Image processing apparatus, radiography apparatus, radiography system, image processing method, operation method of radiography apparatus, and program

Abstract

To provide an image processing apparatus capable of reducing variations in an image signal that can occur according to relative positional relationships by a distance between a radiation irradiation unit and a detection unit, and an irradiation angle.SOLUTION: An image processing apparatus includes a processing unit for correcting an image signal output from a detection unit that has detected a radioactive ray passing through a subject using three-dimensional dosage distribution information on the radioactive ray emitted from a radiation irradiation unit. The dose distribution information is based on a distance in a perpendicular direction of a plane between the radiation irradiation unit and the plane where the detection unit is arranged, and an irradiation angle of the radioactive ray.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The disclosed technology relates to an image processing device, a radiation imaging device, a radiation imaging system, an image processing method, an operation method of a radiation imaging device, and a program. [Background technology]

[0002] As a radiation imaging system used for radiation-based medical image diagnosis and non-destructive testing, a radiation imaging system using a flat panel detector (FPD: Flat Panel Detector) formed of a semiconductor material is known. Some radiation imaging systems using FPDs have a variable position relative to the radiation irradiation device. In such a radiation imaging system, the amount of radiation reaching the FPD can change depending on the relative positional relationship between the radiation irradiation device and the FPD due to the heel effect and differences in the effective thickness of the additional filter.

[0003] Patent Document 1 discloses a technique for correcting a change in a detector's output signal that may occur due to a change in the amount of radiation reaching the detector from the X-ray source. In the technique described in Patent Document 1, distribution information on the radiation irradiated from the X-ray source is stored in advance as two-dimensional distribution information on the plane on which the detector moves, and the detector's output signal is corrected based on the stored two-dimensional distribution information. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2009-171990 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in a radiation imaging system, for example, when the irradiation angle between the radiation irradiation device and the FPD is changed, the amount of radiation reaching the FPD changes due to the oblique incident light characteristic (cosine characteristic). Therefore, for example, even if the output signal of the FPD located outside a certain irradiation angle range from the radiation irradiation device is corrected using radiation dose distribution information acquired by the FPD located within the irradiation angle range, the image signal output from the FPD may become non-uniform due to the change in dose distribution.

[0006] In view of the above problems, one embodiment of the present disclosure has an objective of providing an image processing device that can reduce the variation in image signals that may occur depending on the relative positional relationship due to the distance and irradiation angle between the radiation irradiation unit and the detection unit. [Means for solving the problem]

[0007] An image processing device according to one embodiment of the present disclosure includes a processing unit that corrects an image signal output from a detection unit that detects radiation that has passed through a subject, using three-dimensional dose distribution information regarding the radiation irradiated from a radiation irradiation unit, and the dose distribution information is based on the distance between the radiation irradiation unit and a plane on which the detection unit is positioned in a perpendicular direction to the plane, and the irradiation angle of the radiation. Effect of the Invention

[0008] According to an embodiment of the present disclosure, it is possible to reduce variations in image signals that may occur depending on the relative positional relationship due to the distance and irradiation angle between a radiation irradiation unit and a detection unit. [Brief description of the drawings]

[0009] [Figure 1] 1 shows an overall configuration of an example of a radiation imaging system according to a first embodiment. [Diagram 2] 5 is a flowchart showing a generation process of dose distribution information according to the first embodiment. [Diagram 3] 1 shows an example of a table in which imaging conditions are stored. [Figure 4]FIG. 4 is a diagram for explaining a generation process of dose distribution information according to the first embodiment. [Diagram 5] 5 is a flowchart showing processing from the start to the end of photographing a subject according to the first embodiment. [Figure 6] 5A to 5C are diagrams for explaining a process of correcting image non-uniformity caused by the distribution of X-ray dose according to the first embodiment. [Figure 7] 13 shows an example of gain correction data according to the second embodiment. [Figure 8] 13 shows an example of the positional relationship between a radiation irradiation unit and a radiation detection unit according to the third embodiment. [Figure 9] 13 shows an example of a state in which a part of a sensor surface is shielded by a shielding member according to a fourth embodiment. [Figure 10] 13 is a flowchart showing processing from the start to the end of photographing a subject according to the fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims. Although the embodiments describe a plurality of features, not all of these features are necessarily essential to the invention, and the features may be combined in any manner. Furthermore, in the accompanying drawings, the same or similar configurations are given the same reference numbers, and duplicated descriptions are omitted. In the following embodiments and claims, radiation includes, in addition to X-rays, α-rays, β-rays, γ-rays, and various particle beams, and can also be applied to a radiation imaging system that captures a radiation image of a subject.

[0011] (First embodiment) (Configuration of Radiography System) A radiation imaging system 100 and an image processing method according to the first embodiment will be described below with reference to Fig. 1 to Fig. 6. Fig. 1 shows an example of the overall configuration of the radiation imaging system 100 according to this embodiment. The radiation imaging system 100 is provided with a radiation irradiation unit 101, a radiation detection unit 102, a control device 110, a display unit 120, and an operation unit 130.

[0012] The radiation irradiation unit 101 functions as an example of a radiation irradiation device that irradiates radiation to the subject P. The radiation irradiation unit 101 is provided with a radiation generation unit (bulb) that generates radiation, a collimator that defines the beam spread angle of radiation generated by the radiation generation unit, an aluminum filter that can be attached to and detached from the collimator, and a filter replacement mechanism. In the radiation imaging system 100 of this embodiment, it is possible to use a plurality of types of aluminum filters having different thicknesses, such as 2 mm and 5 mm, as the aluminum filter (hereinafter also referred to as an AL filter). The filter replacement mechanism is capable of performing a filter replacement operation of attaching an aluminum filter to the collimator and removing the aluminum filter from the collimator.

[0013] The radiation detection unit 102 functions as an example of a radiographic apparatus that detects radiation irradiated from the radiation irradiation unit 101. The radiation detection unit 102 may be a flat panel detector (FPD). The radiation detection unit 102 is provided with a sensor 1021 in which pixels including an image pickup element that outputs a radiation signal corresponding to the radiation (incident light) irradiated from the radiation irradiation unit 101 are arranged in an array (a two-dimensional planar area). The radiation detection unit 102 may also be provided with a signal processing unit 1022 that processes an image signal, and a storage unit 1023 that stores the image signal and the like. In this case, the signal processing unit 1022 may be configured using any processor, and the storage unit 1023 may be configured using any storage medium such as a memory. The signal processing unit 1022 may also be configured using a circuit such as an ASIC.

[0014] The imaging element of the radiation detection unit 102 according to this embodiment includes a photoelectric conversion element. The photoelectric conversion element of each pixel converts the light converted by the phosphor into an electrical signal, a radiation signal (hereinafter also referred to as an image signal), and the capacitor of each pixel accumulates the charge of the image signal. The radiation detection unit 102 reads out the image signal accumulated in the capacitor of each pixel, and transmits it to an image processing unit 113 of the control device 110.

[0015] In this embodiment, the radiation detection unit 102 is configured as an indirect conversion type detector that first converts radiation into visible light using a phosphor or the like, and then converts the visible light into an electrical signal using an optical sensor or the like. However, the radiation detection unit 102 may also be a direct conversion type detector that directly converts incident radiation into an electrical signal.

