Image processing apparatus, image processing method, and image processing program

Abstract

To facilitate diagnostic reading by comparing a composite two dimensional image obtained by tomosynthesis imaging with a two dimensional image captured in the past.SOLUTION: The image processing device 16 includes an CPU60A. The CPU60A acquires a series of plural projected images or plural tomographic images obtained by tomosynthesis imaging of the mamma, calculates a virtually projected position, this being a position where the mamma is virtually projected in tomosynthesis imaging, from the position of the radiation source when the two dimensional image was imaged, and generates a synthesized two dimensional image from the plural projected images or the plural tomographic images based on the virtually projected position.SELECTED DRAWING: Figure 4

Description

[Technical Field]

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

[0002] There is known a technology for generating a radiological image equivalent to a normal two-dimensional image obtained by normal imaging by synthesizing a series of multiple projection images obtained by tomosynthesis imaging performed by irradiating the breast with radiation or multiple tomographic images generated from the series of projection images. For example, Patent Document 1 describes an image processing device that generates multiple synthesized two-dimensional images using different generation methods from multiple tomographic images obtained by tomosynthesis imaging. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7203705 Summary of the Invention [Problem to be solved by the invention]

[0004] When interpreting radiological images, particularly radiological images obtained by mammography, it is sometimes necessary to compare a composite two-dimensional image obtained by tomosynthesis with a two-dimensional image taken previously. However, differences in the position of the radiation source during imaging can change the relative positions of lesions and the overlapping of mammary glands, making interpretation difficult.

[0005] The present disclosure has been made in consideration of the above circumstances, and aims to provide an image processing device, an image processing method, and an image processing program that make it easy to compare and interpret a composite two-dimensional image obtained by tomosynthesis imaging with a two-dimensional image taken in the past. [Means for solving the problem]

[0006] In order to achieve the above object, an image processing device of a first aspect of the present disclosure includes a processor that acquires two-dimensional images captured by irradiating a breast with radiation, acquires the position of a radiation source that emits the radiation when the two-dimensional images were captured, acquires a series of multiple projection images or multiple tomographic images obtained by tomosynthesis imaging of the breast, calculates a virtual projection position, which is a position to virtually project the breast in the tomosynthesis imaging, from the position of the radiation source when the two-dimensional images were captured, and generates a composite two-dimensional image from the multiple projection images or the multiple tomographic images based on the virtual projection position.

[0007] In a second aspect of the image processing device of the present disclosure, in the image processing device of the first aspect, when the processor acquires the plurality of projection images, it generates the plurality of tomographic images from the plurality of projection images based on the virtual projection positions, and then generates the composite two-dimensional image from the plurality of tomographic images.

[0008] An image processing device of a third aspect of the present disclosure is the image processing device of the second aspect, wherein the processor generates the composite two-dimensional image from the plurality of tomographic images based on a projection path from the virtual projection position.

[0009] An image processing device of a fourth aspect of the present disclosure is the image processing device of the second aspect, wherein the processor generates the plurality of tomographic images by correcting the magnification ratio for each of the plurality of projection images centered on the virtual projection position, and generates the composite two-dimensional image by parallel projection of the generated plurality of tomographic images.

[0010] An image processing device of a fifth aspect of the present disclosure is the image processing device of the first aspect, wherein when the processor acquires the multiple tomographic images, the processor generates the composite two-dimensional image by combining the multiple tomographic images based on the virtual projection position.

[0011] An image processing device of a sixth aspect of the present disclosure is the image processing device of the first aspect, wherein the processor acquires the plurality of tomographic images with the magnification ratio corrected around the virtual projection position.

[0012] In a seventh aspect of the image processing device of the present disclosure, in the image processing device of the first aspect, the processor acquires the plurality of tomographic images, and if the plurality of tomographic images have not been corrected for magnification or the centers of magnification correction are at different positions, corrects the magnification of the plurality of tomographic images at the virtual projection position, and generates the composite two-dimensional image by parallel projection onto the corrected plurality of tomographic images.

[0013] An image processing device of an eighth aspect of the present disclosure is the image processing device of the first aspect, wherein the processor further acquires at least one of the position of the breast and the imaging angle of the breast when the two-dimensional image was captured, and calculates the virtual projection position from at least one of the position of the radiation source, the position of the breast, and the imaging angle of the breast when the two-dimensional image was captured.

[0014] An image processing device of a ninth aspect of the present disclosure is the image processing device of the eighth aspect, wherein the processor acquires at least one of the position of the radiation source, the position of the breast, and the imaging angle of the breast when the two-dimensional image was captured from imaging information related to the two-dimensional image.

[0015] An image processing device of a tenth aspect of the present disclosure is the image processing device of the eighth aspect, wherein the processor obtains at least one of the position of the radiation source, the position of the breast, and the imaging angle of the breast when the two-dimensional image was captured by calculating the position of the radiation source, the position of the breast, and the imaging angle of the breast from the two-dimensional image.

[0016] An image processing device of an eleventh aspect of the present disclosure is the image processing device of the first aspect, wherein the virtual projection position is a position in the two-dimensional image that most closely matches the position of the radiation source.

[0017] In a twelfth aspect of the image processing device of the present disclosure, in the image processing device of the first aspect, the processor acquires the two-dimensional image for each of a plurality of comparison objects, and generates the composite two-dimensional image corresponding to the two-dimensional image for each of the plurality of comparison objects.

[0018] An image processing device of a thirteenth aspect of the present disclosure is the image processing device of the first aspect, wherein the two-dimensional image includes at least one of a normal two-dimensional image taken by irradiating the breast with radiation and a composite two-dimensional image obtained from a series of multiple projection images taken by tomosynthesis imaging of the breast.

