Irradiation apparatus, operation method for irradiation apparatus, and operation program

Abstract

To provide an irradiation apparatus capable of easily and accurately obtaining a distance from a radiation focus to an object, an operation method for the irradiation apparatus, and an operation program.SOLUTION: An irradiation apparatus comprises: a radiation source which applies radiation to an object; a distance measurement camera which is mounted on the radiation source, which includes the object in a visual field and which generates a distance image with each pixel value representing a distance; and a processor. The processor converts the distance image to a three-dimensional point group, and calculates the distance from a radiation focus to the object on the basis of the converted three-dimensional point group.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The technology disclosed herein relates to a radiation irradiation device, an operation method for a radiation irradiation device, and an operation program. [Background technology]

[0002] In a radiation irradiation device that irradiates an object with radiation, it is known that a ToF (Time of Flight) distance measuring camera is attached to a radiation source and the distance from the radiation source to the object is measured based on a distance image acquired by the distance measuring camera (see Patent Document 1).

[0003] Patent Document 1 describes a method for measuring the distance from a radiation source to an object by disposing a distance measuring camera at a position that can be considered to be substantially the same as the focal point of the radiation source (hereinafter referred to as the radiation focal point) when the radiation source is viewed from the object side. Patent Document 1 also describes a method for measuring the distance from the radiation source to the object by measuring the distance between the radiation focal point and the distance measuring camera in advance and adding the distance between the radiation focal point and the distance measuring camera to the distance measured by the distance measuring camera. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2021-191389 A Summary of the Invention [Problem to be solved by the invention]

[0005] When the radiation focal point and the distance measuring camera are misaligned in the optical axis direction, the amount of misalignment is measured in advance as described above, and the distance from the radiation source to the object can be measured by adding the amount of misalignment to the distance measured by the distance measuring camera.

[0006] However, since the focal point of radiation and the distance measuring camera are also misaligned in a direction perpendicular to the optical axis, the method described in Patent Document 1 cannot accurately measure the distance from the focal point of radiation to the object. In order to accurately measure the distance from the focal point of radiation to the object, it is necessary to measure in advance a three-dimensional positional deviation between the focal point of radiation and the distance measuring camera, and geometrically calculate the distance from the focal point of radiation to the object while taking into account this three-dimensional positional deviation. Specifically, it is necessary to geometrically calculate the center position of the radiation on the distance image, and calculate the distance between this center position of the radiation and the focal point of radiation. Since the center position of the radiation changes depending on the distance from the focal point of radiation to the object, it is not easy to calculate the distance from the focal point of radiation to the object.

[0007] An object of the technology disclosed herein is to provide a radiation irradiation device, an operating method for a radiation irradiation device, and an operating program for the radiation irradiation device, which make it possible to easily and accurately obtain the distance from a radiation focus to an object. [Means for solving the problem]

[0008] In order to achieve the above-mentioned objective, the radiation irradiation device disclosed herein includes a radiation source that irradiates radiation to an object, a distance measurement camera that is attached to the radiation source, includes the object within its field of view, and generates a distance image in which each pixel value represents a distance, and a processor, wherein the processor converts the distance image into a three-dimensional point cloud and calculates the distance from the radiation focus to the object based on the converted three-dimensional point cloud.

[0009] It is preferable that the processor searches for a closest point, which is a point in the three-dimensional point cloud that is closest to the radiation focus, from the radiation focus along the radiation irradiation direction, and calculates the distance from the radiation focus to the closest point detected by the search.

[0010] It is preferable that the processor sets a rectangular parallelepiped extending from the radiation focal point in the irradiation direction of the radiation, searches for a closest point that is a point closest to the radiation focal point from a point group included in the rectangular parallelepiped among the three-dimensional point group, and calculates the distance from the radiation focal point to the closest point detected by the search.

[0011] Preferably, the object is an object being examined and the processor calculates a first distance which is the distance from the radiation focal point to a surface of the object being examined.

[0012] It is preferable that the object is a surface of a member against which the subject contacts and which is located farther from the radiation source than the subject, and the processor calculates a second distance which is the distance from the radiation focus to the surface of the member.

[0013] The member is preferably a bed, an imaging table, or a radiation image detector.

[0014] It is preferable that the processor uses a point cloud from the three-dimensional point cloud that is included in an area centered on the center position of the radiation to create a histogram with the number of points as the first axis and the coordinates of the points related to the irradiation direction of the radiation as the second axis, and calculates the second distance by finding the coordinate value that maximizes the number of points in the histogram.

[0015] The processor preferably varies the size of the region depending on the size of the surface of the member.

[0016] It is preferable that the object includes a specimen and a surface of a member against which the specimen abuts and which is positioned farther from the radiation source than the specimen, and that the processor calculates a first distance which is the distance from the radiation focus to the surface of the specimen and a second distance which is the distance from the radiation focus to the surface of the member, and calculates the difference between the first distance and the second distance as the body thickness of the specimen.

[0017] It is preferable that the processor corrects the imaging conditions defined by the tube voltage and the tube current time product based on the body thickness.

[0018] It is preferable that the processor notifies information relating to the body thickness by the notification device, and corrects the imaging conditions defined by the tube voltage and the tube current time product in response to an input instruction received by the operation device.

[0019] It is preferable that the system further includes an optical camera attached to the radiation source and generating an optical image including the object, and a display device for displaying the optical image, the radiation source having a collimator for limiting the radiation field, and the processor superimposes one or both of the central position and the radiation field on the optical image.

[0020] When the processor has collimator opening information, it is preferable that the processor determines the size of the irradiation field on the optical image based on the opening information.

[0021] When the processor does not have collimator opening information, it is preferable that the processor determines the size of the irradiation field on the optical image based on collimator opening information linked to the imaging menu.

