X-ray imaging system and imaging unit

Abstract

This X-ray imaging system (100) is provided with: an X-ray irradiation unit (10); an X-ray detection unit (20) that detects X-rays; an optical imaging unit (31) that captures an image of an optical image (70) of a subject (101); a display unit (41); and a control unit (32) configured to cause a position reference image (90), which is disposed inside the X-ray detection unit (20) and indicates the position relative to the center of the X-ray detection unit (20), to be superimposed on the optical image (70) and displayed on the display unit (41).

Description

X-ray imaging system and imaging unit

[0001] The present invention relates to an X-ray imaging system and an imaging unit.

[0002] 2. Description of the Related Art Conventionally, an X-ray imaging system including an optical imaging unit has been known. Such an X-ray imaging system is disclosed, for example, in International Publication No. 2022 / 271583.

[0003] WO 2022 / 271583 discloses a radiographic imaging system. In this radiographic imaging system, a camera is disposed in a tube head having an X-ray source. The camera is positioned facing a patient, and a video image of the patient is displayed on a display. A digital X-ray detector is disposed on a bed on which the patient lies. In the X-ray imaging system described in WO 2022 / 271583, the position of the digital X-ray detector in a video image captured by the camera is detected, and a semi-transparent rectangular cursor is overlaid on the video image to indicate the position of the digital X-ray detector in the video image.

[0004] International Publication No. 2022 / 271583

[0005] However, when the position of the X-ray detection unit that detects X-rays is indicated by a rectangle, as in the radiographic imaging system (X-ray imaging system) of International Publication No. 2022 / 271583, it is difficult to confirm the specific position within the rectangular area of ​​the part of the subject that is to be X-rayed. In other words, it is difficult to confirm the specific position within the rectangular area of ​​the part of the subject that is to be X-rayed. Therefore, it is desirable to confirm the position of the subject in the area where X-rays are detected.

[0006] The present invention has been made to solve the above-mentioned problems, and one object of the present invention is to provide an X-ray imaging system and an imaging unit that make it possible to confirm the position of a subject in an area where X-rays are detected.

[0007] An X-ray imaging system according to a first aspect of the present invention includes an X-ray irradiation unit including an X-ray tube, an X-ray detection unit that detects X-rays irradiated from the X-ray irradiation unit and transmitted through a subject, an optical imaging unit that captures an optical image of the subject, a display unit that displays the optical image captured by the optical imaging unit, and a control unit that is disposed inside the X-ray detection unit and configured to superimpose a position reference image indicating the position of the X-ray detection unit relative to the center of the X-ray detection unit on the optical image and display it on the display unit.

[0008] In a second aspect of the present invention, an imaging unit includes an optical imaging section that captures an optical image of a subject, and a control section that is disposed inside an X-ray detection section that detects X-rays that have been irradiated from an X-ray irradiation section and transmitted through the subject in the optical image, and is configured to superimpose a position reference image that indicates the position relative to the center of the X-ray detection section on the optical image and display it on a display section.

[0009] As described above, the X-ray imaging system according to the first aspect and the imaging unit according to the second aspect each include a control unit disposed inside the X-ray detection unit and configured to cause the display unit to display a position reference image, which indicates the position of the subject relative to the center of the X-ray detection unit, superimposed on the optical image. As a result, since the position reference image disposed inside the X-ray detection unit and indicating the position of the subject relative to the center of the X-ray detection unit is displayed superimposed on the optical image, an operator can visually recognize the optical image on which the position reference image is superimposed and confirm the position of the subject inside the X-ray detection unit based on the position reference image. As a result, the position of the subject can be confirmed in the region where X-rays are detected.

[0010] FIG. 1 is a schematic diagram showing the overall configuration of an X-ray imaging system according to an embodiment. FIG. 1 is a schematic diagram showing the configuration of a holding unit according to an embodiment. FIG. 2 is a block diagram showing the overall configuration of an X-ray imaging system according to an embodiment. FIG. 2 is a schematic diagram showing the configuration of an optical image generated by an optical imaging control unit. FIG. 3 is a schematic diagram for explaining the superimposition of a detection unit area display and a position reference image on an optical image. FIG. 4 is a schematic diagram for explaining a change in the size of a position reference image. FIG. 5 is a schematic diagram for explaining a change in the number of displayed position reference displays. FIG. 6 is a schematic diagram for explaining the superimposition of an irradiation field area display on an optical image. FIG. 7 is a schematic diagram for explaining a change in the size of an irradiation field area display. FIG. 8 is a schematic diagram showing an example of the superimposition of a detection unit area display and a position reference image on an optical image of the palm of a subject. FIG. 9 is a flowchart for explaining the control processing of an image display method by an X-ray imaging system.

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described with reference to the accompanying drawings.

[0012] (Configuration of X-Ray Imaging System) The configuration of an X-ray imaging system 100 according to an embodiment of the present invention will be described with reference to FIGS.

[0013] FIG. 1 shows an example of a ceiling-suspended X-ray imaging system 100. The X-ray imaging system 100 includes an X-ray irradiation unit 10, an X-ray detection unit 20, an optical imaging unit 31, a holding unit 40, a moving mechanism 50, an apparatus control unit 60, and an input unit 61. The X-ray imaging system 100 is a system including a medical X-ray imaging device, and is configured to perform X-ray imaging of a subject 101 to be imaged. In the X-ray imaging system 100, X-rays irradiated from the X-ray irradiation unit 10 are detected by the X-ray detection unit 20, thereby performing X-ray imaging of the subject 101. In the X-ray imaging system 100, an optical image 70 (see FIG. 4 ) capturing the appearance of the subject 101 is also captured by the optical imaging unit 31. In addition, in the X-ray imaging system 100, the X-ray irradiation unit 10, the X-ray detection unit 20, the optical imaging unit 31, the holding unit 40, and the moving mechanism 50 are installed in the imaging room 110, and the device control unit 60 and the input unit 61 are installed outside the imaging room 110.

[0014] In the ceiling-suspended X-ray imaging system 100, a holding unit 40 that holds the X-ray irradiation unit 10 is suspended from the ceiling by a moving mechanism 50 arranged on the ceiling of an imaging room 110. The holding unit 40 is held movably within the imaging room 110 by the moving mechanism 50. The vertical (perpendicular) direction is defined as the Z direction, and two mutually orthogonal horizontal directions are defined as the X direction and the Y direction.

[0015] The X-ray imaging system 100 includes an imaging table 21 for imaging a subject 101 in a lying position (supine position), and an imaging stand 22 for imaging a subject 101 in an upright position (standing position). An X-ray detection unit 20 is movably supported on each of the imaging table 21 and the imaging stand 22. The X-ray detection unit 20 includes, for example, a flat panel detector (FPD). The X-ray detection unit 20 is configured to detect X-rays irradiated from the X-ray irradiation unit 10 and transmitted through the subject 101. A moving mechanism 50 is capable of moving the support unit 40 at least between an imaging position in a supine position using the imaging table 21 (see solid line in FIG. 1 ) and an imaging position in an upright position using the imaging stand 22 (see two-dot chain line in FIG. 1 ).

