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

Abstract

To provide an image processing device, image processing method and image processing program which can obtain a difference image in which a contrast agent is clearly imaged and the influence of an artifact component due to an artifact is suppressed in contrast imaging.SOLUTION: A processor of an image processing device acquires a low energy image captured by a radiation detector by irradiating a subject in such a state that a contrast agent is injected with the radiation of the first energy from a radiation source, a high energy image captured by the radiation detector by irradiating the subject with the radiation of the second energy higher than the first energy from the radiation source, and a first difference image showing a difference between the high energy image and the low energy image, specifies an artifact region including an artifact from the first difference image, and generates a second difference image which shows a difference between the high energy image and the low energy image and in which the influence of an artifact component due to the artifact is suppressed on the basis of the artifact region.SELECTED DRAWING: Figure 8

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 technique is known in which a subject injected with a contrast agent is subjected to contrast imaging, in which radiation beams of different energies are emitted to capture a low-energy image and a high-energy image, and a difference image is generated that shows the difference between the high-energy image and the low-energy image, thereby generating a radiological image that emphasizes the contrast agent.

[0003] Furthermore, there are cases where artifacts appear in the radiation image along with the subject. Therefore, a technique for identifying artifacts included in the radiation image is known (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-52957 Summary of the Invention [Problem to be solved by the invention]

[0005] Artifacts tend to be made of materials with relatively high radiation absorption, such as metals, etc. Radiation images that capture such artifacts are affected by artifact components due to the artifacts.

[0006] 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 are capable of obtaining, in contrast imaging, a difference image in which a contrast agent is clearly visible and the influence of artifact components due to man-made objects is suppressed. [Means for solving the problem]

[0007] In order to achieve the above object, 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 radiation detector by irradiating a subject into which a contrast agent has been injected with radiation of a first energy from a radiation source, a high-energy image captured by the radiation detector by irradiating a subject with radiation of a second energy higher than the first energy from the radiation source, and a first difference image showing the difference between the high-energy image and the low-energy image, identifies an artifact region containing an artifact from the first difference image, and generates a second difference image showing the difference between the high-energy image and the low-energy image and in which the influence of artifact components due to the artifact is suppressed based on the artifact region, performing image processing based on the artifact region on the first difference image to generate a second difference image, the image processing being an enhancement process that enhances regions other than the artifact region more than the artifact region; The low-energy image shows the tissue of the subject and artifacts, while the high-energy image shows the tissue of the subject, the contrast agent, and artifacts.

[0008] In order to achieve the above object, an image processing device of a second aspect of the present disclosure includes at least one processor, which acquires a low-energy image captured by a radiation detector by irradiating a subject into which a contrast agent has been injected with radiation of a first energy from a radiation source, a high-energy image captured by a radiation detector by irradiating the subject with radiation of a second energy higher than the first energy from a radiation source, and a first difference image showing the difference between the high-energy image and the low-energy image, identifies an artifact region containing an artifact from the first difference image, shows the difference between the high-energy image and the low-energy image, and generates a second difference image in which the influence of artifact components due to the artifact is suppressed based on the artifact region, performs image processing on the high-energy image and the low-energy image based on the artifact region, and generates a second difference image showing the difference between the high-energy image and the low-energy image after the image processing, the image processing being an enhancement process that enhances regions other than the artifact region more than the artifact region, and the low-energy image shows the subject's tissue and the artifact, and the high-energy image shows the subject's tissue, the contrast agent, and the artifact.

[0009] The image processing device of the third aspect of the present disclosure is the image processing device of the first aspect or the second aspect In the image processing device, the processor An artifact recognition process is performed on the first difference image to identify an artifact region.

[0010] An image processing device according to a fourth aspect of the present disclosure includes: First or second aspect In the image processing device, the processor Pixels in the first difference image that have pixel values ​​equal to or greater than a threshold determined depending on the contrast agent or the artifact are determined to be pixels in the artifact region.

[0011] The image processing device according to the fifth aspect of the present disclosure includes: 1 The mode or the 2 In the image processing device of the aspect, The processor determines pixels in the artifact region that have a luminance value in the first difference image equal to or greater than a predetermined value and that have a luminance value in the low-energy image greater than that in the high-energy image.

[0012] In order to achieve the above object, an image processing device according to a sixth aspect of the present disclosure includes at least one processor, and the processor acquires a first difference image showing a difference between a high-energy image and a low-energy image obtained by contrast imaging, in which a subject injected with a contrast agent is irradiated with radiation of a first energy from a radiation source and photographed by a radiation detector, and a high-energy image is photographed by irradiating with radiation of a second energy higher than the first energy from a radiation source, and detects a contrast agent or an artifact from the first difference image. Pixels having pixel values ​​equal to or greater than a predetermined threshold are identified as pixels in an artifact region containing an artifact, image processing based on the artifact region is performed on the first difference image to generate a second difference image in which the influence of artifact components due to the artifact is suppressed, and image processing based on the artifact region is performed on the first difference image to generate a second difference image, the image processing being an enhancement process that enhances regions other than the artifact region more than the artifact region, and the low-energy image shows the subject's tissue and the artifact, and the high-energy image shows the subject's tissue, the contrast agent, and the artifact.

[0013] In order to achieve the above object, an image processing device according to a seventh aspect of the present disclosure includes at least one processor, and the processor acquires a first difference image showing the difference between a high-energy image and a low-energy image obtained by contrast imaging, in which a subject into which a contrast agent has been injected is irradiated with radiation of a first energy from a radiation source and photographed by a radiation detector, and a high-energy image is taken by irradiating with radiation of a second energy higher than the first energy from a radiation source, and extracts pixels from the first difference image having pixel values ​​equal to or greater than a threshold determined in accordance with the contrast agent or artifact, The pixels are identified as pixels in an artifact region containing an artifact, image processing based on the artifact region is performed on the first difference image to generate a second difference image in which the influence of artifact components due to the artifact is suppressed, image processing based on the artifact region is performed on the high-energy image and the low-energy image to generate a second difference image showing the difference between the high-energy image and the low-energy image after image processing, the image processing is an enhancement process that enhances areas other than the artifact region more than the artifact region, and the low-energy image shows the subject's tissue and the artifact, and the high-energy image shows the subject's tissue, contrast agent, and the artifact.

[0014] In order to achieve the above object, an image processing device according to an eighth aspect of the present disclosure includes at least one processor, and the processor acquires a first difference image showing the difference between the high-energy image and the low-energy image obtained by contrast imaging, in which a subject injected with a contrast agent is irradiated with radiation of a first energy from a radiation source and captured by a radiation detector, and a high-energy image is irradiated with radiation of a second energy higher than the first energy from the radiation source. The processor performs artifact recognition processing on the first difference image to identify an artifact region containing the artifact, and generates a second difference image showing the difference between the high-energy image and the low-energy image, in which the influence of artifact components due to the artifact is suppressed based on the artifact region. The image processing is an enhancement processing that enhances regions other than the artifact region more than the artifact region, and the low-energy image shows the subject's tissue and the artifact, and the high-energy image shows the subject's tissue, the contrast agent, and the artifact.

[0015] In order to achieve the above object, an image processing device according to a ninth aspect of the present disclosure includes at least one processor, and the processor acquires a first difference image showing a difference between a high-energy image and a low-energy image obtained by contrast imaging, in which a subject into which a contrast agent has been injected is irradiated with radiation of a first energy from a radiation source and photographed by a radiation detector, and a high-energy image obtained by irradiating with radiation of a second energy higher than the first energy from the radiation source, and performs artifact recognition processing on the first difference image to detect artifacts. The method identifies an artifact region where artifacts are present, shows the difference between the high-energy image and the low-energy image, generates a second difference image in which the influence of artifact components due to the artifacts is suppressed based on the artifact region, performs image processing on the high-energy image and the low-energy image based on the artifact region, and generates a second difference image showing the difference between the high-energy image and the low-energy image after the image processing, the image processing being an enhancement process that enhances regions other than the artifact region more than the artifact region, and the low-energy image shows the subject's tissue and the artifacts, and the high-energy image shows the subject's tissue, the contrast agent, and the artifacts.

[0016] In order to achieve the above object, the image processing method of the tenth aspect of the present disclosure is method teeth, An image processing method executed by a processor included in an image processing device, in which the processor acquires a low-energy image captured by a radiation detector when a radiation source irradiates a subject into which a contrast agent has been injected with radiation of a first energy, a high-energy image captured by a radiation detector when a radiation source irradiates the subject with radiation of a second energy higher than the first energy, and a first difference image showing the difference between the high-energy image and the low-energy image, identifies an artifact region containing an artifact from the first difference image, shows the difference between the high-energy image and the low-energy image, and generates a second difference image based on the artifact region in which the influence of artifact components due to the artifact is suppressed, and performs image processing on the first difference image based on the artifact region to generate the second difference image, the image processing being an enhancement process that enhances regions other than the artifact region more than the artifact region, and the low-energy image shows the subject's tissue and the artifact, and the high-energy image shows the subject's tissue, the contrast agent, and the artifact.

