A plurality of detection elements are two-dimensionally arranged in the FPD 26a, and scanning lines and signal lines are arranged between the detection elements so as to be orthogonal to each other. A time-series analog signal (video signal) output from the FPD 26 a is converted into a digital signal by an A / D conversion unit (A / D conversion unit 58 in FIG. 7) and output to the image processing device 12. Hereinafter, the digital signal output from the A / D converter 58 is referred to as projection data.

  The compression foot pedal 27 is a pedal for adjusting the position of the breast compression plate 24 in the vertical direction, and the operator can operate it by stepping on the compression foot pedal 27 with his / her foot.

  The information display panel 28 is a panel for displaying various information such as compression information.

  The C-arm vertical / rotation fine adjustment switch 29 is a switch for moving the C-arm constituted by the X-ray tube 20 and the imaging table 26 up and down and rotating.

  The side panel 30 is an operation panel for controlling each part of the mammography apparatus 1.

  The imaging condition setting panel 31 of the operation unit 18 is a panel for setting X-ray imaging conditions.

  The high voltage supply device 32 of the operation unit 18 is a device that supplies a high voltage to the X-ray tube 20.

  When X-rays are generated by the X-ray tube 20 of the imaging table apparatus 11, the irradiation range of the X-rays is reduced by an irradiation field limiting mask (irradiation field limiting mask (X-ray diaphragm) 53 in FIG. 7). Thus, the breast compressed between the breast compression plate 24 and the imaging table 26 is irradiated. The X-rays that have passed through the breast are detected by the FPD 26 a, converted into projection data, and output to the image processing device 12.

  On the other hand, the image processing device 12 is a device that performs various types of image processing on the projection data output from the imaging platform device 11 and displays the image data generated by the image processing.

  FIG. 2 is an external perspective view showing an external configuration of a part of the mammography apparatus 1 in the present embodiment shown in FIG. FIG. 3 is another external perspective view showing an external configuration of a part of the mammography apparatus 1 in the present embodiment shown in FIG. As shown in FIGS. 2 and 3, the mammography apparatus 1 performs X-ray imaging of a breast while compressing the breast by pulling it with a breast compression plate 24.

  In the case of FIG. 2, the mammography apparatus shows a state in which X-ray imaging is performed from MLO (media-lateral-ablique). On the other hand, in the case of FIG. 3, the mammography apparatus 1 shows a state in which X-ray imaging from CC (cranial-caudal; head-to-tail direction) is performed.

  Here, a blind area generated in mammography will be described. In the case of X-ray imaging from MLO, a blind area (that is, a region that is not depicted as an X-ray image in the entire breast) is likely to occur inside the breast.

  FIG. 4 is a diagram showing a blind area or a region that is likely to become a blind area during mammography from the MLO. As shown by the cross-hatched portion in FIG. 4, in the case of X-ray imaging from MLO, the inner back area of the breast is a blind area. In addition, as shown by the hatched portion with a downward-sloping line in FIG. 4, in the case of X-ray imaging from the MLO, the area in front of the blind area inside the breast is an area that tends to be a blind area.

  On the other hand, in the case of X-ray imaging from CC, a blind area tends to occur outside the breast.

  FIG. 5 is a diagram showing a blind area or a region that is likely to become a blind area during mammography from CC. As shown by the cross-hatched portion in FIG. 5, in the case of X-ray imaging from CC, the area outside the breast is a blind area. In addition, as shown by the hatched portion with a downward-sloping line in FIG. 5, in the case of X-ray imaging from CC, the area in front of the blind area outside the breast is an area that tends to be a blind area.

  Here, there is a region that is not a blind area in both the case of X-ray imaging from MLO and the case of X-ray imaging from CC, and breast X-ray imaging is simply performed from two directions as in the past. When this is done, X-rays will be irradiated in duplicate from two directions in this region. As a result, the exposure dose of X-rays irradiated to the subject increases.

  FIG. 6 is a diagram for explaining the cause of an increase in the exposure dose of X-rays irradiated to a subject in conventional mammography. FIG. 6A shows left and right breast images in the case of X-ray imaging from the MLO. In the case of FIG. 6A, the image in the left region with respect to the center line is an image when the right breast is X-rayed from the MLO, and the image in the right region with respect to the center line is the left breast. It is an image when X-ray photography is carried out from MLO.

  FIG. 6B shows left and right breast images in the case of X-ray imaging from CC. In the case of FIG. 6B, the image in the left region with respect to the center line is an image when the right breast is X-rayed from the CC, and the image in the right region with respect to the center line is the left breast. It is an image when X-ray imaging is performed from CC.

  The shaded area in FIG. 6A corresponds to a blind area or an area that is likely to become a blind area during mammography from CC. The shaded area in FIG. 6B corresponds to a blind area or an area that tends to become a blind area when mammography is performed from the MLO.

  The hatched area in FIG. 6 (a) is an area that cannot be rendered as an image during mammography from the CC. In order to reduce the blind area in the breast as much as possible, an image is obtained by X-ray imaging from the MLO. This is the area to be drawn. On the other hand, the hatched area in FIG. 6B is an area that cannot be rendered as an image in mammography from the MLO, and is an area that should be rendered as an image by X-ray imaging from the CC.

  On the other hand, there is a region that is not a blind area in both X-ray imaging from MLO and X-ray imaging from CC. In the conventional imaging method, X-rays are irradiated in duplicate from two directions in this region (double exposure), and as a result, the X-ray exposure dose irradiated to the subject increases. It was.

  Therefore, in the mammography apparatus 1 in the present embodiment, a shielding plate (shielding) for shielding X-rays in X-ray imaging from one direction among X-ray imaging from two directions (for example, two directions of MLO and CC). Member) and limited to X-ray irradiation only in the minimum necessary area so as to avoid overlapping X-ray irradiation in areas that are not blind areas in any of the two directions. To. Thereby, the mammography apparatus 1 in this embodiment can reduce the exposure dose of the X-ray irradiated to a subject. Hereinafter, the detailed configuration and operation of the mammography apparatus 1 in this embodiment using such a concept will be described in detail.

  FIG. 7 is a block diagram showing an internal configuration of the mammography apparatus 1 according to the first embodiment. In addition, the same code | symbol is attached | subjected about the structure similar to FIG. 1, and the description is abbreviate | omitted.

  As shown in FIG. 7, in addition to the configuration shown in FIG. 1, the imaging platform apparatus 11 of the mammography apparatus 1 includes a high voltage control unit 51, a radiation quality adjustment filter 52, an irradiation field restriction mask 53, an irradiation field restriction. It has a mask drive mechanism 54, a shield plate inserter 55, a shield plate inserter drive mechanism 56, a breast compression plate drive mechanism 57, and an A / D converter 58. In addition, the imaging apparatus 11 includes a system control unit 71, a radiation quality adjustment filter control unit 72, an irradiation field restriction mask movement control unit 73, a shielding plate inserter movement control unit 74, an input device 75, and a storage device 77.

  The high voltage control unit 51 controls the tube voltage, mAs value, and the like of the X-ray tube 20 through the high voltage supply device 32 according to the control from the system control unit 71.

  The radiation quality adjustment filter 52 is an adjustment tool that is provided between the X-ray tube 20 and the breast compression plate 24 and adjusts the quality of X-rays generated by the X-ray tube 20. For example, a molybdenum (Mo) filter, a rhodium (Rh) filter, or the like is used for the quality control filter 52. The irradiation field limiting mask 53 is provided between the X-ray tube 20 and the breast compression plate 24 and functions as an X-ray restrictor, and is used to limit the X-ray irradiation field (irradiation range). It is an adjustment device. The irradiation field restriction mask drive mechanism 54 is a drive mechanism having a motor or the like for moving the irradiation field restriction mask 53.

  The shielding plate inserter 55 and the shielding plate inserter drive mechanism 56 are characteristic configurations of the mammography apparatus 1 in the present embodiment. The shielding plate inserter 55 is provided between the X-ray tube 20 and the breast compression plate 24, and shields (shields) X-rays in unnecessary areas irradiated (exposed) to the breast as necessary. It is an instrument for holding and inserting 55a. The shielding plate inserter driving mechanism 56 is a driving mechanism having a motor or the like for moving the shielding plate inserter 55. The shielding plate 55a is made of a material such as lead (Pb) or iron (Fe).

  The breast compression plate drive mechanism 57 is a drive mechanism having a motor or the like for moving the breast compression plate 24.

  The A / D conversion unit 58 converts the time-series analog signal (video signal) output from the FPD 26a into a digital signal, and outputs the digital signal to the image processing device 12 and the system control unit 71 as projection data.

  The system control unit 71 comprehensively controls the mammography apparatus 1 and includes, for example, a CPU 71a (central processing unit) and a memory 71b (both not shown). When a command is input by operating the input device 75 by an operator (operator) such as a doctor or a technician, the CPU 71a controls the operation of the imaging platform device 11 and the entire image processing device 12. Further, when an instruction is input by the operator operating the input device 75 or the like, the CPU 71a of the system control unit 71 loads the program stored in the storage device 77 into the memory 71b and executes it.

  The input device 75 is a device corresponding to the operation unit 18 or the side panel 30 of the imaging platform device 11, and is a device for inputting information on operations by the operator and various setting information.

