Radiation image processing apparatus, method, and program

Abstract

To suppress unnecessary structures that interfere with the observation of tubular structures such as blood vessels in difference images like DSA images in a radiation image processing apparatus, method, and program.SOLUTION: A processor acquires a first radiation image including a tubular structure before injection of a contrast agent and a second radiation image including a tubular structure during the injection of the contrast agent or after the injection of the contrast agent, derives a processed first radiation image by removing scattered radiation components included in the first radiation image, derives a processed second radiation image by removing scattered components included in the second radiation image on the basis of the scattered radiation components of the first radiation image, and derives a difference image between the processed first radiation image and the processed second radiation image.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] Conventionally, contrast radiation imaging diagnostic devices have been used to examine and treat the shape of blood vessels, blood vessel abnormalities, blood flow conditions, and the like. Contrast radiation imaging diagnostic devices are called angiography devices. In angiography devices, a catheter is used to inject a contrast agent into a blood vessel, and a DSA (Digital Subtraction Angiography) image is obtained, which is a difference image between an image (mask image) before the contrast agent is injected and an image (live image) during or after the contrast agent is injected. In a DSA image, structures other than the area where the contrast agent is injected are removed. Therefore, by using a DSA image, a doctor can efficiently examine and treat blood vessels while checking the distribution of blood flow in the blood vessels and the state of the blood vessels, such as stenosis of the blood vessels.

[0003] On the other hand, since the timing at which the mask image and the live image are acquired is different, motion artifacts due to body movement may occur in the DSA image. For this reason, a method for reducing the motion artifacts has been proposed (see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-501692 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-mentioned DSA image, the state of blood vessels can be confirmed based on the region of the contrast agent injected into the blood vessels. However, due to the influence of scattered radiation generated when radiation passes through the subject, structures unnecessary for observation, such as bones, which overlap with the contrast agent in the subject, may not be completely removed even by subtraction and may be included in the DSA image. Such unnecessary structures may hinder confirmation of the state of blood vessels.

[0006] The present disclosure has been made in consideration of the above circumstances, and has an object to suppress unnecessary structures that impede observation of tubular structures such as blood vessels in subtraction images such as DSA images. [Means for solving the problem]

[0007] A radiation image processing device according to the present disclosure includes at least one processor, The processor acquires a first radiographic image including the tubular structure before injection of a contrast agent and a second radiographic image including the tubular structure during or after injection of a contrast agent; deriving a processed first radiographic image by removing scattered radiation components contained in the first radiographic image; deriving a processed second radiographic image by removing the scattered radiation components contained in the second radiographic image based on the scattered radiation components of the first radiographic image; A difference image between the processed first radiographic image and the processed second radiographic image is derived.

[0008] In the radiation image processing device according to the present disclosure, the processor extracts a region of the contrast agent from the second radiation image, for a region of the contrast agent in the second radiographic image, deriving a scattered radiation component of the second radiographic image by correcting a scattered radiation component of a first region corresponding to the region of the contrast agent in the first radiographic image; For regions other than the region of the contrast agent in the second radiographic image, a scattered radiation component of a second region corresponding to the other region in the first radiographic image is derived as a scattered radiation component of the second radiographic image; The processed second radiographic image may be derived by removing the scattered radiation component of the derived second radiographic image from the second radiographic image.

[0009] In addition, in a radiological image processing device according to the present disclosure, the processor may derive the scattered radiation components of the second radiological image for a region of the contrast agent in the second radiological image by correcting the scattered radiation components of the first region based on the amount and concentration of the contrast agent injected into the tubular structure.

[0010] In addition, in a radiological image processing device according to the present disclosure, the processor may derive the scattered radiation components contained in a second radiological image for a region of contrast agent in the second radiological image by correcting the scattered radiation components of the first region based on pixel values ​​of the first region.

[0011] In the radiation image processing device according to the present disclosure, the tubular structure may be a blood vessel.

