Image processing device, image processing method, and image processing program

Abstract

A CPU in this image-processing device acquires: a low-energy image captured by a mammography device while irradiating a breast into which a contrast agent has been injected with radiation having a first energy; and a high-energy image captured by the mammography device while irradiating the breast into which the contrast agent has been injected with radiation having a second energy higher than the first energy. The CPU generates a differential image expressing differences between the low-energy image and the high-energy image. The CPU performs image processing to enhance the differential image. CPU displays the differential image after image processing and contrast amount information about the contrast amount of the differential image before image processing.

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] A contrast imaging technique is used to capture low-energy and high-energy images of a subject injected with a contrast agent by irradiating the subject with radiation of different energies, and then generate a difference image showing the difference between the high-energy and low-energy images. The difference image thus generated is an image in which the subject's body tissue is removed and the contrast agent is clearly visible.

[0003] Furthermore, a technique for enhancing a subtraction image to make it easier to observe a contrast agent in the subtraction image is known. For example, Japanese Patent Application Laid-Open No. 2015-091394 describes a technique for enhancing the contrast of a region of interest. Summary of the Invention [Problem to be solved by the invention]

[0004] The pixel values ​​of pixels in the difference image correspond to the amount of contrast. However, if contrast is enhanced by image processing, the pixel values ​​of pixels in the difference image after the image processing may not correspond to the amount of contrast. Therefore, it may be difficult to determine the actual amount of contrast from the difference image after the image processing.

[0005] The present disclosure has been made in consideration of the above circumstances, and provides an image processing device, an image processing method, and an image processing program that make it easy to observe a contrast agent and to easily evaluate the amount of contrast. [Means for solving the problem]

[0006] An image processing device of a first aspect of the present disclosure includes at least one processor, which acquires a low-energy image captured by a radiographic imaging device by irradiating a subject into which a contrast agent has been injected with radiation of a first energy, and a high-energy image captured by a radiographic imaging device by irradiating a subject into which a contrast agent has been injected with radiation of a second energy higher than the first energy, generates a difference image showing the difference between the low-energy image and the high-energy image, performs image processing to enhance the difference image, and displays the difference image after the image processing and contrast amount information regarding the contrast amount of the difference image before the image processing.

[0007] An image processing device according to a second aspect of the present disclosure is the image processing device according to the first aspect, wherein the contrast amount information is a numerical value representing the contrast amount.

[0008] An image processing device of a third aspect of the present disclosure is the image processing device of the first aspect, wherein the contrast amount information is a heat map of the contrast amount, and the processor displays the heat map superimposed on a difference image after image processing.

[0009] An image processing device according to a fourth aspect of the present disclosure is the image processing device according to the first aspect, wherein the contrast amount information is a difference image before image processing.

[0010] An image processing device according to a fifth aspect of the present disclosure is the image processing device according to any one of the first to fourth aspects, wherein the processor derives contrast amount information from a difference image before image processing.

[0011] An image processing device of a sixth aspect of the present disclosure is an image processing device of any one of the first to fourth aspects, wherein the processor derives contrast amount information from information regarding the contrast amount derived from a difference image after image processing by excluding the influence of the image processing.

[0012] An image processing device of a seventh aspect of the present disclosure is an image processing device of any one of the first to sixth aspects, in which a processor causes a radiological imaging device to capture multiple high-energy images, acquires the captured multiple high-energy images, and generates a difference image for each of the multiple high-energy images.

[0013] An image processing device of an eighth aspect of the present disclosure is an image processing device of any one of the first to sixth aspects, wherein the radiation image capturing device is capable of tomosynthesis imaging in which radiation is irradiated onto a subject from each of a plurality of different irradiation angles to capture low-energy images and high-energy images for each of the plurality of irradiation angles, and the processor generates a difference image showing the difference between a low-energy tomographic image generated by reconstructing the plurality of low-energy images and a high-energy tomographic image generated by reconstructing the plurality of high-energy images.

[0014] An image processing device of a ninth aspect of the present disclosure is an image processing device of any one of the first to sixth aspects, wherein the radiographic imaging device is capable of tomosynthesis imaging in which radiation is irradiated onto a subject from each of a plurality of different irradiation angles and a low-energy image and a high-energy image are captured as a pair of projection images for each of the plurality of irradiation angles, and the processor generates a projection difference image showing the difference between the pair of projection images for each irradiation angle, and generates a tomographic image reconstructed from the generated plurality of projection difference images as a difference image.

[0015] An image processing device of a tenth aspect of the present disclosure is an image processing device of the eighth or ninth aspect, in which a processor derives the length of a region of interest in the transmission direction in which radiation passes from a tomographic image, and derives the density of the contrast agent in the region of interest as contrast amount information based on the derived length of the region of interest.

[0016] An image processing device according to an eleventh aspect of the present disclosure is the image processing device according to any one of the first to tenth aspects, wherein the subject is a breast, and the radiation image capturing device is a mammography device.

[0017] In addition, an image processing method of a twelfth aspect of the present disclosure is a method for a computer to execute a process of acquiring a low-energy image captured by a radiographic imaging device by irradiating a subject into which a contrast agent has been injected with radiation of a first energy, and a high-energy image captured by a radiographic imaging device by irradiating a subject into which a contrast agent has been injected with radiation of a second energy higher than the first energy, generating a difference image showing the difference between the low-energy image and the high-energy image, performing image processing to enhance the difference image, and displaying the difference image after the image processing and contrast amount information regarding the contrast amount of the difference image before the image processing.

[0018] In addition, an image processing program of a thirteenth aspect of the present disclosure is configured to cause a computer to execute a process of acquiring a low-energy image captured by a radiographic imaging device by irradiating a subject into which a contrast agent has been injected with radiation of a first energy, and a high-energy image captured by a radiographic imaging device by irradiating a subject into which a contrast agent has been injected with radiation of a second energy higher than the first energy, generating a difference image showing the difference between the low-energy image and the high-energy image, performing image processing to enhance the difference image, and displaying the difference image after the image processing and contrast amount information regarding the contrast amount of the difference image before the image processing. [Effects of the Invention]

[0019] According to the present disclosure, the contrast agent can be easily observed and the amount of contrast can be easily evaluated. [Brief explanation of the drawings]

[0020] [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 2A] 1 is a side view showing an example of the appearance of a mammography apparatus according to an embodiment. [Figure 2B] FIG. 1 is a diagram illustrating an example of tomosynthesis imaging. [Figure 3] FIG. 2 is a block diagram illustrating an example of a configuration of a console according to an embodiment. [Figure 4] FIG. 2 is a functional block diagram illustrating an example of functions of a console according to an embodiment. [Figure 5] 10 is a time chart showing an example of the timing of capturing low-energy images and high-energy images in contrast imaging and time-series imaging using the mammography apparatus of the embodiment. [Figure 6] 10 is a time chart showing an example of the timing of capturing low-energy images and high-energy images in contrast imaging and tomosynthesis imaging using the mammography apparatus of the embodiment. [Figure 7A] 10A and 10B are diagrams for explaining an example of a method for generating difference images in time-series imaging. [Figure 7B] 10A and 10B are diagrams for explaining another example of a method for generating difference images in time-series imaging. [Figure 8] 10A and 10B are diagrams for explaining an example of a method for generating a difference image and a tomographic image in tomosynthesis imaging. [Figure 9] 10 is a flowchart showing an example of a flow of contrast imaging performed by the radiation image capturing system of the embodiment. [Figure 10] 10 is a flowchart illustrating an example of the flow of a radiographic image capturing process executed in contrast imaging. [Figure 11A] 10 is a flowchart illustrating an example of the flow of a single-shot imaging process executed in the radiation image imaging process. [Figure 11B] 10 is a flowchart illustrating an example of the flow of a time-series imaging process executed in a radiation image imaging process. [Figure 11C] 10 is a flowchart illustrating an example of the flow of tomosynthesis imaging processing executed in the radiation image imaging processing. [Figure 12] 10 is a flowchart illustrating an example of the flow of a subtraction image generation and display process executed in contrast imaging. [Figure 13A] 10A and 10B are diagrams for explaining a form of deriving a numerical value representing a contrast amount as contrast amount information from a tomographic image. [Figure 13B]10A and 10B are diagrams for explaining a form of deriving a numerical value representing a contrast amount as contrast amount information from a tomographic image. [Figure 14A] 10A and 10B are diagrams showing an example of a state in which a difference image before image processing and a difference image after image processing are displayed on a display unit as contrast amount information. [Figure 14B] 10A and 10B are diagrams showing an example of a state in which a heat map and a difference image after image processing are displayed on a display unit as contrast amount information. [Figure 14C] 10 is a diagram showing another example of a state in which a heat map and a difference image after image processing are displayed on the display unit as contrast amount information. FIG. [Figure 14D] FIG. 10 is a diagram showing an example of a state in which a numerical value representing a contrast amount is displayed as contrast amount information. [Figure 15] 10A to 10C are diagrams for explaining another example of a method for generating a difference image and a tomographic image in tomosynthesis imaging. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings, but the present invention is not limited to the embodiment.