[0016] The control device 110 is connected to the radiation irradiation unit 101, the radiation detection unit 102, the display unit 120, and the operation unit 130. The control device 110 can perform radiation imaging by controlling the radiation irradiation unit 101 and the radiation detection unit 102. The control device 110 also functions as an example of an image processing device that can perform image processing on a radiation image based on an image signal obtained by the radiation detection unit 102. The control device 110 is provided with an imaging condition setting unit 111, an imaging control unit 112, an image processing unit 113, a display control unit 114, and a storage unit 115.

[0017] The imaging condition setting unit 111 sets imaging conditions based on information input by an operator via the operation unit 130 or imaging information input from an external device (not shown). The imaging condition information may include, for example, tube voltage, tube current, irradiation time, focal spot size, thickness of an aluminum filter to be added, and distance information between the radiation irradiation unit 101 and the radiation detection unit 102. The imaging condition setting unit 111 sends imaging condition information indicating the imaging conditions to the imaging control unit 112.

[0018] The imaging control unit 112 can control the radiation irradiating unit 101 and the radiation detection unit 102 to perform radiation imaging based on the imaging condition information received from the imaging condition setting unit 111. The imaging control unit 112 can generate an irradiation instruction signal for causing the radiation irradiating unit 101 to irradiate radiation and an imaging control signal for driving the radiation detection unit 102 based on the imaging condition information acquired from the imaging condition setting unit 111. The imaging control unit 112 can control the radiation irradiation timing from the radiation irradiating unit 101 and the imaging timing of the radiation detection unit 102 using the generated irradiation instruction signal and imaging control signal.

[0019] The imaging control unit 112 also controls a position control mechanism (not shown) that controls the relative position between the radiation irradiating unit 101 and the radiation detection unit 102. The imaging control unit 112 can control the operation of the position control mechanism based on imaging condition information so as to align the relative position between the radiation irradiating unit 101 and the radiation detection unit 102 to a predetermined position.

[0020] The image processing unit 113 corrects the image signal output from the radiation detection unit 102 that detects radiation, using dose distribution information based on the irradiation angle of the radiation irradiated from the radiation irradiation unit 101. The image processing unit 113 can also convert the image signal into a two-dimensional image (radiation image data). Furthermore, the image processing unit 113 applies image processing such as gradation processing and noise reduction processing to the image signal and the two-dimensional image based on the image signal. The image processing unit 113 transmits the signal after the image processing to the display control unit 114. The image processing unit 113 can also store the signal after the image processing in the storage unit 115.

[0021] The display control unit 114 outputs (displays) the two-dimensional image, patient information, imaging information, and the like generated by the image processing unit 113 on the display unit 120. The display control unit 114 may convert the image signal acquired from the image processing unit 113 into a two-dimensional image (radiation image data). By checking the image displayed on the display unit 120, the operator can check the radiation image data obtained by imaging the imaging site of the subject.

[0022] The storage unit 115 can store dose distribution information used for image correction, two-dimensional images processed by the image processing unit 113, imaging condition information, etc. The storage unit 115 can also store an operating system (OS), device drivers for peripheral devices, and programs for implementing various application software including programs for performing processes described below.

[0023] The display unit 120 includes any display, and can display various images, patient information, imaging information, etc. under the control of the display control unit 114. The operation unit 130 can be configured using input devices such as a mouse, a keyboard, a touch panel, etc. The operator can input various instructions, imaging-related information, etc. to the control device 110 using the operation unit 130.

[0024] In this embodiment, the control device 110, the display unit 120, the operation unit 130, etc. are configured as separate devices, but they may be configured as an integrated unit. For example, the display unit 120 and the operation unit 130 may be configured as a touch panel display. In addition, the control device 110 may be connected to the radiation irradiation unit 101 and the radiation detection unit 102 by wire or wirelessly.

[0025] The control device 110 can be configured by a computer provided with a processor and a memory. The control device 110 may be configured by a general computer, or may be configured by a computer dedicated to a radiation imaging system. Here, the control device 110 functions as an example of an image processing device according to the present embodiment, but the image processing device according to the present embodiment may be a separate (external) computer communicatively connected to the control device 110. Furthermore, the control device 110 and the image processing device may be, for example, a personal computer (PC), and a desktop PC, a notebook PC, or a tablet PC (portable information terminal) may be used.

[0026] Furthermore, the control device 110 may be configured as a cloud-type computer in which some of the components are arranged in an external device. In this embodiment, the image processing device is configured by the control device 110, but the image processing device only needs to be able to acquire a radiation image and perform image processing on the radiation image, and does not need to control the driving of the radiation detection unit 102 or the radiation irradiation unit 101. Therefore, the image processing device only needs to include the image processing unit 113 and the storage unit 115, and the imaging condition setting unit 111, the imaging control unit 112, and the display control unit 114 may be configured as separate devices, for example. In this case, the imaging condition setting unit 111, the imaging control unit 112, and the display control unit 114 may also be configured by a general computer or a computer dedicated to a radiation imaging system, respectively.

[0027] The processor may be a central processing unit (CPU), or may be a micro processing unit (MPU), a graphical processing unit (GPU), or a field-programmable gate array (FPGA), for example.

[0028] The imaging condition setting unit 111, the imaging control unit 112, the image processing unit 113, and the display control unit 114 may be realized by a processor such as a CPU or an MPU executing software modules stored in the storage unit 115. Furthermore, these components may be configured by a circuit or the like that performs a specific function, such as an ASIC. The storage unit 115 may be configured by any storage medium, such as an optical disk such as a hard disk, a solid state drive, or a memory.

[0029] (Generation of dose distribution information) The image processing unit 113 according to this embodiment acquires dose distribution information based on the irradiation angle regarding the radiation irradiated from the radiation irradiation unit 101 to the radiation detection unit 102, and uses the acquired dose distribution information to correct the image signal output from the radiation detection unit 102. Hereinafter, the generation process of the dose distribution information will be specifically described with reference to Figs. 2 to 4.

[0030] Fig. 2 is a flowchart showing a process of generating (obtaining) dose distribution information of radiation dose. Fig. 3 illustrates a table 300 in which imaging conditions used in the generation process of dose distribution information are stored. An imaging condition number N is assigned to the table 300, and when the imaging control unit 112 selects any number from the table 300, the imaging condition corresponding to the imaging condition number N is set. Here, the imaging control unit 112 or the imaging condition setting unit 111 may store the table 300 in the storage unit 115, or may store the table 300 in an external server and obtain the imaging conditions from the server by communication via a network.

[0031] 4 illustrates an example of the positional relationship between the radiation irradiator 101 and the radiation detector 102 in the process of generating dose distribution information based on the irradiation angle. 0 indicates the vertical distance between the radiation irradiation unit 101 and the radiation detection unit 102. The white circle (◯) marked on the radiation detection unit 102 indicates the position of the system origin coordinates.

[0032] Coordinates (x i,0 ,y j,0 ) is a distance L in the vertical direction from the radiation irradiation unit 101 0 The angle θ is the distance between the Z axis, which is a straight line extending vertically from the radiation exposure unit 101, and the radiation exposure unit 101 and the coordinate (x i,0 ,y j,0 ) and the line connecting the two points. 0 is a distance L in the vertical direction from the radiation irradiation unit 101. 0 4 shows the maximum irradiation angle of radiation with respect to the image signal acquired by the radiation detection unit 102 at .