[0016] In X-ray imaging in a lying position, the holding unit 40 is arranged at a position vertically facing the X-ray detection unit 20 of the imaging table 21, and X-ray imaging of the subject 101 lying on the imaging table 21 is performed between the X-ray irradiation unit 10 and the X-ray detection unit 20 that are vertically facing each other, and an image (optical imaging) of the subject 101 lying on the imaging table 21 is taken by the optical imaging unit 31. In X-ray imaging in a standing position, the holding unit 40 is arranged at a position horizontally facing the X-ray detection unit 20 of the imaging stand 22, and X-ray imaging of the subject 101 standing in front of the imaging stand 22 is performed between the X-ray irradiation unit 10 and the X-ray detection unit 20 that are horizontally facing each other, and an image of the subject 101 standing in front of the imaging stand 22 is taken by the optical imaging unit 31.

[0017] The moving mechanism 50 is configured to hold the holding unit 40 so that it can move in the horizontal direction (X direction and Y direction) and the vertical direction (Z direction). The moving mechanism 50 includes a ceiling suspension unit 51 and a support unit 52. The moving mechanism 50 is supported by rails 53 provided on the ceiling of the radiography room 110. The ceiling suspension unit 51 is configured to be movable in the horizontal direction by the rails 53. The ceiling suspension unit 51 is configured to support the support unit 52. The support unit 52 is configured to support the holding unit 40. The support unit 52 is configured to be extendable and retractable in the vertical direction. The holding unit 40 is configured to be movable in the vertical direction by the support unit 52. The moving mechanism 50 also moves the X-ray detection units 20 arranged on the radiography table 21 and the radiography stand 22.

[0018] As shown in FIG. 2 , the X-ray irradiation unit 10 includes an X-ray tube 11 and a collimator unit 12. The X-ray irradiation unit 10 is configured to irradiate a subject 101 with X-rays from the X-ray tube 11. The X-ray tube 11 is configured to irradiate X-rays by applying a predetermined voltage. The collimator unit 12 has a plurality of shielding plates (collimator leaves) whose positions can be adjusted. The collimator unit 12 is configured to adjust the irradiation field of the X-rays irradiated from the X-ray tube 11 by shielding a portion of the X-rays from the X-ray tube 11. The collimator unit 12 is provided near the X-ray tube 11 in the X-ray irradiation direction of the X-ray tube 11.

[0019] The holding section 40 includes a display operation section 41 and a grip section 42. The holding section 40 is configured to be movable in the horizontal and vertical directions via a movement mechanism 50, either manually or under the control of the device control section 60. In this embodiment, the optical imaging section 31 is provided in the holding section 40 together with the X-ray irradiation section 10. Specifically, the holding section 40 is provided with an imaging unit 30 made up of the optical imaging section 31 and an optical imaging control section 32. The optical imaging control section 32 and the display operation section 41 are examples of the "control section" and the "display section" in the claims, respectively.

[0020] The display operation unit 41 includes, for example, a touch panel type liquid crystal display. The display operation unit 41 is configured to function as an image display unit that displays the optical image 70 (see FIG. 4 ) captured by the optical imaging unit 31, and also as an operation unit through which various operations are input by the operator. The display operation unit 41 outputs a signal indicating the received input operation to the optical imaging control unit 32 and the device control unit 60.

[0021] The grip portion 42 is provided for an operator to hold when manually moving the holding portion 40. The grip portion 42 transmits the operating force of the operator to the holding portion 40.

[0022] The optical imaging unit 31 is provided on an outer surface of the collimator unit 12. In this embodiment, the optical imaging unit 31 is provided on the outer surface of the collimator unit 12 on the longitudinal side of the imaging table 21 when the patient is in a lying position. Furthermore, the optical imaging unit 31 is provided on the outer surface of the collimator unit 12 on the lateral side that intersects with the detection surface of the X-ray detection unit 20 when the patient is in an upright position. The optical imaging unit 31 faces the irradiation direction of X-rays from the X-ray irradiator 10. When the X-ray irradiator 10 faces the subject 101 and the X-ray detection unit 20, the optical imaging unit 31 can capture an optical image 70 of the subject 101 and the X-ray detection unit 20 from the X-ray irradiator 10 side. The imaging range of the optical imaging unit 31 is set to include the range of the irradiation field irradiated with X-rays and to be larger than the range of the X-ray irradiation field.

[0023] As shown in FIG. 3 , the optical imaging unit 31 includes an imaging element 31a. The optical imaging unit 31 is, for example, an optical camera. The imaging element 31a includes, for example, a charge-coupled device (CCD) image sensor or a complementary metal oxide semiconductor (CMOS) image sensor. The optical imaging control unit 32 is, for example, a microcomputer including a central processing unit (CPU), memory, etc. The optical imaging control unit 32 transmits and receives signals to and from the device control unit 60 via a wireless or wired connection.

[0024] 4, the optical imaging unit 31 is configured to capture an optical image 70 of the subject 101. The optical imaging control unit 32 is configured to receive a signal output from the imaging element 31a and generate the optical image 70 based on the input signal. The optical imaging control unit 32 also outputs the generated optical image 70 to the display operation unit 41 for display.

[0025] As shown in FIG. 3 , the device control unit 60 includes a memory 60a. The device control unit 60 controls X-ray imaging by the X-ray irradiator 10 and the X-ray detector 20, and controls the movement of the holder 40. Specifically, the device control unit 60 includes a CPU (Central Processing Unit). The input unit 61 has a function of accepting input operations related to X-ray imaging. The input operations include setting imaging conditions for X-ray imaging and issuing an instruction to start X-ray irradiation. The device control unit 60 controls X-ray imaging based on parameters and various programs that are set in advance and stored in the memory 60a. The device control unit 60 controls the amount of adjustment of the irradiation field by the collimator unit 12.

[0026] In the X-ray imaging system 100, the movement mechanism 50 includes a drive unit 50a such as a motor and a motion detector 50b that detects the operation of the drive unit 50a. The motion detector 50b includes, for example, a potentiometer that detects the rotation of the motor. The drive unit 50a and the motion detector 50b are disposed in various parts of the movement mechanism 50 that move the holder 40, and are also disposed on the imaging table 21 and the imaging stand 22 to change the position of the X-ray detection unit 20. The device controller 60 controls the operation of the movement mechanism 50 based on input operations on the input unit 61 or the display / operation unit 41, or on the operating force applied to the grip 42 of the holder 40, thereby changing the position and angle of the X-ray irradiation unit 10 and the position of the X-ray detection unit 20. The device controller 60 also outputs a control signal that controls the operation of the drive unit 50a and controls the operation of the movement mechanism 50 through feedback control based on a detection signal indicating the operation of the drive unit 50a detected by the motion detector 50b.

[0027] In this embodiment, the device control unit 60 outputs the position and angle of the X-ray irradiator 10 held by the holder 40 and the positions of the X-ray detectors 20 arranged on the radiography table 21 and the radiography stand 22 to the optical imaging control unit 32. The optical imaging control unit 32 acquires the arrangement of the X-ray irradiator 10 and the arrangement of the X-ray detectors 20 based on the input from the device control unit 60. The optical imaging control unit 32 also acquires the amount of adjustment of the irradiation field by the collimator unit 12 based on the input from the device control unit 60.