[0022] 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 device 10 and a console 12. The mammography device 10 of this embodiment is an example of the radiographic imaging device of the present disclosure. Furthermore, the console 12 of this embodiment is an example of the image processing device of the present disclosure.

[0023] First, the mammography device 10 of this embodiment will be described. Fig. 2A shows a side view illustrating an example of the appearance of the mammography device 10 of this embodiment. Fig. 2A also shows an example of the appearance of the mammography device 10 when viewed from the right side of the subject.

[0024] The mammography device 10 of this embodiment is a device that takes a radiographic image of a subject's breast by irradiating the breast with radiation R (e.g., X-rays). Note that the mammography device 10 may be a device that takes images 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).

[0025] The mammography device 10 of this embodiment has the function of performing two types of imaging: so-called contrast imaging, in which imaging is performed after a contrast agent is injected into the subject's breast, and general imaging. In this embodiment, imaging performed after a contrast agent is injected into the subject's breast is referred to as "contrast imaging," and imaging other than contrast imaging is referred to as "general imaging." The mammography device 10 of this embodiment also has the function of performing general imaging, in which imaging is performed by positioning the radiation source at an irradiation position normal to the detection surface 28A of the radiation detector, and so-called tomosynthesis imaging, in which imaging is performed by moving the radiation source 37R to each of multiple irradiation positions. The mammography device 10 is capable of both contrast imaging and general imaging in both general imaging and tomosynthesis.

[0026] As shown in FIG. 2A, the mammography apparatus 10 of this embodiment includes a control unit 20, a memory unit 22, and an I / F (Interface) unit 24 within the imaging table 30. The control unit 20 controls the overall operation of the mammography apparatus 10 under the control of the console 12. The control unit 20 includes a CPU (Central Processing Unit), ROM (Read Only Memory), and RAM (Random Access Memory), all of which are not shown. The ROM stores in advance various programs, including an imaging processing program executed by the CPU for controlling the imaging of radiographic images. The RAM temporarily stores various data.

[0027] The memory unit 22 stores image data of radiographic images captured by the radiation detector 28, as well as various other information. Specific examples of the memory unit 22 include a hard disk drive (HDD) and a solid state drive (SSD). The I / F unit 24 communicates various information with the console 12 via wireless or wired communication. Image data of radiographic images captured by the radiation detector 28 in the mammography apparatus 10 is transmitted to the console 12 via the I / F unit 24 via wireless or wired communication.

[0028] The operation unit 26 is provided as a plurality of switches on the imaging table 30 of the mammography apparatus 10. The operation unit 26 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.

[0029] The radiation detector 28 detects radiation R that has passed through the breast, which is the subject. As shown in Fig. 2A, the radiation detector 28 is disposed inside the imaging table 30. When imaging is performed in the mammography apparatus 10 of this embodiment, the breast of the subject is positioned on the imaging surface 30A of the imaging table 30 by the user.

[0030] The radiation detector 28 detects radiation R that has passed through the subject's breast and the imaging table 30, generates a radiographic image based on the detected radiation R, and outputs image data representing the generated radiographic image. The type of radiation detector 28 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.

[0031] The radiation irradiator 37 includes a radiation source 37R. As shown in Fig. 2A, the radiation irradiator 37 is provided on the arm 32 together with the imaging table 30 and the compression unit 36. As shown in Fig. 2A, a face guard 38 is detachably provided on the arm 32 below the radiation irradiator 37 at a position close to the subject. The face guard 38 is a protective member for protecting the subject from radiation R emitted from the radiation source 37R.

[0032] As shown in Figure 2A, the mammography apparatus 10 of this embodiment includes an arm unit 32, a base 34, and a shaft unit 35. The arm unit 32 is held by the base 34 so that it can move up and down (in the Z-axis direction). The shaft unit 35 also allows the arm unit 32 to rotate relative to the base 34. The shaft unit 35 is fixed to the base 34, and the shaft unit 35 and the arm unit 32 rotate together.

[0033] The shaft 35 and the compression unit 36 ​​are each provided with a gear, 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 ​​and the shaft 35 are connected and rotate together, and a state in which the shaft 35 is separated from the compression unit 36 ​​and the imaging table 30 and rotates freely. Note that the switching between transmitting and non-transmitting power to the shaft 35 is not limited to the gear, and various mechanical elements can be used.

[0034] The arm 32, the imaging table 30, and the compression unit 36 ​​are independently rotatable relative to the base 34, with the shaft 35 serving as a rotation axis. In this embodiment, the base 34, the arm 32, the imaging table 30, and the compression unit 36 ​​are each provided with an engagement portion (not shown), and by switching the state of this engagement portion, the arm 32, the imaging table 30, and the compression unit 36 ​​are each connected to the base 34. One or both of the arm 32, the imaging table 30, and the compression unit 36 ​​connected to the shaft 35 rotate together around the shaft 35.

[0035] The compression unit 36 ​​is provided with a compression plate driver (not shown) that moves the compression plate 40 in the vertical direction (Z-axis direction). The compression plate 40 of this embodiment has the function of compressing the breast of the subject. The support part 46 of the compression plate 40 is detachably attached to the compression plate driver and is moved in the vertical direction (Z-axis direction) by the compression plate driver, compressing the breast of the subject between it and the imaging table 30.

[0036] When performing tomosynthesis imaging in the mammography device 10, the radiation source 37R of the radiation irradiation unit 37 is moved successively to each of a plurality of irradiation positions with different irradiation angles by the rotation of the arm unit 32. FIG. 2B shows a diagram for explaining an example of tomosynthesis imaging. Note that the compression paddle 40 is not shown in FIG. 2B. In this embodiment, as shown in FIG. 2B, the radiation source 37R is moved to irradiation positions 39 with irradiation angles that differ in increments of a predetermined angle θ. k (k=0, 1, . . . K, K=5 in FIG. 2B ). In other words, the radiation detector 28 is moved to a position where the angle of incidence of the radiation R on the detection surface 28A of the radiation detector 28 is different. k In the tomosynthesis imaging, radiation R is irradiated from the radiation source 37R toward the breast W in response to an instruction from the console 12, and a radiographic image is captured by the radiation detector 28. In the following description, in tomosynthesis imaging, a plurality of irradiation positions 39 with different irradiation angles are used. k In the radiation image capturing system 1, the radiation source 37R is positioned at the irradiation position 39. k and move it to each irradiation position 39 k When tomosynthesis imaging is performed to capture projection images at K, K projection images are obtained. Note that, hereinafter, when multiple types of radiation images, such as projection images and the low-energy and high-energy images described below, are collectively referred to as "radiation images."