  The storage device 77 includes an HDD (Hard Disc Drive) or the like, and stores a program installed in the image processing device 12 (including an application program, an OS (operating system), etc.), and collected image data. Device.

  The line quality adjustment filter control unit 72 controls the line quality adjustment filter 52 of the imaging platform device 11 according to the control of the system control unit 71. The irradiation field restriction mask movement control unit 73 controls the irradiation field restriction mask drive mechanism 54 according to the control of the system control unit 71. The shielding plate inserter movement control unit 74 controls the shielding plate inserter drive mechanism 56 in accordance with the control of the system control unit 71.

  On the other hand, the image processing device 12 includes an image processing unit 78 and a display device 76. The image processing unit 78 performs processing such as logarithmic conversion processing (LOG processing) on the projection data output from the A / D conversion unit 58 of the imaging platform device 11 according to control by the system control unit 71, and also enlargement / Various image processing such as gradation / space filter processing, minimum / maximum value tracing processing of projection data accumulated in time series, and addition processing for removing noise are performed. Further, the image processing unit 78 displays an image (hereinafter referred to as a display image) to be displayed on the display device 76 in accordance with the parameters of the auto window function (gradation conversion processing) based on the projection data subjected to the above image processing. ) Is generated. Further, character information and scales of various parameters are added to the display image and output to the display device 76.

  The display device 76 displays the display image output from the image processing unit 78 together with character information and scales of various parameters.

  FIG. 8 is a block diagram illustrating functions of the mammography apparatus 1 according to the first embodiment. When the CPU 71a of the system control unit 71 executes the program, the mammography apparatus 1 has the following functions characteristic of the present embodiment. That is, as shown in FIG. 8, the mammography apparatus 1 includes an input reception unit 101, a setting unit 102, an X-ray imaging execution control unit 103, a projection data acquisition unit 104, a Pre exposure determination unit 105, and a shielding plate insertion. Functions as a determination unit 106, a shielding plate movement amount calculation unit 107, and a main exposure condition calculation unit 108 are provided.

  Note that all or some of the units illustrated in FIG. 8 may be included in the image processing apparatus 12 as hardware.

  The input receiving unit 101 receives various inputs from the input device 75 when the input device 75 is operated by the operator. In particular, the input receiving unit 101 receives an input as to whether or not to start X-ray imaging of the breast in the mammography apparatus 1. The input receiving unit 101 performs X-ray imaging without inserting the shielding plate 55a between the irradiation field limiting mask 53 and the breast compression plate 24 by the shielding plate inserter 55 before the X-ray imaging of the breast. Input of information regarding the imaging direction when performing X-ray imaging by inserting the shielding plate 55a between the irradiation field restriction mask 53 and the breast compression plate 24 by the shielding plate inserter 55. . Further, the input receiving unit 101 receives input of information regarding the imaging direction of the X-ray imaging of the breast to be performed before the X-ray imaging of the breast.

  The setting unit 102 performs various settings in mammography based on the input received by the input receiving unit 101. That is, the setting unit 102 uses the shielding plate inserter 55 to perform the X-ray imaging without inserting the shielding plate 55a between the irradiation field limiting mask 53 and the breast compression plate 24, and the shielding plate insertion. The imaging direction is set based on the input of information regarding the imaging direction when X-ray imaging is performed by inserting the shielding plate 55a between the irradiation field limiting mask 53 and the breast compression plate 24 by the device 55. Further, the setting unit 102 sets the imaging direction of the X-ray imaging of the breast to be executed from now on, based on the input of information regarding the imaging direction of the X-ray imaging of the breast in the mammography apparatus 1 to be executed.

  When receiving an input to start breast X-ray imaging in the mammography apparatus 1, the X-ray imaging execution control unit 103 performs predetermined imaging on the imaging platform apparatus 11 to start X-ray imaging of the breast. X-ray imaging is executed according to conditions and imaging procedures. In particular, when performing AEC (Auto Exposure Control), which will be described later, the X-ray imaging of the breast is performed in two imaging directions (for example, two imaging directions of MLO and CC) and pre-exposure imaging and main exposure. Shoot by shooting in two stages. Here, the imaging by the main exposure means imaging for obtaining an image for breast diagnosis. In addition, imaging by pre-exposure is an X-ray imaging of a breast that is performed at a very low X-ray dose compared to the X-ray dose used for imaging by main exposure before imaging by main exposure. I mean. Based on the image obtained by the pre-exposure photographing, the photographing condition at the time of photographing by the main exposure is calculated.

  In general, the breast contains fat and mammary glands. A breast with a lot of fat tends to transmit X-rays, and a breast with a lot of mammary glands hardly transmits X-rays. Therefore, in the case of a fat-rich breast, it is preferable to set X-rays with a relatively low dose (for example, imaging conditions with a small tube voltage or mAs value) as the imaging conditions for the main exposure, and conversely, there are many breasts. In the case of a breast, it is preferable to set a relatively high dose of X-rays (for example, an imaging condition with a large tube voltage or mAs value) as the main exposure imaging condition. The amount of fat and mammary glands can be estimated from images obtained by pre-exposure. Based on the image obtained by pre-exposure, appropriate imaging conditions for imaging by this exposure are calculated. can do. For this reason, it is possible to automatically obtain an appropriate imaging condition for the main exposure from the pre-exposure image for any breast regardless of whether there is a large amount of fat or mammary gland. This function, that is, a function that automatically obtains an appropriate photographing condition in the main exposure from the Pre-exposure image is called AEC (Auto Exposure Control). In the AEC, an appropriate tube voltage [kV], mAs value, and the like are calculated as imaging conditions for the main exposure, and an appropriate filter type to be used for the main exposure is also obtained. The main exposure condition calculation unit 108 in FIG. 8 performs the above AEC.

  The projection data acquisition unit 104 performs image data of the breast imaged from the A / D converter 58 of the imaging table apparatus 11 after the X-ray imaging of the breast is performed in both cases of pre-exposure and main exposure. (Projection data) is acquired.

  Based on the instruction information from the X-ray imaging execution control unit 103, the Pre exposure determination unit 105 determines whether the projection data acquired by the projection data acquisition unit 104 is projection data in imaging by Pre exposure or based on the main exposure. It is determined whether it is projection data in photographing. When the pre-exposure determination unit 105 determines that the projection data acquired by the projection data acquisition unit 104 is projection data in imaging by the pre-exposure, the pre-exposure determination unit 105 and the main exposure condition calculation Output to the unit 108.

  When the shielding plate insertion determination unit 106 acquires the determination result (determination result that the projection data is projection data in imaging by Pre exposure) from the Pre exposure determination unit 105, the instruction from the X-ray imaging execution control unit 103 is obtained. Based on the information, it is determined whether or not the shielding plate 55a is to be inserted by the shielding plate inserter 55 in the case of photographing by main exposure to be performed in the future. When the shielding plate insertion determining unit 106 determines that the shielding plate 55a is to be inserted by the shielding plate inserter 55 in the case of photographing by main exposure to be performed from now on, the determination result is output to the shielding plate movement amount calculating unit 107.

  When the shielding plate movement amount calculation unit 107 obtains a determination result from the shielding plate insertion determination unit 106 (determination result that the shielding plate 55a is inserted by the shielding plate inserter 55 in the case of imaging by main exposure to be performed in the future). Based on the projection data supplied from the projection data acquisition unit 104, the amount of movement of the shielding plate 55a in the case of photographing by main exposure is calculated. The shielding plate movement amount calculation unit 107 outputs the calculation result to the shielding plate insertion device movement control unit 74.

  When the exposure condition calculation unit 108 acquires the determination result (determination result that the projection data is projection data in imaging by Pre exposure) from the Pre exposure determination unit 105, as described above, the projection data acquisition unit Based on the projection data supplied from 104, an appropriate photographing condition for photographing by the main exposure is calculated. The main exposure condition calculation unit 108 outputs the calculation result to the X-ray imaging execution control unit 103.

  FIG. 9 and FIG. 10 are a series of flowcharts showing a processing example of the mammography apparatus 1 of the first embodiment. In the mammography procedure described with reference to the flowcharts of FIGS. 9 and 10, for example, it is assumed that the breast is X-rayed from the two directions of MLO and CC in the order of CC after MLO. Of course, in the mammography apparatus 1 in the present embodiment, the order of MLO after CC may be used, and is not limited to the case of X-ray imaging from two directions of MLO and CC, and combinations of other imaging directions are also possible. Good. In actual X-ray imaging, the right breast and the left breast are usually X-rayed in each of MLO and CC. However, in the description of this embodiment, the right breast and left breast X-ray imaging are distinguished. Since it is not necessary, the following description will be made without distinguishing both.

  Before starting the X-ray imaging, first, the operator uses the input device 75 to insert the shielding plate 55a between the irradiation field limiting mask 53 and the breast compression plate 24 by the shielding plate inserter 55. An imaging direction when X-ray imaging is performed and an imaging direction when X-ray imaging is performed by inserting the shielding plate 55a between the irradiation field limiting mask 53 and the breast compression plate 24 by the shielding plate inserter 55. Enter information. Specifically, “MLO” is input as an imaging direction when X-ray imaging is performed without inserting the shielding plate 55 a between the irradiation field limiting mask 53 and the breast compression plate 24 by the shielding plate inserter 55. In addition, “CC” is input as an imaging direction when the shielding plate inserter 55 inserts the shielding plate 55 a between the irradiation field limiting mask 53 and the breast compression plate 24 and executes X-ray imaging.