[0022] The operating method of a radiation irradiation device disclosed herein is a method for operating a radiation irradiation device that includes a radiation source that irradiates an object with radiation, and a distance measurement camera that is attached to the radiation source, includes the object within its field of view, and generates a distance image in which each pixel value represents a distance, wherein a processor performs processing that includes converting the distance image into a three-dimensional point cloud and calculating the distance from the radiation focus to the object based on the converted three-dimensional point cloud.

[0023] The operating program disclosed herein is an operating program for operating a radiation irradiation device that includes a radiation source that irradiates an object with radiation, and a distance measurement camera that is attached to the radiation source, includes the object within its field of view, and generates a distance image in which each pixel value represents a distance, and causes a processor to perform processes including converting the distance image into a three-dimensional point cloud and calculating the distance from the radiation focus to the object based on the converted three-dimensional point cloud. Effect of the Invention

[0024] According to the technique of the present disclosure, it is possible to provide a radiation irradiation device, an operating method for a radiation irradiation device, and an operating program that enable the distance from a radiation focus to an object to be easily and accurately calculated. [Brief description of the drawings]

[0025] [Figure 1] FIG. 1 illustrates an example of a radiation imaging system. [Diagram 2] FIG. 2 is a view of the radiation source viewed from a direction perpendicular to the radiation irradiation direction. [Diagram 3] FIG. 2 is a view of the radiation source viewed from a direction parallel to the radiation irradiation direction. [Figure 4] FIG. 2 illustrates an example of the configuration of a console. [Diagram 5] FIG. 4 is a diagram illustrating an example of functions related to determining shooting conditions configured in a CPU. [Figure 6] FIG. 2 is a diagram illustrating an example of a distance image. [Figure 7] FIG. 2 is a diagram illustrating an example of a three-dimensional point cloud. [Figure 8] FIG. 4 is a diagram illustrating an example of the configuration of a body thickness calculation unit. [Figure 9] 11A and 11B are diagrams illustrating an example of a calculation process of SSD and SID. [Figure 10] FIG. 13 is a diagram showing an example of a histogram created when calculating a SID. [Figure 11] FIG. 13 is a diagram showing an example of the center positions of radial lines on a distance image. [Figure 12] FIG. 13 is a diagram showing an example of icons representing a plurality of body types. [Figure 13] FIG. 13 is a diagram illustrating another example of functions related to determining shooting conditions configured in the CPU. [Figure 14] 13A and 13B are diagrams illustrating another example of the calculation process of SSD. [Figure 15] 11A and 11B are diagrams showing an example in which the center position and irradiation field of radiation are superimposed on an optical image; [Figure 16] 11A and 11B are diagrams illustrating an example of a shooting menu and opening degree information. [Figure 17] 13A and 13B are diagrams showing an example in which a frame representing the outer shape of an electronic cassette is superimposed on an optical image. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] FIG. 1 shows an example of a radiation imaging system. As shown in FIG. 1, the radiation imaging system 2 is a system that performs radiation imaging of a subject H using radiation (e.g., X-rays) R, and includes a mobile radiation irradiation device 10 and an electronic cassette 11. In this embodiment, the subject H is a subject such as a patient. The radiation irradiation device 10 has a console 12, a cart unit 14, a radiation source 15, and an irradiation switch 16. The cart unit 14 has four wheels 17 attached to its lower part. The wheels 17 allow the radiation irradiation device 10 to be used for mobile imaging in which the radiation irradiation device 10 performs radiation imaging of the subject H while moving around the rooms in a medical facility. For this reason, the radiation irradiation device 10 is also called a mobile cart.

[0027] 1 illustrates an example of a state in which a frontal chest radiography is performed on a subject H lying supine on a bed 18 in a hospital room. In this case, an operator such as a radiologist inserts an electronic cassette 11 between the subject H and a top plate 18A of the bed 18. In other words, in this example, the electronic cassette 11 is not used while being housed in a holder on an imaging stand installed in a radiography room, but is removed from the holder and used.

[0028] The radiation source 15 is attached to the cart unit 14 via a first arm 19 and a second arm 20. The first arm 19 extends vertically from the front of the cart unit 14 and is capable of extending and contracting in the vertical direction. The extension and contraction of the first arm 19 changes the height position of the radiation source 15. In addition, the first arm 19 is capable of rotating about a vertical axis.

[0029] The second arm 20 extends horizontally from the tip of the first arm 19. The second arm 20 is capable of extending and contracting in the horizontal direction. By extending and contracting the second arm 20, the horizontal position of the radiation source 15 is changed.

[0030] The radiation source 15 has a radiation tube 21 and a collimator 22, and irradiates an object with radiation. In this embodiment, the object is the subject H and the surface of the bed 18. Note that the bed 18 is an example of "a member against which the subject abuts and which is disposed at a position farther from the radiation source than the subject" according to the technology of the present disclosure.

[0031] The radiation tube 21 is provided with a filament, a target, a grid electrode, etc. (all not shown). A tube voltage is applied between the filament, which is a cathode, and the target, which is an anode. The filament emits thermoelectrons according to the applied tube voltage toward a radiation focal point F0 on the target. The radiation focal point F0 on the target emits radiation R due to collision of the thermoelectrons from the filament. The grid electrode is disposed between the filament and the target. The grid electrode changes the flow rate of thermoelectrons from the filament toward the target according to the applied voltage. The flow rate of thermoelectrons from the filament toward the target is called the tube current.

[0032] The collimator 22 limits the irradiation field of the radiation R emitted from the radiation focal point F0 of the radiation tube 21. The collimator 22 is configured to partially block the radiation R using a rectangular aperture 22A (see FIG. 3) formed by four shielding plates made of lead or the like. The collimator 22 changes the irradiation field of the radiation R by changing the position of each shielding plate to change the opening of the aperture 22A.