[0033] As will be specifically described in the processing flow of FIG. 2, in this embodiment, the image processing unit 113 calculates the illumination angle θ by using the relationship of the oblique incident light characteristics (cosine characteristics) depending on the illumination angle. 0In this case, the image processor 113 obtains (estimates) two-dimensional dose distribution information including coordinates at a larger angle than the radiation irradiation unit 101. 0 The angle θ<θ 0 The image signal of this region (gray region in FIG. 4) is used as a reference. Therefore, in this embodiment, the vertical direction (0°) of the radiation irradiation unit 101 is set as the reference irradiation angle. Furthermore, the image processing unit 113 calculates the acquired (estimated) reference distance (L 0 From the two-dimensional dose distribution information at different distances (L k The image processor 113 obtains (estimates) two-dimensional dose distribution information on the plane of the radiation irradiation unit 101 at a distance L 0 Based on the image signal acquired by the radiation detection unit 102 in the position 104, three-dimensional dose distribution information regarding the irradiated radiation based on the distance and irradiation angle can be acquired (estimated).

[0034] In Figure 4, the distance L 0 However, the present invention is not limited to this example, and multiple distances (L 1 ,L 2 It is also possible to generate three-dimensional dose distribution information for each of the above-mentioned points and store it in a database. In this case, the image processor 113 can correct the image signal in response to various imaging conditions including distance when imaging is performed according to the subject's physique and imaging region, for example.

[0035] The process of generating dose distribution information used in the correction process will be described below with reference to the process flow in Fig. 2. The process flow of the main imaging (radiography of a subject) using the three-dimensional dose distribution information will be described with reference to Fig. 5.

[0036] When the operator presses a process start button (not shown) or issues an instruction to start a process of generating dose distribution information using the operation unit 130, the process shown in FIG. 2 starts.

[0037] In step S201, the imaging control unit 112 controls the position control mechanism to set the distance between the radiation irradiation unit 101 and the radiation detection unit 102 to the minimum distance L 0 The positions of the radiation irradiation unit 101 and the radiation detection unit 102 are controlled so that the radiation irradiation unit 101 and the radiation detection unit 102 are positioned as shown in FIG.

[0038] In step S202, the shooting control unit 112 sets the shooting condition number N to an initial value of 1.

[0039] In step S203, the imaging control unit 112 selects an imaging condition corresponding to the imaging condition number N from the imaging condition table 300 illustrated in FIG. 3. The imaging conditions table 300 in FIG. 3 holds imaging conditions such as tube voltage kV, tube current mA, irradiation time ms, focal spot size, and AL filter thickness. The imaging control unit 112 selects (acquires) imaging condition information indicating the imaging condition (tube voltage kV, tube current mA, irradiation time ms, focal spot size, and AL filter thickness) corresponding to the imaging condition number N with reference to the table 300 in FIG. 3. The imaging control unit 112 transmits the selected imaging condition information to the radiation irradiation unit 101.

[0040] In step S204, the radiation irradiator 101 attaches an aluminum filter (radiation filtering filter) that matches the aluminum filter thickness information based on the imaging condition information received from the imaging controller 112 to the collimator using a built-in filter replacement mechanism.

[0041] In step S205, the imaging control unit 112 transmits an irradiation instruction signal to the radiation irradiation unit 101 to instruct irradiation of radiation. Upon receiving the irradiation instruction signal from the imaging control unit 112, the radiation irradiation unit 101 irradiates radiation to the radiation detection unit 102 based on the imaging condition information. Furthermore, the imaging control unit 112 generates an imaging control signal for driving the radiation detection unit 102, and transmits the generated imaging control signal to the radiation detection unit 102. Based on the imaging control signal received from the imaging control unit 112, the radiation detection unit 102 converts the radiation that has reached it into an image signal for each pixel. The image signal (charge) converted by the photoelectric conversion element of each pixel is accumulated in the capacitor of each pixel.

[0042] In step S206, an output section (not shown) of the radiation detection unit 102 reads out signals from each pixel based on the imaging control signal, and transmits an image signal for each pixel to the image processing section 113. That is, the output section of the radiation detection unit 102 transmits the image signal stored in the capacitor of each pixel to the image processing section 113 based on the imaging control signal.

[0043] In step S207, the image processing unit 113 calculates the irradiation angle θ using the relationship of the oblique incident light characteristics (cosine characteristics) depending on the irradiation angle. 0 The coordinate at the larger angle (x i,0 ,y j,0 ) including two-dimensional dose distribution information D i,j,0 Here, the image processing unit 113 obtains (estimates) the distance L 0 The angle θ<θ 0 The image signal in this area (the gray area in Figure 4) is used as a reference.

number

number

[0044] From the formulas (a) and (b), the distance L 0 The two-dimensional dose distribution information is expressed as a function of only the irradiation angle θ. 0 and n are unique values ​​that depend on the imaging condition number N stored in the table 300, and the value of the natural number n can be selected appropriately depending on the type and focal spot size of the radiation irradiation unit 101. As an example, the distance L at which radiation is irradiated from the radiation irradiation unit 101 is 0 On the other hand, when the radiation emitting unit 101 uses a radiation tube with a small focal spot size and high resolution, n=3 or n=4 is preferable. 0The θ<θ 0 From the image signal in the area of ​​a 0 By finding the value of and n, the distance L 0 Two-dimensional dose distribution information D i,j,0 is obtained (estimated) using equation (c).

number

[0045] Furthermore, the image processing unit 113 calculates the acquired reference distance (L 0 ) two-dimensional dose distribution information D i,j,0 From the different distances (L k ) Two-dimensional dose distribution information on the plane D i,j,k is obtained (estimated) using equations (d) and (e).

number

number

[0046] In equations (d) and (e), the distance L k Considering the variable in the Z-axis direction, D i,j,k In this way, the image processor 113 calculates the distance L 0 Based on the image signal acquired by the radiation detection unit 102 in the above, three-dimensional dose distribution information regarding the radiation irradiated from the radiation irradiation unit 101 and based on the distance and irradiation angle can be acquired (estimated).

[0047] The image processing unit 113 stores the acquired dose distribution information in the storage unit 115. 0 The coefficient information of and n is stored in the storage unit 115. Note that the storage unit that stores the dose distribution information is not limited to the storage unit 115 of the control device 110. For example, the storage unit that stores the dose distribution information may be provided in the radiation detection unit 102, or may be provided on an external cloud server that can communicate via a network.

[0048] In step S208, the shooting control unit 112 adds 1 to the shooting condition number N.

[0049] In step S209, the photographing control unit 112 determines whether the photographing condition number N exceeds a preset upper threshold Nmax of the photographing condition number. If the photographing condition number N does not exceed the upper threshold Nmax of the photographing condition number (step S209-No), the photographing control unit 112 returns the process to step S203, and the processes from step S203 to step S208 are similarly repeated.

[0050] On the other hand, if it is determined in step S209 that the imaging condition number N exceeds the upper threshold Nmax of the imaging condition number (step S209-Yes), the imaging control unit 112 ends the process of generating dose distribution information. 0 and coefficient information of n is stored in storage unit 115.