  In step ST11 of FIG. 9, the input receiving unit 101 performs X-ray imaging without inserting the shielding plate 55a between the irradiation field limiting mask 53 and the breast compression plate 24 by the shielding plate inserter 55. Input of information regarding the imaging direction and the imaging direction when X-ray imaging is performed by inserting the shielding plate 55a between the irradiation field limiting mask 53 and the breast compression plate 24 by the shielding plate inserter 55 is accepted. The input receiving unit 101 outputs input information regarding the received shooting direction to the setting unit 102.

  In step ST12, the setting unit 102 sets the imaging direction when performing X-ray imaging without inserting the shielding plate 55a between the irradiation field limiting mask 53 and the breast compression plate 24 by the shielding plate inserter 55. Based on the input of information regarding the imaging direction when X-ray imaging is performed by inserting the shielding plate 55a between the irradiation field limiting mask 53 and the breast compression plate 24 by the shielding plate inserter 55, these imaging directions are determined. Set. In the case of FIG. 9, “MLO” is set as the imaging direction when X-ray imaging is performed without inserting the shielding plate 55a, and the imaging direction when X-ray imaging is performed with the shielding plate 55a inserted. “CC” is set.

  Unlike the processing in steps ST11 and ST12, an ordering system may be used when performing mammography. That is, the system control unit 71 may set the above two shooting directions based on setting information determined in advance without receiving an instruction from the operator. This setting information is assumed to be stored in advance in the memory 71b or the storage device 77 of the system control unit 71.

  The setting unit 102 outputs setting information regarding the imaging direction to the X-ray imaging execution control unit 103. The setting information regarding the shooting direction is stored in the memory 71b of the system control unit 71.

  Next, the operator uses the input device 75 to input information related to the imaging direction of the breast X-ray imaging to be performed before the breast X-ray imaging. In this example, since the imaging is performed first from the MLO and then from the CC, “MLO” is input as the imaging direction of the X-ray imaging of the breast to be executed in the future. Of course, when there are a plurality of shooting directions, the shooting order and the like may be input in advance.

  In step ST13, the input reception unit 101 receives input of information related to the imaging direction of the X-ray imaging of the breast to be performed before the X-ray imaging of the breast. The input receiving unit 101 outputs input information regarding the received shooting direction to the setting unit 102. In step ST14, the setting unit 102 determines the imaging direction of the breast X-ray imaging to be executed from now on, based on the input of information regarding the imaging direction of the breast X-ray imaging in the mammography apparatus 1 to be executed. Set. Thereby, “MLO” is set as the imaging direction of the X-ray imaging of the breast to be executed. Setting information regarding the shooting direction to be executed from now on is stored in the memory 71 b of the system control unit 71.

  The mammography apparatus 1 recognizes the imaging direction to be executed from now on based on the operation of the arm unit 15 by providing a magnetic sensor, an acceleration sensor, and the like in the imaging platform apparatus 11 in advance, and based on the recognition result. The imaging direction of the X-ray imaging of the breast to be executed from now on may be set.

  Next, the operator places the breast of the patient P on the Bucky device 25, presses it with a predetermined pressure using the breast compression plate 24 while expanding the breast, and fixes the breast. At this time, the operator performs positioning while fixing the breast so that X-ray imaging from the MLO can be performed. Then, the operator uses the input device 75 to input when X-ray imaging of the breast from the MLO is started.

  In step ST15, the input receiving unit 101 receives an input to start breast X-ray imaging from the MLO. The input receiving unit 101 outputs input information related to the received command to the X-ray imaging execution control unit 103.

  In step ST16, the X-ray imaging execution control unit 103 controls the entire mammography apparatus 1 and starts executing X-ray imaging from the MLO. X-ray imaging from the MLO is executed by the processing from step ST16 to ST26 described below. X-ray imaging from the MLO has two stages, that is, X-ray imaging by Pre exposure and X-ray imaging by main exposure. First, X-ray imaging from the MLO by Pre exposure is executed under the control of the X-ray imaging execution control unit 103. Note that the X-ray imaging execution control unit 103 determines the pre-exposure judgment based on instruction information regarding whether the X-ray imaging of the breast to be executed is X-ray imaging by pre-exposure or X-ray imaging by main exposure. To the unit 105.

  Specifically, the X-ray imaging execution control unit 103 outputs a command to execute X-ray imaging from the MLO by Pre exposure to each unit of the imaging platform apparatus 11. Then, the X-ray imaging execution control unit 103 determines imaging conditions for X-ray imaging from the MLO by Pre exposure based on information on breast thickness and information on compression pressure supplied from the breast compression plate 24. .

  At this time, the X-ray imaging execution control unit 103 uses the imaging condition calculation table stored in advance in the memory 71b of the system control unit 71 or the storage device 77 to obtain information on the breast thickness supplied from the breast compression plate 24. Based on this, it is possible to determine imaging conditions for X-ray imaging from MLO by Pre exposure.

  FIG. 11 is a diagram illustrating an example of an imaging condition calculation table stored in advance in the memory 71 b or the storage device 77 of the system control unit 71. As shown in FIG. 11, breast thickness [mm], tube voltage [kV], filter, and mAs value are stored in association with each other. In the first row of FIG. 11, when the breast thickness [mm] is 10 [mm], the tube voltage [kV] is 28 [kV], the filter is molybdenum, and the mAs value (current value) And the product value of time) is 2 [mAs] and stored in association with each other. The same applies to the second and subsequent lines in FIG. 11, and a description thereof will be omitted.

  Next, the X-ray imaging execution control unit 103 issues an instruction to the radiation quality adjustment filter control unit 72 in order to control the radiation quality adjustment filter 52 to use the filter determined using the imaging condition calculation table. . The line quality adjustment filter control unit 72 controls the line quality adjustment filter 52 to use the filter determined using the imaging condition calculation table in accordance with an instruction from the X-ray imaging execution control unit 103. In the case of the first row in FIG. 11, when the breast thickness [mm] is 10 [mm], the filter is determined to be molybdenum, so that the line quality adjustment filter 52 is used so that the molybdenum filter is used. Be controlled.

  Subsequently, the X-ray imaging execution control unit 103 operates the irradiation field limiting mask 53 so as to operate the irradiation field limiting mask 53 so as to match the X-ray imaging technique from the MLO to be executed. An instruction is given to the unit 73. The irradiation field restriction mask movement control unit 73 controls the movement of the irradiation field restriction mask 53 in accordance with an instruction from the X-ray imaging execution control unit 103.

  Then, the X-ray imaging execution control unit 103 instructs the high voltage control unit 51 to operate the high voltage supply device 32 with the tube voltage and mAs value determined using the imaging condition calculation table, and the X-ray tube 20 generates desired X-rays.

  Thereafter, the FPD 26a detects X-rays that have passed through the breast, and the time-series analog signal output from the FPD 26a is converted into projection data that is a digital signal by the A / D converter 58.

  In step ST <b> 17, the projection data acquisition unit 104 acquires projection data from the A / D conversion unit 58 after X-ray imaging of the breast is executed. The projection data acquisition unit 104 outputs the acquired projection data to the shielding plate movement amount calculation unit 107 and the main exposure condition calculation unit 108.

  In step ST18, when the projection data acquisition unit 104 acquires the projection data, the Pre exposure determination unit 105 instructs the instruction information from the X-ray imaging execution control unit 103 (the X-ray imaging of the breast to be executed in the future is based on Pre exposure). Whether the projection data acquired by the projection data acquisition unit 104 is projection data in X-ray imaging by Pre-exposure based on instruction information regarding whether X-ray imaging or X-ray imaging by main exposure) It is determined whether it is projection data in X-ray imaging by main exposure.

  Since X-ray imaging from MLO by Pre-exposure is currently being executed, it is determined in step ST18 that the projection data is projection data in X-ray imaging by Pre-exposure. When the pre-exposure determination unit 105 determines that the projection data acquired by the projection data acquisition unit 104 is projection data in X-ray imaging by pre-exposure, the determination result is compared with the shielding plate insertion determination unit 106 and the main exposure. It outputs to the condition calculation part 108.

  In step ST19, when the shielding plate insertion determination unit 106 acquires a determination result (determination result that the projection data is projection data in X-ray imaging by Pre exposure) from the Pre exposure determination unit 105, the X-ray imaging is executed. Based on the instruction information from the control unit 103, it is determined whether or not the shielding plate 55a is inserted by the shielding plate inserter 55 in the case of X-ray imaging by main exposure to be performed in the future. The instruction information from the X-ray imaging execution control unit 103 is irradiated with information indicating whether the currently executed X-ray imaging is imaging from MLO or CC imaging, and the shielding plate 55a. Information on the imaging direction (CC in the case of FIGS. 9 and 10) when X-ray imaging is performed by inserting between the field restriction mask 53 and the breast compression plate 24 is included.