[0017] In order to achieve the above object, an image processing method according to an eleventh aspect of the present disclosure is provided. method teeth, an image processing method executed by a processor included in an image processing device, the method comprising the steps of: acquiring a low-energy image captured by a radiation detector when a radiation source irradiates a subject into which a contrast agent has been injected with radiation of a first energy; acquiring a high-energy image captured by a radiation detector when a radiation source irradiates the subject with radiation of a second energy higher than the first energy; and acquiring a first difference image showing the difference between the high-energy image and the low-energy image; identifying an artifact region containing an artifact from the first difference image; generating a second difference image showing the difference between the high-energy image and the low-energy image and in which the influence of artifact components due to the artifact is suppressed based on the artifact region; performing image processing on the high-energy image and the low-energy image based on the artifact region; and generating a second difference image showing the difference between the high-energy image and the low-energy image after the image processing; the image processing is an enhancement process that enhances regions other than the artifact region more than the artifact region; and the low-energy image shows the subject's tissue and the artifact, and the high-energy image shows the subject's tissue, the contrast agent, and the artifact;

[0018] In order to achieve the above object, an image processing method of an image processing device according to a twelfth aspect of the present disclosure is an image processing method executed by a processor included in the image processing device, the processor comprising: A low-energy image is taken by a radiation detector by irradiating a subject into which a contrast agent has been injected with radiation from a radiation source with a first energy, and a high-energy image is taken by a radiation detector by irradiating the subject with radiation from a radiation source with radiation of a second energy higher than the first energy. A first difference image showing the difference between the high-energy image and the low-energy image is obtained by contrast imaging, pixels in the first difference image having pixel values ​​equal to or greater than a threshold determined depending on the contrast agent or the artifact are identified as pixels in an artifact region containing the artifact, image processing is performed on the first difference image based on the artifact region to generate a second difference image in which the influence of artifact components due to the artifact is suppressed, and image processing is performed on the first difference image based on the artifact region to generate the second difference image, the image processing being an enhancement process that enhances regions other than the artifact region more than the artifact region, and the low-energy image shows the subject's tissue and the artifact, and the high-energy image shows the subject's tissue, the contrast agent, and the artifact. It is a method for a computer to execute a process.

[0019] In order to achieve the above object, an image processing method of an image processing device according to a thirteenth aspect of the present disclosure is an image processing method executed by a processor included in the image processing device, the processor comprising: A low-energy image is taken by a radiation detector by irradiating a subject into which a contrast agent has been injected with radiation from a radiation source with a first energy, and a high-energy image is taken by a radiation detector by irradiating the subject with radiation from a radiation source with radiation of a second energy higher than the first energy. A first difference image showing the difference between the high-energy image and the low-energy image is obtained by contrast imaging. Pixels in the first difference image having pixel values ​​equal to or greater than a threshold determined depending on the contrast agent or the artifact are identified as pixels in an artifact region containing the artifact. Image processing is performed on the first difference image based on the artifact region to generate a second difference image in which the influence of artifact components due to the artifact is suppressed. Image processing is performed on the high-energy image and the low-energy image based on the artifact region to generate a second difference image showing the difference between the high-energy image and the low-energy image after image processing. The image processing is an enhancement process that enhances regions other than the artifact region more than the artifact region. The low-energy image shows the subject's tissue and the artifact, and the high-energy image shows the subject's tissue, the contrast agent, and the artifact. It is a method for a computer to execute a process.

[0020] In order to achieve the above object, an image processing method of an image processing device according to a fourteenth aspect of the present disclosure is an image processing method executed by a processor included in the image processing device, the processor comprising: A low-energy image is taken by a radiation detector by irradiating a subject into which a contrast agent has been injected with radiation from a radiation source with a first energy, and a high-energy image is taken by a radiation detector by irradiating the subject with radiation from a radiation source with radiation of a second energy higher than the first energy. A first difference image showing the difference between the high-energy image and the low-energy image is obtained by contrast imaging, an artifact region containing the artifact is identified by performing artifact recognition processing on the first difference image, and a second difference image is generated that shows the difference between the high-energy image and the low-energy image and suppresses the influence of artifact components due to the artifact based on the artifact region. Image processing based on the artifact region is performed on the first difference image to generate the second difference image, the image processing being an enhancement process that enhances regions other than the artifact region more than the artifact region, and the low-energy image shows the subject's tissue and the artifact, and the high-energy image shows the subject's tissue, the contrast agent, and the artifact. It is a method for a computer to execute a process.

[0021] In order to achieve the above object, the image processing method of the fifteenth aspect of the present disclosure is method teeth, An image processing method executed by a processor included in an image processing device, the method comprising: acquiring a low-energy image captured by a radiation detector by irradiating a subject into which a contrast agent has been injected with radiation from a radiation source with a first energy; and acquiring a high-energy image captured by a radiation detector by irradiating a subject with radiation from a radiation source with a second energy higher than the first energy; acquiring a first difference image showing the difference between the high-energy image and the low-energy image; performing an artifact recognition process on the first difference image to identify an artifact region containing an artifact; and and a low-energy image, generating a second difference image in which the influence of artifact components due to the artifacts is suppressed based on the artifact region, performing image processing on the high-energy image and the low-energy image based on the artifact region, and generating a second difference image in which the difference between the high-energy image and the low-energy image after the image processing is shown, the image processing being an enhancement process that enhances areas other than the artifact region more than the artifact region, and the low-energy image shows the subject's tissue and the artifacts, and the high-energy image shows the subject's tissue, the contrast agent, and the artifacts.

[0022] In order to achieve the above object, an image processing program according to a sixteenth aspect of the present disclosure comprises: A low-energy image is taken by a radiation detector by irradiating a subject into which a contrast agent has been injected with radiation of a first energy from a radiation source, and a high-energy image is taken by a radiation detector by irradiating a subject with radiation of a second energy higher than the first energy from a radiation source. A first difference image showing the difference between the high-energy image and the low-energy image is obtained. An artifact region containing an artifact is identified from the first difference image. A second difference image showing the difference between the high-energy image and the low-energy image and in which the artifact is suppressed based on the artifact region is generated. Image processing based on the artifact region is performed on the first difference image to generate the second difference image. The image processing is an enhancement process that enhances regions other than the artifact region more than the artifact region. The low-energy image shows the subject's tissue and the artifact, and the high-energy image shows the subject's tissue, the contrast agent, and the artifact. It is intended to cause a computer to execute the process.