[0051] (Flow of operation of the radiation imaging system) 5 is a flowchart showing the process from the start to the end of imaging of a subject according to this embodiment. The image processing unit 113 according to this embodiment corrects the image signal output from the output unit of the radiation detection unit 102 by radiography of the subject P, using the three-dimensional dose distribution information acquired in the process flow of FIG.

[0052] 3 based on information input by the operator via the operation unit 130 or imaging information input from an external device (not shown). The operator also selects and inputs one of distances L1 and L2 as the vertical distance between the radiation irradiator 101 and the radiation detector 102 via the operation unit 130. When this information is input, the imaging condition setting unit 111 sends the imaging condition information corresponding to the selected imaging condition number N and the distance information between the radiation irradiator 101 and the radiation detector 102 to the imaging control unit 112.

[0053] In step S502, the imaging control unit 112 controls the position control mechanism based on the imaging condition information and distance information received from the imaging condition setting unit 111 to control the distance between the radiation irradiator 101 and the radiation detection unit 102 and the planar position of the radiation detection unit 102. The imaging control unit 112 may also control a rotation mechanism (not shown) that rotates the radiation detection unit 102 around the irradiation center axis (Z axis) of the radiation irradiator 101 during radiation irradiation. In this case, the imaging control unit 112 can control the rotation mechanism based on predetermined imaging condition information to rotate the radiation detection unit 102.

[0054] Furthermore, the imaging control unit 112 transmits imaging condition information corresponding to the imaging condition number N received from the imaging condition setting unit 111 to the radiation irradiation unit 101. Based on the imaging condition information received from the imaging control unit 112, the radiation irradiation unit 101 sets imaging conditions (tube voltage kV, tube current mA, irradiation time ms, focal spot size, AL filter thickness, etc.).

[0055] Furthermore, the imaging control unit 112 generates an irradiation instruction signal that instructs irradiation of radiation, and transmits the generated irradiation instruction signal to the radiation irradiation unit 101. Upon receiving the irradiation instruction signal, the radiation irradiation unit 101 irradiates the subject P with radiation under the imaging condition set based on the imaging condition number. Furthermore, the imaging control unit 112 generates an imaging control signal that drives the radiation detection unit 102, and transmits the generated imaging control signal to the radiation detection unit 102. Based on the received imaging control signal, the radiation detection unit 102 converts the radiation that has reached it into an image signal for each pixel. The image signal (electric charge) converted by the photoelectric conversion element of each pixel is stored in the capacitor of each pixel.

[0056] In step S503, the radiation detection unit 102 transmits an image signal for each pixel to the image processing unit 113. Specifically, the output unit of the radiation detection unit 102 reads out a signal from each pixel based on the imaging control signal, and transmits the image signal for each pixel to the image processing unit 113.

[0057] In step S504, the image processing unit 113 performs processing on the image signal for each pixel received in step S503 to correct variations in the image signal caused by a three-dimensional dose distribution related to the radiation irradiated from the radiation irradiation unit 101. In other words, the image processing unit 113 performs processing to correct variations in the image signal that may occur depending on the relative positional relationship of the distance and irradiation angle between the radiation irradiation unit 101 and the radiation detection unit 102.

[0058] FIG. 6 is a diagram for explaining a process of correcting an image signal acquired by radiography of a subject P using three-dimensional dose distribution information. In FIG. 6, a distance L k indicates the vertical distance between the radiation irradiation unit 101 and the radiation detection unit 102, which was set in step S501. Also, an effective pixel area 601 (gray area in FIG. 6) in FIG. 6 is a pixel area in which an image signal is generated based on the radiation irradiated onto the radiation entrance surface of the radiation detection unit 102. The imaging control unit 112 can obtain planar position information of the radiation detection unit 102 from the position control mechanism.

[0059] The image processing unit 113 converts the image signal S for each pixel of the object P received in step S503 into i,j,k For each pixel, the dose distribution information D shown by the formula (d) at each corresponding pixel position is calculated as shown in the formula (f) below for all pixels. i,j,k Here, the image processor 113 divides the dose distribution information D i,j,k In addition, 1 / (i×j)×ΣD i,j,k The term is the effective pixel area D i,j,k In this case, the coefficient a of the formula (c) determined in step S207 is 0 and n are used. i,j,k contains the variation in the image signal due to the three-dimensional dose distribution of the radiation irradiated from the radiation irradiator 101. In other words, the image signal S i,j,k The image signal S includes a variation in the image signal that may occur depending on the three-dimensional relative positional relationship between the radiation emitting unit 101 and the radiation detecting unit 102. i,j,k By dividing by the three-dimensional dose distribution information, the image signal (output signal) of each pixel of the radiation detection unit 102 is corrected based on the relative positional relationship of the distance and irradiation angle between the radiation irradiator 101 and the radiation detection unit 102.

number

[0060] Correcting the image signal (output signal) of each pixel of the radiation detection unit 102 can reduce variations in the image signal that may occur depending on the three-dimensional positional relationship between the radiation irradiation unit 101 and the radiation detection unit 102. This makes it possible to suppress non-uniformity in the image that may occur due to the three-dimensional dose distribution of radiation.

[0061] In step S505, the image processing unit 113 converts the divided (dose distribution corrected) image signal P i,j,k The gain correction is performed on the signal. Any known method may be used as the gain correction method.

[0062] In step S506, the image processing unit 113 converts the image signal P i,j,k The image processing unit 113 performs image processing such as gradation processing and noise reduction processing on the two-dimensional image based on the image signal P. The image processing unit 113 sends the two-dimensional image after the image processing such as gradation processing and noise reduction processing to the display control unit 114. i,j,k The image signal after image processing may be sent to the display control unit 114.

[0063] In step S507, the display control unit 114 outputs (displays) the received two-dimensional image (radiation image data) on the display unit 120. When the display control unit 114 receives an image signal, the received signal may be converted into a two-dimensional image and output to the display unit 120. This completes the process of photographing the subject.

[0064] In this embodiment, for the sake of simplicity, the distance between the plane on which the radiation irradiation unit 101 and the radiation detection unit 102 are arranged has been described as the distance in the vertical direction of the radiation irradiation unit 101. However, the radiation detection unit 102 may be arranged at a position other than below the radiation irradiation unit 101 in the vertical direction. Therefore, the distance between the plane on which the radiation irradiation unit 101 and the radiation detection unit 102 are arranged may be the distance between the radiation irradiation unit 101 and the plane on which the radiation detection unit 102 is arranged in the vertical direction of the plane.

[0065] As described above, the radiation imaging system according to this embodiment includes the radiation irradiation unit 101, the radiation detection unit 102, and the control device 110. The radiation irradiation unit 101 functions as an example of a radiation irradiation unit (radiation irradiation device) that irradiates radiation. The radiation detection unit 102 functions as an example of a detection unit (radiation imaging device) that detects radiation and outputs an image signal. The control device 110 functions as an example of an image processing device that performs image processing.

[0066] Here, the control device 110 includes an image processing unit 113. The image processing unit 113 functions as an example of a processing unit that corrects an image signal output from the radiation detection unit 102 that detects the radiation that has passed through the subject, using three-dimensional dose distribution information related to the radiation irradiated from the radiation irradiator 101. Here, the dose distribution information is based on the distance between the radiation irradiator 101 and the plane on which the radiation detection unit 102 is placed in the perpendicular direction to the plane, and the irradiation angle of the radiation.

