IMAGE PROCESSING APPARATUS, RADIOLOGICAL IMAGE CAPTURE SYSTEM, IMAGE PROCESSING METHOD, AND IMAGE PROCESSING PROGRAM

Abstract

To provide an image processing device, a radiation ray image imaging system, an image processing method and an image processing program, capable of accurately deriving a positional deviation amount between projection images.SOLUTION: A CPU 50A of a console 12 acquires a plurality of projection images 80, acquires a plurality of tomographic images 82 which corresponds to each tomographic plane of a breast and which is generated using the plurality of tomographic images 80, then, uses a tomographic image 82 group other than a tomographic image 82 which includes a reference object image 91 which indicates a reference object 90 to be used as reference of derivation of a positional deviation amount between the projection images 80, out of the plurality of tomographic images 82, then performs pseudo projection from a set radiation position 19V corresponding to each radiation position 19 of the plurality of projection images 80 for generating a plurality of reference object absence pseudo projection images 86 which includes no reference object image 91, then, on the basis of a component removal image 88 including the reference object image 91 obtained by removing components of the plurality of reference object absence pseudo projection images 86 from the plurality of projection images 80, derives a positional deviation amount between the projection images 80.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to an image processing device, a radiation image capturing system, an image processing method, and an image processing program. [Background technology]

[0002] 2. Description of the Related Art So-called tomosynthesis imaging is known in which a radiation source irradiates a subject from a plurality of irradiation positions each having a different irradiation angle, and a plurality of projection images of the subject are captured at the different irradiation positions.

[0003] In tomosynthesis imaging, since multiple projection images are captured, positional deviations may occur between the projection images due to the effects of the subject's body movement, deviations in the position of the radiation source at each irradiation position, etc. There is a problem in that a tomographic image generated using multiple projection images with positional deviations becomes a blurred image.

[0004] Therefore, a technique for correcting the positional deviation between projected images is known. For example, Patent Document 1 discloses a technique for deriving the amount of positional deviation between a plurality of projected images on a slice plane corresponding to a slice image on which a feature point is detected, using the feature point as a reference. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2020 / 067475 Summary of the Invention [Problem to be solved by the invention]

[0006] Incidentally, a projection image is an image showing structures arranged in the direction of radiation irradiation and contains a lot of information. Therefore, the projection image may contain information of images of structures that may be an obstacle to deriving the amount of positional shift between the projection images. In the above conventional technology, the accuracy of deriving the amount of positional shift between the projection images may be reduced due to the influence of unnecessary information.

[0007] The present disclosure has been made in consideration of the above circumstances, and aims to provide an image processing device, a radiological image capturing system, an image processing method, and an image processing program that can accurately derive the amount of positional shift between projected images. [Means for solving the problem]

[0008] In order to achieve the above object, an image processing device of a first aspect of the present disclosure is an image processing device that processes a plurality of projection images obtained by irradiating radiation from a radiation source toward a subject from each of a plurality of irradiation positions having different irradiation angles, and includes at least one processor, wherein the processor acquires a plurality of projection images, acquires a plurality of tomographic images generated using the plurality of projection images and corresponding to each of a plurality of tomographic planes of the subject, uses a second group of tomographic images among the plurality of tomographic images other than the first tomographic image including a reference object image representing a reference object used as a basis for deriving the amount of positional deviation between the projection images, and generates a plurality of reference-object-free pseudo-projection images that do not include the reference object image by pseudo-projecting from a set irradiation position corresponding to each irradiation position of the plurality of projection images, and derives the amount of positional deviation between the projection images based on a component-removed image including a reference object image obtained by removing components of the plurality of reference-object-free pseudo-projection images from the plurality of projection images.

[0009] In the image processing device of the second aspect of the present disclosure, in the image processing device of the first aspect, the processor derives the amount of positional deviation based on the component removed image and the first tomographic image.

[0010] An image processing device of a third aspect of the present disclosure is an image processing device of the first or second aspect, in which a processor generates a partial pseudo-projection image as a reference object-free pseudo-projection image by pseudo-projecting onto a partial area of ​​a second group of tomographic images corresponding to a reference object area of ​​a portion of the first tomographic image that includes a reference object image, and generates a component-removed image by removing components of the partial pseudo-projection image from a partial image of the projection image corresponding to the partial pseudo-projection image.

[0011] An image processing device of a fourth aspect of the present disclosure is an image processing device of any one of the first to third aspects, in which a processor generates an image representing the difference between multiple projection images and multiple reference object-free pseudo-projection images as a component-removed image.

[0012] An image processing device of a fifth aspect of the present disclosure is an image processing device of any one of the first to third aspects, in which a processor generates a component-removed image by subtracting, for each corresponding pixel, the pixel value of the reference object-free pseudo-projection image from the pixel value of the projection image.

[0013] An image processing device of a sixth aspect of the present disclosure is an image processing device of any one of the first to third aspects, in which a processor generates a component-removed image by reducing pixel values ​​of pixels in a projection image that are correlated with a reference object-free pseudo-projection image.

[0017] The present disclosure 7 The image processing device of the present embodiment is any one of the first to third embodiments. 6 In the image processing device according to any one of the aspects, the processor further generates a plurality of tomographic images in each of the plurality of tomographic planes based on the plurality of projection images and the positional deviation amount.

[0018] The present disclosure 8 The image processing device of the present embodiment is any one of the first to third embodiments. 7 In the image processing device according to any one of the above aspects, the processor issues a notification when the amount of positional deviation exceeds a preset threshold value.

[0019] The present disclosure 9The image processing device of the present embodiment is any one of the first to third embodiments. 8 In the image processing device of any one of the aspects, the processor If there are multiple reference objects, Multiple Reference Objects Each For each reference object For each standard Second slice image group A pseudo projection is performed using

[0020] The present disclosure 10 The image processing device of the present embodiment is any one of the first to third embodiments. 9 In the image processing device according to any one of the above aspects, the subject is a breast, and the reference object is a calcification or a mammary gland.

[0021] In order to achieve the above object, the first aspect of the present disclosure 11 The radiation image capturing system of this embodiment includes a radiation source that generates radiation, a radiation image capturing device that performs tomosynthesis imaging in which radiation is irradiated from the radiation source toward a subject from each of a plurality of irradiation positions having different irradiation angles, and a projection image of the subject for each irradiation position is captured, and an image processing device of the present disclosure.

[0022] In order to achieve the above object, the first aspect of the present disclosure 12 The image processing method of the embodiment is an image processing method for processing a plurality of projection images obtained by irradiating a subject with radiation from a radiation source from each of a plurality of irradiation positions having different irradiation angles, the image processing method comprising the steps of: acquiring a plurality of projection images; acquiring a plurality of tomographic images generated using the plurality of projection images and corresponding to each of a plurality of tomographic planes of the subject; using a second group of tomographic images among the plurality of tomographic images other than the first tomographic image including a reference object image representing a reference object used as a reference for deriving the amount of positional deviation between the projection images, and performing pseudo-projection from set irradiation positions corresponding to each of the irradiation positions of the plurality of projection images to generate a plurality of reference-object-free pseudo-projection images that do not include the reference object image; and deriving the amount of positional deviation between the projection images based on a component-removed image including a reference object image obtained by removing components of the plurality of reference-object-free pseudo-projection images from the plurality of projection images, the image processing method being performed by a computer.

[0024] In order to achieve the above object, the first aspect of the present disclosure13 The image processing program of the embodiment is an image processing program that processes a plurality of projection images obtained by irradiating a subject with radiation from a radiation source from each of a plurality of irradiation positions having different irradiation angles, and causes a computer to execute a process of acquiring a plurality of projection images, acquiring a plurality of tomographic images generated using the plurality of projection images and corresponding to each of a plurality of tomographic planes of the subject, using a second group of tomographic images among the plurality of tomographic images other than the first tomographic image including a reference object image representing a reference object used as a reference for deriving the amount of positional deviation between the projection images, and generating a plurality of reference-object-free pseudo-projection images that do not include the reference object image by pseudo-projecting from set irradiation positions corresponding to each of the irradiation positions of the plurality of projection images, and deriving the amount of positional deviation between the projection images based on a component-removed image including a reference object image obtained by removing components of the plurality of reference-object-free pseudo-projection images from the plurality of projection images. Effect of the Invention

[0026] According to the present disclosure, the amount of positional deviation between projected images can be derived with high accuracy. [Brief description of the drawings]

[0027] [Figure 1] 1 is a configuration diagram illustrating an example of the overall configuration of a radiation image capturing system according to an embodiment; [Diagram 2] FIG. 1 is a diagram for explaining an example of tomosynthesis imaging. [Diagram 3] 1 is a block diagram showing an example of the configuration of a mammography apparatus and a console according to a first embodiment. [Figure 4] FIG. 2 is a functional block diagram illustrating an example of functions of a console according to the first embodiment. [Diagram 5] 11 is a diagram showing a correspondence relationship between a projection image and a tomographic image generated from a plurality of projection images. FIG. [Figure 6] 11A and 11B are diagrams for explaining generation of a reference object-free pseudo projection image by a pseudo projection image generating unit. [Figure 7]11 is a diagram for explaining generation of a component removed image by a component removed image generating unit. FIG. [Figure 8] 5 is a flowchart showing an example of a flow of image processing by the console of the first embodiment. [Figure 9] FIG. 11 is a block diagram showing an example of the configuration of a control unit of a console according to a second embodiment. [Figure 10] FIG. 11 is a functional block diagram illustrating an example of functions of a console according to a second embodiment. [Figure 11] 13A and 13B are diagrams for explaining generation of a reference object-included pseudo projection image in the second embodiment. [Figure 12] 11A and 11B are diagrams for explaining generation of a reference object-included pseudo projection image by a pseudo projection image generating unit. [Figure 13] 10 is a flowchart showing an example of a flow of image processing by the console of the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiment.