  Since X-ray imaging from the MLO by Pre exposure is currently being executed, in step ST19, it does not coincide with CC which is the imaging direction when the shielding plate 55a is inserted and X-ray imaging is executed. The shielding plate insertion determining unit 106 determines that the shielding plate 55a is not inserted by the shielding plate inserter 55 in the case of X-ray imaging by main exposure to be performed from now on (No in step ST19). Thereafter, the processes of steps ST20 and 21 are skipped. Therefore, when X-ray imaging from the MLO is performed, it is not necessary to insert the shielding plate 55a in the case of X-ray imaging by main exposure, and the calculation processing of the movement amount of the shielding plate is not performed. .

  In step ST22, when the exposure condition calculation unit 108 acquires the determination result (determination result that the projection data is projection data in X-ray imaging by Pre exposure) from the Pre exposure determination unit 105, the projection data acquisition is performed. Based on the projection data supplied from the unit 104, imaging conditions (tube voltage [kV], mAs value, filter type, etc.) at the time of X-ray imaging by main exposure are calculated. The main exposure condition calculation unit 108 outputs the calculation result to the X-ray imaging execution control unit 103.

  In step ST23, the X-ray imaging execution control unit 103 sets imaging conditions for X-ray imaging by main exposure based on the calculation result.

  Thereafter, the process proceeds to step ST26, and the X-ray imaging execution control unit 103 determines whether X-ray imaging for both Pre exposure and main exposure is completed in X-ray imaging from the MLO. Since only X-ray imaging from MLO by Pre exposure is currently being executed, it is determined as “No”, and the process returns to step ST17.

  Then, the X-ray imaging execution control unit 103 executes X-ray imaging from the MLO by the main exposure. Specifically, the X-ray imaging execution control unit 103 issues an instruction to the high voltage control unit 51 and the quality control filter control unit 72 based on the set imaging conditions at the time of imaging by the main exposure, and performs diagnosis. X-rays are generated to obtain an image for use.

  In step ST <b> 17, the projection data acquisition unit 104 acquires projection data from the A / D converter 58 of the imaging table apparatus 11 after the X-ray imaging of the breast is executed. The Pre exposure determination unit 105 determines that the projection data is not the projection data in the imaging by the Pre exposure since the X-ray imaging from the MLO by the main exposure is currently being executed (Step ST18). No). That is, it is determined that the acquired projection data is projection data obtained by the main exposure, and the process proceeds to step ST24.

  In step ST24, the image processing unit 78 performs logarithmic conversion processing (LOG processing) and various types of image processing on the projection data according to control by the system control unit 71 to generate a display image. The character information and scales of the parameters are added to the display device 76 and output. In step ST25, the display device 76 displays a display image and the like. Thereafter, the process proceeds to step ST26, and the X-ray imaging execution control unit 103 determines that the X-ray imaging of both the Pre exposure and the main exposure from the MLO is completed.

  As described above, the X-ray imaging from the MLO is executed by the processing from the above-described steps ST16 to ST26. MLO is an imaging direction when X-ray imaging is performed without inserting the shielding plate 55a between the irradiation field limiting mask 53 and the breast compression plate 24 by the shielding plate inserter 55. The breast is radiographed without use.

  Subsequently, the operator uses the input device 75 to input “CC” as information regarding the imaging direction of the X-ray imaging of the breast to be performed before the X-ray imaging of the breast. In the processing of steps ST27 to ST28, basically the same processing as that of steps ST13 to ST14 already described is executed.

  In step ST29, the input receiving unit 101 receives an input to start X-ray imaging of the breast from the CC. The input receiving unit 101 outputs input information related to the received command to the X-ray imaging execution control unit 103.

  In step ST30, the X-ray imaging execution control unit 103 controls the entire mammography apparatus 1 and starts executing X-ray imaging from the CC. X-ray imaging from the CC is executed by the processing from steps ST31 to ST40. And X-ray imaging from CC consists of two stages of X-ray imaging by pre-exposure and X-ray imaging by main exposure, similarly to X-ray imaging from MLO. Note that the X-ray imaging from the CC executed in the processes from step ST31 to ST40 is the same as the X-ray imaging from the MLO executed in the processes from step ST17 to ST26 except for the processes in steps ST33 to ST35. The same. Therefore, only the processes of steps ST33 to ST35 characteristic of X-ray imaging from CC will be described in detail.

  First, it is assumed that X-ray imaging from CC by Pre exposure is executed. In step ST <b> 33, when the shielding plate insertion determination unit 106 acquires a determination result (determination result that the projection data is projection data in X-ray imaging by Pre exposure) from the Pre exposure determination unit 105, X-ray imaging is executed. Based on the instruction information from the control unit 103, it is determined whether or not the shielding plate 55a is inserted by the shielding plate inserter 55 in the case of X-ray imaging by main exposure to be performed in the future. The instruction information from the X-ray imaging execution control unit 103 includes information indicating whether the currently executed X-ray imaging is X-ray imaging from MLO or X-ray imaging from CC, and shielding. Information on the imaging direction (CC in FIGS. 9 and 10) when X-ray imaging is performed by inserting the plate 55a between the irradiation field restriction mask 53 and the breast compression plate 24 is included.

  And since X-ray imaging from CC by Pre exposure is currently being executed, in step ST33, it coincides with CC that is the imaging direction when X-ray imaging is performed with the shielding plate 55a inserted, The shielding plate insertion determination unit 106 determines that the shielding plate 55a is to be inserted by the shielding plate inserter 55 in the case of X-ray imaging by main exposure to be performed from now on (when the determination is affirmative). If the shielding plate insertion determining unit 106 determines that the shielding plate 55a is to be inserted by the shielding plate inserter 55 in the case of X-ray imaging by main exposure to be performed in the future, the determination result is output to the shielding plate movement amount calculating unit 107. To do.

  In step ST34, the shielding plate movement amount calculation unit 107 inserts the shielding plate 55a by the shielding plate inserter 55 in the case of the X-ray imaging by the main exposure to be performed from the shielding plate insertion determination unit 106. When the determination result is acquired, the movement amount of the shielding plate 55a in the case of X-ray imaging by the main exposure is calculated based on the projection data (CC direction) of Pre exposure supplied from the projection data acquisition unit 104. Hereinafter, a specific example of a method for calculating the amount of movement of the shielding plate 55a in the case of photographing by main exposure will be described.

(2) Calculation Method of Movement Amount of Shielding Plate FIG. 12 shows an image of an average breast in the breast group taken from the CC in the past. As shown in FIG. 12, the outline of the breast is indicated by a skin line.

  The hatched area in FIG. 12 is an area that cannot be rendered as an image during mammography from MLO, and is an area that should be rendered as an image by X-ray imaging from CC. That is, in the case of X-ray imaging from CC, at least the breast area needs to be radiographed in the hatched area in FIG. 12, and the shielding plate is used in the area other than the hatched area in FIG. X-ray irradiation should be shielded by 55a. The two-dimensional positional relationship in the breast in the hatched area in FIG. 12 is defined by the length a and the length b and the angle θ shown in FIG.

  The length a is the length in the longitudinal direction of the breast, the length b is the length from the end of the breast to the shaded area in FIG. 12, and the angle θ determines the range of the shaded area in FIG. Is an angle. Information regarding these three numerical values is stored in advance in the memory 71 b or the storage device 77 of the system control unit 71.

  FIG. 13 is a diagram for explaining a method for obtaining a region that cannot be rendered as an image at the time of mammography from the MLO based on projection data obtained by X-ray imaging by the current Pre exposure.

  The shielding plate movement amount calculation unit 107 first detects a skin line of the breast based on projection data obtained by X-ray imaging using Pre exposure. Next, the shielding plate movement amount calculation unit 107 reads three numerical values (length a, length b, and angle θ) stored in advance in the memory 71 b or the storage device 77 of the system control unit 71. The shielding plate movement amount calculation unit 107 obtains the coordinates of the points P and Q that are both ends of the breast in the longitudinal direction based on the detected skin line, and obtains the length A of the line segment PQ. Based on the ratio of the read lengths a and b and the length A of the line segment PQ, the shielding plate movement amount calculation unit 107 obtains the length B using an equation B = A × b / a. .

  The shielding plate movement amount calculation unit 107 obtains the coordinates of the point R from the coordinates of the point P and the length B. Next, the shielding plate movement amount calculation unit 107 obtains lengths C and D, which are distances from the point R to both ends of the image area. The positions of both ends of the image area can be obtained from projection data obtained by Pre exposure.

  FIG. 14 shows the position of the shielding plate 55a based on the positional relationship between the breast fixed by being compressed by the breast compression plate 24 and the irradiation field restriction mask 53 that is located above the breast and restricts the X-ray irradiation field. It is a figure explaining the method of calculating a movement amount. FIG. 15 is a diagram for explaining a method of obtaining the coordinates of the point R ′ on the irradiation field limiting mask 53 from the ratio of the lengths C and D, which are the distances from the point R to both ends of the image area. It is.