[0067] With this configuration, the control device 110 can reduce variations in image signals that may occur depending on the three-dimensional positional relationship between the radiation irradiation unit 101 and the radiation detection unit 102. Therefore, the control device 110 can suppress non-uniformity in images that may occur due to three-dimensional dose distribution of radiation.

[0068] The processing unit can acquire dose distribution information by using the relationship between the reference irradiation angle of the dose distribution and the oblique incident light characteristics due to the irradiation angle between the radiation detection unit 102 and the radiation irradiation unit 101. Here, the oblique incident light characteristics are defined as follows:

number

[0069] Furthermore, the processing unit can acquire dose distribution information by applying n=3 or n=4 to the oblique incident light characteristics. With this configuration, the control device 110 can more appropriately reduce the variation in the image signal when the radiation irradiation unit 101 uses a radiation tube with a small focal spot size and high resolution. Therefore, the control device 110 can more appropriately suppress the non-uniformity of the image that may occur due to the three-dimensional dose distribution of the radiation. The control device 110 can further include a storage unit that stores the dose distribution information.

[0070] The processing unit can also acquire dose distribution information according to different distance relationships between the radiation detection unit 102 and the radiation application unit 101 in the direction perpendicular to the plane on which the radiation detection unit 102 is arranged. Furthermore, the processing unit can acquire dose distribution information using the relationship between the reference distance of the dose distribution and the square of the distance ratio between the radiation application unit 101 and the plane on which the radiation detection unit 102 is arranged.

[0071] The processing unit can also acquire dose distribution information according to the imaging conditions. Here, the imaging conditions can include at least one of the following conditions: tube voltage, tube current, irradiation time, focal spot size, and radiation filtration filter. In relation to this, the processing unit can correct the image signal using the dose distribution information corresponding to the imaging conditions when the subject is imaged. In this configuration, the control device 110 can correct the image signal using the dose distribution information corresponding to the imaging conditions, and can more appropriately reduce the variation in the image signal. Therefore, the control device 110 can more appropriately suppress the non-uniformity of the image that may occur due to the three-dimensional dose distribution of radiation.

[0072] Second embodiment Next, a second embodiment of the present disclosure will be described with reference to Fig. 7. In the first embodiment, the distance L 0 Image signal D acquired at position i,j,0(θ<θ0) By applying equation (a) using the relationship of the oblique incident light characteristics (cosine characteristics) to the distance L 0 The two-dimensional dose distribution information irradiated from the radiation irradiation unit 101 at the position is expressed as a function of only the irradiation angle θ. i,j,0 contains not only dose distribution information due to the relative positional relationship between the radiation irradiation unit 101 and the radiation detection unit 102, but also pixel value information of inherent IC steps and sensitivity-decreasing pixels and the like caused by the radiation detection unit 102. However, by approximating the two-dimensional dose distribution information as a function of only the irradiation angle θ on the right side of equation (a), pixel value information inherent to the detection unit caused by the radiation detection unit 102 is lost.

[0073] In particular, the distance L 0 Image signal D acquired at position i,j,0(θ<θ0) In the image signal D, the radiation exposure unit 101 and the radiation detection unit 102 are close to each other, so the shading caused by the radiation dose distribution is large. i,j,0(θ<θ0) If the distance L is applied as gain correction data to a radiation detection unit 102 that is located at a position different from the position where the distance L was acquired, the image after gain correction is likely to have uneven irradiation due to differences in the relative positions of the radiation irradiation unit 101 and the radiation detection unit 102. 0 Image signal D acquired at position i,j,0(θ<θ0) It may not be desirable to directly apply this as gain correction data to radiation detection units 102 in different locations.

[0074] The configuration of the radiation imaging system according to this embodiment is similar to that of the radiation imaging system according to the first embodiment, and therefore this embodiment will be described using the same reference numerals as those of the first embodiment for each component. Hereinafter, descriptions that overlap with the first embodiment will be omitted, and only the differences from the first embodiment will be described.

[0075] In this embodiment, the image processing unit 113 calculates the distance L by using the relationship of the oblique incident light characteristic (cosine characteristic). 0 Image signal D acquired at position i,j,0(θ<θ0) 1. The image processing unit 113 removes dose distribution information caused by the relative positional relationship between the radiation irradiation unit 101 and the radiation detection unit 102 from the image signal D i,j,0(θ<θ0) The conversion according to the following formula (g) is applied to the radiation detection unit 102 to obtain the gain correction data D' i,j,0(θ<θ0) Obtain (estimate).

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[0076] Figure 7 shows the gain correction data D' obtained (estimated) from equation (g). i,j,0(θ<θ0)7 shows an example of the image signal D′ converted by the equation (g). The graph in FIG. 7 shows the trend in the X-axis direction obtained by the radiation detection unit 102. i,j,0(θ<θ0) In the figure, it can be seen that although there are IC steps and sensitivity-decreasing pixels specific to the radiation detection unit 102, there is almost no shading due to the irradiation angle. Since there is almost no shading due to the irradiation angle, the image signal D' can be obtained without obtaining relative position information between the radiation irradiation unit 101 and the radiation detection unit 102 from the imaging control unit 112 side. i,j,0(θ<θ0) can be applied as gain correction data.

[0077] In this configuration, in step S207, the dose distribution information described in the first embodiment and the gain correction data D' i,j,0(θ<θ0) is stored in the storage unit 115. In step S505, the image processing unit 113 performs gain correction by applying the following formula (h). In formula (h), 1 / (i×j)×ΣD′ i,j,0 The term is D´ in the effective pixel area, just like in equation (f). i,j,0 represents an average pixel value of the radiation irradiating unit 101 and the radiation detecting unit 102. Moreover, since the gain correction performed in the second embodiment does not depend on the relative positions of the radiation irradiating unit 101 and the radiation detecting unit 102, it is not necessary to create three-dimensional data using the inverse square law. Therefore, in the gain correction, it is possible to apply formula (h) regardless of the vertical distance between the radiation irradiating unit 101 and the radiation detecting unit 102.

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[0078] As described above, the processing unit according to this embodiment can acquire unique gain correction data attributable to the radiation detection unit 102, using the relationship between the reference irradiation angle of the dose distribution and the oblique incident light characteristics due to the irradiation angle between the radiation detection unit 102 and the radiation irradiation unit 101. Furthermore, the processing unit can correct the image signal, using the gain correction data and the dose distribution information. Here, the oblique incident light characteristics are defined as follows:

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[0079] To summarize the first embodiment and this embodiment, the distance L 0 Image signal D acquired at position i,j,0(θ<θ0) By using this, not only shading due to the dose distribution caused by the radiation irradiation unit 101 but also information such as IC steps and sensitivity reduction pixels specific to the radiation detection unit 102 can be corrected.

[0080] Furthermore, the processing unit can acquire gain correction data by applying n=3 or n=4 to the oblique incident light characteristics. With this configuration, the control device 110 can more appropriately reduce the variation in the image signal when the radiation irradiation unit 101 uses a radiation tube with a small focal spot size and high resolution. Therefore, the control device 110 can more appropriately suppress the non-uniformity of the image that may occur due to the three-dimensional dose distribution of the radiation.

[0081] Note that the image signal D i,j,0(θ<θ0) In consideration of the possibility that the center of radiation may be shifted, a correction term for the shift in the irradiation center position can be inserted into formulas (a) to (g). In this case, when the position of the radiation detection unit 102 is shifted from the irradiation center of the radiation irradiation unit 101, the processing unit can correct the shift in the irradiation center position.