[0012] A radiological image processing method according to the present disclosure includes a step of: acquiring a first radiological image including a tubular structure before an injection of a contrast agent, and a second radiological image including the tubular structure during or after the injection of a contrast agent by a computer; deriving a processed first radiographic image by removing scattered radiation components contained in the first radiographic image; deriving a processed second radiographic image by removing the scattered radiation components contained in the second radiographic image based on the scattered radiation components of the first radiographic image; A difference image between the processed first radiographic image and the processed second radiographic image is derived.

[0013] The radiological image processing program according to the present disclosure includes a procedure for acquiring a first radiological image including a tubular structure before an injection of a contrast agent and a second radiological image including the tubular structure during or after the injection of a contrast agent; deriving a processed first radiographic image by removing scattered radiation components contained in the first radiographic image; deriving a processed second radiographic image by removing the scattered radiation component contained in the second radiographic image based on the scattered radiation component of the first radiographic image; and deriving a difference image between the processed first radiographic image and the processed second radiographic image. Effect of the Invention

[0014] According to the present disclosure, it is possible to suppress unnecessary structures that interfere with observation of tubular structures such as blood vessels in a difference image such as a DSA image. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a diagram showing an overview of an angioradiography system to which a radiation image processing device according to an embodiment of the present disclosure is applied; [Diagram 2] FIG. 1 is a diagram showing a schematic configuration of a radiation image processing apparatus according to an embodiment of the present invention; [Diagram 3] FIG. 1 is a diagram showing a functional configuration of a radiation image processing apparatus according to an embodiment of the present invention. [Figure 4] FIG. 1 shows the correction coefficient depending on the amount and concentration of the contrast agent. [Diagram 5] A flowchart showing the processing performed in this embodiment. [Figure 6] Conceptual diagram of processing performed in this embodiment [Figure 7] FIG. 11 is a diagram showing correction coefficients according to pixel values ​​of a first radiographic image. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. Fig. 1 is a schematic block diagram showing the configuration of an angioimaging system to which a radiological image processing device according to an embodiment of the present disclosure is applied. As shown in Fig. 1, an angioimaging system 100 according to this embodiment includes an angioimaging device 1 and a radiological image processing device 10 according to this embodiment.

[0017] The angiography apparatus 1 is an apparatus for inspecting and treating the shape of blood vessels of a subject, blood vessel abnormalities, blood flow conditions, and the like. In this embodiment, the angiography apparatus 1 is used to inspect and treat, for example, the aorta and arteries branching from the aorta. The angiography apparatus 1 has a C-arm 3 attached to a main body 2 by a mounting part 4 so as to be rotatable around an axis X0, i.e., in the direction of an arrow A. The C-arm 3 is also attached to the mounting part 4 so as to be movable in the direction of an arrow B shown in FIG. 1. A radiation source 5 is attached to one end of the C-arm 3, and an imaging unit 6 is attached to the other end. The imaging unit 6 has a built-in radiation detector for detecting radiation transmitted through a subject H on an imaging table 7 and generating a radiation image of the subject H. The main body 2 contains a radiation image processing device 10 according to this embodiment. A blood vessel is an example of a tubular structure.

[0018] In this embodiment, a contrast agent is injected into blood vessels and imaging is performed, but first, imaging of subject H is performed before the contrast agent is injected to obtain a radiographic image of subject H before the contrast agent is injected (hereinafter referred to as a mask image). Then, imaging of subject H is performed during or after the contrast agent is injected to obtain a radiographic image of subject H during or after the contrast agent is injected (hereinafter referred to as a live image). The mask image is an example of a first radiographic image, and the live image is an example of a second radiographic image.

[0019] Next, the radiation image processing device according to the present embodiment will be described. First, referring to FIG. 2, the hardware configuration of the radiation image processing device according to the present embodiment will be described. As shown in FIG. 2, the radiation image processing device 10 is a computer such as a workstation, a server computer, or a personal computer, and includes a CPU (Central Processing Unit) 11, a non-volatile storage 13, and a memory 16 as a temporary storage area. The radiation image processing device 10 also includes a display 14 such as a liquid crystal display, an input device 15 such as a keyboard and a mouse, and an interface 17 such as a network I / F (InterFace) connected to a network 18 and the imaging unit 6. The CPU 11, the storage 13, the display 14, the input device 15, the memory 16, and the network I / F 17 are connected to a bus 18. The CPU 11 is an example of a processor in the present disclosure.