[0028] (Display Control by Optical Imaging Control Unit) As shown in FIG. 5 , in this embodiment, the optical imaging control unit 32 is configured to superimpose a detection unit area display 81 and a position reference image 90 on the optical image 70 and display them on the display operation unit 41. Note that the following description will focus on the control of the display on the display operation unit 41 by the optical imaging control unit 32 when X-ray imaging is performed with the subject 101 in an upright position (standing position). The above control is also similar when X-ray imaging is performed with the subject 101 lying on the imaging table 21 (supine position), and therefore a description thereof will be omitted. Also, FIGS. 5 to 9 show an example of X-ray imaging of the chest of the subject 101, and FIG. 10 shows an example of X-ray imaging of the palm of the subject 101.

[0029] The detection unit region display 81 indicates the region in the optical image 70 where the X-ray detection unit 20 is located. The optical imaging control unit 32 acquires the three-dimensional layout of the X-ray irradiator 10 and the X-ray detection unit 20, as well as the three-dimensional layout of the optical imaging unit 31. Because the optical imaging unit 31 is disposed in the holder 40 together with the X-ray irradiator 10, the optical imaging control unit 32 calculates the three-dimensional position of the optical imaging unit 31 using pre-stored parameters based on the acquired position of the X-ray irradiator 10. The optical imaging control unit 32 then detects the region in the optical image 70 where the X-ray detection unit 20 is located by performing geometric calculations based on the acquired three-dimensional positional relationship between the X-ray irradiator 10, the X-ray detection unit 20, and the optical imaging unit 31. The optical imaging control unit 32 may also acquire the position of the optical imaging unit 31 calculated by the device control unit 60.

[0030] The optical imaging control unit 32 generates a detection unit area display 81 based on the area where the detected X-ray detection unit 20 is located. In the optical image 70, the area where the X-ray detection unit 20 is located is represented by a rectangle. The detection unit area display 81 shows the area where the X-ray detection unit 20 is located as a rectangle. The detection unit area display 81 shows, for example, a square area. The detection unit area display 81 has a center display 82 indicating the center of the area where the X-ray detection unit 20 is located, and four L-shaped area displays 83 indicating the four corners of the rectangular area. The center display 82 has a cross shape and is located at the position where the diagonal lines of the rectangular area intersect. The center display 82 and the four area displays 83 are displayed, for example, in blue. The detection unit area display 81 also provides a guide to the position and range of the area in the optical image 70 where X-rays can be detected by the X-ray detection unit 20. The area indicated by the detection unit area display 81 may be smaller or larger than the area in which X-rays can actually be detected by the X-ray detection unit 20 .

[0031] The position reference image 90 is an image that is arranged inside the X-ray detection unit 20 and indicates the position relative to the center of the X-ray detection unit 20. Here, "inside the X-ray detection unit 20" refers to the inside of the area in the image where the X-ray detection unit 20 is arranged. The position reference image 90 is an image that indicates the position relative to the center of the area in which the X-ray detection unit 20 is arranged, within the area in the optical image 70 where the X-ray detection unit 20 is arranged. The position reference image 90 includes a plurality of linear position reference indicators 91. In the position reference image 90, the position reference indicators 91 indicate the position relative to the center of the detection unit area indicator 81 that is arranged inside the detection unit area indicator 81. The position reference indicators 91 include at least one pair of position reference indicators 91 that are arranged at equal intervals from each other with respect to the center of the detection unit area indicator 81.

[0032] Specifically, in the position reference image 90, a plurality of linear position reference indicators 91 are arranged in a grid pattern, each line perpendicular to one another. That is, in the position reference image 90, the position reference indicators 91 are arranged as grid lines. Furthermore, the position reference image 90 is arranged based on the orientation of each side of the rectangular region of the X-ray detection unit 20 so as to correspond to the rectangular region of the X-ray detection unit 20 in the optical image 70. Specifically, in the position reference image 90, the position reference indicators 91 are arranged along each side of the rectangle of the detector unit region indicator 81 so as to correspond to the rectangular detector unit region indicator 81. That is, the plurality of linear position reference indicators 91 in the position reference image 90 are arranged perpendicular to one another along each side of the rectangle of the detector unit region indicator 81. That is, the plurality of linear position reference indicators 91 arranged parallel to one another along one direction and the plurality of linear position reference indicators 91 arranged parallel to one another along the other direction are arranged perpendicular to one another. In addition, in each of the one direction and the other direction, the linear position reference indicators 91 are arranged side by side at equal intervals. That is, in the position reference image 90, the linear position reference indicators 91 are arranged in a grid pattern, thereby forming a plurality of square cells.

[0033] Furthermore, in this embodiment, one of the linear position reference indicators 91 arranged in a grid pattern in the position reference image 90 is arranged so as to overlap the center of the detection unit area display 81. And one of the linear position reference indicators 91 arranged in a grid pattern in the position reference image 90 is arranged so as to overlap the outer peripheral portion of the detection unit area display 81. In other words, the optical imaging control unit 32 is configured to display the position reference image 90 on the display operation unit 41, superimposed on the optical image 70, in a state where the linear position reference indicators 91 arranged side by side are arranged so as to overlap the center and peripheral portion of the detection unit area display 81.

[0034] For example, a plurality of linear position reference indicators 91 are arranged so that a total of 16 squares are formed, four in one direction (vertical direction) and four in the other direction (horizontal direction), within the rectangular detection unit area display 81. The intersection of a pair of mutually orthogonal position reference indicators 91 is arranged at a position superimposed on a center indicator 82 that is the center of the detection unit area display 81. Furthermore, linear position reference indicators 91 are arranged so as to coincide with the vertical and horizontal sides and to superimpose on the boundary lines of the rectangular area represented by the detection unit area display 81.

[0035] Furthermore, in this embodiment, the optical imaging control unit 32 is configured to superimpose the position reference image 90 on the optical image 70 over an area including the outside of the X-ray detection unit 20 and display it on the display operation unit 41. That is, the optical imaging control unit 32 is configured to superimpose the position reference image 90 on the optical image 70 over an area including the outside of the detection unit area display 81 and display it on the display operation unit 41. Specifically, in the position reference image 90, the position reference indications 91 are arranged over the entire optical image 70. That is, the position reference indications 91 are arranged so as to extend linearly from one edge to the other in both the vertical and horizontal directions of the optical image 70.

[0036] Furthermore, in this embodiment, the optical imaging control unit 32 is configured to display the position reference image 90 on the display operation unit 41 in a transparent state, superimposed on the optical image 70. For example, in the generated position reference image 90, the optical imaging control unit 32 superimposes a linear position reference indication 91 on the optical image 70 in a transparent state with a transparency of 50%. Note that in Fig. 5 and Fig. 6 and subsequent drawings, the position reference indication 91 is shown in a non-transparent state.

[0037] 6 , the optical imaging control unit 32 is configured to change the size of the position reference image 90 in accordance with the size of the X-ray detection unit 20 in the optical image 70. Specifically, the optical imaging control unit 32 is configured to change the spacing between the position reference displays 91 included in the position reference image 90 in accordance with the size of the detection unit area display 81 in the optical image 70. When the device control unit 60 changes the source to image receptor distance (SID), which is the distance between the X-ray irradiator 10 and the X-ray detection unit 20, the optical imaging control unit 32 changes the size of the detection unit area display 81 superimposed on the optical image 70 to correspond to the changed size of the SID. Then, the optical imaging control unit 32 changes the spacing between the position reference displays 91 so that the position reference image 90 is enlarged or reduced in accordance with the changed size of the detection unit area display 81.