[0023] In order to achieve the above object, an image processing program according to a seventeenth aspect of the present disclosure comprises: The method causes a computer to execute the following processing: a low-energy image captured by a radiation detector when a radiation source irradiates a subject into which a contrast agent has been injected with radiation of a first energy; a high-energy image captured by a radiation detector when a radiation source irradiates the subject with radiation of a second energy higher than the first energy; and a first difference image showing the difference between the high-energy image and the low-energy image; an artifact region containing the artifact is identified from the first difference image; a second difference image showing the difference between the high-energy image and the low-energy image and in which the artifact is suppressed based on the artifact region; image processing is performed on the high-energy image and the low-energy image based on the artifact region; and a second difference image showing the difference between the high-energy image and the low-energy image after the image processing is generated; the image processing is an enhancement process that enhances regions other than the artifact region more than the artifact region; the low-energy image shows the subject's tissue and the artifact; and the high-energy image shows the subject's tissue, the contrast agent, and the artifact. In order to achieve the above object, an image processing program according to an eighteenth aspect of the present disclosure is provided, which performs contrast imaging by irradiating a subject into which a contrast agent has been injected with radiation from a radiation source with a first energy and capturing a low-energy image with a radiation detector, and irradiating a subject with radiation from a radiation source with a second energy higher than the first energy and capturing a high-energy image with a radiation detector, and acquires a first difference image showing a difference between the high-energy image and the low-energy image, and extracts from the first difference image an image having a value equal to or greater than a threshold determined depending on the contrast agent or an artifact. The image processing is an enhancement process that enhances areas other than the artifact area more than the artifact area, and causes a computer to execute a process in which the subject's tissue and the artifact are captured in the low-energy image, and the subject's tissue, contrast agent, and the artifact are captured in the high-energy image. In order to achieve the above object, an image processing program according to a nineteenth aspect of the present disclosure provides a contrast imaging program for acquiring a low-energy image captured by a radiation detector by irradiating a subject into which a contrast agent has been injected with radiation of a first energy from a radiation source, and a high-energy image captured by a radiation detector by irradiating a subject with radiation of a second energy higher than the first energy from a radiation source, the program acquiring a first difference image showing a difference between the high-energy image and the low-energy image, and extracting pixels from the first difference image having pixel values ​​equal to or greater than a threshold determined depending on the contrast agent or the artifact, from an artifact region containing the artifact. The image processing is an enhancement process that emphasizes areas other than the artifact areas more than the artifact areas, and the low-energy image shows the tissue of the subject and the artifacts, and the high-energy image shows the tissue of the subject, the contrast agent, and the artifacts, and the high-energy image shows the tissue of the subject, the contrast agent, and the artifacts, and the low-energy image shows the tissue of the subject, the contrast agent, ... Furthermore, in order to achieve the above-mentioned object, an image processing program according to a twentieth aspect of the present disclosure causes a computer to execute the following processing: contrast imaging involves irradiating a subject into which a contrast agent has been injected with radiation of a first energy from a radiation source and capturing an image with a radiation detector; and high-energy image imaging involves irradiating a subject with radiation of a second energy higher than the first energy from a radiation source and capturing an image with a radiation detector; obtaining a first difference image showing the difference between the high-energy image and the low-energy image; performing artifact recognition processing on the first difference image to identify an artifact region containing the artifact; showing the difference between the high-energy image and the low-energy image; generating a second difference image in which the artifact is suppressed based on the artifact region; and performing image processing on the first difference image based on the artifact region to generate the second difference image; the image processing is an enhancement processing that emphasizes regions other than the artifact region more than the artifact region; and the low-energy image shows the subject's tissue and the artifact, and the high-energy image shows the subject's tissue, the contrast agent, and the artifact. In order to achieve the above object, an image processing program according to a twenty-first aspect of the present disclosure acquires a low-energy image captured by a radiation detector by irradiating a subject into which a contrast agent has been injected with radiation from a radiation source with a first energy, and a high-energy image captured by a radiation detector by irradiating a subject with radiation from a radiation source with a second energy higher than the first energy, using contrast imaging to acquire a first difference image showing a difference between the high-energy image and the low-energy image, and performs artifact recognition processing on the first difference image to identify an artifact region containing an artifact, and The method causes a computer to execute the following process: a high-energy image and a low-energy image are imaged; a second difference image is generated based on the artifact region, in which artifacts are suppressed; image processing is performed on the high-energy image and the low-energy image based on the artifact region; a second difference image is generated that shows the difference between the high-energy image and the low-energy image after the image processing; the image processing is an enhancement process that enhances areas other than the artifact region more than the artifact region; the low-energy image shows the subject's tissue and artifacts; and the high-energy image shows the subject's tissue, contrast agent, and artifacts. [Effects of the Invention]

[0024] According to the present disclosure, in contrast imaging, a difference image can be obtained in which the contrast agent is clearly visible and the influence of artifact components due to artificial materials is suppressed. [Brief explanation of the drawings]

[0025] [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] 1 is a side view showing an example of the appearance of a mammography apparatus according to an embodiment. [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] 10A and 10B are diagrams for explaining an example of a high-energy image, a low-energy image, a first difference image, and a second difference image. [Figure 6] 10 is a flowchart showing an example of a flow of contrast imaging performed by the radiation image capturing system of the embodiment. [Figure 7] 10 is a flowchart illustrating an example of a flow of a contrast imaging process according to an embodiment. [Figure 8] 10 is a flowchart illustrating an example of the flow of a difference image generation process according to an embodiment. [Figure 9] 10 is a flowchart illustrating an example of the flow of an artifact region identification process in the difference image generation process according to the embodiment. [Figure 10] 10 is a flowchart illustrating an example of the flow of a second difference image generation process in the difference image generation process according to the embodiment. [Figure 11A] 10 is a flowchart showing an example of the flow of an artificial object region identification process according to Modification 1. [Figure 11B]10 is a flowchart showing an example of the flow of an artificial object region identification process according to Modification 2. [Figure 11C] 13 is a flowchart showing an example of the flow of an artificial object region identification process according to Modification 3. [Figure 12A] 13 is a flowchart illustrating an example of the flow of a second differential image generation process according to the fourth modification. [Figure 12B] 13 is a flowchart illustrating an example of the flow of a second differential image generation process according to the fifth modification. [Figure 13] FIG. 10 is a functional block diagram illustrating another example of the functions of the console according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0026] 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.

[0027] 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.

[0028] First, the mammography device 10 of this embodiment will be described. Figure 2 shows a side view of an example of the appearance of the mammography device 10 of this embodiment. Note that Figure 2 shows an example of the appearance of the mammography device 10 when viewed from the right side of the subject.

[0029] 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).

[0030] The operation unit 26 is provided, for example, 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.

[0031] As shown in FIG. 2, 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 in accordance with 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.

[0032] 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.

[0033] 2, a radiation detector 28 is disposed inside the imaging table 30. When imaging is performed in the mammography apparatus 10 of this embodiment, the user positions the subject's breast on the imaging surface 30A of the imaging table 30. 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 of 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 an electric charge, or a direct conversion type radiation detector that directly converts radiation R into an electric charge.

[0034] The radiation irradiator 37 includes a radiation source 37R. As shown in Fig. 2, 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. 2, 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.

[0035] As shown in Figure 2, the mammography device 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.

[0036] 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.

[0037] 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.

[0038] The compression unit 36 ​​is provided with a compression plate driver 41 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 41 and is moved in the vertical direction (Z-axis direction) by the compression plate driver 41, compressing the breast of the subject between the compression plate 40 and the imaging table 30.

[0039] The mammography device 10 of this embodiment has the function of performing general radiography and the function of performing so-called contrast radiography, in which radiography is performed after a contrast agent is injected into the breast of the subject. The mammography device 10 of this embodiment also has a CEDM (Contrast Enhanced Digital Mammography) function, which performs contrast radiography using energy subtraction radiography, as the contrast radiography function. In this embodiment, "contrast radiography" refers to radiography performed after a contrast agent is injected into the breast of the subject (subject 9), and "general radiography" refers to radiography that is not contrast radiography.

[0040] In contrast imaging, a breast injected with a contrast agent is irradiated with radiation R of a first energy to capture a low-energy image. In contrast imaging, a breast is irradiated with radiation R of a second energy higher than the first energy to capture a high-energy image. In this embodiment, a radiographic image captured by irradiating with radiation R of a first energy is referred to as a "low-energy image," and a radiographic image captured by irradiating with radiation R of a second energy is referred to as a "high-energy image." Furthermore, when referring to mammographic images obtained by the mammography device 10 without distinguishing between low-energy images, high-energy images, and differential images (described later), the term "radiographic image" is used to refer to all mammographic images.

[0041] 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.

[0042] The contrast agent and body tissues such as mammary glands 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, the 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.

[0043] 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.

[0044] 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.

[0045] The control unit 50 of this embodiment controls the overall operation of the console 12. The control unit 50 includes a CPU 50A, a ROM 50B, and a RAM 50C. The ROM 50B stores various programs, including a contrast imaging processing program 51A and a subtraction image generation 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 subtraction image generation program 51B of this embodiment is an example of an image processing program of the present disclosure.

[0046] 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.

[0047] 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.

[0048] The I / F unit 54 communicates various types of information between the mammography apparatus 10 and the RIS 2 via wireless or wired communication. In the radiation image capturing system 1 of this embodiment, the image data of the radiation image captured by the mammography apparatus 10 is received by the console 12 from the mammography apparatus 10 via the I / F unit 54 via wireless or wired communication.

[0049] 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 an energy image acquisition unit 60, a first difference image generation unit 62, an artifact region identification unit 64, a second difference image generation unit 66, and a display control unit 68. As an example, in the console 12 of this embodiment, the CPU 50A of the control unit 50 executes the difference image generation program 51B stored in the ROM 50B, so that the CPU 50A functions as the energy image acquisition unit 60, the first difference image generation unit 62, the artifact region identification unit 64, the second difference image generation unit 66, and the display control unit 68.

[0050] The energy image acquisition unit 60 has a function of acquiring low-energy images and high-energy images obtained by contrast imaging. Specifically, the energy image acquisition unit 60 acquires image data representing low-energy images and high-energy images captured by the radiation detector 28 of the mammography device 10 during contrast imaging via the I / F unit 24 and the I / F unit 54. The energy image acquisition unit 60 outputs the acquired low-energy images and high-energy images to the first subtraction image generation unit 62.