[0029] [First embodiment] First, an example of the overall configuration of the radiation image capturing system of this embodiment will be described. Fig. 1 shows a configuration diagram showing an example of the overall configuration of the radiation image capturing system 1 of this embodiment. As shown in Fig. 1, the radiation image capturing system 1 of this embodiment includes a mammography device 10 and a console 12.

[0030] First, the mammography device 10 of this embodiment will be described. Fig. 1 shows a side view illustrating an example of the appearance of the mammography device 10 of this embodiment. Fig. 1 shows an example of the appearance of the mammography device 10 when viewed from the left side of a subject.

[0031] The mammography device 10 of this embodiment operates under the control of a console 12, and is a device that takes a radiographic image of a subject's breast by irradiating the breast with radiation R (e.g., X-rays) as a subject's subject. Note that the mammography device 10 may be a device that takes an image of the subject's breast not only when the subject is standing (standing position) but also when the subject is sitting in a chair (including a wheelchair) or the like (seated position).

[0032] In addition, the mammography apparatus 10 of this embodiment has the function of performing normal imaging, in which imaging is performed by positioning the radiation source at an irradiation position along the normal direction of the detection surface 20A of the radiation detector, and so-called tomosynthesis imaging, in which imaging is performed by moving the radiation source 29 to each of a plurality of irradiation positions.

[0033] The radiation detector 20 detects radiation R that has passed through the breast, which is the subject. In detail, the radiation detector 20 detects radiation R that has entered the subject's breast and the imaging table 24 and reached the detection surface 20A of the radiation detector 20, generates a radiographic image based on the detected radiation R, and outputs image data representing the generated radiographic image. Hereinafter, a series of operations of irradiating radiation R from the radiation source 29 and generating a radiographic image by the radiation detector 20 may be referred to as "imaging". The type of the radiation detector 20 in this embodiment is not particularly limited, and may be, for example, an indirect conversion type radiation detector that converts radiation R into light and converts the converted light into an electric charge, or a direct conversion type radiation detector that directly converts radiation R into an electric charge.

[0034] 1, the radiation detector 20 is disposed inside an imaging stand 24. In the mammography apparatus 10 of this embodiment, when imaging is performed, the breast of the subject is positioned on the imaging surface 24A of the imaging stand 24 by the user.

[0035] The compression plate 38 used to compress the breast when imaging is performed is attached to a compression unit 36 ​​provided on the imaging table 24. In detail, the compression unit 36 ​​is provided with a compression plate drive section (not shown) that moves the compression plate 38 in a direction toward or away from the imaging table 24 (hereinafter referred to as the "up and down direction"). A support section 39 of the compression plate 38 is detachably attached to the compression plate drive section and is moved in the up and down direction by the compression plate drive section to compress the breast of the subject between the compression plate 38 and the imaging table 24. The compression plate 38 of this embodiment is an example of a compression member of the present disclosure.

[0036] As shown in Fig. 1, the mammography apparatus 10 of this embodiment includes an imaging table 24, an arm unit 33, a base 34, and an axis unit 35. The arm unit 33 is held by the base 34 so as to be movable in the vertical direction (Z-axis direction). The axis unit 35 enables the arm unit 33 to rotate relative to the base 34. The axis unit 35 is fixed to the base 34, and the axis unit 35 and the arm unit 33 rotate together.

[0037] Gears are provided on the shaft 35 and the compression unit 36 ​​of the imaging table 24, and by switching between an engaged state and a non-engaged state of these gears, it is possible to switch between a state in which the compression unit 36 ​​of the imaging table 24 and the shaft 35 are connected and rotate together, and a state in which the shaft 35 is separated from the imaging table 24 and rotates freely. Note that the switching between transmission and non-transmission of power to the shaft 35 is not limited to the above gears, and various mechanical elements can be used.

[0038] The arm unit 33 and the imaging stand 24 are separately rotatable relative to the base 34, with the shaft unit 35 as a rotation axis. In this embodiment, the base 34, the arm unit 33, and the compression unit 36 ​​of the imaging stand 24 are each provided with an engagement unit (not shown), and by switching the state of this engagement unit, each of the arm unit 33 and the compression unit 36 ​​of the imaging stand 24 is connected to the base 34. One or both of the arm unit 33 and the imaging stand 24 connected to the shaft unit 35 rotate together around the shaft unit 35.

[0039] When performing tomosynthesis imaging in the mammography device 10, the radiation source 29 of the radiation irradiation unit 28 is moved sequentially to each of a plurality of irradiation positions having different irradiation angles by the rotation of the arm unit 33. The radiation source 29 has a radiation tube (not shown) that generates radiation R, and the radiation tube is moved to each of the plurality of irradiation positions in accordance with the movement of the radiation source 29. FIG. 2 shows a diagram for explaining an example of tomosynthesis imaging. Note that the compression plate 38 is not shown in FIG. 2. In this embodiment, as shown in FIG. 2, the radiation source 29 is moved sequentially to each of the irradiation positions 19 having irradiation angles that differ in increments of a predetermined angle θ. k (k=1, 2, . . . , the maximum value is 7 in FIG. 2), in other words, the radiation detector 20 is moved to a position where the irradiation angle of the radiation R with respect to the detection surface 20A of the radiation detector 20 is different. k In response to an instruction from the console 12, radiation R is irradiated from the radiation source 29 toward the breast W, and a radiation image is captured by the radiation detector 20. In the radiation image capturing system 1, the radiation source 29 is placed at the irradiation position 19. k 19 to each of the irradiation positions 19 k In the example of Fig. 2, when tomosynthesis imaging is performed to capture radiation images at each irradiation position 19, 13 radiation images are obtained. In the following, when a radiation image captured at each irradiation position 19 in tomosynthesis imaging is to be distinguished from other radiation images, it is referred to as a "projection image." In addition, when radiation images are collectively referred to regardless of the type, such as a projection image or a tomographic image described later, it is simply referred to as a "radiation image." In addition, in the following, when a radiation image is captured at each irradiation position 19, k When collectively referring to the irradiation positions 19, the symbol k for distinguishing each irradiation position is omitted and they are referred to as "irradiation positions 19". k Projection images taken at 19 irradiation positions k The images and the like corresponding to the above images will be described by adding the symbol "k" representing the irradiation position 19k to the symbol representing each image.

[0040] As shown in Fig. 2, the irradiation angle of radiation R refers to the angle α between a normal CL to the detection surface 20A of the radiation detector 20 and a radiation axis RC. The radiation axis RC refers to an axis connecting the focal point of the radiation source 29 at each irradiation position 19 and a preset position such as the center of the detection surface 20A. Hereinafter, the detection surface 20A of the radiation detector 20 is assumed to be a surface that is approximately parallel to the imaging surface 24A. Hereinafter, the predetermined range within which the irradiation angle is changed in tomosynthesis imaging as shown in Fig. 2 will be referred to as an "irradiation angle range."

[0041] On the other hand, when performing normal imaging in the mammography device 10, the radiation source 29 of the radiation irradiation unit 28 is positioned at the irradiation position 19 where the irradiation angle α is 0 degrees. k (Irradiation position along the normal direction 19 k In Fig. 2, the irradiation position is 19 4 In response to an instruction from the console 12, radiation R is emitted from the radiation source 29, and a radiation image is captured by the radiation detector 20.

[0042] Fig. 3 is a block diagram showing an example of the configuration of the mammography apparatus and console of the embodiment. As shown in Fig. 3, the mammography apparatus 10 of the present embodiment further includes a control unit 40, a memory unit 42, an I / F (Interface) unit 44, an operation unit 46, and a radiation source movement unit 47. The control unit 40, the memory unit 42, the I / F unit 44, the operation unit 46, and the radiation source movement unit 47 are connected via a bus 49 such as a system bus or a control bus so that various information can be exchanged between them.

[0043] The control unit 40 controls the overall operation of the mammography apparatus 10 in response to control by the console 12. The control unit 40 includes a CPU (Central Processing Unit) 40A, a ROM (Read Only Memory) 40B, and a RAM (Random Access Memory) 40C. The ROM 40B stores various programs in advance, including an imaging program 41 for controlling radiographic imaging, which is executed by the CPU 40A. The RAM 40C temporarily stores various data.

[0044] The storage unit 42 stores image data of a radiation image captured by the radiation detector 20 and various other information. Specific examples of the storage unit 42 include a hard disk drive (HDD) and a solid state drive (SSD). The I / F unit 44 communicates various information with the console 12 by wireless communication or wired communication. Image data of a radiation image captured by the radiation detector 20 in the mammography apparatus 10 is transmitted to the console 12 via the I / F unit 44 by wireless communication or wired communication.

[0045] In this embodiment, the control unit 40 , the storage unit 42 , and the I / F unit 44 are each provided inside the imaging stand 24 .

[0046] The operation unit 46 is provided as a plurality of switches on, for example, the imaging table 24 of the mammography apparatus 10. The operation unit 46 may be provided as a touch panel switch, or as a foot switch that is operated by a user such as a doctor or technician with his / her foot.

[0047] As described above, when tomosynthesis imaging is performed, the radiation source moving unit 47 has a function of moving the radiation source 29 to each of the multiple irradiation positions 19 under the control of the control unit 40. Specifically, the radiation source moving unit 47 moves the radiation source 29 to each of the multiple irradiation positions 19 by rotating the arm unit 33 relative to the imaging table 24. The radiation source moving unit 47 in this embodiment is provided inside the arm unit 33.

[0048] On the other hand, the console 12 in this embodiment has the function of controlling the mammography apparatus 10 using shooting orders and various information obtained from a RIS (Radiology Information System) or the like via a wireless communication LAN (Local Area Network) or the like, and instructions given by a user via an operation unit 56 or the like.