[0033] The cart unit 14 has a radiation source control device 23 and a tube voltage generator 24 built in. The radiation source control device 23 is connected to the console 12 so as to be able to communicate wirelessly. The radiation source control device 23 also controls the operation of the tube voltage generator 24. The radiation source control device 23 is also connected to an exposure switch 16. The radiation source control device 23 controls the operation of the radiation source 15 in response to various instruction signals from the exposure switch 16. The exposure switch 16 is operated when an operator instructs the radiation source 15 to start irradiating radiation R. The exposure switch 16 is detachably attached to the cart unit 14.

[0034] The radiation source control device 23 sets imaging conditions. For example, the imaging conditions are conditions defined by the tube voltage applied to the radiation tube 21 and the tube current time product (the product of the tube current and the irradiation time). For example, the tube voltage is a value in units of "kV", and the tube current time product is a value in units of "mAs". When an instruction to start irradiating radiation R is given by operating the irradiation switch 16, the radiation source control device 23 operates the tube voltage generator 24 based on the set imaging conditions, and irradiates radiation R from the radiation tube 21. The tube voltage generator 24 generates a tube voltage by boosting an input voltage with a transformer. The tube voltage generated by the tube voltage generator 24 is supplied to the radiation tube 21 via a voltage cable (not shown).

[0035] A cassette storage section 25 and a handle 26 are provided at the rear of the cart section 14. The cassette storage section 25 stores the electronic cassette 11. There are a number of types of electronic cassettes 11, such as 14×14 inches, 14×17 inches, and 17×17 inches in length and width. The cassette storage section 25 is capable of storing a number of electronic cassettes 11, regardless of type. The cassette storage section 25 also has a function of charging the battery of the stored electronic cassette 11.

[0036] The electronic cassette 11 is a portable radiation image detector that detects radiation R that has passed through the subject H and generates a radiation image. The electronic cassette 11 has a detection panel in which a plurality of pixels that accumulate electric charges according to the radiation R are arranged in a two-dimensional matrix. The detection panel is also called an FPD (Flat Panel Detector).

[0037] The handle 26 is held by an operator when moving the cart unit 14. The console 12 is a computer having a built-in processor and memory, and may be incorporated in the cart unit 14 or may be a notebook type personal computer or the like.

[0038] In addition, a camera unit 30 and a monitor 31 are attached to the radiation source 15. For example, the camera unit 30 and the monitor 31 are attached to the outside of a housing of the collimator 22. The camera unit 30 has a built-in distance measuring camera 32 and an optical camera 33 (see FIG. 3 ). The operations of the distance measuring camera 32, the optical camera 33, and the monitor 31 are controlled by the console 12.

[0039] Distance measurement camera 32 generates a distance image including the above-mentioned object within a field of view (FOV) and each pixel representing a distance. The field of view (FOV) is an area including an irradiation field into which radiation R is irradiated by radiation source 15. The distance image is a two-dimensional image composed of a plurality of pixel values, and each pixel value represents a distance. The distance image is also called a depth image.

[0040] For example, the distance measuring camera 32 is a ToF camera. In this case, the distance measuring camera 32 has a light transmitting section and a light receiving section (not shown), and is configured to be able to acquire distance information to the object by measuring the time from when the measuring light is emitted from the light transmitting section toward the object until the measuring light reflected by the object and returned is received by the light receiving section. For example, the measuring light is an infrared laser light. The measuring light may be a pulsed light or an intensity-modulated continuous light. When continuous light is used as the measuring light, the above-mentioned time can be measured by calculating the phase difference between the measuring light emitted from the light transmitting section and the measuring light received by the light receiving section.

[0041] The distance measuring camera 32 is not limited to a ToF camera, and may be a stereo camera that measures distance based on parallax information, etc. The distance measuring camera 32 may be any camera that can measure distance information and generate a distance image.

[0042] The optical camera 33 generates an optical image by optically capturing an image of the object contained within its field of view (FOV). For example, the optical camera 33 is a digital camera having an image sensor such as a complementary metal-oxide-semiconductor (CMOS) sensor in which photodiodes are arranged two-dimensionally. For example, the field of view (FOV) of the optical camera 33 is an area including an irradiation field into which radiation R is irradiated by the radiation source 15, similar to the field of view (FOV) of the distance measurement camera 32. For example, the optical image is a color image composed of red (R), green (G), and blue (B) pixels. The optical image may be a moving image.

[0043] The monitor 31 displays the imaging conditions, the optical image generated by the optical camera 33, and the like. For example, the monitor 31 is a display such as a liquid crystal display. The monitor 31 may be provided with an operation device such as a touch panel. The optical image is used for positioning the subject H with respect to the irradiation field of the radiation R. As will be described in detail later, for example, the imaging conditions are determined by correcting the imaging conditions provisionally determined based on the selected imaging menu, based on the body thickness of the subject H calculated based on the distance image.

[0044] Figures 2 and 3 show the configuration of the radiation source 15. Figure 2 is a diagram of the radiation source 15 viewed from a direction perpendicular to the irradiation direction of the radiation R. Figure 3 is a diagram of the radiation source 15 viewed from a direction parallel to the irradiation direction of the radiation R. In this disclosure, the irradiation direction of the radiation R is defined as the Z direction, one direction perpendicular to the Z direction is defined as the X direction, and a direction perpendicular to the Z direction and the X direction is defined as the Y direction.

[0045] The optical axis A0 of the radiation R is a straight line passing from the radiation focus F0 to the central position of the irradiation field of the radiation R (hereinafter also referred to as the central position of the radiation R) and is parallel to the irradiation direction (Z direction) of the radiation R. The distance measuring camera 32 is disposed so that its optical axis A1 is parallel to the optical axis A0 of the radiation R. The optical axis A1 of the distance measuring camera 32 is a straight line passing from the camera focus F1 to the center of the field of view FOV. The camera focus F1 is a rear focus located on the focal plane of the distance measuring camera 32.