[0051] The first difference image generating unit 62 has a function of generating a first difference image showing the difference between the high-energy image and the low-energy image. As an example, the first difference image generating unit 62 of this embodiment generates image data of the first difference image by subtracting, for each corresponding pixel, image data obtained by multiplying the low-energy image by a predetermined coefficient from image data obtained by multiplying the high-energy image by a predetermined coefficient. An example of the weighting coefficient is the absorption coefficient μg of the mammary gland for radiation R of the first energy. L , the absorption coefficient μa of fat for radiation R of the first energy L , the absorption coefficient of the mammary gland for radiation of the second energy R μg H , and the absorption coefficient μa of fat for the second energy radiation R H Specifically, the weighting coefficient α obtained by the following equation (1) is used. α = (μg L -μa L ) / (μg H -μa H ) ···(1)

[0052] 5 and as described above, high-energy image 100H shows an image 102 of the breast (hereinafter referred to as "breast 102"), which is body tissue such as mammary glands and fat, and an image 104 of a contrast agent (hereinafter referred to as "contrast agent 104"), with contrast agent 104 clearly visible. On the other hand, low-energy image 100L shows breast 102, but does not or barely shows contrast agent 104.

[0053] Furthermore, if an artifact is included in the breast, each of the high-energy image 100H and the low-energy image 100L includes an image 106 of the artifact (hereinafter referred to as the "artifact 106"). The artifact does not include at least a contrast agent. Examples of artifacts include markers present in the breast, biopsy needles used in biopsies, and implants. Such artifacts are often made of materials with relatively high radiation absorption, such as metals. As shown in FIG. 5, the artifact 106 appears white, while an artifact component image 108 (hereinafter referred to as the "artifact component 108") reduces the brightness value around the artifact 106, resulting in a black image. Therefore, the contrast is relatively high at the edge of the artifact 106.

[0054] 5, the first subtraction image 110 is an image in which the mammary gland tissue (breast 102) has been removed and the contrast agent 104 has been enhanced. The first subtraction image 110 also contains an artifact 106 and an artifact component 108 caused by the artifact. The first subtraction image generating unit 62 outputs the generated first subtraction image 110 to the artifact region identifying unit 64.

[0055] The artifact region identifying unit 64 has a function of identifying an artifact region containing an artifact from the first subtraction image 110. As described above, the artifact 106 appears as a white image with a high brightness value in the first subtraction image 110. Furthermore, because an artifact is made of a material with a high radiation absorption rate, the artifact 106 tends to have a higher brightness value than the contrast agent 104. Therefore, the artifact region identifying unit 64 of this embodiment uses a threshold value that is higher than the brightness value of the contrast agent 104 and lower than the brightness value of the artifact 106, and identifies pixels in the first subtraction image 110 whose brightness value is equal to or greater than the threshold as pixels of the artifact 106, thereby identifying the artifact region containing the artifact 106. Note that the brightness value of the contrast agent 104 included in the first subtraction image 110 changes depending on how the contrast agent penetrates body tissue. Specifically, the degree of penetration of the contrast agent differs depending on whether the tumor is benign or malignant, and also depending on the time elapsed from the injection of the contrast agent until it washes out. Therefore, it is preferable that the threshold used to identify the artifact 106 be determined depending on at least one of the type of contrast agent used, the type of object being observed, and the time elapsed from the injection of the contrast agent until imaging is performed. It is also preferable that the threshold used to identify the artifact 106 be determined depending on the thickness of the breast.

[0056] Information representing the artificial object region identified by the artificial object region identifying unit 64 is output to the second difference image generating unit 66.

[0057] The second difference image generation unit 66 generates a second difference image that shows the difference between the high-energy image 100H and the low-energy image 100L and in which the influence of the artifact component 108 due to the artifact is suppressed based on the artifact region. In this embodiment, the second difference image generation unit 66 performs image processing on the first difference image 110, such as enhancement processing, such as tone enhancement processing or frequency enhancement processing. In this enhancement processing, the second difference image generation unit 66 emphasizes the artifact region including the artifact 106 less than the non-artificial region. In other words, the second difference image generation unit 66 performs enhancement processing on the first difference image 110 to emphasize the non-artificial region more than the artifact region. Note that in the enhancement processing, the artifact region may not be emphasized at all, or may be emphasized less than the non-artificial region. By performing such enhancement processing, the edges of the artifact 106 become less noticeable, and a second difference image 120 in which the influence of the artifact component 108 is suppressed is generated.

[0058] The second difference image generating unit 66 outputs the generated second difference image 120 to the display control unit 68.

[0059] The display control unit 68 has a function of causing the display unit 58 to display the second difference image 120.

[0060] 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. Fig. 6 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. 6, 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.

[0061] Next, in step S14, the console 12 performs contrast imaging processing to perform contrast imaging using the mammography apparatus 10. Fig. 7 shows a flowchart illustrating an example of the flow of contrast imaging processing executed by the console 12 of this embodiment. As an example, the console 12 of this embodiment performs the contrast imaging processing, an example of which is shown in Fig. 7, by having the CPU 50A of the control unit 50 execute a contrast imaging processing program 51A stored in the ROM 50B.

[0062] 7, the control unit 50 determines whether or not it has received an instruction to irradiate radiation R. Until an irradiation instruction is received, the determination in step S100 remains negative. On the other hand, if an irradiation instruction is received, the determination in step S100 remains positive, and the process proceeds to step S102.

[0063] In step S102, the control unit 50 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.

[0064] In the next step S104, the control unit 50 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.

[0065] The order in which the low-energy image and the high-energy image are captured is not limited to that in the present embodiment, and the high-energy image may be captured before the low-energy image. That is, the order of the processing in step S102 and the processing in step S104 may be reversed.

[0066] When the contrast imaging process shown in Fig. 7 ends in this way, the contrast imaging process of step S14 shown in Fig. 6 ends. Note that the control unit 50 may notify the user that the contrast imaging process has ended.

[0067] In the next step S16, breast compression is released. Specifically, the control unit 50 outputs an instruction to the mammography device 10 to move the compression paddle 40 away from the imaging table 30. Based on the input instruction, the control unit 50 of the mammography device 10 moves the compression paddle 40 away from the imaging table 30. This releases breast compression. Note that breast compression may be released in response to a user instruction, or automatically when contrast imaging is completed.

[0068] In the next step S18, the console 12 performs a difference image generation process for generating a second difference image. Fig. 8 shows a flowchart illustrating an example of the flow of the difference image generation process executed by the console 12 of this embodiment. As an example, the console 12 of this embodiment performs the difference image generation process, an example of which is shown in Fig. 8, by causing the CPU 50A of the control unit 50 to execute a difference image generation program 51B stored in the ROM 50B.

[0069] In step S200, the energy image acquisition unit 60 acquires the low-energy image 100L and the high-energy image 100H obtained by contrast imaging, as described above.

[0070] In the next step S202, the first subtraction image generating unit 62 generates the first subtraction image 110 from the low-energy image 100L and the high-energy image 100H, as described above.

[0071] In the next step S204, the artifact region identification unit 64 executes artifact region identification processing to identify an artifact region including the artifact 106 from the first difference image 110 generated in step S202. Fig. 9 shows a flowchart illustrating an example of the flow of the artifact region identification processing of this embodiment.

[0072] 9, the artifact region identification unit 64 selects a pixel from the first difference image 110. It is preferable to select one pixel, but in consideration of the processing load, multiple adjacent pixels may be selected.

[0073] In the next step S302, the artifact region identification unit 64 determines whether the luminance value of the pixel selected in step S300 is equal to or greater than the threshold value for identifying the artifact 106. If the luminance value is not equal to or greater than the threshold value, in other words, if the luminance value is less than the threshold value, the determination in step S302 is negative, and the process proceeds to step S306. On the other hand, if the luminance value is equal to or greater than the threshold value, the determination in step S302 is positive, and the process proceeds to step S304.

[0074] In step S304, the artifact region identifying unit 64 identifies pixels whose brightness values ​​are equal to or greater than the threshold value, in other words, the pixels selected in step S300, as pixels in the artifact region.

[0075] In the next step S306, the artifact region identification unit 64 determines whether or not all pixels of the first difference image 110 have been selected in step S300. That is, it determines whether or not a determination has been made as to whether or not all pixels of the first difference image 110 are pixels of an artifact region. If all pixels have not been selected, the determination in step S306 is negative, the process returns to step S300, new pixels are selected, and the processes in steps S300 to S304 are repeated. On the other hand, if all pixels have been selected, the determination in step S306 is positive, and the artifact region identification process shown in FIG. 9 ends.

[0076] In this way, in the artifact region identification process shown in FIG. 9, the region of pixels identified as an artifact region is identified as an artifact region.

[0077] When the artificial object region identification process shown in FIG. 9 is completed, step S204 of the difference image generation process shown in FIG. 8 is completed, and the process proceeds to step S206.