[0019] In an image processing method of a fourteenth aspect of the present disclosure, a computer executes the following steps: acquiring two-dimensional images captured by irradiating a breast with radiation; acquiring the position of a radiation source emitting the radiation when the two-dimensional images were captured; acquiring a series of multiple projection images or multiple tomographic images obtained by tomosynthesis imaging of the breast; calculating a virtual projection position, which is a position to virtually project the breast in the tomosynthesis imaging, from the position of the radiation source when the two-dimensional images were captured; and generating a composite two-dimensional image from the multiple projection images or the multiple tomographic images based on the virtual projection position.

[0020] An image processing program according to a fifteenth aspect of the present disclosure causes a computer to perform the following processes: acquire two-dimensional images captured by irradiating a breast with radiation; acquire the position of a radiation source emitting the radiation when the two-dimensional images were captured; acquire a series of multiple projection images or multiple tomographic images obtained by tomosynthesis imaging of the breast; calculate a virtual projection position, which is a position to virtually project the breast in the tomosynthesis imaging, from the position of the radiation source when the two-dimensional images were captured; and generate a composite two-dimensional image from the multiple projection images or the multiple tomographic images based on the virtual projection position. [Effects of the Invention]

[0021] According to the present disclosure, it is possible to easily perform image interpretation by comparing a composite two-dimensional image obtained by tomosynthesis imaging with a two-dimensional image captured in the past. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a configuration diagram schematically illustrating an example of the overall configuration of a radiation image capturing system according to an embodiment; [Figure 2] FIG. 1 is a diagram illustrating an example of tomosynthesis imaging. [Figure 3] 1 is a block diagram illustrating an example of a configuration of an image processing apparatus according to an embodiment. [Figure 4] FIG. 1 is a block diagram illustrating an example of a functional configuration of an image processing apparatus according to an embodiment. [Figure 5A] FIG. 2 is a diagram showing an example of an irradiation position of a radiation source and a normal two-dimensional image. [Figure 5B] 10A and 10B are diagrams illustrating a virtual projection position calculation process when the irradiation position of the radiation source is changed. [Figure 5C] 10A and 10B are diagrams illustrating a virtual projection position calculation process when the position of the breast changes. [Figure 5D] 10A and 10B are diagrams illustrating a virtual projection position calculation process when the imaging angle of the breast is changed. [Figure 6] FIG. 10 is a diagram illustrating a magnification ratio. [Figure 7] 10 is a flowchart showing an example of a processing flow by an image processing program according to the embodiment. [Figure 8] 10 is a flowchart showing another example of the flow of processing by the image processing program according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the present disclosure is not limited to the embodiments.

[0024] First, an example of the overall configuration of the radiographic imaging system of this embodiment will be described. Fig. 1 shows a configuration diagram illustrating an example of the overall configuration of the radiographic imaging system 1 of this embodiment. As shown in Fig. 1, the radiographic imaging system 1 of this embodiment includes a mammography apparatus 10, a console 12, a PACS (Picture Archiving and Communication Systems) 14, and an image processing device 16. The console 12, the PACS 14, and the image processing device 16 are connected via a network 17 by wired communication or wireless communication.

[0025] First, the mammography device 10 of this embodiment will be described. Figure 1 shows a side view of an example of the appearance of the mammography device 10 of this embodiment. Note that Figure 1 shows an example of the appearance of the mammography device 10 when viewed from the left side of the subject.

[0026] The mammography device 10 of this embodiment operates under the control of the console 12 and is an apparatus that takes a radiographic image of a subject's breast by irradiating the breast with radiation R (e.g., X-rays) from a radiation source 29. The radiation source 29 is, for example, a tube that irradiates the radiation R. The mammography device 10 of this embodiment has the function of performing normal imaging, in which imaging is performed with the radiation source 29 positioned at an irradiation position normal to the detection surface 20A of the radiation detector 20, and so-called tomosynthesis imaging (described later), in which imaging is performed by moving the radiation source 29 to each of multiple irradiation positions.

[0027] As shown in FIG. 1, the mammography apparatus 10 includes an imaging table 24, a base 26, an arm 28, and a compression unit 32.

[0028] A radiation detector 20 is disposed inside the imaging table 24. As shown in Fig. 2, in the mammography apparatus 10 of this embodiment, when imaging is performed, the breast U of the subject is positioned on the imaging surface 24A of the imaging table 24 by the user.

[0029] The radiation detector 20 detects radiation R that has passed through the subject's breast U. In detail, the radiation detector 20 detects radiation R that has entered the subject's breast U 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, the 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 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 then converts the converted light into electric charges, or a direct conversion type radiation detector that directly converts radiation R into electric charges.

[0030] The compression plate 30 used to compress the breast when imaging is attached to a compression unit 32 provided on the imaging table 24, and is moved toward or away from the imaging table 24 (hereinafter referred to as the "up and down direction") by a compression plate drive unit (not shown) provided on the compression unit 32. By moving in the up and down direction, the compression plate 30 compresses the breast of the subject between itself and the imaging table 24.

[0031] The arm 28 can rotate relative to the base 26 via the shaft 27. The shaft 27 is fixed to the base 26, and the shaft 27 and arm 28 rotate together. The shaft 27 and the compression unit 32 of the imaging table 24 are each provided with a gear, and by switching between an engaged state and a disengaged state of these gears, the compression unit 32 of the imaging table 24 and the shaft 27 can be switched between a state in which they are connected and rotate together, and a state in which the shaft 27 is separated from the imaging table 24 and rotates freely. Note that the switching between transmitting and disengaging power to the shaft 27 is not limited to the gear, and various mechanical elements can be used. The arm 28 and the imaging table 24 can rotate independently relative to the base 26, with the shaft 27 as the rotation axis.

