JP2010046355A - Tomography breast imaging system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tomography breast imaging system precisely detecting the lesion in the root of the breast and enhanced in space resolving power so as not to overlook the lesion in the vicinity of the leading end of the breast corresponding to the case of the large breast. <P>SOLUTION: The tomography breast imaging system is equipped with: a top plate 12 equipped with a hole 14 permitting the breast B to pass, a stand 16 loaded with an X-ray generator 20 for radiating a cone beam C and an X-ray detector 18 for detecting the incident intensity of X-rays and rotated around a rotation axis A; and a control unit for executing a first photographing process for rotating the X-ray generator 20 and the X-ray detector 18 around the breast passing hole 14 and acquiring an X-ray transmitting image at a definite angle interval during the rotation period of the stand 16 within the plane vertical to the rotation axis A and a second imaging process for acquiring the X-ray transmitting image at the definite angle interval while advancing the stand 16 in the direction of the rotation axis A with respect to the top plate 12 to rotate the same. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a breast tomographic imaging apparatus using computer tomography (CT), and more particularly to a breast tomographic imaging apparatus equipped with an X-ray transmission image acquisition apparatus that can be advantageously applied to CT used for breast cancer diagnosis.

  Traditionally, breast cancer testing has been performed using palpation and ultrasound. However, these tests can be found only with cancer cells that have grown to some extent. For this reason, mammography using an X-ray transmission image, which is relatively easy to find calcification occurring in early breast cancer, has come to be used in combination. However, since mammography obtains an X-ray transmission image by flattening the breast with a compression plate, there is a risk of pain to the subject. In addition, since the obtained image is a simple X-ray transmission image, it is difficult to determine the lesion when the target tumor part or calcification overlaps an object that forms an X-ray image such as a mammary gland.

  Therefore, a breast tomographic imaging apparatus (mammo CT) using computer tomography (CT) capable of obtaining a 3D image without compressing the breast has been developed. With mammo CT, small calcification can be detected without causing pain to the subject. Moreover, it can be accurately evaluated even when the X-ray opaque parts overlap, and is effective for early detection of breast cancer.

Patent Document 1 discloses an example of mammo CT.
The mammo CT disclosed in Patent Document 1 controls a bed having a hole in the breast position, a gantry that rotates horizontally around the hole, a motor that moves the bed and the gantry, and a switch that operates a measurement device. Device. The measurement apparatus includes an X-ray generation apparatus, an X-ray detection apparatus disposed opposite to the X-ray generation apparatus, and an arithmetic unit that reconstructs a tomographic image from an X-ray transmission image obtained by the X-ray detection apparatus. The X-ray generation device and the X-ray detection device are mounted on a gantry and acquire an X-ray transmission image of the breast from each direction while rotating around the breast together.

  The X-ray generator emits X-rays according to the opening and closing of the ignition switch. The X-ray becomes a cone-shaped cone beam, passes through the subject, and enters the X-ray detection apparatus. The X-ray detection apparatus is a flat panel detector (FPD) in which X-ray detection elements are arranged in a matrix on a plane. Each X-ray detection element accumulates the X-ray projected from the X-ray generator as a measurement signal corresponding to the remaining X-ray intensity absorbed by the substance in the optical path, and the FPD forms an X-ray transmission image at that time Will do. The X-ray detection apparatus can transmit an X-ray transmission image by scanning the measurement signal of each detection element and sequentially outputting it.

  When the subject lies on his / her bed and puts the breast to be measured into the hole, the breast hangs down between the X-ray generator and the X-ray detector. Therefore, while the cone beam X-ray generator and the FPD rotate around the breast as the subject, the X-ray generator is operated at every predetermined angle, an X-ray transmission image is taken with the X-ray detector, and reconstruction calculation is performed. An image signal is transmitted to the apparatus. The reconstruction calculation device reconstructs an X-ray transmission image into 3D, and creates an X-ray tomographic image of the breast. For example, 300 X-ray transmission images are taken and used per rotation.

  In the X-ray tomographic image obtained in this way, since the calcified portion has an image generating ability equivalent to that of bone, relatively small calcification can be easily visualized and early breast cancer can be detected with a high probability. In addition, since the image is a three-dimensional image, it is possible to reliably detect a lesion part on the back side of a tissue such as a mammary gland. Therefore, early diagnosis of breast cancer can be accurately performed by using mammo CT together.