[0037] As shown in FIG. 2B, the incidence angle of radiation R refers to the angle α formed between the normal CL of the detection surface 28A of the radiation detector 28 and the radiation axis RC. Here, the detection surface 28A of the radiation detector 28 is assumed to be a surface that is approximately parallel to the imaging surface 30A. Hereinafter, as shown in FIG. 2B, the predetermined range within which the incidence angle is varied in tomosynthesis imaging will be referred to as the "incident angle range." Specific examples of the incidence angle range include a range of ±10 degrees or ±20 degrees with respect to the normal CL of the detection surface 28A of the radiation detector 28. In this embodiment, the "incident angle" and "irradiation angle" are synonymous with each other for the radiation R.

[0038] On the other hand, when performing normal imaging in the mammography device 10, the radiation source 37R of the radiation irradiation unit 37 is positioned at the irradiation position 39 where the irradiation angle α is 0 degrees. k (Irradiation position along the normal direction 39 k 2B), the radiation source 37R irradiates the patient with radiation R, and the radiation detector 28 captures a radiological image.

[0039] On the other hand, the console 12 of this embodiment has the function of controlling the mammography device 10 using imaging orders and various information obtained from a RIS (Radiology Information System) 2, etc. via a wireless communication LAN (Local Area Network), etc., and instructions given by the user via an operation unit 56, etc.

[0040] 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 via a bus 59 such as a system bus or a control bus so as to be able to exchange various information with each other.

[0041] 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 in advance various programs, including an imaging control processing program 51A and an image processing program 51B (described later), which are executed by the CPU 50A. The RAM 50C temporarily stores various data. The CPU 50A of this embodiment is an example of a processor of the present disclosure. The image processing program 51B of this embodiment is an example of an image processing program of the present disclosure.

[0042] The storage unit 52 stores image data of radiographic images captured by the mammography apparatus 10, as well as various other information. Specific examples of the storage unit 52 include an HDD and an SSD.

[0043] 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 one unit to form a touch panel display.

[0044] The I / F unit 54 communicates various types of information between the mammography apparatus 10 and the RIS 2 via wireless or wired communication. The console 12 of this embodiment receives image data of a radiographic image captured by the mammography apparatus 10 from the mammography apparatus 10 via the I / F unit 54 via wireless or wired communication.

[0045] 4 shows a functional block diagram of an example of the configuration of the console 12 of this embodiment. As shown in Fig. 4, the console 12 includes a control unit 60. As an example, in the console 12 of this embodiment, a CPU 50A of the control unit 50 executes a shooting control processing program 51A stored in a ROM 50B, whereby the CPU 50A functions as the control unit 60.

[0046] The control unit 60 has a function to control contrast imaging, specifically, a function to control the irradiation of radiation R during contrast imaging by the mammography apparatus 10. In this embodiment, when contrast imaging is performed, radiation of a first energy is irradiated from the radiation source 37R onto the breast in which a contrast agent has been injected, thereby capturing a radiographic image. Furthermore, radiation of a second energy higher than the first energy is irradiated from the radiation source 37R onto the breast in which a contrast agent has been injected, thereby capturing a radiographic image. In this embodiment, a radiographic image captured by irradiating the breast with radiation R of the first energy is referred to as a "low-energy image," and a radiographic image captured by irradiating the breast with radiation R of the second energy is referred to as a "high-energy image."

[0047] For example, an iodine contrast agent with a k-absorption edge of 32 keV is commonly used as a contrast agent for contrast imaging. In this case, low-energy images are captured by irradiating the subject with radiation R of a first energy lower than the k-absorption edge of the iodine contrast agent. High-energy images are captured by irradiating the subject with radiation R of a second energy higher than the k-absorption edge of the iodine contrast agent.

[0048] Therefore, in contrast imaging, the control unit 60 of this embodiment controls the radiation source 37R to emit radiation R of a first energy and radiation R of a second energy. In other words, the control unit 60 controls the mammography apparatus 10 to capture low-energy images and high-energy images.

[0049] Body tissues such as mammary glands and contrast agents have different radiation absorption characteristics. Therefore, the high-energy image captured as described above clearly shows the contrast agent in addition to body tissues such as mammary glands and fat. On the other hand, the low-energy image shows almost no contrast agent and clearly shows body tissues such as mammary glands. Therefore, a difference image showing the difference between the low-energy image and the high-energy image can be an image in which the mammary gland structure has been removed and the contrast agent is clearly shown.

[0050] Furthermore, as described above, in contrast imaging using the mammography apparatus 10 of this embodiment, either normal imaging or tomosynthesis imaging is performed. Normal imaging in contrast imaging can be of two types: single-shot imaging and time-series imaging. In single-shot imaging, both low-energy and high-energy images are captured only once.

[0051] On the other hand, time-series imaging captures low-energy images and multiple high-energy images to capture changes in the penetration of contrast agents into the breast over time. For example, lesions such as tumors are more susceptible to contrast agent penetration than mammary glands, and the more malignant the lesion, the faster the contrast agent penetrates and tends to wash out. Therefore, time-series imaging enables observation of the time change in the penetration of contrast agents into a region of interest such as a lesion and the amount of penetration (contrast amount) using multiple subtraction images obtained in time series.

[0052] In this embodiment, to obtain multiple difference images, high-energy images are captured every predetermined time, such as one second, after capturing low-energy images. As described above, to observe the temporal change in contrast enhancement in the region of interest, high-energy images that clearly show the contrast agent must be captured in accordance with the temporal change. On the other hand, if body movement is not taken into consideration, the temporal change in the state of the mammary gland structure, particularly during the imaging time for contrast enhancement, is slight, so low-energy images do not need to be captured as frequently as high-energy images. Therefore, in the time-series imaging performed by the mammography device 10 of this embodiment, low-energy images are captured once. Note that, because the state of the mammary gland structure may change due to the subject's body movement, low-energy images may be captured multiple times.

[0053] Figure 5 shows an example of the timing of capturing low-energy image 70L and high-energy image 70H during contrast imaging and time-series imaging. In the example shown in Figure 5, when contrast imaging begins, low-energy image 70L (see 70L1 in Figure 5) is captured first, and then high-energy images 70H (see 70H1 to 70H4 in Figure 5) are captured every predetermined time until the contrast imaging time ends. In this way, with the mammography device 10 of this embodiment, when contrast imaging and time-series imaging are performed, one low-energy image 70L and multiple high-energy images 70H are captured.

[0054] In the case of contrast imaging and tomosynthesis imaging in the mammography apparatus 10 of this embodiment, the irradiation position 39 of the radiation R k In each imaging session, low-energy images and high-energy images are acquired as projection images. Hereinafter, when a low-energy image that is a projection image is to be distinguished from a low-energy image acquired in another imaging session, it is referred to as a "low-energy projection image." Similarly, when a high-energy image that is a projection image is to be distinguished from a high-energy image acquired in another imaging session, it is referred to as a "high-energy projection image."

[0055] 6 shows an example of the timing of capturing a low-energy projection image 71L and a high-energy projection image 71H in contrast imaging and tomosynthesis imaging. k For each mammography, low-energy projection image 71L (see 71L1 to 71L5 in FIG. 6) and high-energy projection image 71H (see 71H1 to 71H5 in FIG. 6) are captured as projection images. k The same number of low-energy projection images 71L and high-energy projection images 71H as the number of the low-energy projection images 71L and high-energy projection images 71H are taken.

[0056] The console 12 of this embodiment also includes an acquisition unit 62, a generation unit 64, a derivation unit 66, an image processing unit 68, and a display control unit 69. As an example, in the console 12 of this embodiment, the CPU 50A of the control unit 50 executes an image processing program 51B stored in the ROM 50B, so that the CPU 50A functions as the acquisition unit 62, the generation unit 64, the derivation unit 66, the image processing unit 68, and the display control unit 69.