[0049] The console 12 of this embodiment is, for example, a server computer. As shown in Fig. 3, the console 12 includes a control unit 50, a storage unit 52, an I / F unit 54, an operation unit 56, and a display unit 58. The control unit 50, the storage unit 52, the I / F unit 54, the operation unit 56, and the display unit 58 are connected to each other via a bus 59 such as a system bus or a control bus so as to be able to transmit and receive various information to and from each other.

[0050] The control unit 50 of this embodiment controls the overall operation of the console 12. The control unit 50 includes a CPU 50A, a ROM 50B, and a RAM 50C. The ROM 50B stores various programs including an image generation program 51 executed by the CPU 50A in advance. The RAM 50C temporarily stores various data. In this embodiment, the CPU 50A is an example of a processor of the present disclosure, and the console 12 is an example of an image processing device of the present disclosure. Moreover, the image generation program 51 of this embodiment is an example of an image processing program of the present disclosure.

[0051] The storage unit 52 stores image data of radiographic images captured by the mammography apparatus 10, various other information, etc. Specific examples of the storage unit 52 include an HDD and an SSD.

[0052] The operation unit 56 is used by the user to input instructions regarding radiographic image capture, including instructions for irradiating radiation R, and various types of information. The operation unit 56 is not particularly limited, and examples thereof include various switches, a touch panel, a touch pen, and a mouse. The display unit 58 displays various types of information. The operation unit 56 and the display unit 58 may be integrated into a touch panel display.

[0053] The I / F unit 54 communicates various types of information with the mammography apparatus 10, the RIS, and a PACS (Picture Archiving and Communication System) via wireless or wired communication. In the radiation image capturing system 1 of this embodiment, image data of a radiation image captured by the mammography apparatus 10 is received by the console 12 from the mammography apparatus 10 via the I / F unit 54 via wireless or wired communication.

[0054] The console 12 of this embodiment has a function of correcting positional deviations between a plurality of projection images obtained by tomosynthesis imaging. FIG. 4 shows a functional block diagram of an example of a configuration related to a function of correcting positional deviations between a plurality of projection images obtained by tomosynthesis imaging in the console 12 of this embodiment. As shown in FIG. 4, the console 12 includes an image acquisition unit 60, a tomographic image acquisition unit 62, a pseudo projection image generation unit 64, a positional deviation amount derivation unit 66, a notification unit 68, a tomographic image generation unit 70, and a display control unit 72. As an example, the console 12 of this embodiment functions as the image acquisition unit 60, the tomographic image acquisition unit 62, the pseudo projection image generation unit 64, the positional deviation amount derivation unit 66, the notification unit 68, the tomographic image generation unit 70, and the display control unit 72 by the CPU 50A of the control unit 50 executing the image generation program 51 stored in the ROM 50B.

[0055] The image acquisition unit 60 has a function of acquiring a plurality of projection images. Specifically, the image acquisition unit 60 of this embodiment acquires image data representing a plurality of projection images acquired by tomosynthesis imaging in the mammography apparatus 10. The image acquisition unit 60 outputs the image data representing the acquired plurality of projection images to the tomographic image acquisition unit 62 and the positional deviation amount derivation unit 66.

[0056] The tomographic image acquisition unit 62 has a function of acquiring a plurality of tomographic images corresponding to a plurality of tomographic planes of the breast as a subject. Specifically, the tomographic image acquisition unit 62 of this embodiment acquires a plurality of tomographic images by generating a plurality of tomographic images corresponding to a plurality of tomographic planes of the breast using a plurality of projection images acquired by the image acquisition unit 60.

[0057] The method by which the tomographic image acquisition unit 62 generates the multiple tomographic images is not particularly limited, and a known method can be used. For example, reconstruction may be performed by a back projection method such as the FBP (Filter Back Projection) method or the iterative reconstruction method, and known techniques can be applied. The tomographic planes of the multiple tomographic images generated by the tomographic image acquisition unit 62 are planes that are substantially parallel to the detection plane 20A of the radiation detector 20, and in this embodiment, are planes that are substantially parallel to the imaging plane 24A of the imaging table 24. The positions of the tomographic planes of the multiple tomographic images generated by the tomographic image acquisition unit 62, in other words, the heights of the tomographic planes from the imaging plane 24A of the imaging table 24, are not particularly limited. The heights of the tomographic planes can be determined, for example, according to the size of the object of interest, the image quality of the radiation image, the processing load of the arithmetic processing in generating the tomographic images, and instructions from the user. The tomographic image acquisition unit 62 outputs image data representing the multiple acquired tomographic images to the pseudo projection image generation unit 64.

[0058] The pseudo projection image generating unit 64 has a function of generating a plurality of pseudo projection images that do not include a reference object image representing the reference object by using a group of tomographic images other than the tomographic image that includes the reference object used as a reference for deriving the amount of positional deviation between the projection images among the plurality of tomographic images and performing pseudo projection from a set irradiation position corresponding to each irradiation position of the plurality of projection images. In this embodiment, the pseudo projection image that does not include the reference object image is called a "reference object-free pseudo projection image."

[0059] An example of a method for generating a reference object-free pseudo projection image in the pseudo projection image generating unit 64 of this embodiment will be described with reference to Figs. 5 and 6. 1 A projection image 80 taken when the radiation source 29 is located at 1 and projected image 801 The correspondence between the projection images 80 and a tomographic image 82 generated from the projection images 80 is shown. 1 is used to generate a tomographic image 82. 1 There are 82 cross-sectional images 2 A structure image 93A representing a structure 92A present at a height corresponding to 1 , Tomographic image 82 3 A reference object image 91 representing a reference object 90 present at a height corresponding to 1 , and tomographic image 82 5 A structure image 93B representing a structure 92B present at a height corresponding to 1 Contains:

[0060] First, referring to FIG. 5, the pseudo projection image generating unit 64 generates a plurality of tomographic images 82 (82 in FIG. 5). 1 ~82 7 The reference object 90 is extracted from the 7 images (of the 1000 to 1500 images). Specifically, the pseudo projection image generating unit 64 extracts a reference object image 91 representing the reference object 90 from the multiple tomographic images 82. The method of extracting the reference object image 91 by the pseudo projection image generating unit 64 will be described. In the case of tomosynthesis imaging, as described above, multiple projection images 80 are captured by performing imaging at each irradiation position 19. Therefore, due to the influence of the subject's body movement and the positional deviation of the radiation source 29 at each irradiation position 19, etc., a positional deviation may occur between the projection images 80. In the console 12 of this embodiment, the reference object 90 is used as a reference to derive the positional deviation amount between the projection images 80. It is preferable that the reference object 90 has a characteristic structure and that an image representing the reference object 90 is easily extracted from each of the tomographic images 82 and the projection images 80. It is also preferable that the reference object 90 is included in all of the multiple projection images 80 acquired by the image acquiring unit 60. As described above, the reference object 90 is preferably a structure present inside the subject, since it is used as a reference for deriving the amount of positional deviation due to the body movement of the subject. When the subject is a breast, such a reference object 90 may be at least one of calcification and mammary gland. As an example, in this embodiment, it is predetermined that the mammary gland is used as the reference object 90.

[0061] The method by which the pseudo projection image generating unit 64 extracts the reference object 90 from the multiple tomographic images 82 is not particularly limited. The pseudo projection image generating unit 64 first specifies, as a common area, an area included in all the projection images 80 acquired by the image acquiring unit 60 in each of the multiple tomographic images 82. The method by which the pseudo projection image generating unit 64 specifies the common area is not particularly limited. As an example, in this embodiment, the multiple projection images 80 acquired by tomosynthesis photography are given imaging information indicating the irradiation angle range and the irradiation field, and the correspondence relationship between the irradiation angle range and the irradiation field in the tomosynthesis photography and the common area is determined in advance. The pseudo projection image generating unit 64 specifies the common area from the above correspondence relationship based on the imaging information given to the multiple projection images 80 acquired by the image acquiring unit 60.

[0062] When the common region is specified, the pseudo projection image generating unit 64 extracts the mammary gland from the common region in each of the multiple tomographic images 82. The method by which the pseudo projection image generating unit 64 extracts the mammary gland is not particularly limited. The pseudo projection image generating unit 64 of this embodiment extracts a specific structure representing the mammary gland from the common region in each of the tomographic images 82, for example, using a known computer-aided diagnosis (CAD) algorithm. In the CAD algorithm, it is preferable to derive a probability (for example, likelihood) that a pixel in the common region represents a mammary gland, and detect the pixel as a pixel constituting an image of the mammary gland when the probability is equal to or greater than a predetermined threshold. Also, for example, the pseudo projection image generating unit 64 may use a method of extracting the mammary gland from the common region by a filtering process using a filter for extracting the mammary gland. When there are multiple extracted mammary glands, for example, when mammary glands are extracted from each of specific regions in multiple tomographic images 82, the pseudo projection image generating unit 64 extracts one mammary gland as a reference object 90 based on the feature amount of the mammary gland. 3 In this embodiment, the reference object 90 is extracted from the tomographic image 82. 3 is an example of a first tomographic image in the present disclosure, and tomographic image 82 1, 82 2 , 82 4 ~82 7 is an example of a second tomographic image of the present disclosure.