[0032] When performing tomosynthesis imaging in the mammography device 10, the radiation source 29 is moved sequentially to each of a plurality of irradiation positions with different irradiation angles by the rotation of the arm unit 28. 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 paddle 30 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 with irradiation angles that differ by a predetermined angle β. t (t=1, 2, . . . , the maximum value is 7 in FIG. 2), in other words, the radiation detector 20 is moved to a position where the radiation R irradiates the detection surface 20A of the radiation detector 20 at different irradiation angles. t In the radiation imaging system 1, radiation R is irradiated from the radiation source 29 toward the breast U in response to an instruction from the console 12, and a radiation image is captured by the radiation detector 20. t and move to each of the irradiation positions 19 t When tomosynthesis imaging is performed to capture radiographic images, seven radiographic images are obtained in the example shown in Figure 2.

[0033] In tomosynthesis imaging, when describing a radiation image captured at each irradiation position 19 to distinguish it from other radiation images, it is called a "projection image," and multiple projection images captured in one tomosynthesis imaging are called a "series of multiple projection images."

[0034] 2, the irradiation angle of radiation R refers to the angle α formed between a normal CL to the detection surface 20A of the radiation detector 20 and a radiation axis RC. The radiation axis RC is an axis connecting the focal point of the radiation source 29 at each irradiation position 19 and a predetermined position such as the center of the detection surface 20A. Here, the detection surface 20A of the radiation detector 20 is assumed to be a surface that is approximately parallel to the imaging surface 24A.

[0035] On the other hand, when performing normal imaging in the mammography device 10, the radiation source 29 is positioned at the irradiation position 19 where the irradiation angle α is 0 degrees. t(Irradiation position along the normal direction 19 t 2 ), the radiation source 29 irradiates the patient with radiation R, and the radiation detector 20 captures a radiographic image. In this embodiment, a radiographic image captured in normal radiography is referred to as a "normal two-dimensional image" to distinguish it from other radiographic images.

[0036] The mammography device 10 and the console 12 are connected by wired or wireless communication. A radiographic image captured by the radiation detector 20 in the mammography device 10 is output to the console 12 by wired or wireless communication via a communication I / F (Interface) unit (not shown).

[0037] As shown in FIG. 1, the console 12 of this embodiment includes a control unit 40, a storage unit 42, a user I / F unit 44, and a communication I / F unit 46.

[0038] As described above, the control unit 40 of the console 12 has the function of controlling the capture of radiographic images of the breast by the mammography device 10. The control unit 40 may be, for example, a computer system equipped with a CPU (Central Processing Unit), ROM (Read Only Memory), and RAM (Random Access Memory).

[0039] The storage unit 42 has a function of storing information related to radiographic image capture, radiographic images acquired from the mammography apparatus 10, etc. The storage unit 42 is a non-volatile storage unit, such as an HDD (Hard Disk Drive) or an SSD (Solid State Drive).

[0040] The user I / F unit 44 includes input devices such as various buttons and switches operated by users such as technicians in relation to radiographic imaging, and display devices such as lamps and displays that display information about imaging, radiographic images, etc.

[0041] The communication I / F unit 46 communicates various data, such as information related to radiographic image capture and radiographic images obtained by capture, with the mammography apparatus 10 via wired or wireless communication. The communication I / F unit 46 also communicates various data, such as radiographic images, with the PACS 14 and image processing device 16 via the network 17 via wired or wireless communication.

[0042] 1, the PACS 14 of this embodiment includes a storage unit 50 and a communication I / F unit (not shown) that store a radiographic image group 52. The radiographic image group 52 includes radiographic images captured by the mammography device 10 and acquired from the console 12 via the communication I / F unit (not shown).

[0043] The image processing device 16 is used when a doctor or the like (hereinafter simply referred to as "doctor") interprets a radiological image. The image processing device 16 according to this embodiment has a function of generating a composite two-dimensional image from a series of multiple projection images or multiple tomographic images. Multiple tomographic images can be obtained from a series of multiple projection images. Multiple tomographic images are generated by reconstructing a series of multiple projection images using, for example, a simple back projection method, a filtered back projection method, an iterative reconstruction method, or the like. A "composite two-dimensional image" is a pseudo two-dimensional image generated by combining multiple tomographic images. A composite two-dimensional image is generated by combining multiple tomographic images at different distances (height direction positions) from the detection surface 20A of the radiation detector 20 toward the radiation source 29 using, for example, an addition method, an averaging method, a maximum intensity projection method, a minimum intensity projection method, or the like.

[0044] Fig. 3 is a block diagram showing an example of the configuration of the image processing device 16 of this embodiment. As shown in Fig. 3, the image processing device 16 of this embodiment includes a control unit 60, a storage unit 62, a display unit 70, an operation unit 72, and a communication I / F unit 74. The control unit 60, the storage unit 62, the display unit 70, the operation unit 72, and the communication I / F unit 74 are connected via a bus 79 such as a system bus or a control bus so that various information can be exchanged between them.

[0045] The control unit 60 controls the overall operation of the image processing device 16. The control unit 60 includes a CPU 60A, a ROM 60B, and a RAM 60C. The ROM 60B stores various programs and the like for control by the CPU 60A in advance. The RAM 60C temporarily stores various data.

[0046] The storage unit 62 is a non-volatile storage unit, and specific examples include an HDD, an SSD, etc. The storage unit 62 stores an image processing program 62A according to this embodiment.