  As shown in FIG. 14, since the positional relationship between the breast and the irradiation field restriction mask 53 that restricts the X-ray irradiation field and is located above the breast is known in advance, it is on the breast (or the image area). If the coordinates of the point R ′ on the irradiation field limiting mask 53 corresponding to the point R can be obtained, the shielding plate 55a can be moved so that the shielding plate 55a and the irradiation field limiting mask 53 intersect at the point R ′. It becomes possible. As shown in FIG. 15, the isosceles triangle MNO and the isosceles triangle MKL are similar, and the triangle MNR ′ and the triangle MKR are also similar. The positional relationship in the height direction between the breast and the irradiation field restriction mask 53 is also known. Therefore, it is possible to obtain the coordinates of the point R ′ such that the ratio between the lengths C ′ and D ′ and the ratio between the lengths C ′ and D ′, which are distances from the point R to both ends of the image region, are equal.

  As a result, the shielding plate movement amount calculation unit 107 rotates the shielding plate 55a in the clockwise direction by θ degrees, and then moves in parallel so that the shielding plate 55a crosses the irradiation field limiting mask 53 at the point R ′. The amount of movement combined with the parallel movement can be calculated as the amount of movement of the shielding plate 55a. The rotation direction of the shielding plate 55a may be counterclockwise. The shielding plate movement amount calculation unit 107 outputs the calculation result to the shielding plate insertion device movement control unit 74.

  In step ST <b> 35, the shielding plate insertion device movement control unit 74 is configured to perform the shielding plate insertion device driving mechanism toward the execution of X-ray imaging from the CC by the main exposure based on the calculation result by the shielding plate movement amount calculation unit 107. 56 is controlled to move the shielding plate 55a to the predetermined position. Thereafter, the process proceeds to step ST36, and X-ray imaging from CC by main exposure is executed in a state where X-ray shielding by the shielding plate 55a is performed. Then, mammography is completed.

  As described above, the mammography apparatus 1 according to the present embodiment can reduce the exposure dose of X-rays irradiated to the subject. In particular, the mammography apparatus 1 in the first embodiment is a shielding plate that shields X-rays in X-ray imaging from one direction among X-ray imaging from two directions (for example, two directions of MLO and CC). (Shielding member) is used, it is limited to X-ray irradiation only in the minimum necessary area, and X-rays are irradiated redundantly in areas that are not blind areas in either of the two directions (2 Heavy exposure) can be avoided, and the dose of X-rays irradiated to the subject can be reduced. Specifically, it is possible to reduce from 60% to 70% of the total exposure dose by conventional two-directional imaging by significantly reducing the area where X-rays are repeatedly irradiated. it can.

  As a result, it is possible to suppress the X-ray exposure dose in the X-ray imaging of the breast as much as possible, and to reduce the influence on the human body due to the exposure by the screening.

  9 and 10, the mammography apparatus 1 in the first embodiment performs X-ray imaging of a subject without inserting the shielding plate 55a in X-ray imaging from the MLO, and thereafter In the X-ray imaging from the CC, the shielding plate 55a is inserted to perform X-ray imaging of the subject. However, the present invention is not limited to this, and the shielding plate 55a is inserted in the X-ray imaging from the MLO. The specimen may be X-rayed, and then the subject may be X-rayed without inserting the shielding plate 55a in the X-ray photography from the CC.

(3) Modification 1 of the first embodiment
In 1st Embodiment mentioned above, it is set as the structure which avoids double exposure using the shielding board 55a. On the other hand, in the first modification of the first embodiment, the double exposure is avoided by using only the irradiation field limiting mask 53 without using the shielding plate 55a. FIG. 16 is a diagram illustrating an example of a technique for avoiding double exposure using only the irradiation field limiting mask 53 in the first modification of the first embodiment. In the first modification, the width of the partial mask piece 53a of the irradiation field limiting mask 53 is increased, and the partial mask piece 53a is moved in parallel to thereby double the region that is not a blind area in any of the two directions. Avoid exposure. In the first modification, the double exposure region remains slightly as compared with the first embodiment described above, but the shielding plate 55a and its driving mechanism are not required, and the configuration is simplified.

(4) Modification 2 of the first embodiment
In the mammography apparatus 1 according to the first embodiment, the shielding plate 55a is made of a material such as lead (Pb) or iron (Fe). The shielding plate 55a of the first embodiment made of these materials is a non-transmissive shielding plate (non-transmissive shielding member) and overlaps in a region that is not a blind area in any of the two directions. X-ray irradiation can be almost completely shielded. On the other hand, in the second modification of the first embodiment, a transmissive shielding plate (transmissive shielding member) 55b made of a material such as aluminum is used instead of the shielding plate 55a. The transmission type shielding plate 55b can transmit a part of X-rays relatively as compared with the shielding plate 55a made of a material such as lead (Pb) or iron (Fe).

  The mammography apparatus 1 of the second modification of the first embodiment can reduce the exposure dose of X-rays irradiated to the subject as compared with the conventional one, and uses the transmission type shielding plate 55b described above. Thus, a diagnostic image can be acquired and displayed even in a region that is not a blind area in any of the two directions. As a result, breast images can be displayed from two different directions, three-dimensional position information can be provided to the operator, and the positions of lesions and the like hidden in the overlap of breast mammary glands can be determined. It can be accurately identified.

  Although the material of the transmission type shielding plate 55b used in the second modification of the first embodiment is the same lead (Pb) or iron (Fe) as in the first embodiment, the thickness thereof is the first You may comprise so that it may be made thinner than the thickness of the shielding board 55a of embodiment. Even with this configuration, part of the X-rays can be transmitted.

  Here, by using the transmission type shielding plate 55b, a diagnostic image can be acquired even in a region that is not a blind area in any of the two directions, but the intensity of the X-ray detected by the FPD 26a is high. For this reason, the density of the image generated in the area where the transmissive shielding plate 55b is present and the density of the image generated in the area where the transmissive shielding plate 55b is not present naturally take different values. Therefore, it is preferable to make the image level uniform between an image generated in an area where the transmissive shielding plate 55b is present and an image generated in an area where the transmissive shielding plate 55b is not present. For this purpose, first, the pixel value of the image obtained when there is no transmissive shielding plate 55b is S0, the pixel value of the image obtained when there is the transmissive shielding plate 55b is S1, and the ratio ( S0 / S1) is calculated in advance through experiments or the like. The ratio (S0 / S1) is a value larger than 1. The system control unit 71 stores the ratio value in advance in the memory 71 b or the storage device 77 of the system control unit 71. Then, the image processing unit 78 converts the pixel value of the region where X-ray irradiation is shielded by the transmissive shielding plate 55b from the image obtained when the transmissive shielding plate 55b is inserted during image processing. The ratio (S0 / S1) stored in advance is multiplied. That is, the image processing unit 78 multiplies (multiplies) the pixel value of the region where the X-ray irradiation is shielded by the transmission type shielding plate 55b by one or more coefficients.

  The image processing in the image processing unit 78 is executed in step ST38 in the case of the examples of FIGS. 9 and 10, for example.

  As a result, the mammography apparatus 1 makes the image level uniform between an image generated in an area where there is a shielding plate and an image generated in an area where there is no shielding plate, even if a shielding plate is used. It is possible to generate an image close to the image when the shielding plate is not inserted while maintaining the effect that the exposure dose of the X-ray irradiated to the subject can be reduced as compared with the conventional case. Can do.

  Note that by multiplying the pixel value of the region where the X-ray irradiation is shielded by the transmission type shielding plate 55b by a coefficient of 1 or more, noise in the image (image signal) in this region is also amplified. Therefore, the image processing unit 78 performs a process of reducing noise of an image (image signal) in an area where X-ray irradiation is shielded by the transmission type shielding plate 55b before performing image processing for matching the image level. To do. As a result, it is possible to make the image level uniform between an image generated in an area with a shielding plate and an image generated in an area without a shielding plate while suppressing amplification of noise. An image closer to the image when not inserted can be generated.

(5) Second Embodiment The mammography apparatus 1 according to the first embodiment uses the shielding plate 55a for imaging by Pre exposure for calculating imaging conditions at the time of imaging by main exposure. The amount of movement was calculated. However, in the case of the mammography apparatus 1 that does not perform imaging by Pre exposure, the above method cannot be applied. Therefore, in the mammography apparatus 1 according to the second embodiment, a visible light camera, an infrared thermography camera, and the like are provided in the vicinity of the X-ray tube 20. When the consent of the patient is obtained, the amount of movement of the shielding plate 55a is calculated from the data obtained by imaging with the camera instead of the data obtained by X-ray imaging by Pre exposure. For example, before the start of X-ray imaging from CC, the breast is imaged with a camera, the area of the breast is recognized, and the shielding plate is calculated using the method for calculating the movement amount of the shielding plate 55a described in the first embodiment. 55a is moved to a desired position.

  Note that the second embodiment can also be applied to the case where the pre-exposure is performed and the imaging conditions for the main exposure are calculated. In this case, the amount of movement of the shielding plate 55a is calculated by performing camera photography before the Pre exposure. By using the shielding plate 55a for both the pre-exposure and the main exposure, the exposure amount can be reduced not only in the main exposure but also in the pre-exposure.

  Hereinafter, the mammography apparatus 1 in the second embodiment will be described.