[0063] Next, the pseudo projection image generating unit 64 generates a tomographic image 82 3 A reference object region 83 in a portion including a reference object image 91 representing a reference object 90 1 The pseudo projection image generating unit 64 identifies the reference object region 83. 1 The method of identifying the irradiation position 19 where the irradiation angle α is 0 degrees is not particularly limited. 4 (See FIG. 2) 4 In the above, the reference object image 91 of the reference object 90 is set as the center, and the projection image 80 4 A region having a size that is a predetermined ratio of the size of the reference object region 83 1 Furthermore, as shown in FIG. 5, the pseudo projection image generating unit 64 calculates the reference object region 83 1 82 corresponding tomographic images 1 , 82 2 , 82 4 ~82 7 The area in each is the subarea 83 2 Identify as:

[0064] Next, as shown in FIG. 6, the pseudo projection image generating unit 64 generates a tomographic image 82 1 , 82 2 , 82 4 ~82 7 19 on the setting corresponding to each of the irradiation positions 19 of the multiple projection images 80. V (In Fig. 6, the irradiation position is 19 V1 ) to generate a plurality of reference object-free pseudo-projection images that do not include the reference object 90. V The irradiation position 19, which is the actual position of the radiation source 29 when the projection image 80 is captured in the tomosynthesis imaging, may change from the set irradiation position 19 due to changes over time, etc. V In this embodiment, what is known is the irradiation position 19 in the setting.V Therefore, the pseudo projection image generating unit 64 generates a tomographic image 82 1 , 82 2 , 82 4 ~82 7 83 sub-areas of each 2 For the setting, the irradiation position is 19 V By performing pseudo projection from the projection plane 80A, a reference object-free pseudo projection image 86 on the projection plane 80A similar to the projection image 80 is generated. Note that, if it is considered that there is no positional deviation of the irradiation position 19 of the radiation source 29 in the tomosynthesis imaging, the irradiation position 19 in the setting V is the same as the actual irradiation position 19. The reference-object-free pseudo-projection image 86 of this embodiment is an example of a reference-object-free pseudo-projection image of the present disclosure, and is also an example of a partial pseudo-projection image.

[0065] The reference-object-free pseudo-projection image 86 includes a structure image representing a structure other than the reference object 90. In the example shown in FIG. 6, the reference-object-free pseudo-projection image 86 1 There are 82 cross-sectional images 2 A structure image 93A representing a structure 92A present at a height corresponding to 1 , and tomographic image 82 5 A structure image 93B representing a structure 92B present at a height corresponding to 1 Also, the reference object pseudo-projection image 86 1 There are 82 cross-sectional images 3 In this way, the pseudo projection image generating unit 64 does not include the reference object image 91 that represents the reference object 90 that exists at the height corresponding to the irradiation position 19 on the setting. V For each image, a reference object pseudoprojection-free image 86 is generated.

[0066] The pseudo projection image generating unit 64 outputs image data representing the generated multiple reference object-free pseudo projection images 86 to the positional deviation amount deriving unit 66 .

[0067] The positional shift amount derivation unit 66 has a function of deriving the amount of positional shift between the projection images 80. As shown in Fig. 4, the positional shift amount derivation unit 66 of this embodiment includes a component-removed image generation unit 67. The component-removed image generation unit 67 has a function of generating a component-removed image including a reference object obtained by removing components of a plurality of reference-object-free pseudo projection images 86 from a plurality of projection images 80.

[0068] First, the component-removed image generating unit 67 of this embodiment extracts an image of a portion corresponding to the reference object-free pseudo projection image 86 from the projection image 80 as a partial image 84, as shown in Fig. 5. Furthermore, as shown in Fig. 7, the component-removed image generating unit 67 subtracts the pixel value of the reference object-free pseudo projection image 86 from the pixel value of the extracted partial image 84 for each corresponding pixel, thereby generating a component-removed image 88 (in Fig. 7, the component-removed image 88) which represents the difference between the partial image 84 and the reference object-free pseudo projection image 86. 1 ~88 7 )

[0069] Specifically, as shown in FIG. 7, the component-removed image generating unit 67 detects the first irradiation position 19, i.e., the irradiation position 19 1 80 corresponding projection images 1 For each corresponding pixel, 1 From the pixel values ​​of the reference object pseudo-projection image 86 1 The component-removed image 88 is obtained by subtracting the pixel values ​​of 1 In addition, the component removed image generating unit 67 generates the component removed image at the irradiation position 19 2 80 corresponding projection images 2 For each corresponding pixel, 2 From the pixel values ​​of the reference object pseudo-projection image 86 2 The component-removed image 88 is obtained by subtracting the pixel values ​​of 2 In addition, the component removed image generating unit 67 generates the component removed image at the irradiation position 19 3 80 corresponding projection images 3 For each corresponding pixel, 3 From the pixel values ​​of the reference object pseudo-projection image 86 3 The component-removed image 88 is obtained by subtracting the pixel values ​​of 3In this manner, the component-removed image generating unit 67 generates a component-removed image 88 from the partial images 84 of the projection image 80 corresponding to each irradiation position 19 and the reference object-free pseudo projection image 86, and generates the component-removed image 88 from the partial images 84 of the projection image 80 corresponding to each irradiation position 19, which is the last irradiation position 19. 7 80 corresponding projection images 7 For each corresponding pixel, 7 From the pixel values ​​of the reference object pseudo-projection image 86 7 The component-removed image 88 is obtained by subtracting the pixel values ​​of 7 Generate up to

[0070] The projection image 80 is an image showing structures lined up in the direction in which the radiation R is irradiated, and contains a large amount of information. Therefore, as shown in Figs. 5 to 7, the projection image 80 of this embodiment includes a reference object image 91 and structure images 93A and 93B in a state where they are superimposed according to the height at which the reference object 90 and structures 92A and 92B exist. In the example shown in Figs. 5 and 6, a structure 92A exists above the reference object 90. Therefore, the partial image 84 shown in Fig. 7 1 ~84 7 In the structure image 93A 1 ~93A 7 Each of the reference images 91 1 ~91 7 In this way, when an image of another structure such as the structure image 93A is superimposed on the reference object image 91, the image of the other structure such as the structure image 93A becomes an obstacle, making it difficult to extract the contour of the reference object image 91.

[0071] In contrast, the component-removed image 88 1 ~88 7 In the image 88, the structure images 93A and 93B, which are images of other structures, have been removed, so that the reference object image 91 does not overlap with other structure images, and the reference object image 91 is clearly shown. 1 ~88 7 In this image, the structure image 93A representing the structure 92A that is located above the reference object 90, in other words, closer to the radiation source 29 and therefore superimposed on the reference object image 91, has been removed, resulting in an image in which the reference object image 91 is clearly shown.

[0072] As described above, the component removed image generating unit 67 of the present embodiment generates the component removed image 88 by subtracting the pixel value of the reference object-free pseudo projection image 86 from the pixel value of the partial image 84 for each corresponding pixel, but the method by which the component removed image generating unit 67 generates the component removed image 88 is not limited to this embodiment. For example, the component removed image generating unit 67 may generate the component removed image 88 by reducing the pixel values ​​of pixels in each partial image 84 that are correlated with the reference object-free pseudo projection image 86.

[0073] The positional deviation amount deriving unit 66 calculates the component-removed image 88 generated by the component-removed image generating unit 67. 1 ~88 7 The misalignment amount between the projection images 80 is derived based on the component-removed image 88. The method by which the misalignment amount deriving unit 66 derives the misalignment amount between the projection images 80 is not limited. 1 ~88 7 and, tomographic image 82 3 and derives the amount of misalignment between the projection images 80 based on the above. As an example of a specific method, the misalignment amount derivation unit 66 of this embodiment derives the amount of misalignment between the projection images 80 by applying the technology described in International Publication WO 2020 / 067475. International Publication WO 2020 / 067475 discloses a technology for deriving the amount of misalignment between a plurality of projection images based on the feature points on a tomographic plane corresponding to a tomographic image on which the feature points are detected. When this technology is applied to this embodiment, the misalignment amount derivation unit 66 derives each projection image 80 based on the tomographic image 82. 3The misalignment amount derivation unit 66 may derive, for example, the misalignment amount for each partial image 84 as the misalignment amount between the projection images 80. The misalignment amount derivation unit 66 may derive, for example, the misalignment amount of the entire breast, which is a subject included between the projection images 80, as the misalignment amount between the projection images 80. When deriving the misalignment amount of the entire breast between the projection images 80, for example, a parameter indicating how much the entire breast has been misaligned may be set, and the parameter may be optimized according to the misalignment of the reference object 90.

[0074] The amount of positional deviation between the projection images 80 derived by the positional deviation amount derivation unit 66 is output to the notification unit 68 and the tomographic image generation unit 70.

[0075] When the amount of misalignment between the projection images 80 is relatively large, the misalignment between the projection images 80 may not be sufficiently corrected, or the image quality of the tomographic image 82 generated from the projection images 80 may be degraded. For example, when the subject moves significantly during tomosynthesis imaging, the body movement of the breast, which is the subject, may become large, and the amount of misalignment between the projection images 80 may become relatively large. In such a case, for example, it is preferable to re-imaging the projection images 80. Therefore, the notification unit 68 of this embodiment has a function of notifying a warning when the amount of misalignment derived by the misalignment amount derivation unit 66 exceeds a preset threshold. The predetermined threshold used to determine whether to notify a warning may be predetermined according to, for example, the image quality desired as the tomographic image 82, the accuracy of diagnosis, or the like, or may be set by the user. As an example, in this embodiment, the amount of misalignment to the extent that it is preferable to re-imaging is set as the predetermined threshold. The notification method by the notification unit 68 is not particularly limited, and may be, for example, a form in which at least one of a visual display and an audible display is displayed on the display unit 58 of the console 12. The content of the notification by the notification unit 68 is not limited to a warning, and may be, for example, at least one of a visual and an audible notification method, such as displaying a warning message on the display unit 58 of the console 12 or issuing a warning sound from a speaker (not shown) of the console 12. The content of the notification by the notification unit 68 is not limited to a warning, and may be, for example, information indicating that the amount of positional deviation is large or the derived amount of positional deviation itself, and the specific content is not limited.