[0078] In step S206, the second difference image generation unit 66 executes a second difference image generation process to generate a second difference image 120 in which the influence of artifact components due to the artifact is suppressed, based on the artifact region identified in step S204. Fig. 10 shows a flowchart illustrating an example of the flow of the second difference image generation process of this embodiment.

[0079] 10, the second difference image generation unit 66 performs, as described above, enhancement processing on the first difference image 110, which enhances areas other than the artifact area more than the artifact area. By performing enhancement processing on the first difference image 110 in this manner, the edges of the artifact 106 become less noticeable, and a second difference image 120 is generated in which the influence of the artifact component 108 is suppressed.

[0080] When the second difference image generation process shown in FIG. 10 is completed, step S206 of the difference image generation process shown in FIG. 8 is completed, and the process proceeds to step S208.

[0081] In the next step S208, the display control unit 68 controls the display unit 58 to display the second difference image generated in step S206.

[0082] There is no particular limitation on the display format for displaying the second difference image on the display unit 58. For example, in addition to the difference image, the display unit 58 may also display the low-energy image and the high-energy image.

[0083] When the process of step S208 is completed, the subtraction image generation process shown in Fig. 8 is completed. When the subtraction image generation process shown in Fig. 8 is completed in this manner, the subtraction image generation process of step S18 in the contrast imaging shown in Fig. 6 is completed. The low-energy image, the high-energy image, the first subtraction image, and the second subtraction image may be stored in the storage unit 52 of the console 12, a PACS (Picture Archiving and Communication Systems), or the like.

[0084] When the process of step S18 is completed, the series of processes related to contrast imaging of this embodiment shown in FIG. 6 is completed.

[0085] The above-described difference image generation process is merely an example, and various modifications are possible. For example, the difference image generation process may be modified as follows.

[0086] (Modification 1: Modification of artificial object area identification process) In this modification, a modification of the artifact region identification process (step S204 in FIG. 8) in the difference image generation process will be described.

[0087] As described above, since artificial objects are made of materials with relatively high radiation absorption, the lower the energy of the irradiated radiation, the greater the amount of radiation absorbed. That is, in an artificial object, the amount of radiation of a first energy is significantly greater than the amount of radiation of a second energy. For example, the amount of radiation of a first energy absorbed by an artificial object is approximately twice the amount of radiation of a second energy absorbed by an artificial object. On the other hand, since a contrast agent has the k-absorption edge described above, the amount of radiation of a first energy absorbed by the contrast agent is relatively smaller than that of an artificial object. Therefore, the artificial object region identifying unit 64 of this modification identifies an artificial object region by comparing the amount of radiation absorbed in the high-energy image 100H with the amount of radiation absorbed in the low-energy image 100L. That is, the artificial object region identifying unit 64 compares the pixel values ​​of corresponding pixels in the high-energy image and the low-energy image, and identifies pixels whose luminance value in the low-energy image is greater than that in the high-energy image as pixels in the artificial object region.

[0088] 11A shows a flowchart illustrating an example of the flow of the artifact area identification process in the difference image generation process of this modified example. The artifact area identification process of this modified example shown in FIG. 11A differs from the artifact area identification process of the above embodiment (see FIG. 9) in that it includes step S303 between step S302 and step S304.

[0089] As shown in FIG. 11A, in this modification, if the luminance value of the selected pixel is equal to or greater than the threshold value in step S302, the determination is affirmative, and the process proceeds to step S303.

[0090] 11A, the artifact region identifying unit 64 determines whether the luminance value of the low-energy image 100L is greater than the luminance value of the high-energy image 100H for the pixel selected in step S300. If the luminance value of the low-energy image 100L is not greater than the luminance value of the high-energy image 100H, in other words, if the luminance value of the low-energy image 100L is equal to or less than the luminance value of the high-energy image 100H, the determination in step S303 is negative, and the process proceeds to step S306. On the other hand, if the luminance value of the low-energy image 100L is greater than the luminance value of the high-energy image 100H, the determination in step S303 is positive, and the process proceeds to step S304.

[0091] In this manner, in this modification, an artifact region including the artifact 106 is identified from the first subtraction image 110 including the contrast agent 104 and the artifact 106 based on the difference in the amount of radiation absorbed by the contrast agent and the artifact. Therefore, according to this modification, it is possible to identify the artifact region with higher accuracy.

[0092] (Modification 2: Modification of Artificial Object Area Identification Processing) In this modification, a modification of the artifact region identification process (step S204 in FIG. 8) in the difference image generation process will be described.

[0093] FIG. 11B shows a flowchart illustrating an example of the flow of the artifact region identification process in the difference image generation process of this modified example.

[0094] 11B, the artifact region identifying unit 64 performs frequency decomposition on the first difference image 110 to obtain a high-frequency image. That is, the artifact region identifying unit 64 performs frequency decomposition on the first difference image 110 to detect the edges of the contrast agent 104 and the artifact 106. For example, the artifact region identifying unit 64 applies a high-pass filter to the first difference image 110 to obtain a high-frequency image.

[0095] In the next step S322, the artifact region identifying unit 64 identifies a region with high contrast from the high-frequency image acquired in step S320 as an artifact region containing the artifact 106. The artifact 106 included in the first subtraction image 110 has a higher contrast at its edge portion than the contrast at the edge portion of the contrast agent 104 due to the artifact components 108 surrounding it (see also FIG. 5). Therefore, an average value or the like of the contrast at the edge portion of the contrast agent 104 is obtained in advance as a contrast threshold, and an area surrounded by edges having a contrast higher than the contrast threshold can be identified as an artifact region containing the artifact 106. Therefore, the artifact region identifying unit 64 identifies an area with a contrast higher than the average value as an artifact region.

[0096] When the processing in step S322 ends, the artificial object region identification processing of this modified example shown in FIG. 11B ends.

[0097] (Modification 3: Modification of Artificial Object Area Identification Processing) In this modification, a modification of the artifact region identification process (step S204 in FIG. 8) in the difference image generation process will be described.

[0098] FIG. 11C shows a flowchart illustrating an example of the flow of the artifact region identification process in the difference image generation process of this modified example.

[0099] 11C , the artifact region identifying unit 64 applies artifact recognition processing to the first difference image 110 to recognize the artifact 106. In such artifact recognition processing, a plurality of templates according to the type of artifact 106, etc., may be prepared, and the artifact region identifying unit 64 may perform template matching on the first difference image 110 to recognize the artifact 106 and identify the artifact region including the artifact 106. Alternatively, for example, CAD (Computer Aided Diagnosis) may be applied to the first difference image 110 to recognize the artifact 106 and identify the artifact region including the artifact 106. For example, the artificial object area may be identified by applying a trained machine learning model that has been trained to output the artificial object area in the first differential image 110 when the first differential image 110 is input using training data that includes multiple pairs of a first differential image 110 containing the artificial object 106 and information representing the artificial object area in the first differential image 110, and multiple pairs of a first differential image 110 not containing the artificial object 106 and information representing the artificial object area in the first differential image 110.

[0100] When the processing in step S340 ends, the artifact region identification processing of this modified example shown in FIG. 11C ends.

[0101] According to this modification, artifact regions can be identified by applying artifact recognition processing, and therefore, artifact regions can be easily identified.

[0102] (Modification 4: Modification of the Difference Image Generation Process) In this modification, a modification of the second difference image generation process (step S206 in FIG. 8) in the difference image generation process will be described.

[0103] The second difference image generating unit 66 of this modification performs enhancement processing such as tone enhancement processing or frequency enhancement processing as image processing on the low-energy image 100L and the high-energy image 100H instead of the first difference image 110.

[0104] FIG. 12A shows a flowchart illustrating an example of the flow of the second difference image generation process in the difference image generation process of this modified example.

[0105] In step S420 of Fig. 12A, the second difference image generation unit 66 performs enhancement processing on the low-energy image 100L to enhance regions other than the artifact region more than the artifact region. Specifically, the second difference image generation unit 66 identifies an artifact region in the low-energy image 100L that corresponds to the artifact region identified in the first difference image 110. Then, the second difference image generation unit 66 performs enhancement processing on the regions other than the artifact region in the low-energy image 100L to enhance the artifact region more than the artifact region. The enhancement processing performed here is the same as the enhancement processing performed on the first difference image 110 described above (see step S400 of Fig. 10).

[0106] By performing such enhancement processing, the edges of the artifact 106 become less noticeable in the low-energy image 100L, and the influence of the artifact component 108 is suppressed.

[0107] In the next step S422, the second subtraction image generating unit 66 performs enhancement processing on the high-energy image 100H to enhance regions other than the artifact regions more than the artifact regions. Specifically, the second subtraction image generating unit 66 identifies artifact regions in the high-energy image 100H that correspond to the artifact regions identified in the first subtraction image 110. Then, the second subtraction image generating unit 66 performs enhancement processing on the regions other than the artifact regions in the high-energy image 100H to enhance them more than the artifact regions. The enhancement processing performed here is the same as the enhancement processing performed on the first subtraction image 110 described above (see step S400 in FIG. 10).