[0038] The optical imaging control unit 32 changes the spacing between the position reference displays 91 so that the ratio of the spacing between the position reference displays 91 to the size of the detection unit area display 81 is maintained constant. For example, Fig. 6 shows an example in which the distance (SID) between the X-ray irradiation unit 10 and the X-ray detection unit 20 is changed to a smaller value from the state in Fig. 5 . In this case, the size of the area in the optical image 70 in which the X-ray detection unit 20 is located increases. The optical imaging control unit 32 increases the size of the detection unit area display 81 to match the size of the area in which the X-ray detection unit 20 is located, and displays the increased spacing between the position reference displays 91 in the position reference image 90 on the display operation unit 41, superimposed on the optical image 70.

[0039] In addition, when the X-ray irradiation unit 10 is translated relatively to the detection surface of the X-ray detection unit 20 while keeping the distance (SID) between the X-ray irradiation unit 10 and the X-ray detection unit 20 constant, the sizes of the detection unit area display 81 and the position reference image 90 do not change, and the detection unit area display 81 and the position reference image 90 are translated together with the optical image 70 so that their positional relationship with the optical image 70 remains constant.

[0040] 7, the optical imaging control unit 32 is configured to change the number of displayed position reference indicators 91 included in the position reference image 90 so that the intervals between the position reference indicators 91 included in the position reference image 90 become larger than a predetermined size. For example, FIG. 7 shows an example in which the distance (SID) between the X-ray irradiation unit 10 and the X-ray detection unit 20 is significantly changed from the state shown in FIG. 5. In this case, the intervals between the position reference indicators 91 become smaller, so the optical imaging control unit 32 reduces the number of displayed position reference indicators 91 on the display operation unit 41 in the position reference image 90. For example, the optical imaging control unit 32 changes the number of displayed position reference indicators 91 depending on the value of the SID.

[0041] As an example, when the SID value is smaller than a predetermined threshold, the optical imaging control unit 32 displays multiple linear position reference indicators 91 so that a total of 16 squares, four in each direction, are formed within the detection unit area display 81. When the SID value is equal to or greater than the predetermined threshold, the optical imaging control unit 32 displays multiple linear position reference indicators 91 so that a total of four squares, two in each direction, are formed within the detection unit area display 81. When changing the number of displayed indicators, the optical imaging control unit 32 also reduces every other adjacent position reference indicator 91 so that the intervals between the position reference indicators 91 are equal. Furthermore, the optical imaging control unit 32 may increase the number of displayed position reference indicators 91 when the SID value is changed to a smaller value.

[0042] 8 , the optical imaging control unit 32 is configured to display an irradiation field area display 84, which indicates the area irradiated with X-rays by the X-ray irradiation unit 10, on the display operation unit 41, together with the detection unit area display 81 and the position reference image 90, superimposed on the optical image 70. As with the detection unit area display 81, the optical imaging control unit 32 detects the area in the optical image 70 irradiated with X-rays by the X-ray irradiation unit 10 by performing geometric calculations based on the acquired three-dimensional positional relationship between the X-ray irradiation unit 10, the X-ray detection unit 20, and the optical imaging unit 31. Then, the optical imaging control unit 32 generates the irradiation field area display 84 based on the detected area irradiated with X-rays.

[0043] Similar to the detection unit area display 81, the irradiation field area display 84 shows the area irradiated with X-rays in a rectangular shape. The irradiation field area display 84 shows, for example, a square area. The irradiation field area display 84 has an area display 85, which is a rectangular frame line indicating the area of ​​the irradiation field irradiated with X-rays, and a dotted line display 86, which is a pair of straight dotted lines that intersect with each other so as to indicate the center of the area of ​​the irradiation field irradiated with X-rays. The pair of dotted line displays 86 are arranged so as to intersect with each other at right angles and pass through the center position where the diagonal lines of the rectangle of the area display 85 intersect. The pair of dotted line displays 86 are also arranged so as to extend outside the area display 85, which is a rectangular frame line. The area display 85 and the pair of dotted line displays 86 are displayed in a color different from that of the detection unit area display 81, for example, yellow. The irradiation field area display 84 also provides a guide to the position and range of the area irradiated with X-rays in the optical image 70. The area indicated by the radiation field area display 84 may be smaller or larger than the area actually irradiated with X-rays.

[0044] As shown in Fig. 9, the optical imaging control unit 32 is configured to change the size of an irradiation field region display 84 superimposed on the optical image 70 on the display operation unit 41 in accordance with the X-ray irradiation field defined by adjustment of the collimator unit 12. The optical imaging control unit 32 changes the size of a region display 85, which is a rectangular frame line, in the irradiation field region display 84 superimposed on the optical image 70, based on the value of the adjustment amount of the collimator unit 12 acquired from the device control unit 60. For example, Fig. 9 shows an example in which the adjustment amount of the collimator unit 12 is changed so that the region of the X-ray irradiation field is enlarged from the state shown in Fig. 8. In this case, the size of the region display 85 indicated by the rectangular frame line in the irradiation field region display 84 is changed, but the size of the dotted line display 86 is not changed.

[0045] The optical imaging control unit 32 may switch whether or not to display the detection unit area display 81, the irradiation field area display 84, and the position reference image 90 on the display operation unit 41, based on an input operation to the display operation unit 41 or an input operation to the input unit 61. For example, the optical imaging control unit 32 switches from a state in which the detection unit area display 81 and the position reference image 90 are superimposed on the optical image 70 to a state in which the detection unit area display 81, the irradiation field area display 84, and the position reference image 90 are all superimposed on the optical image 70, based on receiving an input operation.

[0046] 10 , when X-ray imaging of the palm of the subject 101 is performed, the optical imaging control unit 32, similar to chest X-ray imaging, causes the display operation unit 41 to display a detection unit area display 81 and a position reference image 90 superimposed on the optical image 70. Even when the size of the target part of the subject 101, such as the palm, is small compared to the area where X-rays are detected, the optical imaging control unit 32 causes the display operation unit 41 to display the position reference image 90 together with the detection unit area display 81 superimposed on the optical image 70 so that the position of the subject 101 can be confirmed in the detection unit area display 81. Similarly to chest X-ray imaging, the optical imaging control unit 32 may also display an irradiation field area display 84 superimposed on the optical image 70 of the palm.

[0047] 5 to 10 illustrate an example in which the X-ray irradiation direction of the X-ray irradiator 10 and the detection surface of the X-ray detector 20 are orthogonal to each other. If the X-ray irradiation direction is not orthogonal but tilted relative to the detection surface of the X-ray detector 20, the inclination and shape of the position reference display 91 in the position reference image 90 may change. When at least one of the X-ray irradiator 10 and the X-ray detector 20 is moved so that the X-ray irradiation direction is tilted relative to the detection surface of the X-ray detector 20, the optical imaging controller 32 may stop displaying the position reference image 90, or may change the display in the position reference image 90 to correspond to the relative positions of the X-ray irradiator 10 and the X-ray detector 20. Furthermore, whether or not to stop displaying the position reference image 90 may be determined based on an input operation by the operator.