[0076] The tomographic image generating unit 70 has a function of generating a plurality of tomographic images in each of the plurality of tomographic planes based on the plurality of projection images 80 acquired by the image acquiring unit 60 and the positional deviation amount derived by the positional deviation amount deriving unit 66. The method in which the tomographic image generating unit 70 generates a plurality of tomographic images in each of the plurality of tomographic planes based on the plurality of projection images 80 and the positional deviation amount is not limited. For example, when the tomographic image generating unit 70 reconstructs a tomographic image from the plurality of projection images 80 by a back projection method, the tomographic image may be generated by reconstructing the tomographic image using the back projection position of the projection image 80 corrected based on the positional deviation amount. Also, for example, the tomographic image generating unit 70 corrects the projection image 80 based on the positional deviation amount to generate a plurality of projection images assuming that no positional deviation occurs. Then, the tomographic image generating unit 70 may generate a plurality of tomographic images using the plurality of projection images 80 whose positional deviations have been corrected.

[0077] Furthermore, the height of the multiple tomographic planes generated by the tomographic image generating unit 70 is not limited. For example, the height of the tomographic planes may be the same as or different from the height of the multiple tomographic images 82 acquired by the tomographic image acquiring unit 62. Furthermore, the height of the tomographic planes may be a height specified by the user.

[0078] The tomographic image generating unit 70 outputs image data representing the generated multiple tomographic images to the display control unit 72.

[0079] The display control unit 72 has a function of displaying the multiple tomographic images generated by the tomographic image generating unit 70 on the display unit 58. The display destination of the multiple tomographic images is not limited to the display unit 58. For example, the display destination may be an image reading device or the like external to the radiation image capturing system 1.

[0080] Next, the operation of the console 12 in tomosynthesis imaging will be described with reference to the drawings. After tomosynthesis imaging is performed by the mammography apparatus 10, the console 12 generates multiple tomographic images using multiple projection images obtained by tomosynthesis imaging, and displays them on the display unit 58, etc.

[0081] As an example, when the tomosynthesis imaging is completed, the mammography apparatus 10 of this embodiment outputs image data of the captured multiple projection images 80 to the console 12. The console 12 stores the image data of the multiple projection images 80 input from the mammography apparatus 10 in the memory unit 52.

[0082] After storing the image data of the multiple projection images 80 in the storage unit 52, the console 12 executes the image processing shown in Fig. 8. Fig. 8 shows a flowchart showing an example of the flow of image processing by the console 12 of this embodiment. As an example, the console 12 of this embodiment executes the image processing example shown in Fig. 8 by causing the CPU 50A of the control unit 50 to execute the image generating program 51 stored in the ROM 50B.

[0083] 8, the image acquisition unit 60 acquires a plurality of projection images 80. As described above, the image acquisition unit 60 of this embodiment acquires image data of a plurality of projection images from the storage unit 52.

[0084] In the next step S102, the tomographic image acquisition unit 62 acquires a plurality of tomographic images 82. As described above, the plurality of projection images 80 acquired in step S100 are used to generate a plurality of tomographic images 82 corresponding to the plurality of tomographic planes of the breast, respectively, to acquire the plurality of tomographic images 82.

[0085] In the next step S104, the pseudo projection image generating unit 64 extracts a reference object 90 used as a reference for deriving the amount of positional deviation between the projection images 80 from the multiple tomographic images 82. As described above, the pseudo projection image generating unit 64 extracts the reference object 90, which is a mammary gland, from the common region of the multiple projection images 80 based on the feature amount.

[0086] In the next step S106, the pseudo projection image generating unit 64 specifies a partial region 83 in the tomographic image 82 that does not include a reference object image 91 representing the reference object 90. As described above, the pseudo projection image generating unit 64 specifies a partial region 83 in the tomographic image 82 that does not include a reference object image 91 representing the reference object 90 extracted in the above step S104. 1 Identify the reference object area 83 1 A partial region 83 in another tomographic image 82 corresponding to 2 In this embodiment, as described above, the pseudo projection image generating unit 64 identifies the tomographic image 82 3 Reference object area 83 1 In addition, the pseudo projection image generating unit 64 determines the tomographic image 82 1 , 82 2 , 82 4 ~82 7 Each of the reference object regions 83 1 The area corresponding to the subarea 83 2 Identify as:

[0087] In the next step S108, the pseudo projection image generating unit 64 generates a reference object-free pseudo projection image 86. As described above, the pseudo projection image generating unit 64 generates the tomographic image 82. 1 , 82 2 , 82 4 ~82 7 83 sub-areas of each 2 For the setting, the irradiation position is 19 V By performing pseudo projection from the above, a reference-object-free pseudo-projection image 86 on the projection plane 80A of the projection image 80 is generated.

[0088] In the next step S110, the component removed image generating unit 67 of the positional deviation amount derivation unit 66 generates a component removed image 88. As described above, the component removed image generating unit 67 extracts an image of a portion corresponding to the reference object-free pseudo projection image 86 from the multiple projection images 80 as a partial image 84. In addition, the component removed image generating unit 67 subtracts the pixel value of the reference object-free pseudo projection image 86 from the pixel value of the extracted partial image 84 for each corresponding pixel, thereby generating a component removed image 88 representing the difference between the partial image 84 and the reference object-free pseudo projection image 86.

[0089] In the next step S112, the positional shift amount derivation unit 66 derives the amount of positional shift between the multiple projection images 80. As described above, the positional shift amount derivation unit 66 derives the amount of positional shift between the projection images 80 based on the component removed image 88 generated in the above step S110.

[0090] In the next step S114, the notification unit 68 determines whether or not the amount of positional deviation between the multiple projected images 80 exceeds a predetermined threshold. In other words, as described above, the notification unit 68 determines whether or not a positional deviation has occurred to an extent that makes it preferable to perform re-imaging. If the amount of positional deviation derived in the above step S112 is equal to or less than the predetermined threshold, the determination in step S114 is negative, and the process proceeds to step S118. On the other hand, if the amount of positional deviation derived in the above step S112 exceeds the predetermined threshold, the determination in step S114 is positive, and the process proceeds to step S116.

[0091] In step S116, the notification unit 68 displays a warning on the display unit 58. As described above, the notification unit 68 of the present embodiment uses the display unit 58 to notify the user of a warning indicating that it is preferable to re-shoot since the amount of positional deviation is large.

[0092] In the next step S118, the tomographic image generating unit 70 generates a plurality of tomographic images in which the positional deviation has been corrected. As described above, the tomographic image generating unit 70 generates a plurality of tomographic images in each of a plurality of tomographic planes based on the plurality of projection images 80 acquired in the above step S100 and the amount of positional deviation derived in the above step S112.

[0093] In the next step S120, the display control unit 72 causes the tomographic image generated in the above step S118 to be displayed on the display unit 58. When the process of step S120 ends, the image processing shown in FIG.

[0094] In this manner, the console 12 of this embodiment processes a plurality of projection images 80 obtained by irradiating the breast with radiation R from each of a plurality of irradiation positions 19 having different irradiation angles α using the radiation source 29. The console 12 includes a CPU 50A. The CPU 50A acquires a plurality of projection images 80, acquires a plurality of tomographic images 82 that are generated using the plurality of projection images 80 and correspond to a plurality of tomographic planes of the breast, and processes a plurality of tomographic images 82 that include a reference object image 91 representing a reference object 90 used as a reference for deriving the amount of positional deviation between the projection images 80 from among the plurality of tomographic images 82. 1 82 tomographic images other than (82 1 , 82 2 , 82 4 ~82 7 ) to determine the irradiation positions 19 on the setting corresponding to the irradiation positions 19 of each of the multiple projection images 80. V By performing pseudo projection from the reference object, a plurality of reference-free pseudo projection images 86 that do not include a reference object image 91 representing the reference object 90 are generated, and the amount of positional deviation between the projection images 80 is derived based on a component-removed image 88 that includes a reference object image 91 obtained by removing the components of the plurality of reference-free pseudo projection images 86 from the plurality of projection images 80.

[0095] The console 12 of this embodiment derives the amount of positional deviation between the projection images 80 using a reference object 90 that serves as a reference for deriving the amount of positional deviation between the projection images 80. The projection image 80 is an image showing structures arranged in a direction in which the radiation R is irradiated, and contains a lot of information. Therefore, the projection image 80 includes a reference object image 91 that shows the reference object 90, as well as structure images that show structures other than the reference object 90. The projection image 80 shown in FIG. 5 includes a structure image 93A that shows a structure 92A and a structure image 93B that shows a structure 92B, as well as the reference object image 91. When images of other structures are superimposed on the reference object image 91, the contour of the reference object image 91 becomes unclear. In particular, a structure image (structure image 93A that shows a structure 92A in this embodiment) that shows a structure existing above the reference object 90, in other words, closer to the radiation source 29, is superimposed on the reference object image 91, and therefore the contour of the reference object image 91 becomes unclear.

[0096] Therefore, the console 12 of this embodiment derives the amount of positional deviation between the projection images 80 based on a component-removed image 88 generated by subtracting, for each corresponding pixel, pixel values ​​of a plurality of reference-free pseudo projection images 86 that do not include the reference object image 91 from pixel values ​​of a partial image 84 of the projection image 80. In this manner, the console 12 of this embodiment derives the amount of positional deviation between the projection images 80 using the component-removed image 88 in which the reference object image 91 representing the reference object 90 is clearly shown. Therefore, according to the console 12 of this embodiment, the amount of positional deviation between the projection images 80 can be derived with high accuracy.