[0046] Similarly, the optical camera 33 is disposed such that its optical axis A2 is parallel to the optical axis A0 of the radiation R. The optical axis A2 of the optical camera 33 is a straight line that passes through the center of the field of view FOV from the camera focus F2. The camera focus F2 is a rear focus located on the focal plane of the optical camera 33.

[0047] The radiation focus F0 and the camera focus F1 are shifted in three-dimensional directions, i.e., in the X, Y, and Z directions. Hereinafter, the amounts of positional shift of the camera focus F1 relative to the radiation focus F0 in the X, Y, and Z directions are defined as ΔX1, ΔY1, and ΔZ1, respectively.

[0048] Similarly, the radiation focus F0 and the camera focus F2 are shifted in three-dimensional directions, i.e., in the X-, Y-, and Z-directions. Although not shown in Figures 2 and 3, the amounts of positional shift of the camera focus F2 in the X-, Y-, and Z-directions with respect to the radiation focus F0 are denoted as ΔX2, ΔY2, and ΔZ2, respectively. For example, the optical camera 33 is disposed so as to satisfy the relationships ΔX1=ΔX2, ΔY1≠Y2, and ΔZ1=ΔZ2.

[0049] 4 shows an example of the configuration of the console 12. The console 12 includes a CPU (Central Processing Unit) 40, a memory 41, a communication I / F (Interface) 42, a display 43, and an input device 44. The display 43 is a liquid crystal display or the like, and displays various screens. The input device 44 includes a keyboard, a mouse, etc., and receives operational instructions from an operator.

[0050] The memory 41 is a storage device such as a flash memory built into or connected to the CPU 40. An operating program 41A, various data, etc. are stored in the memory 41. The CPU 40 executes processing based on the operating program 41A stored in the memory 41. In this way, the CPU 40 comprehensively controls each part of the computer. The CPU 40 is an example of a "processor" according to the technology of the present disclosure. The communication I / F 42 controls the transmission of various information between the electronic cassette 11 and an external device.

[0051] The CPU 40 displays a plurality of types of imaging menus on the display 43 in a selectable form. The imaging menu specifies an imaging technique that is a set of the imaging region of the subject H, the imaging posture of the subject H, and the imaging direction of the subject H, such as "chest, standing, front" or "abdomen, standing, front". The imaging region includes the head, neck, abdomen, lower back, shoulders, elbows, hands, knees, ankles, etc. in addition to the chest. The imaging posture includes the standing position, sitting position, etc. in addition to the supine position. The imaging direction includes the back, side, etc. in addition to the front. The operator operates the input device 44 to select one imaging menu from the plurality of types of imaging menus. In this way, the CPU 40 accepts the selected imaging menu.

[0052] Before starting radiography, the CPU 40 acquires the distance image 32A output from the distance measuring camera 32 and the optical image 33A output from the optical camera 33 via the communication I / F 42. In addition to the selected radiography menu, the CPU 40 calculates the body thickness BT of the subject H based on the distance image 32A, and determines the radiography conditions based on the calculated body thickness BT. The CPU 40 transmits the determined radiography conditions to the radiation source control device 23 via the communication I / F 42.

[0053] Furthermore, the CPU 40 outputs the optical image 33A to the monitor 31 via the communication I / F 42, thereby causing the monitor 31 to display the optical image 33A.

[0054] Furthermore, when an instruction to start irradiation of radiation R is given to the radiation source control device 23 via the irradiation switch 16, the CPU 40 receives from the radiation source control device 23 an irradiation start signal indicating that irradiation of radiation R will start. When the CPU 40 receives the irradiation start signal, it transmits a synchronization signal indicating that irradiation of radiation R will start to the electronic cassette 11. Furthermore, the CPU 40 receives from the radiation source control device 23 an irradiation end signal indicating that irradiation of radiation R has ended. When the CPU 40 receives the irradiation end signal, it transmits a synchronization signal indicating that irradiation of radiation R has ended to the electronic cassette 11.

[0055] The electronic cassette 11 causes the detection panel to start a storage operation when it receives a synchronization signal from the console 12 indicating that irradiation of radiation R has started. Also, the electronic cassette 11 causes the detection panel to start a readout operation when it receives a synchronization signal from the console 12 indicating that irradiation of radiation R has ended.

[0056] The CPU 40 receives the radiation image from the electronic cassette 11 via the communication I / F 42. The CPU 40 performs various image processing on the radiation image, and then displays the radiation image on the display 43 for viewing by the operator.

[0057] 5 shows an example of functions related to determining imaging conditions configured in the CPU 40. The CPU 40 functions as an acquisition unit 50, a data conversion unit 51, a body thickness calculation unit 52, and an imaging condition determination unit 53 by executing processes based on an operating program 41A.

[0058] The acquiring unit 50 acquires a distance image 32A output from the distance measuring camera 32 by controlling the distance measuring camera 32. For example, as shown in Fig. 1, the acquiring unit 50 acquires the distance image 32A in response to an operator operating an operating device such as an input device 44 while the subject H is lying on his back on the bed 18. The field of view FOV of the distance measuring camera 32 includes at least a part of the subject H and the bed 18.

[0059] Data conversion unit 51 converts distance image 32A acquired by acquisition unit 50 into three-dimensional point cloud 32B by a known method. Three-dimensional point cloud 32B is data in which each pixel value included in distance image 32A is converted into each point in three-dimensional space, and is a collection of points in three-dimensional space.

[0060] The body thickness calculation unit 52 calculates the body thickness BT of the subject H in the three-dimensional space based on the three-dimensional point group 32B.