  Since breast cancer occurs relatively frequently near the chest wall, it is essential to examine the vicinity of the breast root. Patent Document 2 discloses a general-purpose computed tomography apparatus in which spatial resolution is improved by rotating a radiation source and a radiation detector n times to acquire one cross-sectional image. The disclosed apparatus shifts the sampling position in the circumferential direction by a predetermined angle every rotation. When acquiring a tomographic image of one cross section by n rotations, the number of samplings per rotation is set to (integer + 1 / n). Yes. Artifacts can be reduced and spatial resolution can be improved by increasing the number of samplings and shifting the data acquisition position for each rotation. If the technique disclosed in Patent Document 2 is applied to mammo CT, the vicinity of the base of the breast can be scrutinized by rotating the gantry many times and measuring.

On the other hand, when the breast is large, the resolution of the image taken so that both the vicinity of the chest wall and the tip of the breast are accommodated on one screen may be small, and a small lesion may not be detected with high sensitivity. In addition, if a high-resolution image is used to accurately examine the vicinity of the chest wall, the tip of the breast protrudes from the image and cannot be evaluated. For this reason, by rotating the gantry equipped with the X-ray generator and the detection unit in the axial direction while rotating, the image is taken along the spiral trajectory so that the image can be accommodated in the image up to the tip without reducing the resolution. Can be configured.
However, since the circumferential angle of the imaging position is the same in the in-plane circular orbit near the chest wall and in the spiral orbit, the image information is duplicated, and the spatial resolution does not improve for a large number of imaging times. .
US Pat. No. 6,480,565 JP 2003-299644 A

  An object of the present invention is to solve the above-described problems, accurately detect a lesion at the base of the breast, and to prevent a lesion near the tip of the breast from being overlooked when the breast is large, and an X-ray generator and an X-ray generator. A breast tomographic imaging apparatus with improved spatial resolution is provided when imaging is performed along a spiral trajectory while rotating a gantry equipped with a line detection apparatus in the axial direction.

In order to solve the above problems, a breast tomography apparatus according to the present invention comprises a top plate that has a hole through which a breast can pass and that allows a subject to lie down on her face and hang a breast from the hole. An X-ray generator that emits a beam of X-rays, and an X-ray having a plurality of X-ray detector elements arranged on the surface that are arranged to face the X-ray generator and detect the incident intensity of X-rays emitted from the X-ray generator A detector that is mounted with a detector and rotates around a rotation axis, and a control device that controls the movement of the top plate, the frame, the X-ray generator, and the operation of the X-ray detector. A first X-ray transmission apparatus and an X-ray detector are rotated around the hole through which the breast passes, and X-ray transmission images are acquired at constant angular intervals while the gantry circulates in a plane perpendicular to the rotation axis. In addition to the shooting process, move the gantry relative to the top plate in the direction of the rotation axis. And a control unit for executing a second imaging step of acquiring X-ray transmission image at a constant angular interval while turning.
In particular, in the second imaging step, it is preferable to start the round from the position shifted by a predetermined angle in the circumferential direction every round.

  According to the breast tomography apparatus according to the present invention, instead of the conventional mammography that compresses the breast at the time of measurement and causes pain, it is a measurement method that does not give any special pain just by hanging the breast. Even if it is, the tip can be measured, the spatial resolution is improved, and a sensitive breast cancer screening suitable for early detection can be performed without overlooking small signs.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a conceptual configuration diagram conceptually showing an image acquisition unit of a breast tomographic imaging apparatus according to an embodiment of the present invention, and FIG. 2 is a system block diagram for explaining the overall configuration of the breast tomographic imaging apparatus.

  As shown in FIG. 1, the breast tomography apparatus 200 according to the present embodiment includes a hole 14 through which a breast is passed, and a subject P can lie down on his / her face and suspend a breast B from the hole 14. And an X-ray generator 20 that emits a radial X-ray cone beam C, and an incident intensity of X-rays that are arranged facing the X-ray generator 20 and are emitted from the X-ray generator 20 and transmitted through the object are detected. A gantry 16 is provided which is mounted with an X-ray detector 18 having a plurality of X-ray detection elements arranged on the surface thereof and rotates around the rotation axis A.