[0108] By performing such enhancement processing, the edges of the artifact 106 become less noticeable in the high-energy image 100H, and the influence of the artifact component 108 is suppressed.

[0109] In the next step S424, the second difference image generation unit 66 generates a second difference image 120 from the low-energy image 100L after the enhancement process in step S420 and the high-energy image 100H after the enhancement process in step S422. That is, the second difference image generation unit 66 generates the second difference image 120 from the low-energy image 100L and the high-energy image 100H in which the influence of the artifact component 108 has been suppressed. The method of generating the second difference image 120 can be the same as the method used by the first difference image generation unit 62 to generate the first difference image 110 from the low-energy image 100L and the high-energy image 100H.

[0110] When the process of step S424 ends, the second difference image generation process of this modified example shown in FIG. 12A ends.

[0111] In this way, according to this modification, a low-energy image 100L and a high-energy image 100H in which the influence of the artifact component 108 of the artifact is suppressed can also be obtained. Therefore, when the user also interprets the low-energy image 100L and the high-energy image 100H, the low-energy image 100L and the high-energy image 100H in which the influence of the artifact component 108 of the artifact is suppressed can be provided.

[0112] (Modification 5: Modification of the Difference Image Generation Process) In this modification, a modification of the second difference image generation process (step S206 in FIG. 8) in the difference image generation process will be described.

[0113] The second difference image generating unit 66 of this modification performs processing to suppress artifact components when generating the second difference image 120 from the low-energy image 100L and the high-energy image 100H.

[0114] FIG. 12B shows a flowchart illustrating an example of the flow of the second difference image generation process in the difference image generation process of this modified example.

[0115] In step S440 of FIG. 12B , the second difference image generation unit 66 generates a second difference image 120 from the low-energy image 100L and the high-energy image 100H, suppressing pixel values ​​in the artifact region. For example, the second difference image generation unit 66 generates a second difference image 120 that shows the difference between the high-energy image 100H and the low-energy image 100L and reduces pixel values ​​in the artifact region compared to the pixel values ​​in the artifact region in the first difference image 110. Note that the method for reducing pixel values ​​in the artifact region in the second difference image 120 is not limited. For example, pixel values ​​in the artifact region in the second difference image 120 may be replaced with pixel values ​​surrounding the artifact region or a pixel value similar to the average of the surrounding pixel values. Alternatively, for example, pixel values ​​in the artifact region in the second difference image 120 may be uniformly set to a predetermined value or less. Alternatively, for example, pixel values ​​may be reduced by applying a nonlinear function to the contrast of the artifact region in the second difference image 120.

[0116] When the process of step S440 ends, the second difference image generation process of this modified example shown in FIG. 12B ends.

[0117] As described above, according to this modification, the process of generating the second difference image 120 from the low-energy image 100L and the high-energy image 100H includes a process of suppressing artifact components.

[0118] As described above, the energy image acquisition unit 60 of the console 12 in each of the above embodiments acquires a low-energy image 100L captured by the radiation detector 28 when the radiation source 37R irradiates a breast injected with a contrast agent with radiation of a first energy, and a high-energy image 100H captured by the radiation detector 28 when the radiation source 37R irradiates the breast with radiation of a second energy higher than the first energy. The first subtraction image generation unit 62 generates a first subtraction image 110 that shows the difference between the high-energy image 100H and the low-energy image 100L, thereby acquiring the first subtraction image 110. The artifact region identification unit 64 identifies an artifact region containing the artifact 106 from the first subtraction image 110. The second subtraction image generation unit 66 generates a second subtraction image 120 that shows the difference between the high-energy image 100H and the low-energy image 100L and in which the influence of the artifact component 108 due to the artifact is suppressed based on the artifact region.

[0119] The first subtraction image 110 showing the difference between the high-energy image 100H and the low-energy image 100L is significantly affected by artifact components 108 due to artifacts, making it difficult to see tissues stained with the contrast agent 104. In particular, when enhancement processing is performed to make the contrast agent 104 more visible, the artifact region including the artifact 106 may be over-enhanced, making it difficult to see tissues stained with the contrast agent 104.

[0120] In contrast to this, in this embodiment, an artifact region including the artifact 106 is identified from the first difference image 110, and a second difference image 120 is generated based on the identified artifact region, in which the influence of the artifact component 108 due to the artifact is suppressed.

[0121] Therefore, according to the console 12 of each of the above embodiments, in contrast imaging, it is possible to obtain the second difference image 120 in which the contrast agent is clearly visible and the influence of the artifact component 108 due to artificial matter is suppressed.

[0122] For example, if the artificial object is a biopsy needle, the influence of the artifact component 108 caused by the biopsy needle is suppressed in the second difference image 120, making it easier to see the tissue stained with the contrast agent 104 that is collected by the biopsy needle, and making it easier to collect the tissue.

[0123] 9, 11B, or 11C and the second subtraction image generation process is the subtraction image generation process shown in FIG. 10, the console 12 may be configured to include a first subtraction image acquisition unit 61 having a function of acquiring a first subtraction image 110, instead of the energy image acquisition unit 60 and the first subtraction image generation unit 62, as shown in FIG. 13. In this case, the first subtraction image acquisition unit 61 acquires the first subtraction image 110 generated by a device external to the console 12. The console 12 shown in FIG. 13 may be configured not to acquire the low-energy image 100L and the high-energy image 100H.

[0124] In the above embodiment, the low-energy image 100L and the high-energy image 100H are captured by irradiating radiation of a first energy and radiation of a second energy from a single irradiation position without moving the position of the radiation source 37R. However, the above embodiments can also be applied to, for example, stereo imaging in which radiation is irradiated from multiple irradiation positions to capture multiple radiation images, or contrast imaging in tomosynthesis imaging. By applying the above embodiments to tomosynthesis imaging, tomographic images in which the influence of artifact components of artificial objects is suppressed can be obtained, allowing the three-dimensional position of tissue stained with a contrast agent to be derived with greater accuracy.

[0125] Furthermore, the console 12 in each of the above embodiments identifies the artificial object area, but it may also be configured to derive the position of the artificial object based on the identified artificial object area, and display information representing the derived position of the artificial object on the display unit 58.

[0126] In the above embodiments, the case where the artifact is present inside the breast has been described, but the location of the artifact is not limited to inside the breast. The artifact may be present outside the breast. In this case, too, the influence of the artifact component of the artifact in the second subtraction image 120 can be suppressed by performing the same processing as in the above embodiments.

[0127] 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.

[0128] In the above embodiment, the subtraction image generation process is performed immediately after the process of S16 in Fig. 6 is completed, but the timing of performing the subtraction image generation process, i.e., the timing of generating the second subtraction image 120, is not limited to this embodiment. For example, the timing of generating the second subtraction image 120 may be performed at a timing desired by the user who interprets the images after contrast imaging.

[0129] 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 energy image acquisition unit 60, the first difference image generation unit 62, the artifact region identification unit 64, the second difference image generation unit 66, and the display control unit 68 may be provided in a device other than the console 12, such as the mammography device 10 or an external device.

[0130] Furthermore, in the above embodiment, the following various processors can be used as the hardware structure of processing units that perform various processes, such as the energy image acquisition unit 60, the first difference image generation unit 62, the artifact region identification unit 64, the second difference image generation unit 66, and the display control unit 68. 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 with 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).

[0131] 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.

[0132] 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.

[0133] Furthermore, more specifically, the hardware structure of these various processors can be an electric circuit that combines circuit elements such as semiconductor elements.