[0057] The acquisition unit 62 has the function of acquiring low-energy images and high-energy images captured by the mammography device 10. Specifically, it acquires image data representing low-energy images and high-energy images captured by the radiation detector 28 of the mammography device 10 via the I / F unit 24 and the I / F unit 54. The acquisition unit 62 outputs the acquired low-energy images and high-energy images to the generation unit 64.

[0058] In the case of single-shot imaging, the acquisition unit 62 acquires one low-energy image and one high-energy image. In the case of time-series imaging, the acquisition unit 62 acquires one low-energy image and multiple high-energy images. In the case of tomosynthesis imaging, the acquisition unit 62 acquires multiple low-energy images as projection images and multiple high-energy images as projection images.

[0059] The generation unit 64 has a function of generating a plurality of difference images showing the differences between a low-energy image and each of a plurality of high-energy images. In the case of single-shot imaging, the generation unit 64 generates a difference image between one low-energy image and one high-energy image. Therefore, in the case of single-shot imaging, the generation unit 64 generates one difference image.

[0060] In this embodiment, as an example, a difference image is generated by deriving the difference between the low-energy image and each high-energy image. Specifically, the generation unit 64 subtracts, for each corresponding pixel, image data obtained by multiplying the low-energy image 70L by a predetermined coefficient from image data obtained by multiplying the high-energy image 70H by a predetermined coefficient, thereby removing mammary gland tissue and generating difference image data representing a difference image in which the contrast agent is clearly visible. In the case of single-shot imaging, the generation unit 64 outputs image data representing the generated difference image to the derivation unit 66 and the image processing unit 68.

[0061] In addition, in the case of time-series imaging, the generation unit 64 generates difference images between one low-energy image and each of multiple high-energy images. As an example, in this embodiment, as shown in FIG. 7A , the generation unit 64 generates a difference image 721 between the low-energy image 70L1 and the high-energy image 70H1, as in the case of single-shot imaging. The generation unit 64 also generates a difference image 722 between the low-energy image 70L1 and the high-energy image 70H2, a difference image 723 between the low-energy image 70L1 and the high-energy image 70H3, and a difference image 724 between the low-energy image 70L1 and the high-energy image 70H4. In this way, in the case of time-series imaging, the generation unit 64 generates the same number of difference images as the number of high-energy images. In the case of time-series imaging, the generation unit 64 outputs image data representing the generated difference images to the derivation unit 66 and the image processing unit 68.

[0062] The method by which the generation unit 64 generates the difference image is not limited to the above-described method. For example, the difference image may be generated by adding the difference between the high-energy images to the difference between the low-energy image and the high-energy image. Specifically, as shown in FIG. 7B , the generation unit 64 generates a difference image 721 between the low-energy image 70L1 and the high-energy image 70H1, as described above. The generation unit 64 also generates a difference image 722 by adding an image showing the difference between the high-energy image 70H2 and the high-energy image 70H1 to the difference image 721, generates a difference image 723 by adding an image showing the difference between the high-energy image 70H3 and the high-energy image 70H2 to the difference image 722, and generates a difference image 724 by adding an image showing the difference between the high-energy image 70H4 and the high-energy image 70H3 to the difference image 723.

[0063] In the case of tomosynthesis imaging, the generation unit 64 generates a difference image for each projection image. k For each shot, the generator 64 generates a difference image between the low-energy projection image 71L1 and the high-energy projection image 71H1 at the irradiation position 391, as shown in FIG. 8 . The generator 64 also generates a difference image 732 between the low-energy projection image 71L2 and the high-energy projection image 71H2, a difference image 733 between the low-energy projection image 71L3 and the high-energy projection image 71H3, and a difference image 734 between the low-energy projection image 71L4 and the high-energy projection image 71H4. The generator 64 also generates a difference image 735 between the low-energy projection image 71L5 and the high-energy projection image 71H5. Therefore, in the case of tomosynthesis imaging, the generator 64 generates a difference image 731 between the low-energy projection image 71L1 and the high-energy projection image 71H1 at the irradiation position 391, as in the case of single-shot imaging. The generator 64 also generates a difference image 732 between the low-energy projection image 71L2 and the high-energy projection image 71H2, a difference image 733 between the low-energy projection image 71L3 and the high-energy projection image 71H3, and a difference image 734 between the low-energy projection image 71L4 and the high-energy projection image 71H4. The generator 64 also generates a difference image 735 between the low-energy projection image 71L5 and the high-energy projection image 71H5. Therefore, in the case of tomosynthesis imaging, the generator 64 generates a difference image 731 between the low-energy projection image 71L1 and the high-energy projection image 71H1 at the irradiation position 391, as shown in FIG. 8 . k The generated difference images 73 correspond to the number of images projected. The difference images 73 of this embodiment are an example of a projected difference image of the present disclosure.

[0064] Furthermore, in the case of tomosynthesis imaging, the generating unit 64 reconstructs the generated series of difference images 73 to generate a series of tomographic images 74 having a predetermined slice thickness. In FIG. 8, f tomographic images (tomographic images 741 to 744) are generated from the series of difference images 73. f ) is generated. The method by which the generating unit 64 generates the tomographic image 74 is not particularly limited. For example, reconstruction may be performed using a back projection method such as the FBP (Filter Back Projection) method or an iterative reconstruction method, and known techniques can be applied. The slice thickness of the generated tomographic image 74 is also not particularly limited and can be determined depending on, for example, the size of the object of interest, the image quality of the radiographic image, the processing load of the arithmetic processing in the generation, instructions from the user, etc. The tomographic image 74 generated by the generating unit 64 in this manner corresponds to a subtraction image, and can be an image in which the mammary gland structure is removed and the contrast agent is clearly visible. In the case of tomosynthesis imaging, the generating unit 64 outputs image data representing the generated tomographic image 74 to the derivation unit 66 and the image processing unit 68.

[0065] The derivation unit 66 has a function of deriving contrast amount information regarding the contrast amount of the difference image generated by the generation unit 64. Examples of the contrast amount information include a numerical value representing the contrast amount and a heat map of the contrast amount. The contrast amount information may also be the difference image generated by the generation unit 64. The form of the contrast amount information may be predetermined, or may be selectable or instructable by the user.

[0066] When the contrast amount information is a numerical value representing the contrast amount of the region of interest, the derivation unit 66 first identifies the region of interest from the difference image. Note that the method by which the derivation unit 66 identifies the region of interest from the difference image is not particularly limited. For example, the derivation unit 66 may identify the region of interest from the difference image by accepting information about the region of interest input by the user. Specifically, at least one image selected from the difference image, the low-energy image, and the high-energy image may be displayed on the display unit 58, and a region designated by the user by operating the operation unit 56 on the displayed image may be accepted as information about the region of interest. Furthermore, for example, the derivation unit 66 may identify the region of interest by applying CAD (Computer Aided Diagnosis) to the difference image.

[0067] The pixel values ​​of pixels in the difference image correspond to the amount of contrast. Therefore, the amount of contrast can be derived from the pixel values ​​of the difference image. The derivation unit 66 derives the amount of contrast based on the pixel values ​​of pixels in the image corresponding to the identified region of interest. The derivation unit 66 may derive any of the total, average, median, and maximum values ​​of the amount of contrast for the entire region of interest. The value to be derived may be predetermined or may be specified by the user. The derivation unit 66 may also derive a numerical value representing the amount of contrast regardless of the region of interest. For example, the derivation unit 66 may derive a numerical value representing the amount of contrast at a position or region designated by the user in the difference image, etc. Alternatively, the derivation unit 66 may derive a numerical value representing the amount of contrast in a region outside the identified region of interest.