[0020] The storage 13 is realized by a hard disk drive (HDD), a solid state drive (SSD), a flash memory, etc. The storage 13 as a storage medium stores the radiation image processing program 12 installed in the radiation image processing device 10. The CPU 11 reads out the radiation image processing program 12 from the storage 13, expands it in the memory 16, and executes the expanded radiation image processing program 12.

[0021] The radiation image processing program 12 is stored in a storage device of a server computer connected to a network or in a network storage in an externally accessible state, and is downloaded and installed in the computer constituting the radiation image processing apparatus 10 upon request. Alternatively, the program is recorded on a recording medium such as a DVD (Digital Versatile Disc) or a CD-ROM (Compact Disc Read Only Memory) and distributed, and is installed in the computer constituting the radiation image processing apparatus 10 from the recording medium.

[0022] Next, the functional configuration of the radiation image processing device according to this embodiment will be described. Fig. 3 is a diagram showing the functional configuration of the radiation image processing device according to this embodiment. As shown in Fig. 3, the radiation image processing device 10 includes an image acquisition section 20, a scattered radiation removal section 21, an image derivation section 22, and a display control section 23. Then, the CPU 11 executes the radiation image processing program 12, whereby the CPU 11 functions as the image acquisition section 20, the scattered radiation removal section 21, the image derivation section 22, and the display control section 23.

[0023] The image acquisition unit 20 acquires the above-mentioned mask image G1 and live image G2 by having the angiography apparatus 1 capture an image of the subject H. When capturing an image, imaging conditions such as the radiation dose, tube voltage, and SID (Source-to-Image receptor Distance: X-ray tube focal plane distance) are set. The set imaging conditions are stored in the storage 13.

[0024] The mask image G1 and the live image G2 may be acquired by a program separate from the radiation image processing program of this embodiment. In this case, the mask image G1 and the live image G2 are stored in the storage 13, and the image acquisition unit 20 reads out the mask image G1 and the live image G2 stored in the storage 13 from the storage 13 for processing.

[0025] Here, when imaging subject H using the angiography apparatus 1, scattered rays are generated when radiation passes through subject H, and thus scattered ray components due to the scattered rays are included in mask image G1 and live image G2. Mask image G1 is acquired before contrast agent injection, whereas live image G2 is acquired during or after contrast agent injection. Since contrast agent absorbs radiation, the scattered ray components of the radiation are also absorbed by the contrast agent. As a result, the scattered ray components included in the blood vessel region injected with contrast agent on live image G2 are less than the scattered ray components of the blood vessel region on mask image G1.

[0026] In this way, when the same scattered radiation removal process is performed on the mask image G1 and the live image G2 in a situation where the scattered radiation components contained are different, the degree of removal of the scattered radiation components will be different between the mask image G1 and the live image G2 in the blood vessel region where the contrast agent is injected. This causes the contrast of the blood vessel region to be different between the mask image G1 and the live image G2. As a result, when a DSA image is derived that is a difference image between the mask image G1 from which the scattered radiation components have been removed and the live image G2 from which the scattered radiation components have been removed, as described below, unnecessary structures such as bones that overlap the blood vessels into which the contrast agent has been injected may not be completely removed and may remain in the DSA image. Such unnecessary structures may be an obstacle when checking the state of the blood vessels.

[0027] In this embodiment, the scattered radiation removal unit 21 derives the scattered radiation components of the mask image G1 and the live image G2, and removes the scattered radiation components of the mask image G1 and the live image G2. In this embodiment, the scattered radiation components of the live image G2 are removed based on the scattered radiation components of the mask image G1. First, the removal of the scattered radiation components from the mask image G1 will be described.

[0028] In this embodiment, the scattered radiation components are removed from the mask image G1 using the methods described in, for example, Japanese Patent Application Laid-Open No. 2014-207958 and Japanese Patent Application Laid-Open No. 2015-043959. Note that the method for removing the scattered radiation components is not limited to this, and any method can be used. Hereinafter, the scattered radiation removal process using the method described in Japanese Patent Application Laid-Open No. 2015-043959 will be described. When using the method described in Japanese Patent Application Laid-Open No. 2015-043959, the body thickness distribution of the subject H and the scattered radiation components for removing the scattered radiation components are derived simultaneously.