[0047] The display unit 70 displays radiographic images and various types of information. The display unit 70 is not particularly limited and may be any of various displays. The operation unit 72 is used by the user to input instructions and various types of information for a doctor to diagnose breast lesions using radiographic images. The operation unit 72 is not particularly limited and may be, for example, any of various switches, a touch panel, a touch pen, a mouse, etc. The display unit 70 and the operation unit 72 may be integrated into a touch panel display.

[0048] The communication I / F unit 74 communicates various types of information with the console 12 and the PACS 14 via the network 17 by wireless or wired communication.

[0049] As mentioned above, when interpreting radiological images obtained by mammography, there are cases where the interpretation involves comparing a composite two-dimensional image obtained by tomosynthesis imaging with a two-dimensional image taken previously. However, differences in the position of the radiation source 29 during imaging can change the positional relationship of lesions, the overlapping of mammary glands, and other factors, making interpretation difficult.

[0050] Therefore, the CPU 60A of the image processing device 16 according to this embodiment writes the image processing program 62A stored in the storage unit 25 into the RAM 60C and executes it, thereby functioning as each unit shown in FIG.

[0051] 4 is a block diagram showing an example of the functional configuration of the image processing device 16 according to the embodiment. The CPU 60A of the image processing device 16 according to the present embodiment functions as a first acquisition unit 101, a second acquisition unit 102, a third acquisition unit 103, a calculation unit 104, and a generation unit 105. Note that although the first acquisition unit 101, the second acquisition unit 102, and the third acquisition unit 103 are distinguished for convenience, they may be realized as a single acquisition unit.

[0052] The first acquisition unit 101 acquires two-dimensional images (hereinafter referred to as "past two-dimensional images") captured by irradiating the breast U with radiation R. The past two-dimensional images include at least one of normal two-dimensional images and synthetic two-dimensional images. The normal two-dimensional image is an image captured by irradiating the breast U with radiation R. The synthetic two-dimensional image is an image obtained from a series of multiple projection images captured by tomosynthesis imaging of the breast U. The past two-dimensional images are acquired, for example, from the PACS 14. Furthermore, when there are multiple comparison targets, the first acquisition unit 101 may acquire a past two-dimensional image for each of the multiple comparison targets.

[0053] The second acquisition unit 102 acquires the irradiation position of the radiation source 29 that emits radiation R when the previous two-dimensional image was captured. The second acquisition unit 102 may further acquire at least one of the position of the breast U and the imaging angle of the breast U when the previous two-dimensional image was captured. The second acquisition unit 102 may acquire at least one of the irradiation position of the radiation source 29, the position of the breast U, and the imaging angle of the breast U when the previous two-dimensional image was captured from imaging information related to the previous two-dimensional image, or may acquire the information by calculating it from the previous two-dimensional image. For example, the position of the breast U can be determined from the center of the radiation detector 20 and the position of the center of gravity of the breast U (e.g., nipple, mammary gland, etc.).

[0054] The third acquisition unit 103 acquires a series of multiple projection images or multiple tomographic images. These multiple projection images or multiple tomographic images are images obtained by capturing the breast U by tomosynthesis imaging.

[0055] The calculation unit 104 calculates a virtual projection position in tomosynthesis imaging from the irradiation position of the radiation source 29 when the previous two-dimensional image was captured. Alternatively, the calculation unit 104 may calculate the virtual projection position from at least one of the irradiation position of the radiation source 29 when the previous two-dimensional image was captured, the position of the breast U, and the imaging angle of the breast U. The virtual projection position is a position to which the breast U is virtually projected in tomosynthesis imaging. It is desirable that the virtual projection position is, for example, a position that most closely matches the irradiation position of the radiation source 29 in the previous two-dimensional image.

[0056] The generating unit 105 generates a composite 2D image from the multiple projection images or multiple tomographic images based on the virtual projection position calculated by the calculating unit 104. Furthermore, when a previous 2D image has been acquired for each of the multiple comparison targets, the generating unit 105 may generate a composite 2D image corresponding to the previous 2D image for each of the multiple comparison targets.

[0057] Here, the virtual projection position calculation process according to this embodiment will be specifically described with reference to FIGS. 5A to 5D.

[0058] Fig. 5A is a diagram showing an example of the irradiation position P1 of the radiation source 29 and a normal two-dimensional image 110. Fig. 5B is a diagram explaining the virtual projection position calculation process when the irradiation position of the radiation source 29 changes. Fig. 5C is a diagram explaining the virtual projection position calculation process when the position of the breast U changes. Fig. 5D is a diagram explaining the virtual projection position calculation process when the imaging angle of the breast U changes.

[0059] 5A, the irradiation position P1 of the radiation source 29 is, for example, a position on the normal line CL. A normal two-dimensional image 110 is generated by performing a normal imaging of the breast U. This normal two-dimensional image 110 is an example of the above-mentioned past two-dimensional image.

[0060] As shown in FIG. 5B , assume that irradiation position P1 in the normal two-dimensional image 110 has changed to irradiation position P2 during tomosynthesis imaging, i.e., the reference tube position in tomosynthesis imaging has shifted. In this case, when breast U is imaged from irradiation position P2 of radiation source 29, projection image 111 is generated. Comparing projection image 111 with normal two-dimensional image 110, it is clear that the positional relationship of lesion L has changed. To align the positional relationship of lesion L with the normal two-dimensional image 110, calculation unit 104 calculates a corresponding virtual projection position P3 from irradiation position P1 in normal two-dimensional image 110. Specifically, for example, the difference between irradiation position P1 in normal two-dimensional image 110 and irradiation position P2 in projection image 111 may be calculated, and irradiation position P2 may be corrected based on the calculated difference. The virtual projection position P3 is calculated for each irradiation position in tomosynthesis imaging based on the calculated difference. The virtual projection position P3 is a position where the breast U is virtually projected during tomosynthesis imaging. That is, since tomosynthesis imaging involves successive imaging at multiple irradiation positions, the virtual projection position corresponding to each irradiation position can be calculated by correcting each irradiation position according to the difference. The generation unit 105 generates a composite two-dimensional image 112 from multiple projection images or multiple tomographic images based on the calculated virtual projection position P3.