[0097] There are cases where the correction of the positional deviation in step S118 is not sufficient. In other words, the image quality of the multiple tomographic images generated by the tomographic image generating unit 70 in step S118 is lower than the image quality of the multiple tomographic images generated by the projection image 80 when it is considered that no positional deviation occurs. In such a case, the process returns to step S106 after step S118 and repeats the processes of steps S106 to S116 until the amount of positional deviation derived in step S112 becomes equal to or less than the level at which it is considered that no positional deviation occurs.

[0098] In this embodiment, the pseudo projection image generating unit 64 detects the reference object region 83 1 A partial region 83 of the tomographic image 82 corresponding to 2 In the above embodiment, the reference-object-free pseudo-projection image 86 is generated by performing pseudo-projection on the tomographic image 82, but the area on which the pseudo-projection is performed is not limited to this embodiment. For example, the pseudo-projection image generating unit 64 may generate the reference-object-free pseudo-projection image 86 by performing pseudo-projection on the entire tomographic image 82.

[0099] [Second embodiment] The overall configuration of the radiation image capturing system 1 of this embodiment is similar to that of the radiation image capturing system 1 of the first embodiment (see FIG. 1), so a detailed description thereof will be omitted. Also, the configuration of the mammography apparatus 10 is similar to that of the mammography apparatus 10 of the first embodiment (see FIGS. 1 to 3), so a detailed description thereof will be omitted.

[0100] In addition, the hardware configuration of the console 12 of this embodiment is the same as that of the first embodiment, except that an image generation program 51A stored in the ROM 50B of the control unit 50 is stored in place of the image generation program 51 of the first embodiment as shown in FIG. 9, and therefore a description thereof will be omitted.

[0101] On the other hand, the console 12 of this embodiment has a different functional configuration from the console 12 of the first embodiment (see FIG. 4), so the functional configuration of the console 12 of this embodiment will be described. FIG. 10 shows a functional block diagram of an example of a configuration related to a function of correcting positional deviation between a plurality of projection images 80 obtained by tomosynthesis imaging in the console 12 of this embodiment. As shown in FIG. 10, the console 12 includes an image acquisition unit 60, a tomographic image acquisition unit 62, a pseudo projection image generation unit 63, a positional deviation amount derivation unit 65, a notification unit 68, a tomographic image generation unit 71, and a display control unit 72. As an example, the console 12 of this embodiment functions as the image acquisition unit 60, the tomographic image acquisition unit 62, the pseudo projection image generation unit 63, the positional deviation amount derivation unit 65, the notification unit 68, the tomographic image generation unit 71, and the display control unit 72 by the CPU 50A of the control unit 50 executing the image generation program 51A stored in the ROM 50B.

[0102] The image acquisition unit 60 has a function of acquiring a plurality of projection images 80, similar to the image acquisition unit 60 of the first embodiment (see FIG. 4). Specifically, the image acquisition unit 60 of this embodiment acquires image data representing a plurality of projection images 80 acquired by tomosynthesis imaging in the mammography apparatus 10. The image acquisition unit 60 outputs the image data representing the acquired plurality of projection images 80 to the tomographic image acquisition unit 62 and the positional deviation amount derivation unit 65.

[0103] The tomographic image acquisition unit 62 has a function of acquiring a plurality of tomographic images 82 corresponding to a plurality of tomographic planes of the breast, which is a subject, similarly to the tomographic image acquisition unit 62 of the first embodiment (see FIG. 4). Specifically, the tomographic image acquisition unit 62 of this embodiment has a function of acquiring a plurality of projection images 80 acquired by the image acquisition unit 60, as shown in FIG. 1 ~80 782 corresponding to each of the multiple tomographic planes of the breast. 1 ~82 7 to obtain a plurality of tomographic images 82. The tomographic image obtaining unit 62 outputs image data representing the generated plurality of tomographic images 82 to the pseudo projection image generating unit 63.

[0104] The pseudo projection image generating unit 63 uses the tomographic image 82 including the reference object image 95 representing the reference object 90 used as a reference for deriving the amount of positional deviation between the projection images 80 out of the multiple tomographic images 82 acquired by the tomographic image acquiring unit 62, and generates a pseudo projection image corresponding to each of the irradiation positions 19 in the multiple projection images 80. V 9. The pseudo projection image generating unit 94 has a function of generating a plurality of pseudo projection images including the reference object image 97 by performing pseudo projection from the reference object image 97. In this embodiment, the pseudo projection image including the reference object image 97 is referred to as a "pseudo projection image with reference object."

[0105] An example of a method for generating a reference object-included pseudo projection image in the pseudo projection image generating unit 63 of this embodiment will be described with reference to FIG. 5 shown in the first embodiment, and to FIGS.

[0106] First, the pseudo projection image generating unit 63 extracts a reference object 90 from the multiple tomographic images 82. Specifically, the pseudo projection image generating unit 63 extracts a reference object image 95 representing the reference object 90 from the multiple tomographic images 82. In this embodiment, the reference object 90 used as a reference for deriving the amount of positional deviation between the projection images 80 is similar to the reference object 90 in the first embodiment. In addition, the method by which the pseudo projection image generating unit 63 extracts the reference object 90 from the multiple tomographic images 82 is similar to the method by which the pseudo projection image generating unit 64 in the first embodiment extracts the reference object 90 from the multiple tomographic images 82, and therefore a description thereof will be omitted. In addition, in this embodiment, like the reference object 90 in the first embodiment, the pseudo projection image generating unit 63 extracts a reference object image 95 representing the reference object 90 from the tomographic images 82. 1 ~82 7 Of these, 82 were tomographic images. 3 A case where a reference object 90 existing at a height corresponding to the above will be explained.

[0107] Next, as shown in FIG. 11, the pseudo projection image generating unit 63 generates a tomographic image 82 3 A reference object region 83 in a portion including a reference object image 95 representing the reference object 90 1 The pseudo projection image generating unit 63 identifies the reference object region 83. 1 The method of identifying the reference object region 83 in the first embodiment is as follows. 1 Since this method is similar to the method for specifying

[0108] Next, as shown in FIG. 11 and FIG. 12, the pseudo projection image generating unit 63 calculates the reference object region 83 1 Using the projection image 80 1 ~80 7 Each irradiation position 19 1 ~19 7 The corresponding irradiation position on the setting is 19 V1 ~19 V7 A pseudoprojection image 89 with a reference object including a reference object image 97 is obtained by pseudoprojecting from the 1 ~89 7 In addition, in FIG. 12, the irradiation position 19 1 The corresponding irradiation position on the setting is 19 V1 A pseudo-projected image 89 with a reference object is pseudo-projected onto a projection surface 80A similar to the projection image 80. 1 is shown.

[0109] The image showing the structure included in the pseudo-projection image 89 with the reference object is the tomographic image 82 3 In the example shown in FIG. 11 and FIG. 12, the tomographic image 82 3 includes a reference object image 95 representing the reference object 90, but does not include a structure image representing the structure 92A or a structure image representing the structure 92B. Therefore, the reference object-included pseudo projection image 89 includes the reference object image 95, but does not include structure images representing the structures 92A and 92B. Therefore, the reference object-included pseudo projection image 89 is an image that does not include a structure image representing a structure that exists at a position different from the reference object 90.

[0110] A tomographic image 82 generated from a plurality of projection images 80 in which positional deviation occurs may have blurring or the like due to the influence of the positional deviation. For example, in the example shown in FIG. 11, the tomographic image 82 is blurred compared to a reference object image 91 included in the projection images 80. 3 The reference object image 95 included in the reference object region 83 becomes blurred or larger in size. 1 is pseudo-projected, the reference object image 97 included in the pseudo projection image 89 with reference object also becomes blurred and larger in size than the reference object image 91 included in the projection image 80. In this way, the pseudo projection image 89 with reference object includes the reference object image 97 in which the positional deviation between the projection images 80 appears.

[0111] The pseudo projection image generating unit 63 outputs image data representing the generated multiple reference object-included pseudo projection images 89 to the positional deviation amount deriving unit 65 .

[0112] The positional deviation amount deriving unit 65 detects the projection image 80 1 ~80 7 and pseudoprojection image with reference object 89 1 ~89 7and has a function of deriving the amount of positional deviation between the projection images 80 based on the above. As described above, the pseudo projection image 89 with reference object includes a reference object image 97 in which the positional deviation between the projection images 80 appears. For example, the reference object image 97 of the pseudo projection image 89 with reference object is larger than the reference object image 91 of the projection image 80. The positional deviation amount derivation unit 65 of this embodiment derives the amount of positional deviation between the projection images 80 by comparing the reference object image 97 included in the pseudo projection image 89 with the reference object image 91 included in the projection image 80. As an example, the positional deviation amount derivation unit 65 derives the amount of positional deviation between the projection images 80 based on the difference between the size and position of the reference object image 97 included in the pseudo projection image 89 with the size and position of the reference object image 91 included in the projection image 80. When it is considered that no positional deviation occurs between the projection images 80, the size and position of the reference object image 97 included in the reference object pseudo projection image 89 are similar to the size and position of the reference object image 91 included in the projection image 80. 1 ~80 7 and pseudoprojection image with reference object 89 1 ~89 7 The method of deriving the amount of positional deviation between the projected images 80 based on the above is not limited to this embodiment.

[0113] The amount of positional deviation between the projection images 80 derived by the positional deviation amount derivation unit 65 is output to the notification unit 68 and the tomographic image generation unit 71.

[0114] The notifying unit 68 has a function of issuing a notification when the amount of positional deviation derived by the positional deviation amount derivation unit 65 exceeds a preset threshold value, similarly to the notifying unit 68 in the first embodiment (see FIG. 4).

[0115] Similar to the tomographic image generating unit 70 (see FIG. 4) of the first embodiment, the tomographic image generating unit 71 has a function of generating a plurality of tomographic images in each of a plurality of tomographic planes based on a plurality of projection images 80 acquired by the image acquiring unit 60 and the amount of misalignment derived by the misalignment amount derivation unit 66. The tomographic image generating unit 71 outputs image data representing the generated plurality of tomographic images to the display control unit 72.