The breast tomography apparatus 200 further includes a control device that controls the movement of the top 12 and the gantry 16 and the operation of the X-ray generator 20 and the X-ray detector 18. The breast tomographic imaging apparatus 200 includes an image processing device and an image display device.
Referring to FIG. 2, the breast tomographic imaging apparatus 200 includes an image generation unit 110, an image processing unit 120, an image storage unit 130, an image display unit 140, an imaging unit 160, and a top plate unit 170.

  Specifically, the image generation unit 110 includes an X-ray generation unit 113 corresponding to the X-ray generation device 20 and an X-ray detection unit 115 corresponding to the X-ray detector 18. When the trigger signal is received from the imaging unit 111, The X-ray generation unit 113 emits the cone beam C, and the X-ray detection unit 115 detects the cone beam C transmitted through the subject, generates an image signal, and transmits the image signal to the image processing unit 120.

The image processing unit 120 includes an image processing unit 121, an image correction unit 123, an image reconstruction unit 125, a confirmation image generation unit 127, and an adjustment value calculation unit 129.
The image processing unit 121 generates an image signal of an X-ray transmission image detected by the X-ray detection unit 115 based on the detection signal input from the image generation unit 110. The generated image signal is transmitted to the image correction unit 123 and also transmitted to the image storage unit 130 and the image display unit 140, and can be referred to as acquired image information.

The image correcting unit 123 corrects the acquired original image signal by removing noise and reducing artifacts, and transmits the corrected image to the image reconstruction unit 125 and the confirmation image generating unit 127.
When the image signals from each direction acquired for the subject are collected, the image reconstruction unit 125 performs a reconstruction operation to generate an image signal for forming the CT screen of the subject, and the image storage unit 130 and the image display To the unit 140.

The confirmation image generation unit 127 generates a confirmation image used for adjustment of the apparatus 200 and sends it to the adjustment value calculation unit 129. An image that shows the positional relationship between the screen and the subject is generated and related to the adjustment values of the device, such as whether the alignment is correct, whether it has the correct resolution, and does not include extra noise. Confirm.
The adjustment value calculation unit 129 calculates an adjustment value necessary for eliminating the deviation from the expected value for the position of the screen frame, the signal intensity, and other environmental values, and the photographing unit control unit 161 and the top panel unit control unit. 171.
The adjustment value can also be directly designated by the operator via the adjustment value input means 151 configured by a data input device using a keyboard, a touch panel, or a mouse.

The image storage unit 130 is provided with image storage means 131 formed by an image memory or the like, and can be easily read and used when image information is required.
The image display unit 140 is provided with an image display unit 141 and a confirmation image display unit 143. The image display unit 141 displays a cross-sectional image or a stereoscopic image of a breast for confirming whether a tumor, calcification, cancer tissue, or the like is present in the breast as an image used for breast cancer diagnosis. The confirmation image display unit 143 displays an image that can be used to monitor or adjust the abnormality or malfunction of the breast tomography apparatus 200. In particular, when the adjustment is performed by the operator, it is necessary to make an adjustment while observing the image displayed by the confirmation image display unit 143.

  The imaging unit 160 includes an imaging unit rotation unit 163 controlled by the imaging unit control unit 161, an imaging unit lifting / lowering unit 165, an X-ray detection unit translation unit 167, and an X-ray generation unit translation unit 169. The imaging unit 111 that has driven the image generation unit 110 supplies a trigger signal to the imaging unit control unit 161 every time an imaging procedure is performed, and X-rays are transmitted via the imaging unit rotation unit 163 and the imaging unit elevating unit 165. The rotation and height of the gantry 16 on which the generation means 113 and the X-ray detection means 115 are mounted are adjusted to the next determined position. Further, the detection sensitivity can be adjusted by adjusting the distance to the X-ray detection means 115 and the X-ray generation means 113 or the subject B, that is, the rotation axis A.

  The top plate portion 170 includes a top plate translation means 173 and a top plate lift means 175 controlled by the top plate control means 171. The position of the cone beam C irradiating the subject B can be easily adjusted by raising and lowering the gantry 16, but since it is in a relative relationship, the height can be adjusted by raising and lowering the top 12 as well. Is possible. Further, when making a diagnosis by switching the left and right breasts, it is necessary to realign the rotation axis A of the gantry 16 with the position of the breast. In particular, when the top plate 12 has two holes that are aligned with the left and right breasts, the other hole is translated to the position of the rotation axis A for alignment.