[0061] As shown in FIG. 5C , assume that the position of the breast U in the normal two-dimensional image 110 has shifted to the left during tomosynthesis imaging, i.e., the position of the breast U has shifted. In this case, when the breast U is imaged from the irradiation position P1 of the radiation source 29, a projection image 113 is generated. Comparing the projection image 113 with the normal two-dimensional image 110, it is clear that the positional relationship of the lesion L has changed. To align the positional relationship of the lesion L with the normal two-dimensional image 110, the calculation unit 104 calculates a corresponding virtual projection position P4 from the position of the breast U in the normal two-dimensional image 110. Specifically, for example, the difference between the position of the breast U in the normal two-dimensional image 110 and the position of the breast U in the projection image 113 may be calculated, and the irradiation position P1 may be corrected based on the calculated difference. The virtual projection position P4 is calculated for each irradiation position during tomosynthesis imaging based on the calculated difference. The virtual projection position P4 is the position to which the breast U is virtually projected during tomosynthesis imaging. The generating unit 105 generates a composite two-dimensional image 114 from a plurality of projection images or a plurality of tomographic images based on the calculated virtual projection position P4.

[0062] As shown in FIG. 5D , assume that the imaging angle of the breast U in the normal two-dimensional image 110 has changed, i.e., the imaging angle of the breast U has shifted. In this case, when the breast U is imaged from the irradiation position P5 of the radiation source 29, a projection image 115 is generated. Comparing the projection image 115 with the normal two-dimensional image 110, it is clear that the positional relationship of the lesion L has changed. To align the positional relationship of the lesion L with the normal two-dimensional image 110, the calculation unit 104 calculates a corresponding virtual projection position P6 from the imaging angle of the breast U in the normal two-dimensional image 110. Specifically, for example, the difference between the imaging angle of the breast U in the normal two-dimensional image 110 and the imaging angle of the breast U in the projection image 115 may be calculated, and the irradiation position P5 may be corrected based on the calculated difference. The virtual projection position P6 is calculated for each irradiation position in tomosynthesis imaging based on the calculated difference. The virtual projection position P6 is the position to which the breast U is virtually projected during tomosynthesis imaging. The generating unit 105 generates a composite two-dimensional image 116 from a plurality of projection images or a plurality of tomographic images based on the calculated virtual projection position P6.

[0063] Next, a case will be described in which projection images are acquired without acquiring tomographic images, and a composite two-dimensional image 112 is generated using a virtual projection position P3 as an example. The third acquisition unit 103 acquires a plurality of projection images. When acquiring a plurality of projection images, the generation unit 105 generates a plurality of tomographic images from the plurality of projection images based on the virtual projection position P3, and then generates the composite two-dimensional image 112 from the plurality of tomographic images.

[0064] Furthermore, the generation unit 105 may generate the composite two-dimensional image 112 from the multiple tomographic images based on the projection path from the virtual projection position P3. That is, the generation unit 105 generates the multiple tomographic images from the multiple projection images without correcting the magnification ratio, and generates the composite two-dimensional image 112 by projecting the multiple tomographic images from the virtual projection position P3.

[0065] FIG. 6 is a diagram illustrating the magnification ratio. The generation unit 105 may generate multiple tomographic images by correcting the magnification ratio for each of the multiple projection images, centered on a virtual projection position P3, and generate a composite two-dimensional image 112 by performing parallel projection on the generated multiple tomographic images. In the example of FIG. 6, the irradiation position P2 of the radiation source 29 is corrected to the corresponding virtual projection position P3. However, the magnification ratio X1 when a cone beam of radiation is irradiated centered on the irradiation position P2 is different from the magnification ratio X2 when a cone beam of radiation is irradiated centered on the virtual projection position P3. Therefore, multiple tomographic images are generated by correcting the magnification ratio X1 to the magnification ratio X2 for each of the multiple projection images.

[0066] Next, a case will be described in which a tomographic image is acquired instead of a projection image, and a composite two-dimensional image 112 is generated using a virtual projection position P3 as an example. The third acquisition unit 103 acquires a plurality of tomographic images. When a plurality of tomographic images are acquired, the generation unit 105 generates the composite two-dimensional image 112 by combining the plurality of tomographic images based on the virtual projection position P3.

[0067] Furthermore, the third acquisition unit 103 may acquire a plurality of tomographic images with the magnification ratio corrected around the virtual projection position P3. In this case, the generation unit 105 generates the composite 2D image 112 by performing parallel projection on the acquired plurality of tomographic images. That is, the magnification ratio of the tomographic image itself may be corrected at a virtual projection position calculated from the previous 2D image, and a composite 2D image may be generated from the tomographic images with the magnification ratio corrected.

[0068] In addition, if the multiple acquired tomographic images have not been corrected for magnification or the centers of magnification correction are at different positions, the generation unit 105 may correct the magnification of the multiple tomographic images at a virtual projection position P3 and generate a composite two-dimensional image 112 by parallel projection onto the corrected multiple tomographic images.