[0048] (Image Display Method) Next, the control processing of the image display method by the X-ray imaging system 100 of this embodiment will be described with reference to Fig. 11. The control processing of the image display method by steps 201 to 205 is executed by the optical imaging control unit 32.

[0049] First, in step 201, the optical image 70 is captured by the optical imaging unit 31 and acquired.

[0050] Next, in step 202, based on a signal from the device control unit 60, the three-dimensional positions of the X-ray irradiation unit 10 and the X-ray detection unit 20 are obtained, and the three-dimensional position of the optical imaging unit 31 is calculated and obtained.

[0051] Next, in step 203, the area in the optical image 70 where the X-ray detection unit 20 is located is detected, and the area irradiated with X-rays is also detected.

[0052] Next, in step 204, it is set which of the detection unit area display 81, the irradiation field area display 84, and the position reference image 90 is to be superimposed on the optical image 70. For example, based on an input operation on the display operation unit 41, it is set which of the detection unit area display 81, the irradiation field area display 84, and the position reference image 90 is to be superimposed on the optical image 70.

[0053] Next, in step 205, any one of the detection unit area display 81, the irradiation field area display 84, and the position reference image 90 set in step 204 is superimposed on the optical image 70 and displayed on the display operation unit 41. For example, the detection unit area display 81 and the position reference image 90 are superimposed on the optical image 70 and displayed on the display operation unit 41.

[0054] The optical imaging control unit 32 repeatedly executes the control processes of steps 201 to 205 at predetermined control intervals. In addition, either step 201 or step 202 may be executed first.

[0055] (Effects of this embodiment) In this embodiment, the following effects can be obtained.

[0056] As described above, this embodiment includes the optical imaging control unit 32 (control unit), which is disposed inside the X-ray detection unit 20 and configured to display the position reference image 90, which indicates the position relative to the center of the X-ray detection unit 20, on the display operation unit 41 (display unit) so as to be superimposed on the optical image 70. As a result, the position reference image 90, which is disposed inside the X-ray detection unit 20 and indicates the position relative to the center of the X-ray detection unit 20, is displayed superimposed on the optical image 70, and the operator can confirm the position of the subject 101 inside the X-ray detection unit 20 based on the position reference image 90 by visually recognizing the optical image 70 on which the position reference image 90 is superimposed. As a result, the position of the subject 101 can be confirmed in the region where X-rays are detected.

[0057] Furthermore, because the position reference image 90 is displayed superimposed on the optical image 70, when X-ray imaging is performed multiple times at predetermined intervals to observe changes over time in a target region, it is possible to confirm the position of the subject 101 in the region where X-rays are detected in each of the multiple X-ray imaging sessions. Therefore, it is easy to align the target region of the subject 101 in the region where X-rays are detected in each of the multiple X-ray imaging sessions. As a result, when changes over time in the same region of the subject 101 are observed by X-ray imaging, it is possible to ensure consistency in the position of the target region of the subject 101 in the X-ray images generated by the X-ray imaging sessions.

[0058] Furthermore, in this embodiment, the following additional effects can be obtained by the following configuration.

[0059] That is, in the present embodiment, as described above, the optical imaging control unit 32 (control unit) is configured to cause the display operation unit 41 (display unit) to display, on the optical image 70, a detection unit area display 81 indicating the area in the optical image 70 where the X-ray detection unit 20 is located, and a position reference image 90 including a position reference display 91 arranged within the detection unit area display 81 and indicating the position relative to the center of the detection unit area display 81, superimposed on the optical image 70. With this configuration, the position reference image 90 including the position reference display 91 indicating the position relative to the center of the detection unit area display 81 arranged within the detection unit area display 81 is displayed superimposed on the optical image 70. Therefore, the operator can visually recognize the optical image 70 on which the position reference image 90 is superimposed and confirm the position of the subject 101 within the X-ray detection unit 20 based on the position reference display 91 of the position reference image 90. As a result, the position of the subject 101 can be confirmed in the area where X-rays are detected.

[0060] Furthermore, in this embodiment, as described above, the optical imaging control unit 32 (control unit) is configured to superimpose a position reference image 90 including at least one pair of position reference indicators 91 arranged at positions equidistant from each other relative to the center of the detection unit area display 81 on the optical image 70 and display it on the display operation unit 41 (display unit). With this configuration, the position reference indicators 91 in the position reference image 90 are arranged at positions equidistant from each other relative to the center of the detection unit area display 81, so that the operator can confirm the positional relationship between the center of the detection unit area display 81, which indicates the area where the X-ray detection unit 20 is arranged, and the position of the subject 101. Therefore, by visually recognizing the optical image 70 on which the position reference image 90 is superimposed, the operator can confirm in detail the position of the subject 101 within the detection unit area display 81 based on the position reference indicators 91. As a result, the operator can confirm in detail the position of the subject 101 in the area where X-rays are detected.

[0061] Furthermore, in this embodiment, as described above, the optical imaging control unit 32 (control unit) is configured to superimpose the position reference image 90, in which multiple linear position reference indicators 91 are arranged in a grid pattern, orthogonal to each other, on the optical image 70 and display it on the display operation unit 41 (display unit). This configuration allows the operator to confirm the positional relationship between the linear position reference indicators 91 arranged in a grid pattern in the position reference image 90 and the subject 101. Therefore, by visually recognizing the optical image 70 on which the position reference image 90 is superimposed, the operator can confirm in more detail the position of the subject 101 within the detection unit area indicator 81, which indicates the area where the X-ray detection unit 20 is located, based on the position reference indicators 91. As a result, the position of the subject 101 can be confirmed in more detail in the area where X-rays are detected. Furthermore, because the position reference indicators 91 in the position reference image 90 are linear, the operator can easily confirm whether the subject 101 is tilted in the area where X-rays are detected. For example, when taking an X-ray of the chest of subject 101, by visually recognizing the optical image 70 on which the position reference image 90 including the linear position reference display 91 is superimposed, it is possible to easily check whether the chest of subject 101 is tilted to the left or right, and therefore it is possible to easily prevent an X-ray image from being taken in which the left and right lungs are different sizes due to the tilt of the chest of subject 101.

[0062] Furthermore, in this embodiment, as described above, the optical imaging control unit 32 (control unit) is configured to display the position reference image 90 on the display operation unit 41 (display unit) in a state in which one of the linear position reference indicators 91 arranged in a grid pattern in the position reference image 90 is positioned so as to be superimposed on the center of the detection unit area indicator 81. With this configuration, since one of the linear position reference indicators 91 arranged in a grid pattern in the position reference image 90 is positioned so as to be superimposed on the center of the detection unit area indicator 81, the operator can visually recognize the optical image 70 on which the position reference image 90 is superimposed and thereby check in more detail the positional relationship between the center of the detection unit area indicator 81, which indicates the area in which the X-ray detection unit 20 is located, and the position of the subject 101, based on the position reference indicator 91. As a result, the position of the subject 101 can be checked in even more detail in the area in which X-rays are detected.