At the time of diagnosis, when the subject P climbs on the top board 12 and becomes prone and drops the breast B into the hole 14 of the top board 12, the breast B carries the X-ray generator 20 and the X-ray detector 18. It hangs down near the rotation axis A of the gantry 16 and falls within the observation position. Therefore, when the breast tomographic imaging apparatus 200 is started, the imaging means 111 generates a trigger at every predetermined angle while the gantry 16 rotates, causing the X-ray generation means 113 to emit the cone beam C, and the X-ray detection means. 115 generates an X-ray transmission image of the breast B and transmits an image signal to the image processing unit 120.
Since breast cancer often occurs at the base of the breast, the gantry 16 circulates while irradiating the base position and examines the dangerous part.

FIG. 3 is a drawing for explaining the positional relationship among the breast of the subject, the X-ray generator, and the X-ray detector.
The main object to be detected using X-ray CT is calcification in the breast, and since calcification has a clear image like bone, it can be clearly detected even if the resolution of the device is large enough . However, if the area of the portion to be measured per detection element in the X-ray detection device 18 is reduced in order to increase the resolution, the tip of the breast B is the screen of the X-ray detection device 18 as shown in FIG. It will stick out. In addition, even when a large breast is targeted, there may be a case where information on the vicinity of the nipple cannot be obtained outside the screen. On the other hand, if the subject area per screen is increased so that the entire large breast can be accommodated on one screen, the effect of early screening will be rejected by overlooking small calcification.

Therefore, the breast tomography apparatus 200 according to the present embodiment rotates the gantry 16 to rotate the X-ray generator 20 and the X-ray detector 18 around the hole 14 through which the breast passes, and the gantry 16 rotates. In addition to the first imaging step of acquiring X-ray transmission images at constant angular intervals while circling in a plane perpendicular to the axis A, a driving shaft for raising and lowering the gantry 16 by the imaging unit elevating means 165 is provided. As shown in FIG. 3 (b), the second imaging step of acquiring X-ray transmission images at constant angular intervals is performed while moving the gantry 16 relative to the top plate 12 in the direction of the rotation axis and turning around. A control device is provided.
As a result, the distal end portion of the breast B is also observed while ensuring sufficient spatial resolution, so that the calcification or tumor can be detected with high sensitivity over the entire breast B, and breast cancer is detected early and diagnosed. The effect can be enhanced.

  In addition, in the second imaging step, if the circuit starts around a position shifted by a predetermined angle in the circumferential direction every round, not only the noise can be suppressed to a low level by using a large number of images, but also the first imaging process. X-ray transmission images acquired in the first imaging process and the second imaging process are acquired from different directions, and artifacts can be reduced to obtain a high-quality X-ray tomographic image.

FIG. 4 is a perspective view showing a trajectory of the X-ray generator 20 at the time of X-ray transmission image capturing, and FIG. 5 is a (a) plan view and (b) elevation view of the trajectory. A black circle represents the position of the X-ray generator at the time of imaging, and a number represents the imaging order. The X-ray detection device 18 is located at a position facing the X-ray generator 20 across the breast B, and moves the same distance together with the X-ray generator 20 when the gantry 16 moves in the vertical direction.
When the breast B overflows from the X-ray cone beam C, when the gantry 16 is shifted in the axial direction and is rotated a plurality of times, imaging is performed so that the angles at the time of imaging do not overlap in the circumferential direction. , The angular resolution can be improved.

In clinical research, there are examples of taking 300 images per rotation, but in FIGS. 4 and 5, the number of images taken per round is 8 for simplicity. The shooting interval is 45 degrees, but the same number of shots is taken for the first and second rounds, and the shooting start position for the second round is shifted by 22.5 degrees. In other words, in the first imaging step of making a round in the horizontal plane at the base of the breast B, the second imaging step is performed in which images are taken eight times at 45 degrees from 0 degrees to 315 degrees and imaged in a spiral shape with reference to the imaging start position. In this example, 8 images are taken every 45 degrees from 22.5 degrees to 337.5 degrees. The 16 X-ray transmission images are obtained by imaging the breast B from different directions.
If these 16 X-ray transmission images are used, a high-quality CT screen with few artifacts can be obtained.