[0061] The imaging condition determination unit 53 determines the imaging condition by correcting the imaging condition provisionally determined based on the selected imaging condition based on the body thickness BT calculated by the body thickness calculation unit 52. Specifically, the imaging condition determination unit 53 estimates the body size of the subject H from among a plurality of body sizes based on the body thickness BT, and corrects the imaging condition based on the estimated body size. For example, the imaging condition determination unit 53 increases the tube current and / or the tube current time product as the body size increases. For example, the plurality of body sizes are three body sizes, namely, "large", "medium", and "small". Note that the imaging condition determination unit 53 may correct the imaging condition based on the SID calculated by the SID calculation unit 52B described later in addition to the body thickness BT. For example, the tube current and / or the tube current time product may increase as the SID increases.

[0062] The imaging conditions determined by the imaging condition determination unit 53 are transmitted to the radiation source control device 23. The radiation source control device 23 operates the tube voltage generator 24 based on the received imaging conditions.

[0063] FIG. 6 shows an example of a distance image 32A output from the distance measuring camera 32. FIG. 7 shows an example of a three-dimensional point group 32B converted by the data conversion unit 51. For example, the three-dimensional point group 32B is expressed in coordinates with the X axis parallel to the X direction, the Y axis parallel to the Y direction, and the Z axis parallel to the Z direction as the coordinate axes. As shown in FIG. 2 and FIG. 3, since the positional relationship between the radiation focus F0 and the camera focus F1 is known, the coordinates of the radiation focus F0 in the three-dimensional point group 32B are specified based on the camera focus F1. For example, the coordinates of the radiation focus F0 can be expressed as (X F0 ,Y F0,Z F0 ), and the coordinates of the camera focus F1 are (X F1 ,Y F1 ,Z F1 ), then (X F0 ,Y F0 ,Z F0 )=(X F1 +ΔX1,Y F1 -ΔY1,Z F1 -ΔZ1), where ΔX1>0, ΔY1>0, and ΔZ1>0.

[0064] FIG. 8 shows an example of the configuration of the body thickness calculation unit 52. The body thickness calculation unit 52 is composed of an SSD calculation unit 52A that calculates a source-to-surface distance (SSD), an SID calculation unit 52B that calculates a source-to-image distance (SID), and a difference calculation unit 52C. As shown in FIG. 6, SSD is the distance from the radiation focal point F0 to the surface of the subject H, and corresponds to the "first distance" according to the technology of the present disclosure. In this embodiment, SID is the distance from the radiation focal point F0 to the surface of the top board 18A of the bed 18, and corresponds to the "second distance" according to the technology of the present disclosure. Note that SSD and SID are lengths along the Z direction. Also, SSD is the length in the Z direction starting from the radiation focal point F0.

[0065] The SSD calculation unit 52A calculates the SSD based on the three-dimensional point group 32B in a three-dimensional space. The SID calculation unit 52B calculates the SID based on the three-dimensional point group 32B in a three-dimensional space. The difference calculation unit 52C calculates the difference between the SID calculated by the SID calculation unit 52B and the SID calculated by the SSD calculation unit 52A as the body thickness BT. Specifically, the difference calculation unit 52C calculates the body thickness BT using the relational expression BT=SID-SSD.

[0066] Fig. 9 shows an example of calculation processing of SSD and SID. As shown in Fig. 9, the SSD calculation unit 52A searches for a point P (hereinafter referred to as the closest point P) that is closest to the radiation focus F0 among the three-dimensional point group 32B along the Z direction (i.e., the irradiation direction of the radiation R) from the radiation focus F0. Then, the SSD calculation unit 52A calculates the distance from the radiation focus F0 to the closest point P detected by the search as the SSD. The closest point P is a point on the surface of the subject H at the center position of the radiation R.

[0067] The SID calculation unit 52B sets a predetermined region S centered on the central position of the radiation R (i.e., the central position of the irradiation field). The SID calculation unit 52B then detects a plane perpendicular to the Z direction (i.e., the XY plane) from the point group included in the region S of the three-dimensional point group 32B, which is on the far side of the radiation focal point F0 with the closest point P detected when the SSD calculation unit 52A calculates the SSD as the origin, and calculates the difference between the Z coordinate of the detected plane and the radiation focal point F0 as the SID. For example, the region S is a rectangular region that is larger than the planar shape of the electronic cassette 11 and smaller than the surface of the tabletop 18A.

[0068] Specifically, the SID calculation unit 52B uses the three-dimensional point group 32B included in the region S to create a histogram in which the vertical axis represents the number of points and the horizontal axis represents the Z coordinate (i.e., the coordinate of the point in the irradiation direction of the radiation R) as shown in Fig. 10, and obtains the value Zp of the Z coordinate at which the number of points is maximum. Since the value Zp is estimated to be the Z coordinate of the surface of the tabletop 18A, the SID calculation unit 52B calculates SID=Zp-Z F0 The SID is calculated using the following relational expression. The vertical axis is an example of the "first axis" according to the technology of the present disclosure. The horizontal axis is an example of the "second axis" according to the technology of the present disclosure.

[0069] The size of the region S may be changed according to the surface size of the top plate 18A. The size of the region S is preferably set so as not to include the outer region of the top plate 18A. The size of the region S may be appropriately changed according to the size of the electronic cassette 11, etc. For example, the size of the region S may be set to be equal to or smaller than the size of the electronic cassette 11. In this case, the surface of the electronic cassette 11 is detected as a plane perpendicular to the Z direction described above. That is, the SID may be the distance in the Z direction from the radiation focus F0 to the surface of the electronic cassette 11. In this case, the electronic cassette 11 is an example of a "member against which the subject abuts and which is disposed at a position farther from the radiation source than the subject" according to the technology of the present disclosure.