[0029] When removing the scattered radiation components, a low-frequency image representing the low-frequency components of the mask image G1 and the live image G2 may be generated, and the body thickness distribution may be derived using the low-frequency image.

[0030] First, the scattered radiation removal unit 21 acquires a virtual model K1 of the subject H having an initial body thickness distribution Ts(x,y). The virtual model K1 is data virtually representing the subject H in which the body thickness according to the initial body thickness distribution Ts(x,y) is associated with the coordinate position of each pixel of the mask image G1. Note that the virtual model K1 of the subject H having the initial body thickness distribution Ts(x,y) is pre-stored in the storage 13, but may be acquired from an external server in which the virtual model K1 is saved.

[0031] Next, the scattered radiation removal unit 21 derives an estimated primary radiation image Ip(x,y) that is an estimate of a primary radiation image obtained by photographing the virtual model K1, and an estimated scattered radiation image Is(x,y) that is an estimate of a scattered radiation image obtained by photographing the virtual model K1, based on the virtual model K1, as shown in the following formula (1) and (2). Furthermore, the scattered radiation removal unit 21 derives an image obtained by combining the estimated primary radiation image Ip(x,y) and the estimated scattered radiation image Is(x,y) as an estimated image Im(x,y) that is an estimate of a mask image G1 obtained by photographing the subject H, as shown in the following formula (3). Ip(x,y) = Io(x,y)×exp(-μls×T(x,y)) (1) Is(x,y) = Io(x,y)*Sσ(T(x,y)) (2) Im(x,y) = Is(x,y) + Ip(x,y) (3)

[0032] Here, (x, y) are the coordinates of the pixel position of the mask image G1, Ip(x, y) is the primary ray component at the pixel position (x, y), Is(x, y) is the scattered ray component at the pixel position (x, y), Io(x, y) is the incident dose to the surface of the subject H at the pixel position (x, y), μls is the attenuation coefficient of the subject H, and Sσ(T(x, y)) is a convolution kernel that represents the scattering characteristics according to the body thickness distribution T(x, y) of the subject H at the pixel position (x, y). Note that when deriving the first estimated image Im(x, y), the initial body thickness distribution Ts(x, y) is used as the body thickness distribution T(x, y) in equations (1) and (2). Equation (1) is based on the known exponential attenuation law, and equation (2) is based on the method described in "JM Boon et al., An analytical model of the scattered radiation distribution in diagnostic radiolog, Med. Phys. 15(5), Sep / Oct 1988" (Reference 1). The incident dose Io(x,y) on the surface of the subject H is an exposure dose derived based on the imaging conditions. The attenuation coefficient μls of the subject H in equation (1) is the attenuation coefficient of soft tissue for the low-energy image of the subject H.

[0033] In addition, * in formula (2) is an operator representing a convolution operation. The nature of the kernel changes depending on the body thickness of the subject H, as well as the distribution of the irradiation field in the angiography device 1 (when the irradiation field aperture is used), the distribution of the composition of the subject H, the irradiation dose during imaging, the tube voltage, the imaging distance, and the characteristics of the radiation detector used in the imaging unit 6. According to the method described in Reference 1, the scattered radiation can be approximated by convolution of the point spread function (Sσ(T(x,y)) in formula (3)) for the primary radiation. Note that Sσ(T(x,y)) can be experimentally obtained according to the irradiation field information, the subject information, the imaging conditions, and the like.

[0034] In this embodiment, Sσ(T(x,y)) may be calculated based on the irradiation field information, object information, and imaging conditions at the time of imaging, but a table that associates various irradiation field information, various object information, and various imaging conditions with Sσ(T(x,y)) may be stored in storage 13, and Sσ(T(x,y)) may be obtained by referring to this table based on the irradiation field information, object information, and imaging conditions at the time of imaging. Sσ(T(x,y)) may be approximated by T(x,y).