[0068] Furthermore, when the contrast amount information is a heat map of the contrast amount, the derivation unit 66 derives the contrast amount of the entire subtraction image and generates a heat map in which the derived contrast amount values ​​are expressed as colors or shading. Note that the heat map may be configured to express only the contrast amount when it exceeds a threshold. Furthermore, since the pixel values ​​of the subtraction image correspond to the contrast amount as described above, the derivation unit 66 may generate a heat map based on the pixel values ​​of the subtraction image without deriving the contrast amount.

[0069] Furthermore, when the contrast amount information is a difference image, the derivation unit 66 sets the difference image generated by the generation unit 64 as the contrast amount information. Note that the difference image used as the contrast amount information does not have to be equivalent to a difference image that has been subjected to image processing by the image processing unit 68, and does not have to be the difference image itself generated by the generation unit 64. In other words, the difference image used as the contrast amount information only needs to be an image in which the contrast amount in the difference image generated by the generation unit 64 appears. Therefore, for example, the derivation unit 66 may perform correction on the difference image generated by the generation unit 64 to remove artifacts such as scattered radiation components and oblique radiation components, and derive the corrected difference image as the contrast amount information. Note that, for example, the technology described in International Publication No. 2020 / 059306 can be used as a technology for removing artifacts in this case.

[0070] The contrast amount information thus derived by the derivation unit 66 is output to the display control unit 69.

[0071] The image processing unit 68 has a function of performing image processing to enhance the difference image. Examples of image processing performed by the image processing unit 68 include tone enhancement processing and frequency enhancement processing. In this embodiment, the image processing unit 68 performs an analysis such as a histogram analysis on the difference image generated by the generation unit 64 to determine whether tone enhancement processing or frequency enhancement processing should be performed and the degree of enhancement. The image processing unit 68 performs image processing on the difference image according to the determined image processing and degree of enhancement. It is preferable that the image processing unit 68 identify a region of interest from the difference image and perform image processing to enhance the identified region of interest. The method by which the image processing unit 68 identifies the region of interest is not particularly limited and may be the same as the method by which the derivation unit 66 identifies the region of interest described above. Because the image processing unit 68 enhances the difference image, particularly the region of interest in the difference image, in this manner, the amount of contrast represented by the difference image after image processing may differ from the actual amount of contrast.

[0072] The image data representing the difference image after image processing generated by the image processing unit 68 in this manner is output to the display control unit 69.

[0073] The display control unit 69 has a function of causing the display unit 58 to display the contrast amount information derived by the derivation unit 66 and the difference image after image processing generated by the image processing unit 68. In other words, the display control unit 69 has a function of causing the display unit 58 to display the contrast amount information regarding the contrast amount of the difference image before image processing by the image processing unit 68 and the difference image after image processing.

[0074] Next, the operation of the console 12 in contrast imaging by the radiation image capturing system 1 of this embodiment will be described with reference to the drawings.

[0075] Fig. 9 is a flowchart showing an example of the flow of contrast imaging using the radiation imaging system 1 of this embodiment. When performing contrast imaging, first, as shown in step S10 of Fig. 9, the user injects a contrast agent into the breast to be examined. Next, as shown in step S12, the user positions the breast of the examinee on the imaging table 30 of the mammography device 10 and compresses the breast with the compression paddle 40.

[0076] Next, in step S14, the console 12 performs the radiographic image capturing process shown in Fig. 10 to capture low-energy images and high-energy images using the mammography apparatus 10. In the console 12 of this embodiment, as an example, the CPU 50A of the control unit 50 executes the imaging control processing program 51A stored in the ROM 50B to perform the radiographic image capturing process, an example of which is shown in Fig. 10. Fig. 10 shows a flowchart illustrating an example of the flow of the radiographic image capturing process executed by the console 12 of this embodiment.

[0077] 10, the control unit 60 determines whether the type of imaging to be performed is tomosynthesis imaging. If the type of imaging set in the imaging menu is not tomosynthesis imaging, in other words, if the type of imaging set in the imaging menu is single-shot imaging or tomosynthesis imaging, the determination in step S100 is negative, and the control unit 60 proceeds to step S102.

[0078] In step S102, the control unit 60 determines whether or not it has received an instruction to irradiate radiation R. Until an irradiation instruction is received, the determination in step S102 remains negative. On the other hand, if an irradiation instruction is received, the determination in step S102 remains positive, and the process proceeds to step S104.

[0079] In step S104, the control unit 60 determines whether the type of photography to be performed is time-series photography. If the type of photography set in the photography menu is not time-series photography, in other words, if the type of photography set in the photography menu is single-shot photography, the determination in step S104 is negative, and the control unit 60 proceeds to step S106.

[0080] In step S106, the control unit 60 executes the single-shot imaging process shown in Fig. 11A. In step S150 of the single-shot imaging process shown in Fig. 11A, the control unit 60 outputs an instruction to the mammography apparatus 10 to irradiate the breast with radiation R of the first energy. In the mammography apparatus 10, the control unit 20 causes the radiation source 37R to irradiate the breast with radiation R of the first energy based on an instruction input from the console 12, and a low-energy image is captured by the radiation detector 28.

[0081] In the next step S152, the control unit 60 outputs an instruction to the mammography apparatus 10 to irradiate the breast with radiation R of the second energy. In the mammography apparatus 10, the control unit 20 causes the radiation source 37R to irradiate the breast with radiation R of the second energy based on an instruction input from the console 12, and a high-energy image is captured by the radiation detector 28. When the processing of step S152 ends, the present single-shot imaging process ends. When the single-shot imaging process ends, step S106 of the radiographic imaging process shown in FIG. 10 ends, and the radiographic imaging process ends. Note that in this embodiment, a configuration in which a low-energy image is captured first and then a high-energy image is captured is described, but the order of capturing the low-energy image and the high-energy image may be reversed. In other words, the order of the processing of step S150 and the processing of step S152 in the single-shot imaging process may be reversed.

[0082] On the other hand, if the type of imaging to be performed is time-series imaging, the determination in step S104 of the radiation image imaging process is affirmative, and the process proceeds to step S108.

[0083] In step S108, the control unit 60 executes the time-series imaging process shown in Fig. 11B. In step S160 of the time-series imaging process shown in Fig. 11B, the control unit 60 outputs an instruction to the mammography apparatus 10 to irradiate the breast with radiation R of the first energy. In the mammography apparatus 10, the control unit 20 causes the radiation source 37R to irradiate the breast with radiation R of the first energy based on an instruction input from the console 12, and a low-energy image is captured by the radiation detector 28.

[0084] In the next step S162, the control unit 60 determines whether a predetermined time has elapsed. Until the predetermined time has elapsed, the determination in step S162 remains negative. On the other hand, once the predetermined time has elapsed, the determination in step S162 remains positive, and the process proceeds to step S164.

[0085] In step S164, the control unit 60 outputs an instruction to the mammography apparatus 10 to irradiate the second energy radiation R. In the mammography apparatus 10, based on the instruction input from the console 12, the control unit 20 causes the radiation source 37R to irradiate the breast with the second energy radiation R, and a high-energy image is captured by the radiation detector 28.

[0086] In the next step S166, the control unit 60 determines whether to terminate the time-series imaging. The determination in step S166 is negative until a predetermined termination condition is met, and the process returns to step S162, repeating the processes in steps S162 and S164. On the other hand, if the termination condition is met, the determination in step S166 is positive, and the time-series imaging process is terminated. The termination condition is not limited. Examples of termination conditions include termination when the elapsed time since the injection of contrast medium into the breast has exceeded a predetermined imaging time, when the elapsed time since the start of irradiation with radiation R has exceeded a predetermined cumulative irradiation time for contrast imaging, when the number of radiographic images has reached a predetermined number, and when an instruction to terminate imaging is received from the user. Another termination condition is termination when the control unit 60 analyzes the captured radiographic images and finds that the contrast level no longer changes. Specifically, termination may be determined when the difference between high-energy images is equal to or less than a threshold, particularly when the difference between pixel values ​​of the region of interest in the high-energy images is equal to or less than a threshold. When the time-series imaging process is completed, step S108 of the radiation image imaging process shown in FIG. 10 is completed, and the radiation image imaging process is completed.