[0070] As described above, according to the technology disclosed herein, the distance image 32A acquired by the distance measuring camera 32 attached to the radiation source 15 is converted into a three-dimensional point cloud 32B, and the distance from the radiation focus F0 to the object is calculated based on the converted three-dimensional point cloud 32B, so that the distance from the radiation focus F0 to the object can be easily and accurately determined.

[0071] Fig. 11 shows an example of the central position C0 of radial line R on distance image 32A. In Fig. 11, C1 indicates the central position of distance image 32A, i.e., the position through which optical axis A1 passes. W indicates the length of distance image 32A in the X direction. H indicates the length of distance image 32A in the Y direction. The lengths W and H are expressed in units of pixels. O is the origin.

[0072] If the coordinate in the X direction of the center position C0 of the radial line R relative to the origin O is Xc and the coordinate in the Y direction is Yc, the coordinates Xc and Yc are expressed by the following equations (1A) and (1B), respectively. Xc = (W / 2) × (1 + α x / d) ···(1A) Yc = (H / 2) × (1-α Y / d) ···(1B)

[0073] Here, d is the distance from the camera focal point F1 to the imaging plane, and is expressed, for example, by the following formula (2). d = SID - ΔZ1 (2)

[0074] α x ,α Y is represented by the following formulas (3A) and (3B). α x =ΔX1 / tan(ω X / 2) ···(3A) α Y =ΔY1 / tan(ω Y / 2) ···(3B)

[0075] Here, ω X is the angle of view of the distance measuring camera 32 in the X direction. Y is the angle of view in the Y direction of the distance measuring camera 32. ΔX1, ΔY1, and ΔZ1 are the amounts of positional deviation between the above-mentioned radiation focus F0 and the camera focus F1.

[0076] If the center position C0 of the radiation R on the distance image 32A can be identified, the distance from the focal point F0 to the object can be calculated based on the distance image 32A. However, as can be seen from the above formulas (1A) and (1B), the center position C0 of the radiation R on the distance image 32A varies according to a hyperbolic function depending on the distance d, and therefore it is not easy to identify it. In particular, in the radiation imaging system 2 using the mobile radiation irradiation device 10 as in the above embodiment, the distance d varies each time the operator positions the radiation source 15 and the subject H, and therefore the center position C0 of the radiation R varies. In this way, when the center position C0 of the radiation R varies, it is difficult to accurately identify the center position C0 of the radiation R on the distance image 32A, and therefore the distance from the focal point F0 to the object cannot be accurately calculated. In contrast, in the three-dimensional point cloud 32B converted from the distance image 32A, the coordinates of the radiation focus F0 can be easily identified based on the positional deviation amounts ΔX1, ΔY1, and ΔZ1, so that the distance from the radiation focus F0 to the object can be easily and accurately determined.

[0077] Various modifications of the above embodiment will be described below.

[0078] In the above embodiment, the CPU 40 corrects the imaging conditions based on the body thickness BT calculated by the body thickness calculation unit 52, but the information on the calculated body thickness BT may be notified by the notification device, and the imaging conditions may be corrected according to an input instruction received by the operation device. For example, the notification device is a display device such as the display 43 or the monitor 31. The operation device is an input device 44, etc.

[0079] 12, the CPU 40 displays icons 60 representing a plurality of physiques 61 to 63 on a display device such as the display 43 or the monitor 31, and allows an operator to select one of the plurality of physiques 61 to 63 using an operation device such as the input device 44. One of the plurality of physiques 61 to 63 is a physique estimated based on the body thickness BT calculated by the body thickness calculation unit 52. The physique estimated based on the body thickness BT is an example of "information related to body thickness" related to the technology of the present disclosure.

[0080] 12, the CPU 40 displays a mark 64 to enable identification of a physique 62 estimated based on the body thickness BT calculated by the body thickness calculation unit 52, thereby suggesting to the operator to select a physique 62. The CPU 40 corrects the imaging conditions according to the physique selected by the operator, determines the corrected imaging conditions, and transmits them to the radiation source control device 23. The operator can also select a physique other than the suggested physique.

[0081] In the above embodiment, the data conversion unit 51 of the CPU 40 converts the distance image 32A acquired from the distance measuring camera 32 into the three-dimensional point cloud 32B, but an image obtained by performing noise removal processing on the distance image 32A may be converted into the three-dimensional point cloud 32B. Specifically, as shown in FIG. 13, a noise removal processing unit 54 is added between the acquisition unit 50 and the data conversion unit 51. The noise removal processing unit 54 removes noise from the distance image 32A by performing filtering processing such as a median filter on the distance image 32A, and inputs the distance image 32A after the noise removal processing to the data conversion unit 51. In this way, by performing noise removal processing on the distance image 32A, noise is removed from the three-dimensional point cloud 32B, and the calculation accuracy of the SSD and SID is improved. This improves the calculation accuracy of the body thickness BT.

[0082] In the above embodiment, since the radiation irradiation direction and the optical axis A1 of the distance measuring camera 32 are parallel to each other, the SSD calculation unit 52A detects the closest point P by searching the three-dimensional point group 32B from the radiation focus F0 in the radiation irradiation direction (i.e., the Z direction). However, in reality, the radiation irradiation direction and the optical axis A1 may not be parallel to each other, and when the radiation irradiation direction and the optical axis A1 are not parallel to each other, it is considered that the detection accuracy of the closest point P will decrease if a search is performed in the radiation irradiation direction from the radiation focus F0.

[0083] Therefore, the deviation angle between the radiation irradiation direction and the optical axis A1 may be obtained in advance by calibration, the coordinates of the three-dimensional point group 32B may be converted by a rotation operation according to the obtained deviation angle, and the coordinate-converted three-dimensional point group 32B may be used to search along the converted Z direction to detect the closest point P and calculate the SSD. Specifically, the three-dimensional point group 32B is subjected to coordinate conversion by a rotation operation from a three-dimensional coordinate system in which the direction of the optical axis A1 is the Z axis to a three-dimensional coordinate system in which the radiation irradiation direction is the Z axis, based on the deviation angle obtained by calibration.