[0069] The image processing device 16 according to this embodiment may also be configured to acquire past two-dimensional images, imaging information including the irradiation position of the radiation source 29, and multiple tomographic images from, for example, the PACS 14. With this configuration, for example, an image viewer can generate a composite two-dimensional image by combining the acquired multiple tomographic images at a virtual projection position, and the past two-dimensional image and the composite two-dimensional image can be compared for interpretation.

[0070] Next, the operation of the image processing device 16 according to this embodiment will be described with reference to FIGS.

[0071] 7 is a flowchart showing an example of the flow of processing by the image processing program 62A according to this embodiment. In FIG. 7, a case where a projection image is acquired without acquiring a tomographic image will be described.

[0072] First, when the image processing device 16 receives an instruction to start image processing, the CPU 60A reads and executes the image processing program 62A.

[0073] 7, CPU 60A acquires a past two-dimensional image from, for example, PACS 14. As described above, the past two-dimensional image may be, for example, a normal two-dimensional image or a composite two-dimensional image.

[0074] In step S102, the CPU 60A acquires the irradiation position of the radiation source 29 when the previous two-dimensional image was captured, for example, from imaging information related to the previous two-dimensional image. The irradiation position of the radiation source 29 may be acquired by calculation from the previous two-dimensional image. Furthermore, at least one of the irradiation position of the radiation source 29, the position of the breast U, and the imaging angle of the breast U may be acquired.

[0075] In step S103, CPU 60A acquires a series of multiple projection images obtained by performing tomosynthesis imaging of breast U as a subject.

[0076] In step S104, CPU 60A calculates a virtual projection position of breast U in tomosynthesis imaging from the irradiation position of radiation source 29 when the previous two-dimensional image was captured. The virtual projection position is a position to which breast U is virtually projected, and is, for example, a position that most closely matches the irradiation position of radiation source 29 in the previous two-dimensional image.

[0077] In step S105, CPU 60A determines whether or not to correct the magnification ratio of each of a series of multiple projected images centered on the virtual projection position. If it is determined that the magnification ratio is to be corrected (if the determination is affirmative), the process proceeds to step S106, and if it is determined that the magnification ratio is not to be corrected (if the determination is negative), the process proceeds to step S108.

[0078] In step S106, CPU 60A corrects the magnification of each of the series of multiple projection images with the virtual projection position as the center, thereby generating multiple tomographic images.

[0079] In step S107, the CPU 60A generates a composite two-dimensional image by parallel projection of the generated plurality of tomographic images, and ends a series of processes by the image processing program 62A.

[0080] On the other hand, in step S108, CPU 60A generates a plurality of tomographic images for each of the series of a plurality of projection images without correcting the magnification ratio.

[0081] In step S109, the CPU 60A generates a composite two-dimensional image by projecting the generated tomographic images from a virtual projection position, and ends a series of processes by the image processing program 62A.

[0082] 8 is a flowchart showing another example of the flow of processing by the image processing program 62A according to this embodiment. In FIG. 8, a case where a tomographic image is acquired instead of a projection image will be described.

[0083] First, when the image processing device 16 receives an instruction to start image processing, the CPU 60A reads and executes the image processing program 62A.

[0084] 8, CPU 60A acquires a past two-dimensional image from, for example, PACS 14. As described above, the past two-dimensional image may be, for example, a normal two-dimensional image or a composite two-dimensional image.

[0085] In step S112, the CPU 60A acquires the irradiation position of the radiation source 29 when the previous two-dimensional image was captured, for example, from imaging information related to the previous two-dimensional image. The irradiation position of the radiation source 29 may be acquired by calculation from the previous two-dimensional image. Furthermore, at least one of the irradiation position of the radiation source 29, the position of the breast U, and the imaging angle of the breast U may be acquired.

[0086] In step S113, CPU 60A acquires a plurality of tomographic images from PACS 14, for example.

[0087] In step S114, CPU 60A calculates a virtual projection position of breast U in tomosynthesis imaging from the irradiation position of radiation source 29 when the previous two-dimensional image was captured. The virtual projection position is a position to which breast U is virtually projected, and is, for example, a position that most closely matches the irradiation position of radiation source 29 in the previous two-dimensional image.

[0088] In step S115, CPU 60A determines whether or not the magnification ratios of the acquired multiple tomographic images have been corrected around the virtual projection position. If it is determined that the magnification ratios have not been corrected (in the case of a negative determination), the process proceeds to step S116, and if it is determined that the magnification ratios have been corrected (in the case of a positive determination), the process proceeds to step S117.

[0089] In step S116, the CPU 60A generates a composite two-dimensional image by projecting the acquired multiple tomographic images from the calculated virtual projection position, and ends a series of processes by the image processing program 62A.

[0090] On the other hand, in step S117, the CPU 60A generates a composite two-dimensional image by performing parallel projection on the acquired multiple tomographic images, and ends a series of processes by the image processing program 62A.

[0091] In addition, if the magnification ratios of the multiple tomographic images acquired in step S113 have not been corrected around the virtual projection position, or if the centers of the magnification ratio corrections are at different positions, the magnification ratios of the multiple tomographic images may be corrected using the virtual projection position calculated in step S114, and a composite two-dimensional image may be generated by parallel projection.

[0092] As described above, according to this embodiment, when the irradiation position of the radiation source during tomosynthesis imaging is shifted relative to a previously captured two-dimensional image, a virtual projection position corrected for the shift in the irradiation position is calculated. Then, based on the calculated virtual projection position, a composite two-dimensional image is generated from a series of multiple projection images or multiple tomographic images obtained by tomosynthesis imaging. Because the irradiation position of the generated composite two-dimensional image has been corrected to match the previous two-dimensional image, it becomes easy to compare the composite two-dimensional image with the previous two-dimensional image for interpretation.