[0134] In the above-described embodiments, the contrast imaging processing program 51A and the subtraction image generation program 51B are pre-stored (installed) in the ROM 50B. However, the present invention is not limited to this. The contrast imaging processing program 51A and the subtraction image generation 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. The contrast imaging processing program 51A and the subtraction image generation program 51B may be downloaded from an external device via a network. [Explanation of symbols]

[0135] 1. Radiography system 2 RIS 10 Mammography equipment 12 Console 20, 50 control unit, 20A, 50A CPU, 20B, 50B ROM, 20C, 50C RAM 22, 52 Storage section 24, 54 I / F section 26, 56 Operation section 27 Grid 28 Radiation detector Buses 29 and 59 30 imaging table, 30A imaging surface 31 Grid moving section 32 Arm section 34 Foundation 35 Shaft 36 Compression Unit 37 Radiation irradiation section, 37R radiation source 38 Face Guard 40 Compression Plate 41 Compression plate drive unit 51A contrast imaging processing program, 51B difference image generation program 58 Display section 60 Energy image acquisition unit 62 First differential image generation unit 64 Artifact area identification part 66 Second differential image generation unit 68 Display control unit 100H high energy image, 100L low energy image 102 Breast 104 Contrast agents 106 Artifacts 108 Artifact Components 110 First difference image 120 Second difference image R Radiation

Claims

1. at least one processor; The processor: a low-energy image captured by a radiation detector by irradiating a subject into which a contrast agent has been injected with radiation from a radiation source with radiation of a first energy; a high-energy image captured by the radiation detector by irradiating a subject from the radiation source with radiation of a second energy higher than the first energy; and a first difference image showing a difference between the high-energy image and the low-energy image; Identifying an artifact region containing an artifact from the first difference image; generating a second difference image that shows a difference between the high-energy image and the low-energy image, and in which the influence of artifact components due to the artifact is suppressed based on the artifact region; performing image processing based on the artifact region on the first difference image to generate the second difference image; the image processing is an enhancement process for enhancing an area other than the artificial object area more than the artificial object area, the low-energy image shows the tissue of the subject and the artifact; the high-energy image shows the tissue of the subject, the contrast agent, and the artifact; Image processing device.

2. at least one processor; The processor: a low-energy image captured by a radiation detector by irradiating a subject into which a contrast agent has been injected with radiation from a radiation source with radiation of a first energy; a high-energy image captured by the radiation detector by irradiating a subject from the radiation source with radiation of a second energy higher than the first energy; and a first difference image showing a difference between the high-energy image and the low-energy image; Identifying an artifact region containing an artifact from the first difference image; generating a second difference image that shows a difference between the high-energy image and the low-energy image, and in which the influence of artifact components due to the artifact is suppressed based on the artifact region; performing image processing on the high-energy image and the low-energy image based on the artifact region; generating a second difference image showing a difference between the high-energy image and the low-energy image after the image processing; the image processing is an enhancement process for enhancing an area other than the artificial object area more than the artificial object area, the low-energy image shows the tissue of the subject and the artifact; the high-energy image shows the tissue of the subject, the contrast agent, and the artifact; Image processing device.

3. The processor: The artifact region is identified by performing an artifact recognition process on the first difference image.

3. The image processing device according to claim 1.

4. The processor: Pixels in the first difference image having pixel values ​​equal to or greater than a threshold determined according to the contrast agent or the artifact are determined as pixels in the artifact region.

3. The image processing device according to claim 1.

5. The processor: A pixel whose brightness value in the first difference image is equal to or greater than a predetermined value and whose brightness value in the low-energy image is greater than that in the high-energy image is determined to be a pixel in the artificial object region.

3. The image processing device according to claim 1.

6. at least one processor; The processor: a first difference image showing a difference between the high-energy image and the low-energy image obtained by contrast imaging, the low-energy image being captured by a radiation detector when a radiation source irradiates a subject into which a contrast agent has been injected with radiation, and the high-energy image being captured by the radiation detector when the radiation source irradiates with radiation of a second energy higher than the first energy; identifying pixels from the first difference image having pixel values ​​equal to or greater than a threshold determined according to the contrast agent or the artifact as pixels in an artifact region including the artifact; performing image processing based on the artifact region on the first difference image to generate a second difference image in which the influence of the artifact component due to the artifact is suppressed; performing image processing based on the artifact region on the first difference image to generate the second difference image; the image processing is an enhancement process for enhancing an area other than the artificial object area more than the artificial object area, the low-energy image shows the tissue of the subject and the artifact; the high-energy image shows the tissue of the subject, the contrast agent, and the artifact; Image processing device.

7. at least one processor; The processor: a first difference image showing a difference between the high-energy image and the low-energy image obtained by contrast imaging, the low-energy image being captured by a radiation detector when a radiation source irradiates a subject into which a contrast agent has been injected with radiation, and the high-energy image being captured by the radiation detector when the radiation source irradiates with radiation of a second energy higher than the first energy; identifying pixels from the first difference image having pixel values ​​equal to or greater than a threshold determined according to the contrast agent or the artifact as pixels in an artifact region including the artifact; performing image processing based on the artifact region on the first difference image to generate a second difference image in which the influence of the artifact component due to the artifact is suppressed; performing image processing on the high-energy image and the low-energy image based on the artifact region; generating a second difference image showing a difference between the high-energy image and the low-energy image after the image processing; the image processing is an enhancement process for enhancing an area other than the artificial object area more than the artificial object area, the low-energy image shows the tissue of the subject and the artifact; the high-energy image shows the tissue of the subject, the contrast agent, and the artifact; Image processing device.

8. at least one processor; The processor: a first difference image showing a difference between the high-energy image and the low-energy image obtained by contrast imaging, the low-energy image being captured by a radiation detector when a radiation source irradiates a subject into which a contrast agent has been injected with radiation, and the high-energy image being captured by the radiation detector when the radiation source irradiates with radiation of a second energy higher than the first energy; performing an artifact recognition process on the first difference image to identify an artifact region containing an artifact; generating a second difference image that shows a difference between the high-energy image and the low-energy image, and in which the influence of artifact components due to the artifact is suppressed based on the artifact region; performing image processing based on the artifact region on the first difference image to generate the second difference image; the image processing is an enhancement process for enhancing an area other than the artificial object area more than the artificial object area, the low-energy image shows the tissue of the subject and the artifact; the high-energy image shows the tissue of the subject, the contrast agent, and the artifact; Image processing device.

9. at least one processor; The processor: a first difference image showing a difference between the high-energy image and the low-energy image obtained by contrast imaging, the low-energy image being captured by a radiation detector when a radiation source irradiates a subject into which a contrast agent has been injected with radiation, and the high-energy image being captured by the radiation detector when the radiation source irradiates with radiation of a second energy higher than the first energy; performing an artifact recognition process on the first difference image to identify an artifact region containing an artifact; generating a second difference image that shows a difference between the high-energy image and the low-energy image, and in which the influence of artifact components due to the artifact is suppressed based on the artifact region; performing image processing on the high-energy image and the low-energy image based on the artifact region; generating a second difference image showing a difference between the high-energy image and the low-energy image after the image processing; the image processing is an enhancement process for enhancing an area other than the artificial object area more than the artificial object area, the low-energy image shows the tissue of the subject and the artifact; the high-energy image shows the tissue of the subject, the contrast agent, and the artifact; Image processing device.

10. An image processing method executed by a processor included in an image processing device, The processor: a low-energy image captured by a radiation detector by irradiating a subject into which a contrast agent has been injected with radiation from a radiation source with radiation of a first energy; a high-energy image captured by the radiation detector by irradiating a subject from the radiation source with radiation of a second energy higher than the first energy; and a first difference image showing a difference between the high-energy image and the low-energy image; Identifying an artifact region containing an artifact from the first difference image; generating a second difference image that shows a difference between the high-energy image and the low-energy image, and in which the influence of artifact components due to the artifact is suppressed based on the artifact region; performing image processing based on the artifact region on the first difference image to generate the second difference image; the image processing is an enhancement process for enhancing an area other than the artificial object area more than the artificial object area, the low-energy image shows the tissue of the subject and the artifact; the high-energy image shows the tissue of the subject, the contrast agent, and the artifact; An image processing method for an image processing device.

11. An image processing method executed by a processor included in an image processing device, The processor: a low-energy image captured by a radiation detector by irradiating a subject into which a contrast agent has been injected with radiation from a radiation source with radiation of a first energy; a high-energy image captured by the radiation detector by irradiating a subject from the radiation source with radiation of a second energy higher than the first energy; and a first difference image showing a difference between the high-energy image and the low-energy image; Identifying an artifact region containing an artifact from the first difference image; generating a second difference image that shows a difference between the high-energy image and the low-energy image, and in which the influence of artifact components due to the artifact is suppressed based on the artifact region; performing image processing on the high-energy image and the low-energy image based on the artifact region; generating a second difference image showing a difference between the high-energy image and the low-energy image after the image processing; the image processing is an enhancement process for enhancing an area other than the artificial object area more than the artificial object area, the low-energy image shows the tissue of the subject and the artifact; the high-energy image shows the tissue of the subject, the contrast agent, and the artifact; An image processing method for an image processing device.

12. An image processing method executed by a processor included in an image processing device, The processor: a first difference image showing a difference between the high-energy image and the low-energy image obtained by contrast imaging, the low-energy image being captured by a radiation detector when a radiation source irradiates a subject into which a contrast agent has been injected with radiation, and the high-energy image being captured by the radiation detector when the radiation source irradiates with radiation of a second energy higher than the first energy; identifying pixels from the first difference image having pixel values ​​equal to or greater than a threshold determined according to the contrast agent or the artifact as pixels in an artifact region including the artifact; performing image processing based on the artifact region on the first difference image to generate a second difference image in which the influence of the artifact component due to the artifact is suppressed; performing image processing based on the artifact region on the first difference image to generate the second difference image; the image processing is an enhancement process for enhancing an area other than the artificial object area more than the artificial object area, the low-energy image shows the tissue of the subject and the artifact; the high-energy image shows the tissue of the subject, the contrast agent, and the artifact; An image processing method for an image processing device.