[0082] As described above, the image signal D′ can be generated without obtaining relative position information between the radiation irradiator 101 and the radiation detector 102 from the imaging controller 112. i,j,0(θ<θ0) Therefore, for example, the gain correction data D′ can be stored in the storage unit 1023 of the radiation detection unit 102. i,j,0(θ<θ0) By storing the above and using it for gain correction, it is possible to perform gain correction specific to the detection unit only on the radiation detection unit 102 side for each imaging (in real time).

[0083] In such a configuration, after the process of step S502, the gain correction process of step S505 is performed. In step S505, the signal processing unit 1022 of the radiation detection unit 102 generates gain correction data D' i,j,0(θ<θ0) Using this, gain correction is performed by applying the above formula (h). Then, the process proceeds to step S503. After the image signal transmission process in step S503 is performed, the image processing unit 113 performs dose distribution correction described in the first embodiment on the received signal in step S504. Then, the process proceeds to step S506. The subsequent processes are the same as those in the first embodiment, and therefore will not be described.

[0084] In this case, the signal processing unit 1022 can function as an example of a processing unit that acquires unique gain correction data attributable to the radiation detection unit 102, using the relationship between the reference irradiation angle of the dose distribution and the oblique incident light characteristics due to the irradiation angle between the radiation detection unit 102 and the radiation irradiation unit 101. The processing unit can perform gain correction on the image signal by using the gain correction data.

[0085] Third embodiment Next, a third embodiment of the present disclosure will be described with reference to Fig. 8. The configuration of the radiation imaging system according to this embodiment is similar to that of the radiation imaging system according to the first embodiment, and therefore, this embodiment will be described using the same reference numerals as those of the first embodiment for each component. Hereinafter, descriptions that overlap with the first and second embodiments will be omitted, and only the differences from the first and second embodiments will be described. In the third embodiment, the imaging control unit 112 controls the rotation mechanism to rotate the radiation irradiation unit 101 and the radiation detection unit 102 in synchronous with each other in opposite directions.

[0086] 8 is a diagram illustrating an example of the positional relationship between the radiation irradiator 101 and the radiation detector 102 in the process of generating dose distribution information in this embodiment. As shown in FIG. 8, the radiation irradiator 101 is located at z=L 0The radiation detection unit 102 rotates at a radius R on the xy plane at z=0. The angle at which the vertical axis of the radiation irradiation unit 101 intersects with the line connecting the centers of the radiation irradiation unit 101 and the radiation detection unit 102 is defined as θ a Then, cosθ a can be expressed by the following equations (i) and (j).

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[0087] In this embodiment, by rotating the radiation detection unit 102 once, the angle θ to θ a The image signal of the area (gray area in FIG. 8) is obtained by rotating the radiation detection unit 102 once. a The image signal in this region is expressed by the following equation (k).

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[0088] Here, the acquired image signal on the left side of equation (k) is approximated by the right side of equation (k) to an image signal obtained by rotating the radiation emitting unit 101 at a radius r+R when the radiation emitting unit 101 is fixed on the z-axis. 0 Find the value of n and the distance L 0 Two-dimensional dose distribution information D i,j,0 In step S504, the image processor 113 acquires (estimates) the estimated two-dimensional dose distribution information D i,j,0 Three-dimensional dose distribution information D estimated using i,j,k Dose distribution correction is performed using

[0089] As described above, the processing unit according to this embodiment can obtain a reference image signal that is obtained by rotating the radiation detection unit 102 once relative to the radiation irradiation unit 101, and can obtain dose distribution information using the reference image signal. This allows the control device 110 to suppress image non-uniformity that may occur due to a three-dimensional dose distribution related to radiation, even when the radiation irradiation unit 101 moves or rotates. Note that by setting r=0 in equation (k), this can also be applied to a case where the radiation irradiation unit 101 is fixed and does not move or rotate.

[0090] (Fourth embodiment) In the first embodiment, the imaging control unit 112 controls the position control mechanism based on the imaging condition information and distance information received from the imaging condition setting unit 111, and controls the distance between the radiation irradiating unit 101 and the radiation detection unit 102 and the planar position of the radiation detection unit 102. For this reason, in the first embodiment, relative position information between the radiation irradiating unit 101 and the radiation detection unit 102 is acquired from the imaging control unit 112.

[0091] In contrast, in a fourth embodiment of the present disclosure, a method will be described in which the radiation detection unit 102 acquires relative position information between the radiation application unit 101 and the radiation detection unit 102 using an image captured by the radiation detection unit 102. The radiation detection unit 102 itself acquires relative position information between the radiation application unit 101 and the radiation detection unit 102, allowing the radiation detection unit 102 to perform correction due to uneven irradiation distribution on its own. Hereinafter, "position information" described in this embodiment refers to "relative position information between the radiation application unit 101 and the radiation detection unit 102."

[0092] Hereinafter, the radiation imaging system according to this embodiment will be described with reference to Figures 9 and 10. Note that since the configuration of the radiation imaging system according to this embodiment is similar to that of the radiation imaging system according to the first embodiment, this embodiment will be described using the same reference numerals as the components of the first embodiment. Hereinafter, descriptions that overlap with the first embodiment will be omitted, and only the differences from the first embodiment will be described.

[0093] One method for acquiring position information from a captured image is to place a marker material made of a material that attenuates radiation between the radiation irradiation unit 101 and the radiation detection unit 102, and acquire position information from the amount of movement and brightness center coordinates of the marker material projected onto the captured image. In this embodiment, a member inside the radiation detection unit 102 is used as a member equivalent to the marker material, thereby proposing a method that can acquire position information with a simpler configuration than conventional methods without adding new members.

[0094] Normally, a shielding member that attenuates radiation is configured inside the radiation detection unit 102 to protect electrical components (such as ICs) inside the radiation detection unit 102 from radiation. Therefore, in this embodiment, a shielding member is disposed inside the radiation detection unit 102 such that a part of the shielding member inside the radiation detection unit 102 is projected onto a captured image based on the irradiation angle of the radiation irradiation unit 101 and the relative positional relationship with the radiation detection unit 102. By using the radiation detection unit 102 configured in this way, it is possible to acquire position information by calculating the amount of movement of the shielding member and the luminance center coordinates from the captured image.

[0095] Fig. 9 is a diagram of the radiation irradiation unit 101 and the radiation detection unit 102 viewed from directly above. Fig. 9 shows how radiation irradiated from a focal position 901 of the radiation irradiation unit 101 is shielded from radiation in a partial area 903 of the sensor surface of the radiation detection unit 102 by a shielding member 902 configured inside the radiation detection unit 102. Note that if the shielding member 902 is positioned so that a portion of the shielding member 902 is projected outside the effective pixel area of ​​the captured image, the influence of unnecessary artifacts on the captured image can be reduced.

[0096] 9, when a part of the shielding member 902 has a characteristic shape (such as a notch or a protrusion), position information can in principle be acquired if there are at least two straight lines connecting the coordinates to which this characteristic shape has moved and the position of the notch inside the detection unit 102. According to this embodiment, the radiation detection unit 102 itself can acquire position information for each imaging (in real time) and correct uneven irradiation distribution, without obtaining position information from the imaging control unit 112 side.