[0093] While one form of the image processing device 16 has been described above using the embodiment, the disclosed form of the image processing device 16 is merely an example, and the form of the image processing device 16 is not limited to the scope described in the embodiment. Various changes or improvements can be made to the embodiment without departing from the gist of the present disclosure, and forms incorporating such changes or improvements are also included in the technical scope of the disclosure.

[0094] In the above embodiment, an example has been described in which the control processing of the image processing device 16 is realized by software processing. However, the control processing of the image processing device 16 may be performed by hardware. In this case, the processing speed can be increased compared to when it is realized by software processing.

[0095] In the above embodiments, the term "processor" refers to a processor in a broad sense, including general-purpose processors (e.g., CPUs) and dedicated processors (e.g., GPUs: Graphics Processing Units, ASICs: Application Specific Integrated Circuits, FPGAs: Field Programmable Gate Arrays, programmable logic devices, etc.).

[0096] Furthermore, the operations of the processors in the above embodiments may not only be performed by a single processor, but may also be performed by multiple processors located at physically separate locations working together. Furthermore, the order of the operations of the processors is not limited to the order described in the above embodiments, and may be changed as appropriate.

[0097] In the above embodiment, an example has been described in which the image processing program 62A is stored in the storage unit 62. However, the storage destination of the image processing program 62A is not limited to the storage unit 62. The image processing program 62A of the present disclosure can also be provided in a form stored in a computer-readable storage medium. It may also be in the form of a computer program product including the image processing program 62A. The present disclosure can be applied to programs and program products.

[0098] For example, the image processing program 62A may be provided in a form stored on an optical disk such as a CD-ROM, a DVD-ROM, or a Blu-ray disc. The image processing program 62A may also be provided in a form stored on a portable semiconductor memory such as a USB (Universal Serial Bus) memory or a memory card. These CD-ROMs, DVD-ROMs, Blu-ray discs, USBs, and memory cards are examples of non-transitory storage media.

[0099] The following additional notes are provided regarding the above-described embodiments.

[0100] (Appendix 1) a processor; The processor: Radiation is applied to the breast to obtain two-dimensional images. acquiring a position of a radiation source that emits the radiation when the two-dimensional image is captured; obtaining a series of projection images or tomographic images of the breast by tomosynthesis imaging; calculating a virtual projection position, which is a position where the breast is virtually projected in the tomosynthesis imaging, from the position of the radiation source when the two-dimensional image is captured; generating a composite two-dimensional image from the plurality of projection images or the plurality of tomographic images based on the virtual projection positions; Image processing device. (Appendix 2) When acquiring the plurality of projection images, the processor generates the plurality of tomographic images from the plurality of projection images based on the virtual projection positions, and then generates the composite two-dimensional image from the plurality of tomographic images. 2. The image processing device according to claim 1. (Appendix 3) the processor generates the composite two-dimensional image from the plurality of tomographic images based on a projection path from the virtual projection position. 3. The image processing device according to claim 2. (Appendix 4) the processor generates the plurality of tomographic images by correcting a magnification ratio for each of the plurality of projection images around the virtual projection position; generating the composite two-dimensional image by performing parallel projection on the generated plurality of tomographic images; 3. The image processing device according to claim 2. (Appendix 5) When acquiring the plurality of tomographic images, the processor generates the composite two-dimensional image by combining the plurality of tomographic images based on the virtual projection position. 2. The image processing device according to claim 1. (Appendix 6) the processor acquires the plurality of tomographic images with the magnification ratio corrected around the virtual projection position; 2. The image processing device according to claim 1. (Appendix 7) The processor acquires the plurality of tomographic images, and if the plurality of tomographic images have not been subjected to magnification correction or the centers of magnification correction are at different positions, corrects the magnification of the plurality of tomographic images at the virtual projection position; generating the composite two-dimensional image by performing parallel projection on the corrected multiple tomographic images; 2. The image processing device according to claim 1. (Appendix 8) The processor further acquires at least one of a position of the breast and an imaging angle of the breast when the two-dimensional image is captured; calculating the virtual projection position from at least one of the position of the radiation source, the position of the breast, and the imaging angle of the breast when the two-dimensional image was captured; 8. The image processing device according to any one of Supplementary Note 1 to Supplementary Note 7. (Appendix 9) the processor acquires at least one of a position of the radiation source, a position of the breast, and an imaging angle of the breast when the two-dimensional image was captured from imaging information related to the two-dimensional image; 9. The image processing device according to claim 8. (Appendix 10) the processor calculates at least one of the position of the radiation source, the position of the breast, and the imaging angle of the breast when the two-dimensional image was captured from the two-dimensional image; 9. The image processing device according to claim 8. (Appendix 11) the virtual projection position is a position in the two-dimensional image that most closely matches the position of the radiation source; 11. The image processing device according to claim 1. (Appendix 12) The processor acquires the two-dimensional image for each of a plurality of comparison objects; generating a composite two-dimensional image corresponding to the two-dimensional image for each of the plurality of comparison objects; 12. The image processing device according to claim 1. (Appendix 13) The two-dimensional image includes at least one of a normal two-dimensional image taken by irradiating the breast with radiation and a composite two-dimensional image obtained from a series of multiple projection images taken by tomosynthesis imaging of the breast. 13. The image processing device according to claim 1. (Appendix 14) Radiation is applied to the breast to obtain two-dimensional images. acquiring a position of a radiation source that emits the radiation when the two-dimensional image is captured; obtaining a series of projection images or tomographic images of the breast by tomosynthesis imaging; calculating a virtual projection position, which is a position where the breast is virtually projected in the tomosynthesis imaging, from the position of the radiation source when the two-dimensional image is captured; generating a composite two-dimensional image from the plurality of projection images or the plurality of tomographic images based on the virtual projection positions; A computer-implemented image processing method. (Appendix 15) Radiation is applied to the breast to obtain two-dimensional images. acquiring a position of a radiation source that emits the radiation when the two-dimensional image is captured; obtaining a series of projection images or tomographic images of the breast by tomosynthesis imaging; calculating a virtual projection position, which is a position where the breast is virtually projected in the tomosynthesis imaging, from the position of the radiation source when the two-dimensional image is captured; generating a composite two-dimensional image from the plurality of projection images or the plurality of tomographic images based on the virtual projection positions; An image processing program to be executed by a computer. [Explanation of symbols]