[0063] Furthermore, in this embodiment, as described above, the optical imaging control unit 32 (control unit) is configured to display the position reference image 90 on the display operation unit 41 (display unit) in a state in which one of the linear position reference indicators 91 arranged in a grid pattern in the position reference image 90 is positioned so as to overlap the outer periphery of the detection unit area display 81. With this configuration, the position of the subject 101 relative to the position reference indicator 91, which serves as a reference within the detection unit area display 81, can be more easily recognized than when the linear position reference indicator 91 is positioned offset from the outer periphery of the detection unit area display 81. As a result, by visually recognizing the optical image 70 on which the position reference image 90 is superimposed, the operator can check the position of the subject 101 in more detail in the area where X-rays are detected based on the position reference indicator 91.

[0064] Furthermore, in this embodiment, as described above, the optical imaging control unit 32 (control unit) is configured to change the size of the position reference image 90 in accordance with the size of the X-ray detection unit 20 in the optical image 70. With this configuration, even when the size of the X-ray detection unit 20 in the optical image 70 changes by changing the separation distance between the X-ray irradiator 10 and the X-ray detection unit 20, it is possible to prevent a change in the positional relationship of the subject 101 with respect to the position reference image 90 by changing the size of the X-ray detection unit 20 in the optical image 70. As a result, even when the separation distance between the X-ray irradiator 10 and the X-ray detection unit 20 is changed, it is possible to confirm the position of the subject 101 in the region where X-rays are detected.

[0065] Furthermore, in this embodiment, as described above, the optical imaging control unit 32 (control unit) is configured to change the number of displayed position reference indicators 91 included in the position reference image 90 so that the intervals between the position reference indicators 91 included in the position reference image 90 become larger than a predetermined size. With this configuration, it is possible to prevent a decrease in the visibility of the optical image 70 on which the position reference image 90 is superimposed, which would be caused by the intervals between the position reference indicators 91 becoming too small. As a result, it is possible to prevent a decrease in the visibility of the optical image 70 from making it difficult to confirm the position of the subject 101 in the area where X-rays are detected.

[0066] Furthermore, in this embodiment, as described above, the optical imaging control unit 32 (control unit) is configured to superimpose the position reference image 90, which is positioned based on the orientation of each side of the rectangular area of ​​the X-ray detection unit 20 so as to correspond to the rectangular area of ​​the X-ray detection unit 20 in the optical image 70, on the display operation unit 41 (display unit) and display the position reference image 90. With this configuration, the position reference image 90 is positioned based on the orientation of each side of the rectangular area of ​​the X-ray detection unit 20, so that the position reference image 90 can be positioned in accordance with the shape of the area where X-rays are detected. Therefore, it is possible to confirm the position of the subject 101 in accordance with the shape of the area where X-rays are detected.

[0067] Furthermore, in this embodiment, as described above, the optical imaging control unit 32 (control unit) is configured to superimpose the position reference image 90 on the optical image 70 over an area including the outside of the X-ray detection unit 20 and display it on the display operation unit 41 (display unit). With this configuration, the operator can confirm the position of the subject 101 within the X-ray detection area while referring to the position of the subject 101 located outside the X-ray detection area based on the position reference image 90. Therefore, the operator can confirm the position of the subject 101 within the X-ray detection area in more detail than when the position reference image 90 is located only within the X-ray detection area. For example, when X-raying the chest of the subject 101, the operator can confirm the positions of not only the chest of the subject 101 located within the X-ray detection area, but also the shoulders, arms, head, and other parts of the subject 101 located outside the X-ray detection area, using the position reference image 90. Therefore, the position of the subject's 101 chest within the area where X-rays are detected can be confirmed by referring to the positions of the subject's 101 shoulders, arms, head, etc., so the position of the subject 101 can be confirmed in more detail than when the position reference image 90 is placed only at a position corresponding to the chest that is the target of X-ray imaging.

[0068] Furthermore, in this embodiment, as described above, the optical imaging control unit 32 (control unit) is configured to display the irradiation field area display 84, which indicates the area irradiated with X-rays by the X-ray irradiation unit 10, on the display operation unit 41 (display unit) by superimposing the irradiation field area display 84, which indicates the area irradiated with X-rays by the X-ray irradiation unit 10, together with the detection unit area display 81 and the position reference image 90, on the optical image 70. With this configuration, the operator can visually recognize the optical image 70 on which the position reference image 90, the detection unit area display 81, and the irradiation field area display 84 are superimposed, and can confirm the arrangement of the X-ray irradiation field relative to the area where X-rays are detected by referring to the position reference display 91 in the position reference image 90. Therefore, in addition to the arrangement of the subject 101 in the area where X-rays are detected, the operator can also confirm the arrangement of the X-ray irradiation field relative to the area where X-rays are detected based on the position reference display 91. Furthermore, when adjusting the irradiation field of the X-rays irradiated from the X-ray tube 11 of the X-ray irradiation unit 10 using the collimator unit 12, the operator can easily adjust the irradiation field of the X-rays using the collimator unit 12 by visually recognizing the position reference image 90 and the irradiation field area display 84 that are displayed superimposed on the optical image 70.

[0069] Furthermore, in this embodiment, as described above, the optical imaging control unit 32 (control unit) is configured to superimpose the position reference image 90 on the optical image 70 in a transmitted state and display it on the display operation unit 41 (display unit). With this configuration, the position reference image 90 is superimposed on the optical image 70 in a transmitted state, so that even when the position reference image 90 is superimposed on the optical image 70, it is possible to prevent a decrease in visibility of the optical image 70. As a result, it is possible to prevent a decrease in visibility of the optical image 70 from making it difficult to confirm the position of the subject 101 in the region where X-rays are detected.

[0070] Furthermore, in this embodiment, as described above, the X-ray imaging system 100 includes a holding unit 40 that holds the X-ray irradiator 10. The optical imaging unit 31 is provided in the holding unit 40 together with the X-ray irradiator 10. With this configuration, since both the X-ray irradiator 10 and the optical imaging unit 31 are provided in the holding unit 40, the irradiation direction of the X-rays irradiated from the X-ray irradiator 10 and the imaging direction of the optical imaging unit 31 can be aligned. Therefore, the positioning of the X-ray irradiator 10 can be easily performed by referring to the optical image 70 captured by the optical imaging unit 31.

[0071] [Modifications] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the description of the above-mentioned embodiments, and further includes all modifications (modifications) within the meaning and scope of the claims.

[0072] For example, in the above embodiment, the optical imaging control unit 32 (control unit) including a microcomputer is configured to superimpose the position reference image 90 on the optical image 70 and display it on the display operation unit 41 (display unit). However, the present invention is not limited to this. In the present invention, the device control unit that controls X-ray imaging may be configured to superimpose the position reference image on the optical image and display it. Furthermore, the control unit (optical imaging control unit) may output the optical image on which the position reference image is superimposed to the outside, and display the optical image on a display unit located away from the control unit with the position reference image superimposed on the optical image. For example, the optical image on which the position reference image is superimposed may be displayed on a display unit provided in the device control unit located outside the imaging room. Furthermore, the control unit may be configured with a personal computer, a processor, or a circuit. Furthermore, each control process performed by the control unit may be performed by a combination of different hardware.

[0073] Furthermore, in the above embodiment, the detector region display 81 indicating the region where the X-ray detection unit 20 is located and the position reference image 90 are superimposed on the optical image 70, and the position reference image 90, which is located inside the X-ray detection unit 20 and indicates its position relative to the center of the X-ray detection unit 20, includes the position reference display 91 indicating its position relative to the center of the detector region display 81, which is located inside the detector region display 81 indicating the region where the X-ray detection unit 20 is located. However, the present invention is not limited to this. In the present invention, the position reference display in the position reference image may indicate the position relative to the center of the X-ray detection unit in the optical image, rather than the center of the detector region display. For example, the detector region display indicating the region where the X-ray detection unit is located may not be superimposed on the optical image.