[0116] The display control unit 72 has a function of causing the display unit 58 to display a plurality of tomographic images generated by the tomographic image generating unit 70, similar to the display control unit 72 (see FIG. 4) in the first embodiment.

[0117] Next, the function of the console 12 in tomosynthesis imaging will be described with reference to the drawings. As an example, when tomosynthesis imaging is completed, the mammography apparatus 10 of this embodiment outputs image data of the captured multiple projection images 80 to the console 12. The console 12 stores the image data of the multiple projection images 80 input from the mammography apparatus 10 in the storage unit 52.

[0118] After storing the image data of the multiple projection images 80 in the storage unit 52, the console 12 executes the image processing shown in Fig. 13. Fig. 13 shows a flowchart showing an example of the flow of image processing by the console 12 of this embodiment. As an example, the console 12 of this embodiment executes the image processing, an example of which is shown in Fig. 12, by the CPU 50A of the control unit 50 executing an image generating program 51A stored in the ROM 50B.

[0119] 13, the image acquisition unit 60 acquires a plurality of projection images 80. The image acquisition unit 60 acquires image data of the plurality of projection images from the storage unit 52, similar to step S100 (see FIG. 8) of the image processing in the first embodiment.

[0120] In the next step S102, the tomographic image acquiring unit 62 acquires a plurality of tomographic images 82. As in step S102 (see FIG. 8) of the image processing in the first embodiment, the tomographic image acquiring unit 62 acquires the plurality of tomographic images 82 by generating a plurality of tomographic images 82 corresponding to the plurality of tomographic planes of the breast, respectively, using the plurality of projection images 80 acquired in the above step S100.

[0121] In the next step S104, the pseudo projection image generating unit 63 extracts a reference object 90 used as a reference for deriving the amount of positional deviation between the projection images 80 from the multiple tomographic images 82. The pseudo projection image generating unit 63 extracts the reference object 90, which is a mammary gland, from the common region of the multiple projection images 80 based on the feature amount, similar to step S104 (see FIG. 8) of the image processing in the first embodiment.

[0122] In the next step S107, the pseudo projection image generating unit 63 calculates the reference object region 83 of the tomographic image 82 including the reference object image 95 representing the reference object 90. 1 As described above, the pseudo projection image generating unit 63 generates the tomographic image 82 including the reference object image 95 representing the reference object 90 extracted in the above step S104. 3 In the above, a reference object region 83 including a reference object image 95 is 1 Identify.

[0123] In the next step S109, the pseudo projection image generating unit 63 generates a reference object pseudo projection image 89. As described above, the pseudo projection image generating unit 63 generates the tomographic image 82. 3 Of the 83 reference object regions 1 For the setting, the irradiation position is 19 V By performing pseudo projection from the above, a pseudo projection image 89 with a reference object on the projection plane 80A of the projection image 80 is generated.

[0124] In the next step S113, the positional deviation amount derivation unit 65 derives the amount of positional deviation between the multiple projection images 80. As described above, the positional deviation amount derivation unit 65 derives the amount of positional deviation between the projection images 80 based on the reference object image 97 included in the reference object-included pseudo projection image 89 generated in the above step S109 and the reference object image 91 included in the projection image 80.

[0125] In the next step S114, the notification unit 68 determines whether or not the amount of positional deviation between the multiple projected images 80 exceeds a predetermined threshold. The notification unit 68 determines whether or not a positional deviation has occurred to an extent that makes it preferable to perform re-imaging, similarly to step S114 (see FIG. 8) of the image processing in the first embodiment. If the amount of positional deviation derived in the above step S112 is equal to or less than the predetermined threshold, the determination in step S114 is negative, and the process proceeds to step S118. On the other hand, if the amount of positional deviation derived in the above step S112 exceeds the predetermined threshold, the determination in step S114 is positive, and the process proceeds to step S116.

[0126] In step S116, the notification unit 68 displays a warning on the display unit 58. As in step S116 (see FIG. 8) of the image processing in the first embodiment, the notification unit 68 uses the display unit 58 to notify the user of a warning indicating that it is preferable to re-shoot since the amount of positional deviation is large.

[0127] In the next step S118, the tomographic image generating unit 70 generates a plurality of tomographic images in which the positional deviation has been corrected. Similar to step S118 (see FIG. 8) of the image processing in the first embodiment, the tomographic image generating unit 70 generates a plurality of tomographic images in each of a plurality of tomographic planes based on the plurality of projection images 80 acquired in the above step S100 and the amount of positional deviation derived in the above step S113.

[0128] In the next step S120, the display control unit 72 causes the tomographic image generated in the above step S118 to be displayed on the display unit 58. When the process of step S120 ends, the image processing shown in FIG.

[0129] In this manner, the console 12 of this embodiment processes a plurality of projection images 80 obtained by irradiating the breast with radiation R from each of a plurality of irradiation positions 19 having different irradiation angles α using the radiation source 29. The console 12 includes a CPU 50A. The CPU 50A acquires a plurality of projection images 80, acquires a plurality of tomographic images 82 that are generated using the plurality of projection images 80 and correspond to a plurality of tomographic planes of the breast, and processes a plurality of tomographic images 82 that include a reference object image 95 used as a reference for deriving the amount of positional deviation between the projection images 80 from among the plurality of tomographic images 82. 3 19 on the setting corresponding to each of the irradiation positions 19 of the multiple projection images 80. V A plurality of pseudo projection images with a reference object including a reference object image 97 are generated by performing pseudo projection from the plurality of projection images 80, and the amount of positional deviation between the projection images 80 is derived based on the plurality of projection images 80 and the plurality of pseudo projection images with a reference object.

[0130] The console 12 of this embodiment derives the amount of positional deviation between the projected images 80 by using a reference object 90 that serves as a reference for deriving the amount of positional deviation between the projected images 80. The projected image 80 is an image showing structures arranged in the direction in which the radiation R is irradiated, and contains a lot of information. Therefore, the projected image 80 includes an image showing structures other than the reference object 90, in addition to a reference object image 91 showing the reference object 90. When an image of another structure is superimposed on the reference object image 91, the contour of the reference object image 91 becomes unclear. In particular, an image showing a structure existing above the reference object 90, in other words, closer to the radiation source 29 (a structure image 93A showing a structure 92A in FIG. 11) is superimposed on the reference object image 91, and therefore the contour of the reference object image 91 becomes unclear.

[0131] Therefore, the console 12 of this embodiment selects the tomographic image 82 including the reference object image 95 from among the multiple tomographic images 82. 3 19 on the setting corresponding to each of the irradiation positions 19 of the multiple projection images 80. V9, a plurality of pseudo-projection images with reference object 89 including a reference object image 97 are generated. As a result, the pseudo-projection images with reference object 89 do not include a structure image representing a structure existing at a position different from the reference object 90, and the reference object image 97 is clearly displayed. In this manner, the console 12 of this embodiment derives the amount of positional deviation between the projected images 80 using the pseudo-projection images with reference object 89 including a clear reference object image 97, which shows the positional deviation between the projected images 80. Therefore, the console 12 of this embodiment can derive the amount of positional deviation between the projected images 80 with high accuracy.

[0132] There are cases where the correction of the positional deviation in step S118 is not sufficient. In other words, the image quality of the multiple tomographic images generated by the tomographic image generating unit 70 in step S118 is lower than the image quality of the multiple tomographic images generated by the projection image 80 when it is considered that no positional deviation occurs. In such a case, the process returns to step S107 after step S118 and repeats the processes of steps S107 to S116 until the amount of positional deviation derived in step S113 becomes equal to or less than the level at which it is considered that no positional deviation occurs.

[0133] In this embodiment, the pseudo projection image generating unit 63 detects the reference object region 83 1 Although the embodiment in which the pseudo projection image with reference object 89 is generated by performing pseudo projection onto the tomographic image 82 has been described, the area in which the pseudo projection is performed is not limited to this embodiment. For example, the pseudo projection image generating unit 63 may generate the pseudo projection image with reference object 89 by performing pseudo projection onto the entire tomographic image 82.

[0134] As described above, according to the console 12 of each of the above embodiments, the reference object 90 is used as a reference for deriving the amount of positional shift between the projection images 80, and the amount of positional shift between the projection images 80 is derived using the component-removed image 88 or the pseudo projection image with reference object 89 that does not include a structural image representing a structure other than the reference object 90. Therefore, according to the console 12 of each of the above embodiments, the amount of positional shift between the projection images 80 can be derived with high accuracy.

[0135] In the above embodiments, the case where one reference object 90 is provided has been described, but a plurality of reference objects 90 may be provided. In this case, the console 12 may perform pseudo projection for each of the plurality of reference objects 90. Specifically, in the first embodiment, the pseudo projection image generating unit 64 generates a reference object region 83 for each of the plurality of reference objects 90. 1 and sub-area 83 2 Further, the pseudo projection image generating unit 64 generates a reference object-free pseudo projection image 86 by performing pseudo projection using the partial region 832 for each reference object 90. The positional deviation amount derivation unit 66 may derive the positional deviation amount for each reference object 90 by using a component removed image 88 generated using the reference object-free pseudo projection image 86. In the second embodiment, the pseudo projection image generating unit 63 generates the reference object region 83 for each of the multiple reference objects 90. 1 A pseudo projection image with a reference object 89 is generated by performing pseudo projection using the pseudo projection image with a reference object 89. Furthermore, the pseudo projection image generating unit 63 may be configured to derive the amount of positional deviation for each reference object 90 using the pseudo projection image with a reference object 89. When a plurality of reference objects 90 are provided in this manner, for example, the amount of positional deviation of a region determined for each reference object 90 may be derived, or the amount of positional deviation of the entire projection image 80 may be derived by averaging the amount of positional deviation for each reference object 90.