[0087] On the other hand, if the type of imaging to be performed is tomosynthesis imaging, the determination in step S100 of the radiation image imaging process is affirmative, and the process proceeds to step S110.

[0088] In step S110, the control unit 60 executes the tomosynthesis imaging process shown in FIG. 11C.

[0089] In step S170 of the tomosynthesis imaging process shown in FIG. 11C, the control unit 60 determines the irradiation position 39 as the starting position for starting irradiation of radiation. k The radiation source 37R is moved to the

[0090] In the next step S172, the control unit 60 determines whether or not an instruction to irradiate radiation R has been received, similarly to step S102 of the above-described radiographic image capturing process. Until an irradiation instruction is received, the determination in step S172 remains negative. On the other hand, if an irradiation instruction is received, the determination in step S172 remains positive, and the process proceeds to step S174.

[0091] In step S174, the control unit 60 outputs an instruction to the mammography apparatus 10 to irradiate the breast with radiation R of the first energy. In the mammography apparatus 10, the control unit 20 causes the radiation source 37R to irradiate the breast with radiation R of the first energy based on the instruction input from the console 12, and a low-energy image is captured by the radiation detector 28.

[0092] In the next step S176, the control unit 60 outputs an instruction to the mammography apparatus 10 to irradiate the second energy radiation R. In the mammography apparatus 10, based on the instruction input from the console 12, the control unit 20 causes the radiation source 37R to irradiate the breast with the second energy radiation R, and a high-energy image is captured by the radiation detector 28.

[0093] In the next step S178, the control unit 60 determines whether to end the tomosynthesis imaging. k If the position is not located at a position corresponding to the position of the arrow A, the determination in step S178 is negative, and the process proceeds to step S180.

[0094] In step S180, the control unit 60 controls the next irradiation position 39 k After the radiation source 37R is moved to the final irradiation position 39, the process returns to step S174 and the processing of steps S174 to S178 is repeated. k If the irradiation position 39 corresponds to the irradiation angle α of 0 degrees, the determination in step S178 becomes positive, and the process proceeds to step S182. k (Irradiation position along the normal direction 39 k, radiation source 37R is moved to a position (irradiation position 393 in FIG. 2B). When the processing of step S182 is completed, tomosynthesis imaging is completed. When the tomosynthesis imaging is completed, step S110 of the radiographic image capturing process shown in FIG. 10 is completed, and the radiographic image capturing process is completed. Note that in this embodiment, as in the single-shot imaging described above, a mode in which a low-energy image is captured and then a high-energy image is captured has been described, but the order in which the low-energy image and the high-energy image are captured may be reversed. In other words, the order of the processing of step S174 and the processing of step S176 in the tomosynthesis imaging process may be reversed.

[0095] When the radiographic image capturing process shown in FIG. 10 is completed in this manner, contrast imaging is completed, and the process of step S14 shown in FIG. 9 is completed.

[0096] Next, in step S16, the console 12 performs the differential image generation and display process shown in Fig. 12. In the console 12 of this embodiment, as an example, the CPU 50A of the control unit 50 executes the image processing program 51B stored in the ROM 50B to perform the differential image generation and display process, an example of which is shown in Fig. 12. Fig. 12 shows a flowchart illustrating an example of the flow of the differential image generation and display process executed in the console 12 of this embodiment.

[0097] In step S200, the acquisition unit 62 acquires low-energy images and high-energy images captured by contrast imaging from the mammography device 10, as described above. Specifically, if the type of imaging performed is tomosynthesis imaging, low-energy projection images and high-energy projection images are acquired as described above. The timing at which the acquisition unit 62 acquires the low-energy images and high-energy images is not limited. For example, the acquisition unit 62 may acquire the low-energy images and high-energy images from the mammography device 10 each time a low-energy image and a high-energy image are captured. Alternatively, for example, the acquisition unit 62 may acquire the low-energy images and high-energy images stored in the memory unit 22 of the mammography device 10 after all low-energy images and high-energy images have been captured. The order in which the low-energy images and high-energy images are acquired is also not limited.

[0098] In the next step S202, the generation unit 64 determines whether the type of imaging performed was tomosynthesis imaging. If the type of imaging performed was not tomosynthesis imaging, in other words, if the type of imaging performed was single-shot imaging or time-series imaging, the determination in step S202 is negative, and the process proceeds to step S204.

[0099] In step S204, the generation unit 64 generates a difference image from the low-energy image and the high-energy image acquired in step S200, as described above, and then proceeds to step S210. As described above, if the type of imaging performed is single-shot imaging, the generation unit 64 generates one difference image. Also, if the type of imaging performed is time-series imaging, the generation unit 64 generates a plurality of difference images, the same number as the number of high-energy images acquired in step S200.

[0100] On the other hand, if the type of imaging performed is tomosynthesis imaging, the determination in step S202 is affirmative, and the process proceeds to step S206. kSpecifically, the generation unit 64 generates a difference image of the projection image at each irradiation position 39 as described above. k For each image, a difference image is generated from the low-energy projection image and the high-energy projection image.

[0101] In the next step S208, the generating unit 64 generates a tomographic image by reconstructing the plurality of difference images generated in step S206 as described above, and then the process proceeds to step S210.

[0102] In step S210, the derivation unit 66 identifies the region of interest from the difference image as described above. If the type of imaging performed is single-shot imaging or time-series imaging, the derivation unit 66 identifies the region of interest from the difference image generated in step S204. On the other hand, if the type of imaging performed is tomosynthesis imaging, the derivation unit 66 identifies the region of interest from the tomographic image generated in step S208.

[0103] In the next step S212, the derivation unit 66 derives contrast amount information as described above. If the type of imaging performed is single-shot imaging or time-series imaging, the derivation unit 66 derives contrast amount information from the difference image generated in step S204.

[0104] On the other hand, if the type of imaging performed is tomosynthesis imaging, the derivation unit 66 derives contrast amount information from the tomographic images generated in step S208. With reference to FIG. 13A, a mode of deriving a numerical value representing the contrast amount as contrast amount information from the tomographic images 74 will be described. When deriving a numerical value representing the contrast amount as contrast amount information from the tomographic images 74, the derivation unit 66 may derive a numerical value representing the contrast amount from each of the series of tomographic images 74. In the example shown in FIG. 13A, the derivation unit 66 derives a numerical value representing the contrast amount from G tomographic images 74 (741 to 744). G 13A.) Alternatively, the derivation unit 66 may derive a numerical value representing the contrast amount for each of the transmission paths in the transmission direction r through which the radiation R, indicated by the arrow in FIG. 13A, passes.

[0105] In addition, the derivation unit 66 may derive the density of the contrast agent in the region of interest as a numerical value representing the amount of contrast. g ) is generated. In the example shown in FIG. 13A and the example shown in FIG. 13B, the thickness of the breast WB in FIG. 13B is thinner than the thickness of the breast WA in FIG. 13A. Because the slice thickness is the same in the example shown in FIG. 13A and the example shown in FIG. 13B, the number g of tomographic images 74 for the breast WB is smaller than the number G of tomographic images 74 for the breast WA. Furthermore, the length of the region of interest 75B in the transmission direction r is shorter than that of the region of interest 75A. Therefore, even if the densities of the regions of interest 75A and 75B are the same, the total contrast amount in the transmission path differs between the regions of interest 75A and 75B. As such, the density of the region of interest cannot be determined from the total contrast amount in the transmission path. Therefore, it is difficult to determine the penetration of the contrast amount in the region of interest, such as a lesion, from the total contrast amount in the transmission path. Therefore, the derivation unit 66 may derive the density of the contrast amount in the region of interest as the contrast amount information. For example, the derivation unit 66 may identify the position of the tomographic image 74 in which the image of the identified region of interest is captured, derive the length of the region of interest in the transmission direction r from the identified position of the tomographic image 74, and derive the density of the contrast amount by dividing the total value of the contrast amount in the transmission path by the length of the region of interest.