[0084] For example, the calibration is performed by acquiring distance image 32A with SID set to a predetermined value, without placing subject H, and with center position C0 of radiation R aligned with a predetermined position on the surface of top board 18A of bed 18. By measuring the amount by which center position C0 identified in acquired distance image 32A is shifted in the X and Y directions from a geometrically determined position, the above-mentioned angle of deviation between the radiation irradiation direction and optical axis A1 can be obtained.

[0085] Alternatively, the closest point P may be detected by the following method. As shown in FIG. 14, the SSD calculation unit 52A sets a rectangular parallelepiped 70 extending from the radiation focal point F0 in the radiation irradiation direction, and searches for the closest point P from the points included in the rectangular parallelepiped 70 among the three-dimensional point group 32B. The point closest to the radiation focal point F0 among the points included in the rectangular parallelepiped 70 may be set as the closest point P. Alternatively, the average value of the coordinates of the points included in the rectangular parallelepiped 70 may be calculated, and a point having the average value as its coordinate may be set as the closest point P. Specifically, the average values ​​of the X coordinate, Y coordinate, and Z coordinate of the points included in the rectangular parallelepiped 70 are calculated, and the point having the calculated average values ​​of the X coordinate, Y coordinate, and Z coordinate as its X coordinate, Y coordinate, and Z coordinate, respectively, is set as the closest point P.

[0086] A cross section 71 of a rectangular parallelepiped 70 is defined based on the upper limit of the angle between the radiation irradiation direction and the optical axis A1, and the upper limit of SID. The cross section 71 is a rectangular surface having sides parallel to the X direction and Y direction. The length Xr of the side parallel to the X direction and the length Yr of the side parallel to the Y direction are expressed by the following formulas (4A) and (4B), respectively. Xr=SID max ×sin(θ Xmax ) ···(4A) Yr=SID max ×sin(θ Ymax ) (4B)

[0087] where SID max is the upper limit of the expected SID. Xmax is the X-direction component of the upper limit of the angle between the radiation irradiation direction and the optical axis A1. Ymaxis the Y-direction component of the upper limit of the angle between the radiation irradiation direction and the optical axis A1.

[0088] In the above embodiment, the CPU 40 displays the optical image 33A output from the optical camera 33 on the monitor 31. As shown in Fig. 15, the CPU 40 may superimpose the center position C0 of the radiation R on the optical image 33A displayed on the monitor 31. The center position C0 of the radiation R corresponds to the closest point P. The CPU 40 calculates the coordinates of the center position C0 of the radiation R on the optical image 33A using the above-mentioned positional deviations ΔX2, ΔY2, and ΔZ2 between the radiation focus F0 and the camera focus F2 and the SID calculated by the SSD calculation unit 52A, and displays a mark indicating the center position C0 of the radiation R at the calculated coordinates.

[0089] Specifically, the X coordinate Xc' and the Y coordinate Yc' of the center position C0 of the radiation R on the optical image 33A are expressed by the following equations (5A) and (5B), respectively. Xc' = (W' / 2) × (1 + β x / d') ···(5A) Yc' = (H' / 2) × (1-β Y / d') ···(5B)

[0090] Here, d' is the distance from the camera focal point F2 to the imaging plane, and is expressed by, for example, the following formula (6). W' indicates the length of the optical image 33A in the X direction. H' indicates the length of the optical image 33A in the Y direction. d' = SID - ΔZ2 (6)

[0091] β x ,β Y is expressed by the following formulas (7A) and (7B). β x =ΔX2 / tan(Ω X / 2) ···(7A) β Y =ΔY2 / tan(Ω Y / 2) (7B)

[0092] Here, Ω Xis the angle of view of the optical camera 33 in the X direction. Ω Y is the angle of view of the optical camera 33 in the Y direction.

[0093] The CPU 40 may also display the irradiation field 80 of the radiation R superimposed on the optical image 33A displayed on the monitor 31, with the center position C0 of the radiation R as the center. When the radiation irradiating device 10 has the aperture information of the aperture 22A of the collimator 22, the CPU 40 determines the size of the irradiation field 80 to be superimposed on the optical image 33A based on the aperture information. For example, the aperture information of the aperture 22A is stored in the memory 41, and the CPU 40 determines the size of the irradiation field 80 on the optical image 33A based on the aperture information read from the memory 41. When the radiation irradiating device 10 does not have the aperture information, the CPU 40 determines the size of the irradiation field 80 on the optical image 33A based on the aperture information linked to the imaging menu selected by the operator. For example, as shown in FIG. 16, the imaging menu and the aperture information are linked.

[0094] Furthermore, the CPU 40 may superimpose a frame representing the outer shape of the electronic cassette 11 on the optical image 33A displayed on the monitor 31, with the center position C0 of the radiation R at the center. For example, as shown in FIG. 17, the CPU 40 displays a frame 90 representing the outer shapes of a plurality of types of electronic cassettes 11 that can be used in the radiation imaging system 2, with the center position C0 of the radiation R at the center. For example, the frame 90 represents the outer edge of a 14×14 inch electronic cassette 11 and the outer edge of a 17×17 inch electronic cassette 11. Since the electronic cassette 11 may be disposed behind the subject H and not appear in the optical image 33A, the frame representing the outer shape of the electronic cassette 11 is superimposed on the optical image 33A, so that the operator can recognize the outer shape of the electronic cassette 11 when positioning the subject H.