  FIG. 17 is a block diagram showing an internal configuration of the mammography apparatus 1 in the second embodiment. In addition, the same code | symbol is attached | subjected about the structure similar to FIG. 7, and the description is abbreviate | omitted. The imaging table apparatus 11 of the mammography apparatus 1 includes a camera 151 (for example, a visible light camera or an infrared thermography camera) as an imaging unit in the vicinity of the X-ray tube 20. The camera 151 can take an image of a breast that is compressed and fixed by the breast compression plate 24 under the control of the system control unit 71. The camera 151 outputs captured image data to the system control unit 71.

  FIG. 18 is a block diagram showing functions of the mammography apparatus 1 in the second embodiment. When the CPU 71a of the system control unit 71 of the image processing apparatus 12 shown in FIG. 18 executes the program, the mammography apparatus 1 has the following functions characteristic of the present embodiment. The mammography apparatus 1 includes an input reception unit 101, a setting unit 102, an X-ray imaging execution control unit 103, a shielding plate insertion determination unit 106, a shielding plate movement amount calculation unit 107, a camera control unit 161, and an image data acquisition unit. The function as 162 is provided. In addition, the same code | symbol is attached | subjected about the structure similar to FIG. 8, and the description is abbreviate | omitted fundamentally.

  When receiving an input to start breast X-ray imaging in the mammography apparatus 1, the X-ray imaging execution control unit 103 performs predetermined imaging on the imaging platform apparatus 11 to start X-ray imaging of the breast. X-ray imaging is executed according to conditions and imaging procedures. In particular, for breast X-ray imaging, only imaging by main exposure is performed in each of two imaging directions (for example, two imaging directions of MLO and CC).

  When the operation of the breast compression plate 24 by the operator is completed, the shielding plate insertion determination unit 106 shields in the case of X-ray imaging by main exposure to be performed based on instruction information from the X-ray imaging execution control unit 103. It is determined whether or not the plate 55a is inserted by the shielding plate inserter 55. When the shielding plate insertion determination unit 106 determines that the shielding plate 55a is to be inserted by the shielding plate inserter 55 in the case of X-ray imaging by main exposure to be performed in the future, the determination result is output to the camera control unit 161.

  The camera control unit 161 controls the driving of the camera 151 of the imaging platform device 11. When the camera control unit 161 obtains a determination result from the shielding plate insertion determining unit 106 (determination result that the shielding plate 55a is inserted by the shielding plate inserter 55 in the case of imaging by main exposure to be performed in the future), breast compression A command is issued to the camera 151 in order to photograph the breast pressed and fixed by the plate 24. The camera control unit 161 notifies the image data acquisition unit 162 that a shooting command has been issued to the camera 151.

  The image data acquisition unit 161 acquires image data related to the breast from the camera 151 and outputs the acquired image data to the shielding plate movement amount calculation unit 107.

  FIG. 19 is a flowchart illustrating a processing example of the mammography apparatus 1 according to the second embodiment. In the mammography described with reference to the flowchart of FIG. 19, it is assumed that the breast is X-rayed from two directions of MLO and CC in the order of CC after MLO, for example. Of course, the mammography apparatus 1 in the present embodiment is not limited to the case of X-ray imaging from two directions of MLO and CC. Further, in mammograms described with reference to the flowchart of FIG. 19, the setting of imaging conditions at the time of X-ray imaging by main exposure is performed by the operator using the input device 75 before starting each X-ray imaging. Alternatively, it is performed based on information input by operating the photographing condition setting panel 31 of the operation unit 18.

  Note that the processing in steps ST101 to ST104 in FIG. 19 is basically the same as the processing in steps ST11 to ST14 in FIG.

  First, the operator places the breast of the patient P on the Bucky device 25, presses it with a predetermined pressure using the breast compression plate 24 while expanding the breast, and fixes the breast. At this time, the operator performs positioning while fixing the breast so that X-ray imaging from the MLO can be performed.

  When the operation of the breast compression plate 24 by the operator is completed, in step ST105, the shielding plate insertion determination unit 106 performs X-ray imaging by main exposure to be performed based on instruction information from the X-ray imaging execution control unit 103. In this case, it is determined whether or not the shielding plate 55a is inserted by the shielding plate inserter 55. The instruction information from the X-ray imaging execution control unit 103 includes information indicating whether the currently executed X-ray imaging is X-ray imaging from MLO or X-ray imaging from CC, and shielding. Information on the imaging direction (CC in the case of FIG. 19) when X-ray imaging is performed by inserting the plate 55a between the irradiation field limiting mask 53 and the breast compression plate 24 is included.

  At present, since X-ray imaging from the MLO by this exposure is about to be executed, in step ST105, it does not coincide with CC which is the imaging direction when the X-ray imaging is executed by inserting the shielding plate 55a. The shielding plate insertion determination unit 106 determines that the shielding plate 55a is not inserted by the shielding plate inserter 55 in the case of X-ray imaging by main exposure to be performed from now on (determination of NO). Thereafter, the processes of steps ST106 and ST109 are skipped. Therefore, when X-ray imaging from the MLO is being performed, it is not necessary to insert the shielding plate 55a in the case of imaging by main exposure, and the calculation processing of the movement amount of the shielding plate is not performed.

  Then, the operator uses the input device 75 to input when X-ray imaging of the breast from the MLO is started.

  In step ST110, the input receiving unit 101 receives an input to start X-ray imaging of the breast from the MLO. The input receiving unit 101 outputs input information related to the received command to the X-ray imaging execution control unit 103.

  In step ST111, the X-ray imaging execution control unit 103 controls the entire mammography apparatus 1 and first starts executing X-ray imaging from the MLO. Specifically, the X-ray imaging execution control unit 103 outputs a command to execute X-ray imaging from the MLO by the main exposure to each unit of the imaging platform apparatus 11. The X-ray imaging execution control unit 103 controls the radiation quality adjustment filter control unit 72 and the irradiation field restriction mask movement control unit 73 on the basis of the imaging conditions at the time of imaging by the determined main exposure, and the high voltage The controller 51 is controlled to generate desired X-rays from the X-ray tube 20.

  Thereafter, the FPD 26a detects X-rays that have passed through the breast, and the time-series analog signal output from the FPD 26a is converted into projection data that is a digital signal by the A / D converter 58.

  In step ST <b> 112, the image processing unit 78 acquires projection data from the A / D conversion unit 58 of the imaging platform device 11. In step ST113, the image processing unit 78 performs various types of image processing in addition to performing logarithmic conversion processing and the like on the projection data in accordance with control by the system control unit 71. Then, the image processing unit 78 generates a display image according to the parameters of the auto window function (gradation conversion processing) based on the projection data subjected to the image processing. Further, character information and scales of various parameters are added to the display image and output to the display device 76. In step ST114, the display device 76 displays a display image and the like.

  Thereafter, the process proceeds to step ST115, and the X-ray imaging execution control unit 103 determines whether both the X-ray imaging from the MLO and the X-ray imaging from the CC (both main exposure) have been completed. Currently, since only X-ray imaging from the MLO is being performed, the X-ray imaging execution control unit 103 determines that both X-ray imaging has not been completed yet (no determination). Thereafter, the process returns to step ST103.

  Subsequently, the operator uses the input device 75 to input “CC” as information regarding the imaging direction of the X-ray imaging of the breast to be performed before the X-ray imaging of the breast. And the process of step S103 and ST104 is performed similarly.

  At present, since X-ray imaging from CC by the main exposure is about to be executed, in step ST105, it coincides with CC which is an imaging direction when X-ray imaging is executed with the shielding plate 55a inserted, and is shielded. The plate insertion determination unit 106 determines that the shielding plate 55a is to be inserted by the shielding plate inserter 55 in the case of X-ray imaging by main exposure to be performed from now on (when the determination is affirmative). When the shielding plate insertion determination unit 106 determines that the shielding plate 55a is to be inserted by the shielding plate inserter 55 in the case of photographing by main exposure to be performed in the future, the determination result is output to the camera control unit 161.

  In step ST106, the camera control unit 161 determines the determination result from the shielding plate insertion determination unit 106 (determination result that the shielding plate 55a is inserted by the shielding plate inserter 55 in the case of X-ray imaging by main exposure to be performed in the future). Is acquired, a command is issued to the camera 151 in order to photograph the breast compressed and fixed by the breast compression plate 24. The camera control unit 161 notifies the image data acquisition unit 162 that a shooting command has been issued to the camera 151. Then, the camera 151 takes an image of the breast that is compressed and fixed by the breast compression plate 24 according to the control of the camera control unit 161. The camera 151 outputs the captured image data to the image data acquisition unit 162 of the system control unit 71.

  In step ST107, the image data acquisition unit 161 acquires image data related to the breast from the camera 151, and outputs the acquired image data to the shielding plate movement amount calculation unit 107. In step ST108, the shielding plate movement amount calculation unit 107 calculates the movement amount of the shielding plate 55a in the case of X-ray imaging by main exposure based on the image data regarding the breast supplied from the image data acquisition unit 161. . This calculation method is the same as the calculation method described in the first embodiment, and a description thereof will be omitted.

  In step ST109, based on the calculation result by the shielding plate movement amount calculation unit 107, the shielding plate inserter movement control unit 74 prepares for the shielding plate inserter drive mechanism to execute the X-ray imaging from the CC by the main exposure. 56 is controlled to move the shielding plate 55a to the predetermined position. Thereafter, the process proceeds to step ST110, the processes after step ST110 are executed, and the X-ray imaging from the CC is executed.