  FIGS. 6A and 6B are (a) a plan view and (b) an elevation view showing a photographing position in another embodiment of the present embodiment. In this embodiment, by shifting the positions of the X-ray detection device 18 and the X-ray generator 20 in the axial direction, X-ray transmission images are acquired with the same number of shots per rotation, while making one round of the horizontal plane. It is. In the figure, in addition to the first imaging step that makes one round at the base of the breast B, two horizontal rotation trajectories are provided as the second imaging step. The photographing start position is shifted by 15 degrees in each horizontal rotation trajectory. That is, in the first shooting process, 8 shots are taken every 45 degrees from 0 to 315 degrees, and in the first lap of the second shooting process, 8 shots are taken every 45 degrees from 15 degrees to 330 degrees. In one lap after the process, images are taken eight times at intervals of 45 degrees from 30 degrees to 345 degrees.

  The advantage of this embodiment is that not only the angular resolution is improved, but also the rotational movement is performed after shifting and fixing in the direction of the rotation axis, so that the mechanically simple control is sufficient, and the reconstruction calculation is also only the rotational scan. Is to simplify the algorithm.

  FIG. 7A is a plan view and FIG. 7B is an elevation view showing a photographing position in still another embodiment of the present embodiment. In this embodiment, in addition to the first imaging process that makes one round at the base of the breast B, as the second imaging process, the first imaging process is performed while the positions of the X-ray detection device 18 and the X-ray generator 20 are shifted in the axial direction. In contrast, an X-ray transmission image is acquired by making one round so that the number of shots per rotation is halved. In other words, in the first shooting process, shooting is performed 8 times at intervals of 45 degrees from 0 degrees to 315 degrees, and in the second shooting process, the starting point is shifted and shooting is performed 4 times at intervals of 90 degrees from 67.5 degrees to 337.5 degrees. is doing.

  Since the breast B is thickest at the root and becomes thinner as it approaches the tip, even if the number of shots is reduced in spiral shooting, the angular resolution is improved as compared with only rotation in the horizontal plane, and even compared with the shooting method shown in FIG. There is no major decline. On the other hand, compared with the method in FIG. 3, the number of shots in spiral shooting is reduced, so that there is an effect of reducing exposure. A total of 12 X-ray transmission images can obtain high-quality X-ray tomographic images with little imaging angle and little artifact.

  FIG. 8A is a plan view and FIG. 8B is an elevation view showing a photographing position in still another embodiment of the present embodiment. In this embodiment, in addition to the first imaging process that makes one round at the base of the breast B, X-ray generation is performed while the positions of the X-ray detector 18 and the X-ray generator 20 are shifted in the axial direction as the second imaging process. An X-ray transmission image is acquired by making one round of the spiral so that the apparatus 20 approaches the rotation axis A. In other words, in the first shooting process, 8 shots are taken every 45 degrees from 0 degrees to 315 degrees, and in the second shooting process, the start point is shifted and 8 shots are taken every 45 degrees from 22.5 degrees to 337.5 degrees. However, during this time, the distance from the rotation axis A is decreased, and finally it is halved.

  Since the breast B becomes thinner as it goes to the tip, enlargement imaging proceeds by shortening the distance from the rotation axis A as the position of the X-ray generator 20 is moved in a spiral. As a result, the enlargement ratio of the distal end portion of the breast B is increased, the substantial angular resolution is improved, and an abnormality can be detected with high sensitivity. However, since the enlargement ratio of the X-ray transmission image acquired by spiral imaging changes, it is necessary to perform a reconstruction calculation after adjusting the enlargement ratio to obtain a tomographic image.

In the above-described embodiment, the number of shots per round in the second shooting step is the same as the number of shots in the first shooting step or is an integer. By doing so, it is possible to simplify the mechanical control in the breast tomographic imaging apparatus and image processing such as FFT at the time of image reconstruction, thereby reducing the cost of the apparatus. However, it goes without saying that it is not always necessary to set it to 1.
Note that the necessity of the second imaging step mainly depends on the size of the breast, so the operator can evaluate the breast size and make a judgment, or the computer can determine the nipple from several images obtained in the first imaging step. It is possible to determine whether the tip is missing and automatically set it. Alternatively, a low-dose pre-shot image can be taken for positioning confirmation, and the determination can be made based on this.