[0106] In the next step S214, the image processing unit 68 performs image processing as described above. If the type of imaging performed is single-shot imaging or time-series imaging, the image processing unit 68 performs image processing to enhance the difference image generated in step S204. On the other hand, if the type of imaging performed is tomosynthesis imaging, the image processing unit 68 performs image processing to enhance the tomographic image generated in step S208.

[0107] In the next step S216, the display control unit 69 controls the display unit 58 to display the contrast amount information derived in step S212 and the difference image after image processing in step S214, as described above, and then terminates this difference image generation and display process.

[0108] FIG. 14A shows an example of a state in which contrast amount information and a difference image after image processing are displayed on the display unit 58. FIG. 14A shows an example of a case in which a difference image 80A before image processing is displayed as contrast amount information. As shown in FIG. 14A, the display control unit 69 of this embodiment causes the display unit 58 to display a difference image 82 after image processing and a difference image 80A before image processing. Also, as shown in FIG. 14A, when a radiographic image 84 of the subject breast captured by general radiography, in other words, a radiographic image 84 captured without an injected contrast agent, exists, the display control unit 69 also causes the display unit 58 to display the radiographic image 84 as a comparative example. Note that, in the example shown in FIG. 14A, the difference image 80A before image processing and the difference image 82 after image processing are displayed side by side. However, it is also possible to display either the difference image 80A before image processing or the difference image 82 after image processing, and switch the image to be displayed in response to a user instruction. In addition, when the type of imaging performed is time-series imaging, a plurality of difference images generated by the generation unit 64 may be displayed successively in chronological order as a moving image as the difference image 80A before image processing. In this embodiment, the term "moving image" refers to displaying still images one after another at high speed so that the image is perceived as a moving image. Therefore, depending on the degree of "high speed" in the display, so-called "frame-by-frame" is also included in the moving image. In addition, when the type of imaging performed is tomosynthesis imaging, when the tomographic position specified by the user is switched, the display may be switched between the difference image 80A before image processing (tomographic image) and the difference image 82 after image processing (tomographic image) displayed on the display unit 58 according to the tomographic position.

[0109] FIG. 14B shows an example of a case where a heat map 80B is displayed as contrast amount information. The example shown in FIG. 14B shows an example of a display in which the heat map 80B is superimposed on a difference image 82 after image processing. FIG. 14C shows another example of a display in which the heat map 80B is superimposed on a low-energy image 85. By displaying the heat map 80B superimposed on the low-energy image 85, the relationship between the mammary gland structure and the contrast amount can be displayed in an easily understandable manner.

[0110] Furthermore, Fig. 14D shows an example of a case where a numerical value 80C representing the contrast amount is displayed as contrast amount information. The example shown in Fig. 14C shows an example of a form in which a numerical value (see "150" in Fig. 14) representing the contrast amount of the region of interest designated by the user (see the white arrow in Fig. 14) is displayed in a subtraction image 82 after image processing.

[0111] 12 ends in this way, the subtraction image generation and display process of step S16 shown in Fig. 9 ends. This completes a series of processes related to contrast imaging in the radiation image capturing system 1 of this embodiment. Note that the low-energy image and multiple high-energy images captured by the mammography apparatus 10 of this embodiment, the multiple subtraction images generated by the console 12, the tomographic images, contrast amount information, etc. may be stored in the memory unit 52 of the console 12, a PACS (Picture Archiving and Communication Systems), etc.

[0112] 9, in other words, after the end of contrast imaging, the subtraction image generation and display process is performed continuously. However, the timing of the subtraction image generation and display process, i.e., the timing of generating and displaying the subtraction image, is not limited to this embodiment. For example, the timing of generating and displaying the subtraction image may be set according to the user's wishes after contrast imaging.

[0113] As described above, the console 12 of each of the above embodiments includes a CPU 50A as at least one processor. The CPU 50A acquires a low-energy image captured by the mammography device 10 by irradiating a breast injected with a contrast agent with radiation R of a first energy, and a high-energy image captured by the mammography device 10 by irradiating a breast injected with a contrast agent with radiation R of a second energy higher than the first energy. The CPU 50A also generates a difference image showing the difference between the low-energy image and the high-energy image. The CPU 50A also performs image processing to enhance the difference image. The CPU 50A also displays the difference image after image processing and contrast amount information related to the contrast amount in the difference image before image processing.

[0114] As described above, the console 12 of this embodiment displays a difference image after image processing that enhances the difference image, and contrast amount information regarding the contrast amount of the difference image before image processing. The difference image after image processing is an image in which the mammary gland structure has been removed and the contrast agent has been enhanced, making it easier to see. On the other hand, the contrast amount information regarding the contrast amount of the difference image before image processing is information that represents the contrast amount that is not affected by image processing or from which the influence of image processing has been removed, and therefore provides an accurate contrast amount. Therefore, the console 12 of this embodiment makes it easy to observe the contrast agent and to easily evaluate the contrast amount.

[0115] In the above embodiment, the image processing unit 68 performs image processing on the difference image generated by the generation unit 64 as image processing to enhance the difference image. However, the target of image processing by the image processing unit 68 is not limited to the difference image. For example, the image processing unit 68 may perform image processing on each of the low-energy image and the high-energy image. In this case, the generation unit 64 generates a difference image showing the difference between the low-energy image after image processing and the high-energy image after image processing, so that the generated difference image can be enhanced in the same way as in the above embodiment.

[0116] Although the above embodiment has been described in which the derivation unit 66 generates contrast amount information from the difference image before image processing, the method of generating contrast amount information is not limited to this embodiment. For example, the derivation unit 66 may derive contrast amount information relating to the contrast amount of the difference image before image processing by removing the influence of the image processing from the contrast amount derived from the difference image after image processing by the image processing unit 68.

[0117] In the above embodiment, when the type of imaging is tomosynthesis imaging, as described with reference to FIG. 8, the generation unit 64 generates a difference image 73 between each low-energy projection image 71L and a high-energy projection image 71H, and reconstructs the generated difference images 73 to generate a tomographic image 74. However, the method of generating a tomographic image is not limited to this embodiment. For example, a difference image between a tomographic image generated by reconstructing a low-energy image and a tomographic image generated by reconstructing a high-energy image may be generated. An example of this case will be described in detail with reference to FIG. 15. In the example shown in FIG. 15, the generation unit 64 reconstructs a low-energy projection image 71L (see FIG. 15, 71L1 to 71L5) to generate a tomographic image 74L (see FIG. 15, 74L1 to 74L5). f The generating unit 64 also reconstructs the high-energy projection image 71H (see 71H1 to 71H5 in FIG. 15) to generate a tomographic image 74H (see 74H1 to 74H in FIG. 15). f ) which is a difference image showing the difference between the tomographic image 74L and the tomographic image 74H at the corresponding slice position. f By this processing, a tomographic image 74 is generated, similarly to the above embodiment. The tomographic image 74L of this embodiment is an example of a low-energy tomographic image of the present disclosure, and the tomographic image 74H of this embodiment is an example of a high-energy tomographic image of the present disclosure.

[0118] In the above embodiment, when the type of imaging is tomosynthesis imaging, the irradiation position 39 k In this case, radiation R of a first energy is irradiated to capture a low-energy image, and radiation R of a second energy is irradiated to capture a high-energy image.k However, the method of tomosynthesis imaging is not limited to this. For example, k After irradiating the target with radiation R of the first energy at each irradiation position 39 and capturing a low-energy image, k In the above, radiation R of the second energy may be irradiated to capture a high-energy image.