[0074] Furthermore, in the above embodiment, an example was shown in which the position reference image 90 including the position reference indicators 91 arranged at positions equidistant from one another relative to the center of the detection unit area display 81 was superimposed on the optical image 70 and displayed, but the present invention is not limited to this. In the present invention, the position reference indicators do not have to be arranged at positions equidistant from one another relative to the center of the detection unit area display. In the position reference image, multiple position reference indicators may be arranged at equal intervals from one another while being shifted from the center of the detection unit area display. Furthermore, the position reference indicators may not be arranged at equal intervals from one another, but may be arranged at symmetrical positions with respect to the center of the detection unit area display.

[0075] In the above embodiment, the position reference image 90 includes a plurality of transparent, linear position reference indicators 91 arranged in a grid pattern, each perpendicular to another. However, the present invention is not limited to this. In the present invention, the position reference indicators may be arranged as dots arranged side by side, rather than as straight lines. For example, the position reference indicators may be arranged as dots representing the intersections of a plurality of straight lines arranged in a grid pattern. Alternatively, the position reference indicators may be multiple straight lines arranged parallel to each other without intersecting. Furthermore, the position reference indicators may be represented by dotted lines rather than solid lines. Furthermore, the position reference indicators do not need to be transparent. Furthermore, the display unit may display the position reference indicators by flashing. Furthermore, at least one pair of position reference indicators may be arranged in the position reference image. The shape of the position reference indicator is not limited to a straight line or a dot, but may be a figure of another shape, such as a rectangle or a circle, or a combination of multiple shapes.

[0076] Furthermore, in the above embodiment, an example was shown in which the linear position reference indicator 91 was arranged so as to overlap the center and periphery of the detection unit area indicator 81, but the present invention is not limited to this. In the present invention, the linear position reference indicator may be arranged in a position that does not overlap the center of the detection unit area indicator. For example, the center of a square formed by mutually orthogonal lattice-shaped position reference indicators may be arranged so as to overlap the center of the detection unit area indicator. Furthermore, the position reference indicator may not overlap the periphery of the detection unit area indicator.

[0077] Furthermore, in the above embodiment, the position reference indicators 91 are arranged along each side of the rectangular detector area display 81 to correspond to the detector area display 81, and the spacing between the position reference indicators 91 is changed depending on the size of the detector area display 81. However, the present invention is not limited to this. In the present invention, the position reference indicators may be arranged regardless of the size, position, and orientation of the detector area display. For example, a position reference image in which the position reference indicators are arranged so as to be in a constant arrangement may be displayed in the display area of ​​the optical image. In other words, the position reference image may not be changed even when the position and size of the X-ray detector in the optical image are changed. Furthermore, the position reference indicators may be arranged along each side of the rectangular detector area display, and the spacing between the position reference indicators may not be changed even when the size of the detector area display is changed.

[0078] Furthermore, in the above embodiment, an example was shown in which the number of displayed position reference displays 91 was changed according to the value of the SID when the spacing between the position reference displays 91 was changed, but the present invention is not limited to this. In the present invention, the number of displayed position reference displays may be changed based on the size of the spacing between the position reference displays in the position reference image, rather than the value of the SID. Also, the number of displayed position reference displays included in the position reference image may be set not to exceed a predetermined threshold. The number of displayed position reference displays may be changed based on the ratio of the spacing between the position reference displays to the display area of ​​the optical image. Also, the number of displayed position reference displays may not be changed.

[0079] Furthermore, in the above embodiment, an example has been shown in which the position reference image 90 is superimposed on the optical image 70 and displayed over an area including the outside of the X-ray detection unit 20, but the present invention is not limited to this. In the present invention, the position reference image may be displayed only inside the area of ​​the X-ray detection unit. Furthermore, even when the position reference image is displayed over an area including the outside of the area of ​​the X-ray detection unit, the position reference image may be displayed over a partial area of ​​the optical image rather than the entire area.

[0080] In the above embodiment, the detection unit area display 81, the irradiation field area display 84, and the position reference image 90 are displayed superimposed on the optical image 70, but the present invention is not limited to this. In the present invention, the irradiation field area display may not be displayed superimposed on the optical image. For example, an illumination unit may be disposed that irradiates the subject with illumination light to indicate the area irradiated with X-rays.

[0081] In the above embodiment, the imaging unit 30 including the optical imaging section 31 and the optical imaging control section 32 (control section) is disposed in the holding section 40 that holds the X-ray irradiation section 10, but the present invention is not limited to this. In the present invention, the optical imaging section and the control section may be disposed at positions spaced apart from each other. Also, the optical imaging section may be disposed at a position different from the holding section, such as on the ceiling or wall of the imaging room. Also, the imaging unit may be configured as a unit that is added to the X-ray imaging device.

[0082] In the above embodiment, the position and angle of the X-ray irradiator 10 and the position of the X-ray detector 20 are acquired based on detection signals from the motion detector 50b in the moving mechanism 50 that moves the X-ray irradiator 10 and the X-ray detector 20. However, the present invention is not limited to this. In the present invention, a detector such as a magnetic sensor may be disposed in at least one of the X-ray detector and the X-ray irradiator to acquire the relative positional relationship between the X-ray detector and the X-ray irradiator. Furthermore, the area in which the X-ray detector is located may be detected in the optical image by performing image processing on the optical image. For example, a marker element indicating the position of the X-ray detector may be disposed together with the X-ray detector, and the area in which the X-ray detector is located may be detected by detecting the marker element in the captured optical image.

[0083] In the above embodiment, the detection unit area display 81 includes a cross-shaped center display 82 and four area displays 83 indicating the four corners, and the irradiation field area display 84 includes a rectangular frame area display 85 and a pair of dotted line displays 86. However, the present invention is not limited to this. In the present invention, the detection unit area display and the irradiation field area display may be displayed in a manner different from that of the above embodiment. For example, either the detection unit area display or the irradiation field area display may not include an indication indicating the center of the area. Furthermore, the detection unit area display may indicate the range of the area using a rectangular frame line. The irradiation field area display may indicate the range of the rectangular area using only the four corners. At least one of the detection unit area display and the irradiation field area display may be displayed transparently or flashing.

[0084] Aspects It will be appreciated by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0085] (Item 1) An X-ray imaging system comprising: an X-ray irradiation unit including an X-ray tube; an X-ray detection unit that detects X-rays irradiated from the X-ray irradiation unit and transmitted through a subject; an optical imaging unit that captures an optical image of the subject; a display unit that displays the optical image captured by the optical imaging unit; and a control unit that is arranged inside the X-ray detection unit and is configured to superimpose a position reference image indicating a position relative to the center of the X-ray detection unit on the optical image and display it on the display unit.

[0086] (Item 2) The X-ray imaging system according to Item 1, wherein the control unit is configured to superimpose on the optical image a detection unit area display indicating an area in the optical image where the X-ray detection unit is located, and the position reference image including a position reference display arranged within the detection unit area display indicating a position relative to a center of the detection unit area display, on the optical image and display the same on the display unit.