[0097] Here, the flow of the operation method of the radiation imaging system 100 according to this embodiment will be described. Note that in this embodiment, in step S207, the generated dose distribution information is stored in the storage unit 1023 of the radiation detection unit 102. Also, in the flow of the operation method of the radiation imaging system 100 according to this embodiment, the same reference numerals are used for processes similar to those in the first embodiment, and descriptions thereof will be omitted.

[0098] In the operation method of the radiation imaging system 100 according to this embodiment, X-ray irradiation is performed in step S502, and an image signal is acquired by the radiation detection unit 102. Note that in step S502, imaging condition information indicating the set imaging conditions may be sent from the imaging control unit 112 to the radiation detection unit 102 together with imaging control information. When the image signal is acquired in step S502, the process proceeds to step S1001.

[0099] In step S1001, the signal processing unit 1022 of the radiation detection unit 102 calculates the movement amount and luminance barycenter coordinates of the shielding member using the acquired image signal to acquire position information. The signal processing unit 1022 may acquire the position information based on, for example, a characteristic shape of a part of the shielding member 902 as described above.

[0100] In step S1002, the signal processor 1022 performs dose distribution correction on the image signal using the acquired position information and the three-dimensional dose distribution information corresponding to the set imaging conditions, similarly to step S504. At this time, the signal processor 1022 may acquire the three-dimensional dose distribution information stored in the storage unit 1023 and use it in the dose distribution correction process.

[0101] In step S1003, the signal processor 1022 performs gain correction on the image signal that has been subjected to the dose distribution correction, similarly to step S505. As in the first embodiment, the gain correction may be performed by any known method.

[0102] In step S1004, the radiation detection unit 102 transmits the image signal that has been subjected to the gain correction to the image processing unit 113. After the image signal is transmitted in step S1004, the process proceeds to step S506. The subsequent processes are similar to those in the first embodiment, and therefore will not be described.

[0103] As described above, the radiation detection unit 102 according to this embodiment functions as an example of a radiographic apparatus that detects radiation. The radiation detection unit 102 includes a signal processing unit 1022. The signal processing unit 1022 functions as an example of a processing unit that corrects an image signal obtained by detecting radiation that has passed through a subject, using three-dimensional dose distribution information related to the radiation irradiated from the radiation irradiator 101. Here, the dose distribution information is based on the distance between the radiation irradiator 101 and the plane on which the radiation detection unit 102 is disposed in the perpendicular direction to the plane, and the irradiation angle of the radiation.

[0104] With this configuration, the radiation detection unit 102 can reduce variations in image signals that may occur depending on the three-dimensional positional relationship between the radiation irradiation unit 101 and the radiation detection unit 102. Therefore, the radiation detection unit 102 can suppress non-uniformity in images that may occur due to three-dimensional dose distribution related to radiation. The radiation detection unit 102 can further include a storage unit 1023 that stores dose distribution information.

[0105] Furthermore, the radiation detection unit 102 may further include a member that transmits or attenuates radiation. Here, the member may be disposed such that a part of the shape of the member is projected in the image signal. In this case, the processing unit may acquire relative position information between the radiation irradiation unit 101 and the radiation detection unit 102, using the amount of movement and luminance center of gravity coordinates of the member projected in the image signal. With this configuration, the radiation detection unit 102 may acquire position information from the image signal without acquiring position information from the imaging control unit 112, and may perform correction processing of the image signal using the acquired position information.

[0106] The member that transmits or attenuates radiation can be arranged so that part of its shape is projected outside the effective pixel area of ​​the captured image. In this case, the influence of unnecessary artifacts on the captured image can be reduced. The member can also include a shielding member that protects electrical components inside the radiation detection unit 102 from radiation. With this configuration, the radiation detection unit 102 can acquire position information with a simpler configuration without adding new members.

[0107] Furthermore, a part of the shape of the member projected onto the image signal may have one or more predetermined shapes that transmit or attenuate radiation. In this case, the shape of the member projected onto the image signal can be recognized based on the predetermined shapes, thereby improving the recognition accuracy.

[0108] The configuration of the radiation detection unit 102 described in the second embodiment can also be applied to the configuration of this embodiment. In this case, the processing unit can acquire unique gain correction data attributable to the radiation detection unit 102 by using the relationship between the reference irradiation angle of the dose distribution and the oblique incident light characteristics due to the irradiation angle between the radiation detection unit 102 and the radiation irradiation unit 101. Furthermore, in step S1003, the processing unit can perform gain correction on the image signal by using the acquired gain correction data. With this configuration, the distance L 0 Image signal D acquired at position i,j,0(θ<θ0)By using this, not only shading due to the dose distribution caused by the radiation irradiation unit 101 but also information such as IC steps and sensitivity reduction pixels specific to the radiation detection unit 102 can be corrected.

[0109] In this embodiment, the signal processing unit 1022 of the radiation detection unit 102 acquires the relative position information between the radiation irradiation unit 101 and the radiation detection unit 102 from the image signal. In contrast to this, in the first to third embodiments, the image processing unit 113 of the control device 110 may acquire the relative position information between the radiation irradiation unit 101 and the radiation detection unit 102 from the image signal in a similar manner.

[0110] In the first to fourth embodiments, the imaging conditions may include imaging positions (supine, standing, sitting, etc.). In this case, the dose distribution information used for dose distribution correction may be stored for each arrangement of the radiation irradiator 101 and the radiation detector 102 for radiography corresponding to the imaging positions. In this case, the dose distribution information corresponding to the arrangement of the subject at the time of imaging may be selected and used in the dose distribution correction process.

[0111] Furthermore, in the fourth embodiment, the signal processing unit 1022 of the radiation detection unit 102 acquires relative position information between the radiation application unit 101 and the radiation detection unit 102 from the captured image. Alternatively, the signal processing unit 1022 may acquire the relative position information between the radiation application unit 101 and the radiation detection unit 102 from the imaging control unit 112. Even in this case, the radiation detection unit 102 can reduce variations in image signals that may occur depending on the three-dimensional positional relationship between the radiation application unit 101 and the radiation detection unit 102. Therefore, the radiation detection unit 102 can suppress non-uniformity in images that may occur due to three-dimensional dose distribution of radiation.

[0112] In the first to fourth embodiments, the gain correction is performed after the dose distribution correction. In contrast, the dose distribution correction may be performed after the gain correction. In addition, in the first, third, and fourth embodiments, the gain correction may be performed arbitrarily, and the gain correction may not be performed.

[0113] (Other embodiments) The present disclosure can also be realized by a process in which a program for implementing one or more functions of the above-described embodiments is supplied to a system or device via a network or a storage medium, and one or more processors in the computer of the system or device read and execute the program. It can also be realized by a circuit (e.g., ASIC) for implementing one or more functions. A computer may have one or more processors or circuits, and may include separate computers or a network of separate processors or circuits for reading and executing computer-executable instructions.

[0114] The processor or circuitry may include a central processing unit (CPU), a microprocessing unit (MPU), a graphics processing unit (GPU), an application specific integrated circuit (ASIC), or a field programmable gateway (FPGA), and the processor or circuitry may include a digital signal processor (DSP), a data flow processor (DFP), or a neural processing unit (NPU).