  According to the present invention, a breast tomographic imaging apparatus that contributes to early detection of breast cancer can be provided. Especially when the breast is large and the resolution of the device becomes a problem, a high-resolution X-ray transmission image is acquired by a sampling method that can be applied to a large breast, so that a tomographic image useful for early detection of breast cancer is obtained. Can do.

It is a conceptual block diagram which showed notionally about the image acquisition part of the breast tomography apparatus which concerns on one Embodiment of this invention. It is a system block diagram explaining the whole structure of the breast tomography apparatus concerning this embodiment. It is drawing explaining the positional relationship of the subject, X-ray generator, and X-ray detector in this embodiment. It is a perspective view showing the locus of X-ray generation device 20 at the time of X-ray transmission image photography in one mode of this embodiment. It is the top view and elevation of the locus | trajectory of the X-ray generator in this embodiment. It is the top view and elevation which show the locus | trajectory of the X-ray generator in another implementation of this embodiment. It is the top view and elevation which show the locus | trajectory of the X-ray generator in another implementation of this embodiment. It is the top view and elevation which show the locus | trajectory of the X-ray generator in another implementation of this embodiment.

Explanation of symbols

200 Breast Tomography Imaging Device 12 Top Plate 14 Breast Passing Hole 16 Base 18 X-ray Detector 20 X-ray Generation Device 110 Image Generation Unit 111 Imaging Unit 113 X-ray Generation Unit 115 X-ray Detection Unit 120 Image Processing Unit 121 Image Processing Means 123 Image correction means 125 Image reconstruction means 127 Confirmation image generation means 129 Adjustment value calculation means 130 Image storage section 131 Image storage means 140 Image display section 141 Image display means 143 Confirmation image display means 151 Adjustment value input means 160 Imaging section 161 Imaging unit control unit 163 Imaging unit rotation unit 165 Imaging unit lifting / lowering unit 167 X-ray detection unit translation unit 169 X-ray generation unit translation unit 170 Top plate unit 171 Top plate unit control unit 170 Top plate unit 171 Top plate unit control unit 173 Top Plate translation means 175 Top plate lifting means

Claims (8)

A top plate with a hole through which the breast passes and the subject lying on his / her face down and hanging the breast from the hole;
An X-ray generator that emits a cone-shaped X-ray beam, and an X-ray detection element that is disposed opposite to the X-ray generator and detects the incident intensity of X-rays emitted from the X-ray generator A plurality of X-ray detectors mounted on the base and rotating around the rotation axis;
A control device for controlling the movement of the top plate and the gantry and the operation of the X-ray generator and the X-ray detector, wherein the gantry is rotated to move the X-ray generator and the X-ray detector to the breast In addition to the first imaging step of acquiring X-ray transmission images at a constant angle interval while rotating around the hole through which the gantry circulates in a plane perpendicular to the rotation axis. A control device that executes a second imaging step of acquiring X-ray transmission images at constant angular intervals while moving around in the direction of the rotation axis relative to the top plate;
A breast tomography apparatus comprising:   2. The breast tomographic imaging apparatus according to claim 1, wherein the second imaging step starts to circulate starting from a position shifted by a predetermined angle in the circumferential direction every round.   3. The breast tomography according to claim 1, wherein the second imaging step acquires an X-ray transmission image by circularly rotating in a plane perpendicular to the rotation axis at a position shifted by a predetermined distance in the rotation axis direction. Image shooting device.   The breast tomographic imaging apparatus according to claim 1, wherein the imaging positions in the second imaging step are connected in a spiral shape.   The breast tomographic imaging apparatus according to claim 4, wherein an imaging position in the second imaging step approaches the rotation axis as imaging progresses.   5. The breast tomography according to claim 3, wherein the number of imaging in the second imaging step is the same as the number of imaging in the first imaging step, or is 1 / number of rotations for each rotation of imaging while rotating. Image shooting device.   The breast tomographic imaging apparatus according to claim 3 or 4, wherein the number of imaging in the second imaging process is smaller than the number of imaging in the first imaging process.   When it is determined that an X-ray transmission image of the whole breast can be acquired in the first imaging step based on the image acquired in the first imaging step or a pre-shot image acquired separately, the second imaging The breast tomographic imaging apparatus according to claim 1, wherein the step is omitted.