[0119] In the above embodiment, a breast is used as an example of a subject of the present disclosure, and mammography device 10 is used as an example of a radiological imaging device of the present disclosure. However, the subject is not limited to a breast, and the radiological imaging device is not limited to a mammography device. For example, the subject may be a chest or abdomen, or the radiological imaging device may be a radiological imaging device other than a mammography device.

[0120] Furthermore, in the above embodiment, the console 12 is an example of the image processing device of the present disclosure, but the functions of the image processing device of the present disclosure may be provided in a device other than the console 12. In other words, some or all of the functions of the control unit 60, the acquisition unit 62, the generation unit 64, the derivation unit 66, the image processing unit 68, and the display control unit 69 may be provided in a device other than the console 12, such as the mammography device 10 or an external device.

[0121] In the above embodiment, the following various processors may be used as the hardware structure of processing units that perform various processes, such as the control unit 60, the acquisition unit 62, the generation unit 64, the derivation unit 66, the image processing unit 68, and the display control unit 69. As described above, the various processors include a CPU, which is a general-purpose processor that executes software (programs) and functions as various processing units, as well as dedicated electrical circuits that are processors having a circuit configuration specifically designed to perform specific processes, such as a programmable logic device (PLD), a processor whose circuit configuration can be changed after manufacture, such as an FPGA (Field Programmable Gate Array), and an ASIC (Application Specific Integrated Circuit).

[0122] 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.

[0123] Examples of configuring multiple processing units with a single processor include, first, 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 typified by computers such as client and server. Second, a form in which a processor is used to realize the functions of the entire system including multiple processing units with a single IC (Integrated Circuit) chip, as typified by systems on chips (SoCs). In this way, various processing units are configured using one or more of the above-mentioned various processors as a hardware structure.

[0124] Furthermore, more specifically, the hardware structure of these various processors can be an electric circuit that combines circuit elements such as semiconductor elements.

[0125] In the above-described embodiments, the shooting control processing program 51A and the image processing program 51B are pre-stored (installed) in the ROM 50B, but the present invention is not limited to this. Each of the shooting control processing program 51A and the image processing program 51B 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 shooting control processing program 51A and the image processing program 51B may be downloaded from an external device via a network.

[0126] The disclosure of Japanese Patent Application No. 2020-162696, filed on September 28, 2020, is incorporated herein by reference in its entirety.

[0127] All publications, patent applications, and technical standards mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent application, or technical standard was specifically and individually indicated to be incorporated by reference. [Explanation of symbols]

[0128] 1. Radiography system 2 RIS 10 Mammography equipment 12 Console 20, 50 Control unit 22, 52 Storage section 24, 54 I / F section 26, 56 Operation section 28 Radiation detector, 28A detection surface 30 imaging table, 30A imaging surface 32 Arm section 34 Foundation 35 Shaft 36 Compression Unit 37 Radiation irradiation section, 37R radiation source 38 Face Guard 39 k , 393 irradiation positions 40 Compression Plate 46 Support part 50A CPU, 50B ROM, 50C RAM 51A Irradiation control processing program, 51B Image processing program 58 Display section 59 Bus 60 Control Unit 62 Acquisition Department 64 Generation part 66 Derivation part 68 Image Processing Unit 69 Display control unit 70L1, 70L2 low energy images 71L1~71L5 Low-energy projection images (low-energy images) 70H1~70H4 high energy images 71H1~71H5 High-energy projection images (high-energy images) 721~724, 731~735 difference images 74, 741, 742, 743, 74 f , 74 G-2 , 74 G-1 , 74 G , 74 g-2 , 74 g-1 , 74 g , 74L1, 74L2, 74L f , 74H1, 74H2, 74H f Tomographic images 75A, 75B Area of ​​interest 80A Subtraction image before image processing: contrast volume information 80B Heat map: contrast volume information 80C Numerical value representing the amount of contrast: Contrast amount information 82 Subtraction image after image processing: contrast volume information 84 Radiography 85 Low Energy Images CL normal r through direction R radiation RC Radiation Axis W, WA, WB breasts α and θ angles

Claims

1. at least one processor; The processor: a low-energy image captured by a radiographic imaging device by irradiating a subject into which a contrast agent has been injected with radiation of a first energy, and a high-energy image captured by the radiographic imaging device by irradiating the subject into which the contrast agent has been injected with radiation of a second energy higher than the first energy, and generating a difference image showing the difference between the low-energy image and the high-energy image; performing image processing to enhance the contrast agent in the difference image; displaying the difference image after the image processing and contrast amount information relating to the contrast amount of the difference image before the image processing; The image processing is at least one of tone enhancement processing and frequency enhancement processing. Image processing device.

2. The contrast amount information is a numerical value representing the contrast amount. The image processing device according to claim 1 .

3. the contrast amount information is a heat map of the contrast amount; The processor: The heat map is displayed superimposed on the difference image after the image processing. The image processing device according to claim 1 .

4. The contrast amount information is a difference image before the image processing. The image processing device according to claim 1 .

5. The processor: The contrast amount information is derived from the difference image before the image processing. The image processing device according to any one of claims 1 to 4.

6. The processor: causing the radiographic imaging device to capture a plurality of high-energy images, and acquiring the captured high-energy images; generating the difference image for each of the plurality of high-energy images; The image processing device according to any one of claims 1 to 5.

7. the radiographic imaging device is capable of tomosynthesis imaging in which radiation is irradiated onto the subject from each of a plurality of different irradiation angles and the low-energy image and the high-energy image are captured for each of the plurality of irradiation angles; The processor: A difference image showing the difference between a low-energy tomographic image generated by reconstructing the plurality of low-energy images and a high-energy tomographic image generated by reconstructing the plurality of high-energy images is generated as the difference image. The image processing device according to any one of claims 1 to 5.

8. the radiographic imaging device is capable of tomosynthesis imaging in which radiation is irradiated onto the subject from each of a plurality of different irradiation angles, and the low-energy image and the high-energy image are captured as a pair of projection images for each of the plurality of irradiation angles; The processor: generating a projection difference image indicating a difference between the pair of projection images for each of the illumination angles; A tomographic image is generated by reconstructing the generated plurality of projection difference images as the difference image. The image processing device according to any one of claims 1 to 5.

9. The processor: deriving a length of a region of interest in a transmission direction in which the radiation penetrates from the tomographic image; As the contrast amount information, a density of the contrast agent in the region of interest is derived based on the derived length of the region of interest.

9. The image processing device according to claim 7 or 8.

10. the subject is a breast, The radiation imaging device is a mammography device. The image processing device according to any one of claims 1 to 9.

11. a low-energy image captured by a radiographic imaging device by irradiating a subject into which a contrast agent has been injected with radiation of a first energy, and a high-energy image captured by the radiographic imaging device by irradiating the subject into which the contrast agent has been injected with radiation of a second energy higher than the first energy, and generating a difference image showing the difference between the low-energy image and the high-energy image; performing image processing to enhance the contrast agent in the difference image; displaying the difference image after the image processing and contrast amount information relating to the contrast amount of the difference image before the image processing; The image processing is at least one of tone enhancement processing and frequency enhancement processing. An image processing method in which processing is performed by a computer.

12. a low-energy image captured by a radiographic imaging device by irradiating a subject into which a contrast agent has been injected with radiation of a first energy, and a high-energy image captured by the radiographic imaging device by irradiating the subject into which the contrast agent has been injected with radiation of a second energy higher than the first energy, and generating a difference image showing the difference between the low-energy image and the high-energy image; performing image processing to enhance the contrast agent in the difference image; displaying the difference image after the image processing and contrast amount information relating to the contrast amount of the difference image before the image processing; The image processing is at least one of tone enhancement processing and frequency enhancement processing. An image processing program that causes a computer to perform the processing.

Images