  In step ST115, the X-ray imaging execution control unit 103 determines that both the X-ray imaging from the MLO and the X-ray imaging from the CC are completed, and the mammography is completed.

  As described above, the mammography apparatus 1 according to the second embodiment does not perform X-ray imaging by Pre-exposure, and even a visible light camera or infrared thermography provided in the vicinity of the X-ray tube 20. For example, a breast can be imaged before the start of X-ray imaging from CC using a camera or the like, and the amount of movement of the shielding plate 55a can be calculated based on the image. Thereby, the mammography apparatus 1 in the second embodiment can reduce the exposure dose of X-rays irradiated to the subject. As a result, it is possible to suppress the X-ray exposure dose in the X-ray imaging of the breast as much as possible, and to reduce the influence on the human body due to the exposure by the screening.

  Note that the configuration such as the transmission type shielding plate 55b described in the first embodiment can also be applied to the mammography apparatus 1 in the second embodiment.

(6) Third Embodiment By the way, breast cancer and other lesions in breast tissue may be hidden in the overlap of mammary glands in the breast. In order for doctors, technicians, and the like to find such difficult lesions, it is essential to make a diagnosis by comparing a plurality of images taken from a plurality of different imaging directions.

  Therefore, when X-ray imaging is performed from two directions from the MLO and the CC, the operator performs an operation based on an image obtained by X-ray imaging from the imaging direction performed in advance (for example, X-ray imaging from the MLO). When an operator suspects a lesion or the like, the operator uses the input device 75 to input an instruction not to insert the shielding plate 55a in X-ray imaging from the next imaging direction. On the other hand, when the operator does not find any suspected lesion or the like, the operator inputs an instruction to insert the shielding plate 55a by X-ray imaging from the next imaging direction using the input device 75. As a result, the mammography apparatus 1 can provide the operator with a plurality of images that are images that do not use the shielding plate 55a and that are captured from a plurality of different imaging directions. Therefore, it is possible for the operator to make a diagnosis by comparing a plurality of images taken from a plurality of different imaging directions with respect to what is suspected to be a lesion, and can interpret a more accurate image. The three-dimensional position can be accurately grasped. Hereinafter, the mammography apparatus 1 in the third embodiment will be described.

  Note that the concept of the invention according to the third embodiment can be applied to both the mammography apparatus 1 in the first embodiment and the mammography apparatus 1 in the second embodiment. When the concept of the invention according to the third embodiment is applied to the mammography apparatus 1 in the first embodiment, the internal configuration of the mammography apparatus 1 in the third embodiment is as follows. FIG. 7 and FIG. 8 are the same as the internal configuration of the mammography apparatus 1 in the first embodiment described with reference to FIGS. Further, when the concept of the invention according to the third embodiment is applied to the mammography apparatus 1 in the second embodiment, the internal configuration of the mammography apparatus 1 in the third embodiment is as follows. FIG. 17 and FIG. 18 are the same as the internal configuration of the mammography apparatus 1 in the second embodiment.

  The mammography in the mammography apparatus 1 in the third embodiment is basically the same as the process described in the first embodiment or the second embodiment. Only the processing described in the first embodiment or the second embodiment will be briefly described.

  First, when the concept of the invention according to the third embodiment is applied to the mammography apparatus 1 in the first embodiment, after the processing of step ST29 in FIG. 75 is operated to input an instruction not to insert the shielding plate 55a in the X-ray imaging from the next imaging direction or not. In response thereto, as a new process in the third embodiment, the input receiving unit 101 receives an instruction to insert the shielding plate 55a or not to insert the shielding plate 55a in the X-ray imaging from the next imaging direction. . The input receiving unit 101 outputs input information related to the received instruction to the X-ray imaging execution control unit 103.

  Thereafter, when the shielding plate insertion determination unit 106 acquires a determination result (determination result that the projection data is projection data in X-ray imaging by Pre exposure) from the Pre-exposure determination unit 105 in Step ST33, Based on the instruction information from the imaging execution control unit 103, it is determined whether or not the shielding plate 55a is to be inserted by the shielding plate inserter 55 in the case of X-ray imaging by main exposure to be executed in the future. The instruction information from the X-ray imaging execution control unit 103 is irradiated with information indicating whether the currently executed X-ray imaging is imaging from MLO or CC imaging, and the shielding plate 55a. Information about the imaging direction (CC in the case of FIGS. 9 and 10) when X-ray imaging is performed by inserting between the field restriction mask 53 and the breast compression plate 24, and X from the next imaging direction Information indicating whether or not to insert the shielding plate 55a in line imaging is included.

  And even if X-ray imaging from CC by Pre exposure is currently being executed, if an instruction not to insert the shielding plate 55a is given in X-ray imaging from the next imaging direction. In step ST33, the shielding plate insertion determining unit 106 determines that the shielding plate 55a is not inserted by the shielding plate inserter 55 in the case of X-ray imaging by main exposure to be performed from now on (determination of NO). On the other hand, when X-ray imaging from CC by Pre-exposure is currently being executed and an instruction to insert the shielding plate 55a is made in X-ray imaging from the next imaging direction It is determined that the shielding plate 55a is inserted by the shielding plate inserter 55 in the case of X-ray imaging by main exposure to be performed from now on (positive determination).

  In this way, whether or not the shielding plate 55a is finally inserted can be related to the input by the operator, and the operator can select a plurality of different imaging directions for what is suspected to be a lesion or the like. It is possible to make a diagnosis by comparing a plurality of images taken from the image, more accurately interpret the image, and accurately grasp the three-dimensional position of a lesion or the like. As a result, the mammography apparatus 1 in the third embodiment can reduce the exposure dose of X-rays irradiated to the subject, while providing an image that contributes to interpretation to the operator as necessary. Can be provided.

  On the other hand, when the concept of the invention according to the third embodiment is applied to the mammography apparatus 1 in the second embodiment, the same input as described above is accepted after the process of step ST104 in FIG. Based on this, a determination process of whether or not to insert the shielding plate 55a is executed in step ST105. The content of the determination process in step ST105 is basically the same as the content of the determination process in step ST33 described above, and the description thereof is omitted.

  In the above case, whether or not the shielding plate 55a is finally inserted is related to the operator's input, and an instruction as to whether or not the shielding plate 55a is to be inserted by X-ray imaging from the next imaging direction. However, the present invention is not limited to such a case, and the system control unit 71 uses CAD (Computer-Aided Detection) to determine whether there is a suspected lesion or the like on the image. (Automatic detection of a lesion or the like) may be issued, and a command as to whether or not to insert the shielding plate 55a may be issued by X-ray imaging from the next imaging direction.

  In other words, the system control unit 71 determines the presence or absence of a suspected lesion or the like using CAD based on an image obtained by X-ray imaging (for example, X-ray imaging from MLO) performed in advance. Then, based on the determination result, a command is issued as to whether or not the shielding plate 55a is to be inserted in the X-ray imaging from the next imaging direction. Subsequent processing is the same as that described above.

  Thereby, an operator's input work can be reduced, maintaining said effect.

(7) Fourth Embodiment In general, in the case of a patient having a high mammary gland density, the mammary gland and the lesion are overlapped, and there is a tendency that the lesion or the like is difficult to find. Therefore, it is more preferable to diagnose a patient having a high breast density by comparing a plurality of images taken from a plurality of different imaging directions. Therefore, in the fourth embodiment, the mammary gland density is calculated from the data obtained by the Pre exposure, and the system control unit 71 determines whether or not to insert the shielding plate 55a based on the mammary gland density calculation result. Based on the determination result, a command is issued to determine whether or not to insert the shielding plate 55a in X-ray imaging from the next imaging direction.

  First, a case where the fourth embodiment according to this concept is applied to the mammography apparatus 1 in the first embodiment will be described. FIG. 20 is a block diagram showing a functional configuration inside the mammography apparatus 1 in this case. In addition, the same code | symbol is attached | subjected about the same thing as the structure of FIG. 8, The description is abbreviate | omitted.

  The mammary gland density calculation unit 201 calculates the mammary gland density based on the projection data supplied from the projection data acquisition unit 104. Specifically, the mammary gland density calculation unit 201 calculates (estimates) the mammary gland density of the subject's breast based on the skin surface dose and the pixel value in a predetermined region of the X-ray image data. Note that the more specific content of the calculation method for calculating the mammary gland density from the projection data is the same as the content described in Japanese Patent Laid-Open No. 2009-268726.

  When the shielding plate insertion determination unit 106 acquires a determination result (determination result that the projection data is projection data in X-ray imaging by Pre exposure) from the Pre-exposure determination unit 105, the shielding plate insertion determination unit 106 receives the determination result from the X-ray imaging execution control unit 103. Whether or not the shielding plate 55a is to be inserted by the shielding plate inserter 55 is determined based on the instruction information and the calculation result from the mammary gland density calculation unit 201 in the case of X-ray imaging by main exposure to be performed in the future. If the shielding plate insertion determining unit 106 determines that the shielding plate 55a is to be inserted by the shielding plate inserter 55 in the case of X-ray imaging by main exposure to be performed in the future, the determination result is output to the shielding plate movement amount calculating unit 107. To do.