[0035] Next, the scattered radiation removal unit 21 corrects the initial body thickness distribution Ts(x,y) of the virtual model K1 so that the difference between the estimated image Im and the mask image G1 becomes small. The scattered radiation removal unit 21 repeatedly generates the estimated image Im using the corrected body thickness distribution T(x,y) and corrects the body thickness distribution T(x,y) until the difference between the estimated image Im and the mask image G1 satisfies a predetermined end condition. When the end condition is satisfied, the scattered radiation removal unit 21 subtracts the scattered radiation component Is(x,y) derived by the formula (2) from the mask image G1. In the following description, the scattered radiation component derived for the mask image G1 is referred to as the scattered radiation component Is1(x,y). As a result, the scattered radiation component contained in the mask image G1 is removed. G11 is used as a reference symbol for the processed mask image from which the scattered radiation component has been removed.

[0036] Next, the removal of scattered radiation components from the live image G2 will be described. First, the scattered radiation removal unit 21 derives the scattered radiation component Is2(x,y) of the live image G2 based on the scattered radiation component (x,y) of the mask image G1. For this reason, the scattered radiation removal unit 21 extracts the region A0 of the contrast agent from the live image G2. Here, in the live image G2, the region of the contrast agent has a higher luminance (lower density) than other regions other than the contrast agent. For this reason, the scattered radiation removal unit 21 extracts the region A0 of the contrast agent from the live image G2 by threshold processing. Note that the region A0 of the contrast agent may be extracted from the live image G2 using a trained model that has been machine-learned to extract the region A0 of the contrast agent from a radiation image.

[0037] For the region A0 of the contrast agent extracted from the live image G2, the scatter removal unit 21 derives the scatter component Is2(x, y) by correcting the scatter component Is1(x, y) of the first region A1 corresponding to the region of the contrast agent in the mask image G1 based on the amount and concentration of the contrast agent injected into the blood vessel. Specifically, as shown in the following formula (4), the scatter component Is2(x, y) is derived by multiplying the scatter component Is1(x, y) of the first region A1 in the mask image G1 by the correction coefficient α1.

[0038] The correction coefficient α1 has a value of 1 or less determined by, for example, the amount and concentration of the contrast agent as shown in FIG. 4. FIG. 4 shows the relationship between the amount of the contrast agent and the correction coefficient α1 for three types of concentrations D1 to D3 (D1 < D2 < D3). As shown in FIG. 4, the correction coefficient α1 has a value such that the higher the concentration and the larger the amount of the contrast agent, the smaller the value from 1.0. Note that the value of the correction coefficient α1 also varies depending on the type of the contrast agent. Is2(x,y)=Is1(x,y)×α1 (4)

[0039] On the other hand, for regions other than the region A0 of the contrast agent in the live image G2, the scatter removal unit 21 directly derives the scatter component Is1(x, y) derived in the second region A2 corresponding to the other region in the mask image G1 as the scatter component Is2(x, y) of the live image G2.

[0040] The scatter removal unit 21 derives a processed live image G22 with the scatter component removed by subtracting the derived scatter component Is2(x, y) from the live image G2.

[0041] The image derivation unit 22 derives a difference image in which the blood vessel region in the subject H injected with the contrast agent is emphasized, that is, a DSA image Gp, by subtracting the processed mask image G11 from the processed live image G22 as shown in the following formula (5). Gp(x,y)=G22(x,y)-G11(x,y) (5)

[0042] The display control unit 23 displays the DSA image Gp on the display 14. A doctor performs examination and treatment of blood vessels while viewing the DSA image Gp displayed on the display.

[0043] Next, the processing performed in this embodiment will be described. Fig. 5 is a flowchart showing the processing performed in this embodiment, and Fig. 6 is a conceptual diagram of the processing performed in this embodiment. It is assumed that the mask image G1 and the live image G2 are acquired by photography and stored in the storage 13.

[0044] When an instruction to start processing is input from the input device 15, the image acquisition unit 20 acquires the mask image G1 and the live image G2 from the storage 13 (step ST1). Next, the scattered radiation removal unit 21 derives the scattered radiation component Is1 contained in the mask image G1 (step ST2), and subtracts the derived scattered radiation component Is1 from the mask image G1 to remove the scattered radiation component of the mask image G1, thereby deriving a processed mask image G11 (step ST3).