[0136] In the above embodiment, the console 12 is an example of the image processing device of the present disclosure, but a device other than the console 12 may have the functions of the image processing device of the present disclosure. In other words, some or all of the functions of the image acquisition unit 60, the tomographic image acquisition unit 62, the pseudo projection image generation unit 64, the positional deviation amount derivation unit 66, the notification unit 68, the tomographic image generation unit 70, and the display control unit 72 may be provided by a device other than the console 12, such as the mammography device 10 or an external device. In addition, the image processing device of the present disclosure may be configured by a plurality of devices. For example, some of the functions of the image processing device may be provided by a device other than the console 12.

[0137] In the above embodiment, a breast is applied as an example of a subject of the present disclosure, and a mammography device 10 is applied as an example of a radiation image capturing device of the present disclosure, but the subject is not limited to a breast, and the radiation image capturing device is not limited to a mammography device. For example, the subject may be a chest or abdomen, and the radiation image capturing device may be a radiation image capturing device other than a mammography device.

[0138] In the above embodiment, the following various processors can be used as the hardware structure of the processing unit that executes various processes, such as the image acquisition unit 60, the tomographic image acquisition unit 62, the pseudo projection image generation unit 64, the positional deviation amount derivation unit 66, the notification unit 68, the tomographic image generation unit 70, and the display control unit 72, or the image acquisition unit 60, the tomographic image acquisition unit 62, the pseudo projection image generation unit 63, the positional deviation amount derivation unit 65, the notification unit 68, the tomographic image generation unit 71, and the display control unit 72. As described above, the above various processors include a CPU, which is a general-purpose processor that executes software (programs) and functions as various processing units, as well as a programmable logic device (PLD), which is a processor whose circuit configuration can be changed after manufacture, such as an FPGA (Field Programmable Gate Array), a dedicated electric circuit, which is a processor having a circuit configuration designed specifically to execute specific processes, such as an ASIC (Application Specific Integrated Circuit), etc.

[0139] A single processing unit may be configured with one of these various processors, or may be configured with a combination of two or more processors of the same or different types (for example, a combination of multiple FPGAs, or a combination of a CPU and an FPGA). Also, multiple processing units may be configured with a single processor.

[0140] As an example of configuring multiple processing units with one processor, first, there is a form in which one processor is configured with a combination of one or more CPUs and software, and this processor functions as multiple processing units, as represented by computers such as client and server. Second, there is a form in which a processor is used to realize the functions of the entire system including multiple processing units with one IC (Integrated Circuit) chip, as represented by a system on chip (SoC). In this way, the various processing units are configured using one or more of the above various processors as a hardware structure.

[0141] Furthermore, more specifically, the hardware structure of these various processors can be an electric circuit that combines circuit elements such as semiconductor elements.

[0142] In the above embodiments, the photographing program 41 is pre-stored (installed) in the ROM 40B, and the image generating program 51 or the image generating program 51A is pre-stored (installed) in the ROM 50B, but the present invention is not limited to this. Each of the photographing program 41, the image generating program 51, and the image generating program 51A may be provided in a form recorded on a recording medium such as a CD-ROM (Compact Disc Read Only Memory), a DVD-ROM (Digital Versatile Disc Read Only Memory), or a USB (Universal Serial Bus) memory. Each of the photographing program 41, the image generating program 51, and the image generating program 51A may be downloaded from an external device via a network. [Explanation of symbols]

[0143] 1 Radiography system 10 Mammography equipment 12 Console 19 1 ~19 7Irradiation position, 19 V , 19 V1 Irradiation position in settings 20 Radiation detector, 20A detection surface 24 Imaging Table, 24A Imaging Surface 28 Radiation Department 29 Radiation source 33 Arm section 34 Foundation 35 Shaft 36 Compression Unit 38 Compression Plate 39 Support part 40A, 50A CPU, 40B, 50B ROM, 40C, 50C RAM 41 Shooting Program 42, 52 Storage section 44, 54 I / F section 46, 56 Operation section 47 Source moving part 49, 59 Bus 51, 51A Image generation program 58 Display section 60 Image acquisition unit 62 Tomographic image acquisition unit 63, 64 Pseudo projection image generation unit 65, 66 Position deviation amount derivation section 67 Component removal image generation unit 68 Notification Department 70, 71 Tomographic image generating unit 72 Display control section 80, 80 1 Projection image, 80A projection surface 82 82 1 ~82 7 Tomographic images 83 1 Reference object area, 83 2 partial area 84, 84 1 ~84 7 Partial Image 86, 86 1 ~86 7 Pseudo projection image without reference object 88 1 ~88 7 Component removal image 90 Reference object 91, 91 1 ~91 7 , 95, 97 1 ~97 7 Reference object image 92A, 92B structures 93A, 93B, 93A 1 ~93A 7 , 93B 1 ~93B 7 Structure image CL normal line R radiation, RC radiation axis W breast α, θ angles

Claims

1. 1. An image processing device that processes a plurality of projection images obtained by irradiating a subject with radiation from a radiation source from each of a plurality of irradiation positions having different irradiation angles, comprising: At least one processor; The processor, acquiring the plurality of projection images; acquiring a plurality of tomographic images that are generated using the plurality of projection images and that correspond to a plurality of tomographic planes of the subject, respectively; using a second group of tomographic images other than the first tomographic images including a reference object image representing a reference object used as a reference for deriving the amount of positional deviation between the projection images among the plurality of tomographic images, and performing pseudo projection from a set irradiation position corresponding to each of the irradiation positions of the plurality of projection images, thereby generating a plurality of reference-object-free pseudo projection images not including the reference object image; A positional deviation amount between the projection images is derived based on a component-removed image including the reference object image obtained by removing components of the plurality of reference object-free pseudo projection images from the plurality of projection images. Image processing device.

2. The processor, The amount of positional deviation is derived based on the component removed image and the first tomographic image. The image processing device according to claim 1 .

3. The processor, generating a partial pseudo-projection image as the reference object-free pseudo-projection image by pseudo-projecting a partial region of the second tomographic images corresponding to a reference object region of a portion of the first tomographic images including the reference object image; generating a component-removed image by removing a component of the partial pseudoprojection image from a partial image of the projection image corresponding to the partial pseudoprojection image; 3. The image processing device according to claim 1 or 2.

4. The processor, As the component-removed image, an image representing a difference between the plurality of projection images and the plurality of reference object-free pseudo-projection images is generated. The image processing device according to any one of claims 1 to 3.

5. The processor, The component-removed image is generated by subtracting the pixel value of the reference object-free pseudo-projection image from the pixel value of the projection image for each corresponding pixel. The image processing device according to any one of claims 1 to 3.

6. The processor, The component-removed image is generated by reducing pixel values ​​of pixels in the projection image that are correlated with the reference object-free pseudo-projection image. The image processing device according to any one of claims 1 to 3.

7. The processor, Further, a plurality of tomographic images are generated for each of a plurality of tomographic planes based on the plurality of projection images and the amount of positional deviation. The image processing device according to claim 1 .

8. The processor, When the amount of positional deviation exceeds a preset threshold, a notification is given. The image processing device according to any one of claims 1 to 7.

9. The processor, When there are a plurality of reference objects, a pseudo projection is performed for each of the plurality of reference objects using the second group of tomographic images for each of the reference objects. The image processing device according to any one of claims 1 to 8.

10. the subject is a breast, The fiducial is a calcification or a mammary gland. The image processing device according to any one of claims 1 to 9.

11. A radiation source that generates radiation; a radiation image capturing apparatus that performs tomosynthesis imaging by irradiating a subject with radiation from a radiation source from each of a plurality of irradiation positions having different irradiation angles and capturing a projection image of the subject for each of the irradiation positions; An image processing device according to any one of claims 1 to 10; A radiation imaging system comprising:

12. 1. An image processing method for processing a plurality of projection images obtained by irradiating a subject with radiation from a radiation source from each of a plurality of irradiation positions having different irradiation angles, the method comprising: acquiring the plurality of projection images; acquiring a plurality of tomographic images that are generated using the plurality of projection images and that correspond to a plurality of tomographic planes of the subject, respectively; using a second group of tomographic images other than the first tomographic images including a reference object image representing a reference object used as a reference for deriving the amount of positional deviation between the projection images among the plurality of tomographic images, and performing pseudo projection from a set irradiation position corresponding to each of the irradiation positions of the plurality of projection images, thereby generating a plurality of reference-object-free pseudo projection images not including the reference object image; A positional deviation amount between the projection images is derived based on a component-removed image including the reference object image obtained by removing components of the plurality of reference object-free pseudo projection images from the plurality of projection images. An image processing method in which the processing is performed by a computer.

13. An image processing program for processing a plurality of projection images obtained by irradiating a subject with radiation from a radiation source from each of a plurality of irradiation positions having different irradiation angles, the program comprising: acquiring the plurality of projection images; acquiring a plurality of tomographic images that are generated using the plurality of projection images and that correspond to a plurality of tomographic planes of the subject, respectively; using a second group of tomographic images other than the first tomographic images including a reference object image representing a reference object used as a reference for deriving the amount of positional deviation between the projection images among the plurality of tomographic images, and performing pseudo projection from a set irradiation position corresponding to each of the irradiation positions of the plurality of projection images, thereby generating a plurality of reference-object-free pseudo projection images not including the reference object image; A positional deviation amount between the projection images is derived based on a component-removed image including the reference object image obtained by removing components of the plurality of reference object-free pseudo projection images from the plurality of projection images. An image processing program that causes a computer to carry out the processing.

Images