[0087] (Item 3) The X-ray imaging system according to Item 2, wherein the control unit is configured to superimpose the position reference image, including at least a pair of the position reference displays arranged at positions equidistant from each other with respect to the center of the detection unit area display, on the optical image and display it on the display unit.

[0088] (Item 4) In the X-ray imaging system according to Item 2 or 3, the control unit is configured to superimpose the position reference image, in which multiple linear position reference indications are arranged in a grid pattern perpendicular to each other, on the optical image and display the position reference image on the display unit.

[0089] (Item 5) The X-ray imaging system according to Item 4, wherein the control unit is configured to superimpose the position reference image on the optical image and display it on the display unit, with one of the linear position reference displays arranged in a grid pattern in the position reference image being positioned so as to be superimposed on the center of the detection unit area display.

[0090] (Item 6) The X-ray imaging system according to Item 4 or 5, wherein the control unit is configured to superimpose the position reference image on the optical image and display it on the display unit, with one of the linear position reference displays arranged in a grid pattern in the position reference image being positioned so as to overlap the outer periphery of the detection unit area display.

[0091] (Item 7) The X-ray imaging system according to any one of Items 1 to 6, wherein the control unit is configured to change the size of the position reference image in accordance with the size of the X-ray detection unit in the optical image.

[0092] (Item 8) The X-ray imaging system according to any one of Items 2 to 6, wherein the control unit is configured to change the number of the position reference indications included in the position reference image so that the intervals between the position reference indications included in the position reference image become larger than a predetermined size.

[0093] (Item 9) The X-ray imaging system according to any one of Items 1 to 8, wherein the control unit is configured to superimpose the position reference image on the optical image and display the position reference image on the display unit, the position reference image being positioned based on the orientation of each side of the rectangular area of ​​the X-ray detection unit so as to correspond to the rectangular area of ​​the X-ray detection unit in the optical image.

[0094] (Item 10) The X-ray imaging system according to any one of Items 1 to 9, wherein the control unit is configured to superimpose the position reference image on the optical image over an area including the outside of the X-ray detection unit and display the superimposed image on the display unit.

[0095] (Item 11) The X-ray imaging system according to any one of Items 2 to 6, wherein the control unit is configured to cause the display unit to display an irradiation field area display indicating an area to which X-rays are irradiated by the X-ray irradiation unit, together with the detection unit area display and the position reference image, superimposed on the optical image.

[0096] (Item 12) The X-ray imaging system according to any one of Items 1 to 11, wherein the control unit is configured to superimpose the position reference image on the optical image in a transparent state and display the position reference image on the display unit.

[0097] (Item 13) The X-ray imaging system according to any one of Items 1 to 12, further comprising a holding unit that holds the X-ray irradiation unit, wherein the optical imaging unit is provided on the holding unit together with the X-ray irradiation unit.

[0098] (Item 14) An imaging unit comprising: an optical imaging section that captures an optical image of a subject; and a control section that is disposed inside an X-ray detection section that detects X-rays that are irradiated from an X-ray irradiation section and transmitted through the subject in the optical image, and that is configured to superimpose a position reference image that indicates a position relative to the center of the X-ray detection section on the optical image and display it on a display section.

[0099] REFERENCE SIGNS LIST 10 X-ray irradiation unit 11 X-ray tube 20 X-ray detection unit 30 Imaging unit 31 Optical imaging unit 32 Optical imaging control unit (control unit) 40 Holding unit 41 Display operation unit (display unit) 70 Optical image 81 Detection unit area display 84 Irradiation field area display 90 Position reference image 91 Position reference display 100 X-ray imaging system 101 Subject

Claims

1. The X-ray irradiation section includes an X-ray tube, An X-ray detection unit detects X-rays irradiated from the aforementioned X-ray irradiation unit and transmitted through the subject, An optical imaging unit that captures an optical image of the subject, A display unit that displays the optical image captured by the optical imaging unit, The system includes a control unit disposed inside the X-ray detection unit and configured to display a position reference image indicating the position of the X-ray detection unit relative to the center of the unit on the display unit by superimposing it on the optical image, The aforementioned position reference image includes a plurality of position reference displays arranged at predetermined intervals, in an X-ray imaging system.

2. The X-ray imaging system according to claim 1, wherein the control unit is configured to display on the display unit a detection unit area display indicating a region in the optical image in which the X-ray detection unit is located, and a position reference image including a position reference display indicating the position of the detection unit area display with respect to the center of the detection unit area display, superimposed on the optical image.

3. The X-ray imaging system according to claim 2, wherein the control unit is configured to display on the display unit a position reference image, which includes at least one pair of position reference displays arranged at equal intervals from each other with respect to the center of the detection unit area display, superimposed on the optical image.

4. The X-ray imaging system according to claim 2, wherein the control unit is configured to display on the display unit a position reference image in which a plurality of linear position reference indicators are arranged in a grid pattern with mutual orthogonality, superimposed on the optical image.

5. The X-ray imaging system according to claim 4, wherein the control unit is configured to display the position reference image on the display unit by superimposing the position reference image on the optical image, with one of the linear position reference displays arranged in a grid pattern in the position reference image superimposed on the center of the detection unit area display.

6. The X-ray imaging system according to claim 4, wherein the control unit is configured to display the position reference image on the display unit by superimposing the position reference image on the optical image, with one of the linear position reference displays arranged in a grid pattern in the position reference image superimposed on the outer edge portion of the detection unit area display.

7. The X-ray imaging system according to claim 1, wherein the control unit is configured to change the size of the position reference image according to the size of the X-ray detection unit in the optical image.

8. The X-ray imaging system according to claim 2, wherein the control unit is configured to change the number of position reference displays included in the position reference image so that the spacing between the position reference displays included in the position reference image becomes larger than a predetermined size.

9. The X-ray imaging system according to claim 1, wherein the control unit is configured to display on the display unit a position reference image, which is arranged based on the orientation of each side of the rectangular region of the X-ray detection unit so as to correspond to the rectangular region of the X-ray detection unit in the optical image, superimposed on the optical image.

10. The X-ray imaging system according to claim 1, wherein the control unit is configured to superimpose the position reference image onto the optical image over a region including the area outside the X-ray detection unit and display it on the display unit.

11. The X-ray imaging system according to claim 2, wherein the control unit is configured to display on the display unit an irradiation field area display indicating the area irradiated with X-rays by the X-ray irradiation unit, superimposed on the optical image together with the detection unit area display and the position reference image.

12. The X-ray imaging system according to claim 1, wherein the control unit is configured to display the position reference image on the display unit by superimposing it on the optical image while allowing the position reference image to pass through.

13. The X-ray irradiation unit is further supported by a holding unit, The X-ray imaging system according to claim 1, wherein the optical imaging unit is provided in the holding unit together with the X-ray irradiation unit.

14. An optical imaging unit that captures an optical image of the subject, The optical image comprises a control unit, which is located inside an X-ray detection unit that detects X-rays irradiated from an X-ray irradiation unit and transmitted through the subject, and is configured to display a position reference image indicating the position of the X-ray detection unit relative to the center of the optical image on a display unit, The aforementioned position reference image includes an imaging unit that includes a plurality of position reference displays arranged at predetermined intervals.