  21 and 22 are flowcharts showing a series of processing examples of the mammography apparatus 1 of the fourth embodiment according to the above concept. Note that steps ST201 to ST208 and steps ST210 to ST217 in FIG. 21 are the same as the processes in steps ST11 to ST18 and steps ST19 to ST26 in FIG. Also, steps ST218 to ST223 and steps ST225 to ST232 in FIG. 22 are the same as the processes in steps ST27 to ST32 and steps ST33 to ST40 in FIG.

  In step ST209 in FIG. 21, the mammary gland density calculating unit 201 calculates the mammary gland density based on the projection data supplied from the projection data acquiring unit 104. The mammary gland density calculation unit 201 supplies the calculation result to the shielding plate insertion determination unit 106. In step ST210, when the shielding plate insertion determination unit 106 acquires a determination result (determination result that the projection data is projection data in X-ray imaging by Pre exposure) from the Pre exposure determination unit 105, the X-ray imaging is executed. Based on the instruction information from the control unit 103 and the calculation result from the mammary gland density calculation unit 201, whether or not the shielding plate 55a is inserted by the shielding plate inserter 55 in the case of X-ray imaging by main exposure to be performed in the future. judge.

  Since X-ray imaging from the MLO by Pre exposure is currently being executed, in step ST210, it does not coincide with CC that is the imaging direction when X-ray imaging is performed with the shielding plate 55a inserted. The shielding plate insertion determination unit 106 determines that the shielding plate 55a is not inserted by the shielding plate inserter 55 in the case of imaging by main exposure to be performed from now on (determination of NO). In this case, the calculation result from the mammary gland density calculation unit 201 does not affect the above determination result because it does not coincide with CC that is the imaging direction when the shielding plate 55a is inserted and X-ray imaging is performed. .

  Next, in step ST224 of FIG. 22, the mammary gland density calculation unit 201 calculates the mammary gland density based on the projection data supplied from the projection data acquisition unit 104. The mammary gland density calculation unit 201 supplies the calculation result to the shielding plate insertion determination unit 106. In step ST225, when the shielding plate insertion determination unit 106 acquires the determination result (determination result that the projection data is projection data in imaging by Pre exposure) from the Pre exposure determination unit 105, the X-ray imaging execution control unit Based on the instruction information from 103 and the calculation result from the mammary gland density calculation unit 201, it is determined whether or not the shielding plate 55a is inserted by the shielding plate inserter 55 in the case of X-ray imaging by main exposure to be performed in the future. .

  Here, since X-ray imaging from CC by Pre exposure is currently being executed, this coincides with CC that is the imaging direction when X-ray imaging is performed with the shielding plate 55a inserted. However, when the calculation result from the mammary gland density calculation unit 201 is higher than the threshold value (reference value), the shielding plate insertion determination unit 106 is a case where the main exposure to be performed from now is X-ray imaging from the CC. However, it is determined that the shielding plate 55a is not inserted by the shielding plate inserter 55 (determination of NO). On the other hand, when the calculation result from the mammary gland density calculation unit 201 is equal to or less than the threshold value (reference value), the shielding plate insertion determination unit 106 inserts the shielding plate 55a into the shielding plate as in the first embodiment. It is determined to be inserted by the device 55 (positive determination). The threshold value (reference value) is stored in advance in the memory 71b or the storage device 77.

  When the shielding plate insertion determining unit 106 determines that the shielding plate 55a is to be inserted by the shielding plate inserter 55 in the case of photographing by main exposure to be performed from now on, the determination result is output to the shielding plate movement amount calculating unit 107.

  Thereby, when the density of the mammary gland is high, the system control unit 71 determines that the shielding plate 55a is not inserted based on the result of the mammary gland density without increasing the work of the operator, and the X from the next imaging direction is determined. It is possible to issue an instruction not to insert the shielding plate 55a in line imaging. As a result, the mammography apparatus 1 reduces the X-ray dose irradiated to the subject when the mammary gland density is relatively low, and images from a plurality of different imaging directions when the mammary gland density is high. A plurality of images can be provided to the operator.

  Note that any of the configurations described in the first to fourth embodiments can be combined as much as possible.

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

DESCRIPTION OF SYMBOLS 1 Mammography apparatus 11 Imaging stand apparatus 12 Image processing apparatus 15 Arm part 16 Stand part 17 Connection part 18 Operation part 20 X-ray tube 23 Face guard 24 Breast compression board 25 Bucky apparatus 26 Imaging stand 27 Compression foot pedal 28 Information display Panel 29 C-arm vertical / rotational fine adjustment switch 30 Side panel 31 Imaging condition setting panel 32 High voltage supply device 51 High voltage controller 52 Radiation quality adjustment filter 53 Irradiation field restriction mask 54 Irradiation field restriction mask drive mechanism 55 Shield plate inserter 55a Shield plate 56 Shield plate inserter drive mechanism 57 Breast compression plate drive mechanism 58 A / D converter 71 System controller 72 Radiation quality adjustment filter controller 73 Irradiation field restriction mask movement controller 74 Shield plate inserter movement controller 75 Input device 76 Display device 77 Storage device 78 Image processing unit 79 Bus 101 Input reception unit 1 02 Setting unit 103 X-ray imaging execution control unit 104 Projection data acquisition unit 105 Pre exposure determination unit 106 Shield plate insertion determination unit 107 Shield plate movement amount calculation unit 108 Main exposure condition calculation unit 151 Camera 161 Camera control unit 162 Image data Acquisition unit 201 Breast density calculation unit

Claims (14)

An X-ray tube that irradiates a subject with X-rays and a diaphragm that limits the X-ray irradiation range, and includes at least a first imaging direction and a second imaging direction using the X-rays. In a mammography apparatus that images the subject from a plurality of different imaging directions,
The X-ray tube is configured to be movable so as to be inserted between the subject's breast and the X-ray tube, and at the time of insertion, the X-ray irradiation on the subject is shielded in a part of the irradiation range. A shielding member that,
The shielding member shields the X-ray irradiation in a region other than a region corresponding to a blind area when the subject is imaged from the first imaging direction in the X-ray irradiation range. A calculation unit for calculating a movement amount when moving the shielding member;
A movement control unit that controls movement of the shielding member based on a calculation result by the calculation unit;
With
The movement control unit does not insert the shielding member between the breast of the subject and the X-ray tube when imaging the subject from the first imaging direction, and the second imaging direction. Inserting the shielding member between the breast of the subject and the X-ray tube when imaging the subject from
A mammography apparatus characterized by the above. A determination unit that determines whether or not the shielding member is inserted based on whether or not the imaging direction of the X-ray imaging to be executed is the second imaging direction;
When the determination unit determines that the shielding member is inserted, the calculation unit calculates the movement amount;
The mammography apparatus according to claim 1, wherein: Even when it is determined that the shielding member is inserted by the determination unit, when there is input information that the shielding member is not inserted between the breast of the subject and the diaphragm, the movement is performed. The control unit does not insert the shielding member,
The mammography apparatus according to claim 2, wherein: Even if it is determined that the shielding member is inserted by the determination unit, it is determined using CAD that there is a suspicious lesion in the captured image from the first imaging direction. Sometimes, the movement control unit does not insert the shielding member,
The mammography apparatus according to claim 2 or 3, characterized in that Even when the determination unit determines that the shielding member is inserted, the mammary gland density calculated based on the projection data obtained by X-ray imaging from the first imaging direction is a predetermined threshold value. When larger, the movement control unit does not insert the shielding member,
The mammography apparatus according to any one of claims 2 to 4, wherein the apparatus is a mammogram. The shielding member is a non-transmissive shielding member that substantially shields the X-ray irradiation on the subject, or a transmissive shielding member that transmits a part of the X-ray irradiation on the subject and shields the remainder thereof. Is,
The mammography apparatus according to any one of claims 1 to 5, wherein When the shielding member is the transmissive shielding member, a multiplication unit that multiplies a pixel value in a region where X-ray irradiation is shielded by the shielding member by a predetermined coefficient;
The mammography apparatus according to claim 6, further comprising: An image processing unit for reducing noise of an image signal in a region where X-ray irradiation is shielded by the shielding member;
The mammography apparatus according to claim 7, further comprising: The material of the non-transmissive shielding member is lead or iron,
The mammography apparatus according to claim 6. The material of the transmission type shielding member is aluminum,
The mammography apparatus according to claim 6. The calculation unit calculates the amount of movement based on data relating to an image acquired before imaging the subject from the second imaging direction;
The mammography apparatus according to any one of claims 1 to 10, wherein the apparatus is a mammogram. The data relating to the image is projection data obtained by X-ray imaging by Pre exposure when X-ray imaging by Pre exposure is performed.
The mammography apparatus according to claim 11. An imaging unit that images the breast of the subject in the vicinity of the X-ray tube;
The data relating to the image is image data captured by the imaging unit when X-ray imaging by Pre exposure is not performed.
The mammography apparatus according to claim 11. The combination of the first shooting direction and the second shooting direction is a combination of any two of MLO, CC, and ML.
The mammography apparatus according to any one of claims 1 to 13, wherein the apparatus is a mammogram.