[0101] 1. Radiography system 10 Mammography equipment 12 Console 14 PACS 16 Image processing device 17 Network 191-197, 19 t Irradiation position 20 Radiation detector, 20A detection surface 24 imaging table, 24A imaging surface 26 Foundation 27 Shaft 28 Arm section 29 Radiation source 30 Compression Plate 32 Compression Unit 40, 60 Control unit 42, 50, 62 storage section 44 User I / F section 46, 74 Communication I / F section 52 Radiography images 60A CPU, 60B ROM, 60C RAM 62A Image Processing Program 70 Display section 72 Control section 79 Bus 101 First acquisition part 102 Second acquisition part 103 Third acquisition part 104 Calculation Unit 105 Generation part 110 Normal 2D image 111, 113, 115 Projected images 112, 114, 116 Composite 2D images

Claims

1. a processor; The processor: Radiation is applied to the breast to obtain two-dimensional images. acquiring a position of a radiation source that emits the radiation when the two-dimensional image is captured; obtaining a series of projection images or tomographic images of the breast by tomosynthesis imaging; calculating a virtual projection position, which is a position to virtually project the breast during the tomosynthesis imaging, from the position of the radiation source when the two-dimensional image was captured; generating a composite two-dimensional image from the plurality of projection images or the plurality of tomographic images based on the virtual projection positions; Image processing device.

2. When acquiring the plurality of projection images, the processor generates the plurality of tomographic images from the plurality of projection images based on the virtual projection positions, and then generates the composite two-dimensional image from the plurality of tomographic images. The image processing device according to claim 1 .

3. the processor generates the composite two-dimensional image from the plurality of tomographic images based on a projection path from the virtual projection position. The image processing device according to claim 2 .

4. the processor generates the plurality of tomographic images by correcting a magnification ratio for each of the plurality of projection images around the virtual projection position; generating the composite two-dimensional image by performing parallel projection on the generated plurality of tomographic images; The image processing device according to claim 2 .

5. When acquiring the plurality of tomographic images, the processor generates the composite two-dimensional image by combining the plurality of tomographic images based on the virtual projection position. The image processing device according to claim 1 .

6. the processor acquires the plurality of tomographic images with the magnification ratio corrected around the virtual projection position; The image processing device according to claim 1 .

7. The processor acquires the plurality of tomographic images, and if the plurality of tomographic images have not been subjected to magnification correction or the centers of magnification correction are at different positions, corrects the magnification of the plurality of tomographic images at the virtual projection position; generating the composite two-dimensional image by performing parallel projection on the corrected tomographic images; The image processing device according to claim 1 .

8. The processor further acquires at least one of a position of the breast and an imaging angle of the breast when the two-dimensional image is captured; calculating the virtual projection position from at least one of the position of the radiation source, the position of the breast, and the imaging angle of the breast when the two-dimensional image was captured; The image processing device according to claim 1 .

9. the processor acquires at least one of a position of the radiation source, a position of the breast, and an imaging angle of the breast when the two-dimensional image is captured from imaging information related to the two-dimensional image; The image processing device according to claim 8 .

10. the processor calculates at least one of the position of the radiation source, the position of the breast, and the imaging angle of the breast when the two-dimensional image was captured from the two-dimensional image; The image processing device according to claim 8 .

11. the virtual projection position is a position in the two-dimensional image that most closely matches the position of the radiation source; The image processing device according to claim 1 .

12. The processor acquires the two-dimensional image for each of a plurality of comparison objects; generating a composite two-dimensional image corresponding to the two-dimensional image for each of the plurality of comparison objects; The image processing device according to claim 1 .

13. The two-dimensional image includes at least one of a normal two-dimensional image captured by irradiating the breast with radiation and a composite two-dimensional image obtained from a series of multiple projection images captured by tomosynthesis imaging of the breast. The image processing device according to claim 1 .

14. Radiation is applied to the breast to obtain two-dimensional images. acquiring a position of a radiation source that emits the radiation when the two-dimensional image is captured; obtaining a series of projection images or tomographic images of the breast by tomosynthesis imaging; calculating a virtual projection position, which is a position to virtually project the breast during the tomosynthesis imaging, from the position of the radiation source when the two-dimensional image was captured; generating a composite two-dimensional image from the plurality of projection images or the plurality of tomographic images based on the virtual projection positions; A computer-implemented image processing method.

15. Radiation is applied to the breast to obtain two-dimensional images. acquiring a position of a radiation source that emits the radiation when the two-dimensional image is captured; obtaining a series of projection images or tomographic images of the breast by tomosynthesis imaging; calculating a virtual projection position, which is a position to virtually project the breast during the tomosynthesis imaging, from the position of the radiation source when the two-dimensional image was captured; generating a composite two-dimensional image from the plurality of projection images or the plurality of tomographic images based on the virtual projection positions; An image processing program to be executed by a computer.

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