[0045] Next, the scattered radiation removal unit 21 extracts the region A0 of the contrast agent from the live image G2 (step ST4), and then derives the scattered radiation component for the live image G2 (step ST5).

[0046] That is, for the contrast agent region A0 in the live image G2, the scattered ray component Is2(x,y) is derived by correcting the scattered ray component Is1(x,y) of the first region A1 corresponding to the contrast agent region in the mask image G1 as shown in the above formula (4). For other regions in the live image G2 other than the contrast agent region A0, the scattered ray component Is1(x,y) of the second region A2 corresponding to the other region in the mask image G1 is derived as it is as the scattered ray component Is2(x,y).

[0047] Then, the scattered radiation removal unit 21 subtracts the derived scattered radiation component Is2(x,y) from the live image G2 to derive a processed live image G22 (step ST6). Next, the image derivation unit 22 subtracts the processed mask image G11 from the processed live image G22 to derive a DSA image Gp (step ST7). Then, the display control unit 23 displays the DSA image Gp on the display 14 (step ST8), and the process ends.

[0048] In this manner, in this embodiment, the scattered ray components contained in the live image G2 are removed based on the scattered ray components of the mask image G1. Therefore, in the region of the contrast agent, the scattered ray components can be accurately removed from the live image. Therefore, according to this embodiment, when a difference image such as a DSA image is derived, it is possible to suppress the remaining of structures such as bones that are superimposed on the contrast agent in the region of the contrast agent, and therefore it is possible to prevent unnecessary structures from interfering with checking the state of the blood vessels.

[0049] In particular, in this embodiment, the scattered ray component Is2(x,y) of the contrast agent region A0 in the live image G2 is derived by correcting the scattered ray component Is1(x,y) of the first region A1 in the mask image G1. As a result, even if the scattered ray components differ between the mask image G1 and the live image G2 due to the influence of the contrast agent, the scattered ray components can be appropriately removed from each of the mask image G1 and the live image G2 by taking the difference into consideration. Therefore, it is possible to reliably prevent unnecessary structures from remaining in the contrast agent region of the DSA image.

[0050] In the above embodiment, for the region of the contrast agent in the live image G2, the scattered radiation component Is2(x,y) is derived by correcting the scattered radiation component Is1(x,y) of the first region A1 in the mask image G1 based on the concentration and amount of the contrast agent, but this is not limited to this. The scattered radiation component Is2(x,y) of the live image G2 may be derived by correcting the scattered radiation component Is1(x,y) of the mask image G1 based on the pixel values ​​of the first region A1 in the mask image G1.

[0051] Here, since the contrast agent absorbs radiation, the greater the degree of absorption, the smaller the pixel value becomes, resulting in a lower concentration (higher brightness). Therefore, as shown in Fig. 7 below, by previously deriving the relationship between the pixel value and the correction coefficient α2 so that the larger the pixel value is, the closer it becomes to 1.0, the scattered radiation component Is1(x,y) of the mask image G1 may be corrected to derive the scattered radiation component Is2(x,y) of the live image G2, as shown in the following formula (6). Is2(x,y)=Is1(x,y)×α2 (6)

[0052] Moreover, the radiation in the above embodiment is not particularly limited, and in addition to X-rays, α-rays, γ-rays, etc. can be used.

[0053] In addition, in the above embodiment, blood vessels are used as the tubular structures, but the present invention is not limited to this and may be applied to any tubular structures that are examined using a contrast medium, such as the esophagus and the large intestine.

[0054] In the above embodiment, the following various processors can be used as the hardware structure of the processing unit that executes various processes, such as the image acquisition unit 20, the scattered radiation removal unit 21, the image derivation unit 22, and the display control unit 23. As described above, the above various processors include a CPU, which is a general-purpose processor that executes software (programs) and functions as various processing units, as well as a programmable logic device (PLD), which is a processor whose circuit configuration can be changed after manufacture, such as an FPGA (Field Programmable Gate Array), and a dedicated electric circuit, which is a processor having a circuit configuration designed specifically for executing specific processes, such as an ASIC (Application Specific Integrated Circuit).