13. An image processing method executed by a processor included in an image processing device, The processor: a first difference image showing a difference between the high-energy image and the low-energy image obtained by contrast imaging, the low-energy image being captured by a radiation detector when a radiation source irradiates a subject into which a contrast agent has been injected with radiation, and the high-energy image being captured by the radiation detector when the radiation source irradiates with radiation of a second energy higher than the first energy; identifying pixels from the first difference image having pixel values ​​equal to or greater than a threshold determined according to the contrast agent or the artifact as pixels in an artifact region including the artifact; performing image processing based on the artifact region on the first difference image to generate a second difference image in which the influence of the artifact component due to the artifact is suppressed; performing image processing on the high-energy image and the low-energy image based on the artifact region; generating a second difference image showing a difference between the high-energy image and the low-energy image after the image processing; the image processing is an enhancement process for enhancing an area other than the artificial object area more than the artificial object area, the low-energy image shows the tissue of the subject and the artifact; the high-energy image shows the tissue of the subject, the contrast agent, and the artifact; An image processing method for an image processing device.

14. An image processing method executed by a processor included in an image processing device, The processor: a first difference image showing a difference between the high-energy image and the low-energy image obtained by contrast imaging, the low-energy image being captured by a radiation detector when a radiation source irradiates a subject into which a contrast agent has been injected with radiation, and the high-energy image being captured by the radiation detector when the radiation source irradiates with radiation of a second energy higher than the first energy; performing an artifact recognition process on the first difference image to identify an artifact region containing an artifact; generating a second difference image that shows a difference between the high-energy image and the low-energy image, and in which the influence of artifact components due to the artifact is suppressed based on the artifact region; performing image processing based on the artifact region on the first difference image to generate the second difference image; the image processing is an enhancement process for enhancing an area other than the artificial object area more than the artificial object area, the low-energy image shows the tissue of the subject and the artifact; the high-energy image shows the tissue of the subject, the contrast agent, and the artifact; An image processing method for an image processing device.

15. An image processing method executed by a processor included in an image processing device, The processor: a first difference image showing a difference between the high-energy image and the low-energy image obtained by contrast imaging, the low-energy image being captured by a radiation detector when a radiation source irradiates a subject into which a contrast agent has been injected with radiation, and the high-energy image being captured by the radiation detector when the radiation source irradiates with radiation of a second energy higher than the first energy; performing an artifact recognition process on the first difference image to identify an artifact region containing an artifact; generating a second difference image that shows a difference between the high-energy image and the low-energy image, and in which the influence of artifact components due to the artifact is suppressed based on the artifact region; performing image processing on the high-energy image and the low-energy image based on the artifact region; generating a second difference image showing a difference between the high-energy image and the low-energy image after the image processing; the image processing is an enhancement process for enhancing an area other than the artificial object area more than the artificial object area, the low-energy image shows the tissue of the subject and the artifact; the high-energy image shows the tissue of the subject, the contrast agent, and the artifact; An image processing method for an image processing device.

16. a low-energy image captured by a radiation detector by irradiating a subject into which a contrast agent has been injected with radiation from a radiation source with radiation of a first energy; a high-energy image captured by the radiation detector by irradiating a subject from the radiation source with radiation of a second energy higher than the first energy; and a first difference image showing a difference between the high-energy image and the low-energy image; Identifying an artifact region containing an artifact from the first difference image; generating a second difference image showing the difference between the high-energy image and the low-energy image, the second difference image being based on the artifact region and suppressing the artifact; performing image processing based on the artifact region on the first difference image to generate the second difference image; the image processing is an enhancement process for enhancing an area other than the artificial object area more than the artificial object area, the low-energy image shows the tissue of the subject and the artifact; the high-energy image shows the tissue of the subject, the contrast agent, and the artifact; An image processing program that causes a computer to perform the processing.

17. a low-energy image captured by a radiation detector by irradiating a subject into which a contrast agent has been injected with radiation from a radiation source with radiation of a first energy; a high-energy image captured by the radiation detector by irradiating a subject from the radiation source with radiation of a second energy higher than the first energy; and a first difference image showing a difference between the high-energy image and the low-energy image; Identifying an artifact region containing an artifact from the first difference image; generating a second difference image showing the difference between the high-energy image and the low-energy image, the second difference image being based on the artifact region and suppressing the artifact; performing image processing on the high-energy image and the low-energy image based on the artifact region; generating a second difference image showing a difference between the high-energy image and the low-energy image after the image processing; the image processing is an enhancement process for enhancing an area other than the artificial object area more than the artificial object area, the low-energy image shows the tissue of the subject and the artifact; the high-energy image shows the tissue of the subject, the contrast agent, and the artifact; An image processing program that causes a computer to perform the processing.

18. a first difference image showing a difference between the high-energy image and the low-energy image obtained by contrast imaging, the low-energy image being captured by a radiation detector when a radiation source irradiates a subject into which a contrast agent has been injected with radiation, and the high-energy image being captured by the radiation detector when the radiation source irradiates with radiation of a second energy higher than the first energy; identifying pixels from the first difference image having pixel values ​​equal to or greater than a threshold determined according to the contrast agent or the artifact as pixels in an artifact region including the artifact; performing image processing based on the artifact region on the first difference image to generate a second difference image in which the artifact is suppressed; performing image processing based on the artifact region on the first difference image to generate the second difference image; the image processing is an enhancement process for enhancing an area other than the artificial object area more than the artificial object area, the low-energy image shows the tissue of the subject and the artifact; the high-energy image shows the tissue of the subject, the contrast agent, and the artifact; An image processing program that causes a computer to perform the processing.

19. a first difference image showing a difference between the high-energy image and the low-energy image obtained by contrast imaging, the low-energy image being captured by a radiation detector when a radiation source irradiates a subject into which a contrast agent has been injected with radiation, and the high-energy image being captured by the radiation detector when the radiation source irradiates with radiation of a second energy higher than the first energy; identifying pixels from the first difference image having pixel values ​​equal to or greater than a threshold determined according to the contrast agent or the artifact as pixels in an artifact region including the artifact; performing image processing based on the artifact region on the first difference image to generate a second difference image in which artifacts are suppressed; performing image processing on the high-energy image and the low-energy image based on the artifact region; generating a second difference image showing a difference between the high-energy image and the low-energy image after the image processing; the image processing is an enhancement process for enhancing an area other than the artificial object area more than the artificial object area, the low-energy image shows the tissue of the subject and the artifact; the high-energy image shows the tissue of the subject, the contrast agent, and the artifact; An image processing program that causes a computer to perform the processing.

20. a first difference image showing a difference between the high-energy image and the low-energy image obtained by contrast imaging, the low-energy image being captured by a radiation detector when a radiation source irradiates a subject into which a contrast agent has been injected with radiation, and the high-energy image being captured by the radiation detector when the radiation source irradiates with radiation of a second energy higher than the first energy; performing an artifact recognition process on the first difference image to identify an artifact region containing an artifact; generating a second difference image showing the difference between the high-energy image and the low-energy image, the second difference image being based on the artifact region and suppressing the artifact; performing image processing based on the artifact region on the first difference image to generate the second difference image; the image processing is an enhancement process for enhancing an area other than the artificial object area more than the artificial object area, the low-energy image shows the tissue of the subject and the artifact; the high-energy image shows the tissue of the subject, the contrast agent, and the artifact; An image processing program that causes a computer to perform the processing.

21. a first difference image showing a difference between the high-energy image and the low-energy image obtained by contrast imaging, the low-energy image being captured by a radiation detector when a radiation source irradiates a subject into which a contrast agent has been injected with radiation, and the high-energy image being captured by the radiation detector when the radiation source irradiates with radiation of a second energy higher than the first energy; performing an artifact recognition process on the first difference image to identify an artifact region containing an artifact; generating a second difference image showing the difference between the high-energy image and the low-energy image, the second difference image being based on the artifact region and suppressing the artifact; performing image processing on the high-energy image and the low-energy image based on the artifact region; generating a second difference image showing a difference between the high-energy image and the low-energy image after the image processing; the image processing is an enhancement process for enhancing an area other than the artificial object area more than the artificial object area, the low-energy image shows the tissue of the subject and the artifact; the high-energy image shows the tissue of the subject, the contrast agent, and the artifact; An image processing program that causes a computer to perform the processing.

Images