[0115] The above disclosure includes the following configurations, methods, and programs. (Configuration 1) a processing unit that corrects an image signal output from a detection unit that detects radiation that has passed through a subject, using three-dimensional dose distribution information regarding radiation irradiated from a radiation irradiation unit; An image processing device, wherein the dose distribution information is based on a distance between the radiation irradiation unit and a plane on which the detection unit is disposed in a direction perpendicular to the plane, and an irradiation angle of the radiation. (Configuration 2) the processing unit acquires the dose distribution information using a relationship between a reference irradiation angle of a dose distribution and oblique incident light characteristics due to an irradiation angle between the detection unit and the radiation irradiation unit; The oblique incident light characteristics are

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[0116] Although the present disclosure has been described above with reference to the embodiments, the present disclosure is not limited to the above embodiments. Inventions modified within the scope of the present disclosure and inventions equivalent to the present disclosure are also included in the present disclosure. In addition, the above-mentioned embodiments can be appropriately combined within the scope of the present disclosure. [Explanation of symbols]

[0117] 101: Radiation department 102: Radiation detection unit (detection unit) 110: Image processing device 113: Image processing unit (processing unit)

Claims

1. a processing unit that corrects an image signal output from a detection unit that detects radiation that has passed through a subject, using three-dimensional dose distribution information regarding radiation irradiated from a radiation irradiation unit; An image processing device, wherein the dose distribution information is based on a distance between the radiation irradiation unit and a plane on which the detection unit is disposed in a direction perpendicular to the plane, and an irradiation angle of the radiation.

2. the processing unit acquires the dose distribution information using a relationship between a reference irradiation angle of a dose distribution and oblique incident light characteristics due to an irradiation angle between the detection unit and the radiation irradiation unit; The oblique incident light characteristics are [0010] The image processing device according to claim 1 , wherein:

3. The image processing apparatus according to claim 2 , wherein the processing unit acquires the dose distribution information by applying n=3 or n=4 to the oblique incident light characteristics.

4. The image processing device according to claim 1 , wherein the processing unit acquires the dose distribution information according to different distance relationships between the detection unit and the radiation irradiation unit in the vertical direction.

5. The image processing device according to claim 1 , wherein the processing unit acquires the dose distribution information using a relationship between a reference distance of the dose distribution and a square of a distance ratio between the radiation irradiation unit and a plane on which the detection unit is disposed.

6. The image processing apparatus according to claim 1 , wherein the processing unit acquires the dose distribution information according to an imaging condition.

7. The image processing device according to claim 6 , wherein the imaging conditions include at least one of a tube voltage, a tube current, an exposure time, a focal spot size, a radiation filtering filter, and an imaging position.

8. The image processing apparatus according to claim 1 , further comprising a storage unit that stores the dose distribution information.

9. The image processing device according to claim 1 , wherein the processing unit corrects the image signal by using the dose distribution information corresponding to an imaging condition when the subject was imaged.

10. the processing unit acquires unique gain correction data attributable to the detection unit using a relationship between a reference irradiation angle of a dose distribution and oblique incident light characteristics due to an irradiation angle between the detection unit and the radiation irradiation unit; The image processing apparatus according to claim 1 , wherein the processing unit corrects the image signal by using the gain correction data and the dose distribution information.

11. The oblique incident light characteristics are [0025] is expressed as The image processing device according to claim 10 , wherein the processing unit acquires the gain correction data by applying n=3 or n=4 to the oblique incident light characteristics.

12. The image processing device according to claim 1 , wherein the processing unit corrects the deviation of the irradiation center position when the position of the detection unit deviates from the irradiation center of the radiation irradiation unit.

13. The image processing device according to claim 1 , wherein the processing unit acquires a reference image signal that serves as a reference and is acquired by rotating the detection unit once relative to the radiation irradiation unit, and acquires the dose distribution information using the reference image signal.

14. The image processing device according to claim 1 , wherein the processing unit acquires relative position information of the radiation irradiation unit and the detection unit from an imaging control unit that controls the radiation irradiation unit and the detection unit.

15. The image processing device according to claim 1 , wherein the processing unit obtains relative position information of the radiation irradiation unit and the detection unit by using the image signal.

16. A radiation imaging device for detecting radiation, comprising: a processing unit that corrects an image signal obtained by detecting radiation that has passed through the subject, using three-dimensional dose distribution information regarding the radiation irradiated from the radiation irradiation unit; The radiation imaging apparatus, wherein the dose distribution information is based on a distance between the radiation irradiation unit and a plane on which the radiation imaging apparatus is placed in a direction perpendicular to the plane, and an irradiation angle of the radiation.

17. The radiation imaging apparatus according to claim 16 , further comprising a storage unit that stores the dose distribution information.

18. Further comprising a member that transmits or attenuates radiation, the member is disposed so that a part of the shape of the member is projected in the image signal; The radiation imaging apparatus according to claim 16 , wherein the processing unit acquires relative position information between the radiation irradiation unit and the radiation imaging apparatus, using the amount of movement and luminance barycenter coordinates of the member projected onto the image signal.

19. The radiation imaging apparatus according to claim 18 , wherein the member is disposed so that a part of the shape is projected outside an effective pixel area of ​​a captured image.

20. The radiation imaging apparatus according to claim 18 , wherein the member includes a shielding member that protects electrical components inside the radiation imaging apparatus from radiation.

21. 20. The radiographic apparatus of claim 18, wherein the portion of the shape comprises one or more predetermined shapes that transmit or attenuate radiation.

22. the processing unit acquires gain correction data specific to the radiation imaging apparatus using a relationship between a reference irradiation angle of a dose distribution and oblique incident light characteristics due to an irradiation angle between the radiation imaging apparatus and the radiation irradiator; and The radiation imaging apparatus according to claim 16 , wherein the processing unit corrects the image signal by using the gain correction data and the dose distribution information.

23. The radiation imaging apparatus according to claim 16 , wherein the processing unit acquires relative position information between the radiation irradiation unit and the radiation imaging apparatus from an imaging control unit that controls the radiation irradiation unit and the radiation imaging apparatus.

24. a radiation irradiation unit that irradiates radiation; a detection unit that detects the radiation and outputs an image signal; An image processing device according to any one of claims 1 to 15, A radiation imaging system comprising:

25. a radiation irradiation unit that irradiates radiation; A radiographic imaging apparatus according to any one of claims 16 to 23, A radiation imaging system comprising:

26. correcting an image signal output from a detection unit that detects radiation that has passed through the subject, using three-dimensional dose distribution information regarding radiation irradiated from a radiation irradiation unit; An image processing method, wherein the dose distribution information is based on a distance between the radiation irradiation unit and a plane on which the detection unit is disposed in a direction perpendicular to the plane, and an irradiation angle of the radiation.

27. A method for operating a radiographic imaging device to detect radiation, comprising the steps of: correcting an image signal obtained by detecting radiation that has passed through the subject, using three-dimensional dose distribution information regarding radiation irradiated from a radiation irradiation unit; A method for operating a radiation imaging apparatus, wherein the dose distribution information is based on a distance between the radiation irradiation unit and a plane on which the radiation imaging apparatus is placed in a direction perpendicular to the plane, and an irradiation angle of the radiation.

28. A program which, when executed by a processor, causes the processor to carry out each step of the image processing method according to claim 26 or the operating method according to claim 27.

Images