[0055] 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 (e.g., 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.

[0056] As an example of configuring multiple processing units with one processor, first, there is a form in which one processor is configured with a combination of one or more CPUs and software, as typified by computers such as client and server, and this processor functions as multiple processing units. Second, there is a form in which a processor is used that realizes the functions of the entire system including multiple processing units with one IC (Integrated Circuit) chip, as typified by System On Chip (SoC), etc. In this way, the various processing units are configured using one or more of the above various processors as a hardware structure.

[0057] Furthermore, more specifically, the hardware structure of these various processors can be an electric circuit that combines circuit elements such as semiconductor elements.

[0058] The following are appended claims to this disclosure. [Explanation of symbols]

[0059] 1 Angiography equipment 2 Main unit 3 Arm 4 Mounting part 5 Radiation source 6. Photography Department 7. Shooting stand 10 Radiation image processing device 11 CPU 12 Radiological image processing program 13. Storage 14 Display 15 Input Devices 16 Memory 17 Network Interface 18 Bus 20 Image acquisition section 21 Scattered radiation removal section 22 Image extraction section 23 Display control section 100 Angio Imaging System A0 Contrast media area A1 First Area A2 Second Area D1~D3 concentration G1 Mask Image G2 Live Image G11 Processed mask image G22 Processed Live Image Gp DSA image α1, α2 correction coefficients

Claims

1. At least one processor; The processor, acquiring a first radiographic image including the tubular structure before injection of a contrast agent and a second radiographic image including the tubular structure during or after injection of a contrast agent; deriving a processed first radiographic image by removing scattered radiation components contained in the first radiographic image; deriving a processed second radiographic image by removing the scattered radiation components contained in the second radiographic image based on the scattered radiation components of the first radiographic image; A radiation image processing device that derives a difference image between the processed first radiation image and the processed second radiation image.

2. The processor extracts a region of the contrast agent from the second radiological image; for a region of the contrast agent in the second radiographic image, a scattered radiation component of the second radiographic image is derived by correcting a scattered radiation component of a first region corresponding to the region of the contrast agent in the first radiographic image; for a region other than the region of the contrast agent in the second radiographic image, a scattered radiation component of a second region corresponding to the other region in the first radiographic image is derived as a scattered radiation component of the second radiographic image; The radiation image processing apparatus according to claim 1 , wherein the processed second radiation image is derived by removing a scattered radiation component of the derived second radiation image from the second radiation image.

3. 3. The radiological image processing device according to claim 2, wherein the processor derives the scattered radiation components of the second radiological image by correcting the scattered radiation components of the first region based on the amount and concentration of the contrast agent injected into the tubular structure, for the region of the contrast agent in the second radiological image.

4. 3. The radiological image processing device according to claim 2, wherein the processor derives the scattered radiation components contained in the second radiological image by correcting the scattered radiation components of the first region based on pixel values ​​of the first region for the region of the contrast agent in the second radiological image.

5. The radiation image processing apparatus according to claim 1 , wherein the tubular structure is a blood vessel.

6. The computer acquiring a first radiographic image including the tubular structure before injection of a contrast agent and a second radiographic image including the tubular structure during or after injection of a contrast agent; deriving a processed first radiographic image by removing scattered radiation components contained in the first radiographic image; deriving a processed second radiographic image by removing the scattered radiation components contained in the second radiographic image based on the scattered radiation components of the first radiographic image; A radiological image processing method comprising: deriving a difference image between the processed first radiological image and the processed second radiological image.

7. obtaining a first radiographic image of the tubular structure before injection of a contrast agent and a second radiographic image of the tubular structure during or after injection of a contrast agent; deriving a processed first radiographic image by removing scattered radiation components contained in the first radiographic image; deriving a processed second radiographic image by removing the scattered radiation components contained in the second radiographic image based on the scattered radiation components of the first radiographic image; and deriving a difference image between the processed first radiographic image and the processed second radiographic image.

Images