[0095] The size of the frame 90 is preferably expressed as the size on the surface of the subject H on the optical image 33A. For example, if the length of the frame 90 in the X direction is D', the actual length of the electronic cassette 11 in the X direction is D, and the distance from the camera focus F2 to the surface of the subject H is k (=SSD-ΔZ2), then the length D' of the frame 90 in the X direction is expressed by the following formula (8). D'=D×{W' / (2×k×tan(Ω X / 2))} ···(8)

[0096] Here, W' is the length of the optical image 33A in the X direction. X is the angle of view in the X direction of the optical camera 33. The length of the frame 90 in the Y direction can be calculated using a similar formula.

[0097] 15 is also preferably expressed as a size on the surface of the subject H on the optical image 33A. The length L of the radiation R radiation field on the surface of the subject H in the X direction is expressed as a solid angle Φ X Then, it is expressed by the following equation (9). L = 2 × SSD × tan(Φ X / 2) ···(9)

[0098] The length L' in the X direction of the irradiation field 80 displayed on the optical image 33A is expressed by the following formula (10) similarly to the above formula (8) using the length L calculated by the above formula (9). L'=L×{W' / (2×k×tan(Ω X / 2))} ···(10)

[0099] The length in the Y direction of the irradiation field 80 displayed on the optical image 33A can be calculated using a similar formula.

[0100] In the above embodiment, the technology of the present disclosure is described by taking the radiography system 2 having the mobile radiation irradiation device 10 as an example. The technology of the present disclosure is not limited to the mobile radiography system, and can also be applied to a radiography system in which the radiation irradiation device is installed in a radiography room or the like. For example, the radiation irradiation device of the present disclosure may be movably supported by a ceiling traveling device or a floor traveling device via a support unit. In this case, the subject is placed on an imaging table such as an upright imaging table or a lying imaging table. Also, the electronic cassette is stored in a holder provided on the imaging table. In this case, the imaging table is an example of "a member against which the subject abuts and which is placed farther from the radiation source than the subject" according to the technology of the present disclosure.

[0101] The hardware configuration of the processor in the above embodiment can be modified in various ways as follows. The processor includes a CPU, a PLD (Programmable Logic Device), a dedicated electric circuit, or a combination of these. As is well known, a CPU is a general-purpose processor that executes software (i.e., a program) and functions as various processing units. A PLD is a processor whose circuit configuration can be changed after manufacture, such as an FPGA (Field Programmable Gate Array). A dedicated electric circuit is a processor having a circuit configuration designed specifically for executing specific processing, such as an ASIC (Application Specific Integrated Circuit). Furthermore, the hardware structure of these various processors is, more specifically, an electric circuit (circuitry) that combines circuit elements such as semiconductor elements.

[0102] The above-described embodiment and each modified example may be combined in two or more forms as long as no contradiction occurs.

[0103] The technology of the present disclosure is not limited to the above-described embodiment and each modified example, and various configurations can be adopted without departing from the gist of the present disclosure. Furthermore, the technology of the present disclosure extends to a computer-readable storage medium that non-temporarily stores a program, in addition to a program.

[0104] The above explanation makes it possible to understand the following techniques. [Additional note 1] A radiation source that irradiates a target object with radiation; a distance measurement camera attached to the radiation source, the distance measurement camera including the object within a field of view, and generating a distance image in which each pixel value represents a distance; A processor; Equipped with The processor converts the distance image into a three-dimensional point cloud, and calculates a distance from the radiation focus to the object based on the converted three-dimensional point cloud. Radiation irradiation equipment. [Additional note 2] The processor, searching for a closest point, which is a point closest to the radiation focus, among the three-dimensional point cloud along the irradiation direction of the radiation from the radiation focus; calculating a distance from the radiation focus to the closest point detected by the search; Item 1. The radiation irradiation device according to item 1. [Additional note 3] The processor, a rectangular parallelepiped extending from the radiation focal point in an irradiation direction of the radiation is set; A closest point that is a point closest to the radiation focus is searched for from the three-dimensional point group included in the rectangular parallelepiped; calculating a distance from the radiation focus to the closest point detected by the search; Item 1. The radiation irradiation device according to item 1. [Additional note 4] The object is a specimen, The processor calculates a first distance, the first distance being a distance from the radiation focal point to a surface of the object. Item 3. The radiation irradiation device according to any one of items 1 to 3. [Additional note 5] the target object is a surface of a member that is in contact with an object to be examined and that is disposed at a position farther from the radiation source than the object to be examined, the processor calculates a second distance, the second distance being a distance from the radiation focal point to a surface of the member. Item 3. The radiation irradiation device according to any one of items 1 to 3. [Additional note 6] The member is a bed, an imaging table, or a radiation image detector. 6. The radiation irradiation device according to claim 5. [Additional note 7] The processor, a histogram is created using the three-dimensional point cloud included in an area centered on the center position of the radiation, with the number of points as a first axis and the coordinates of the points related to the irradiation direction of the radiation as a second axis; calculating the second distance by determining the coordinate value at which the number of points is maximum in the histogram; 7. The radiation irradiation device according to claim 5 or 6. [Additional note 8] The processor changes the size of the region according to the size of the surface of the member. 8. The radiation irradiation device according to claim 7. [Additional note 9] the target object includes an object to be examined and a surface of a member with which the object to be examined is in contact and which is disposed at a position farther from the radiation source than the object to be examined; The processor, calculating a first distance which is a distance from the focal point to a surface of the object, and calculating a second distance which is a distance from the focal point to a surface of the member; A difference between the first distance and the second distance is calculated as a body thickness of the subject. Item 3. The radiation irradiation device according to any one of items 1 to 3. [Additional Note 10] The processor corrects an imaging condition defined by a tube voltage and a tube current time product based on the body thickness. 10. The radiation irradiation device according to claim 9. [Additional Note 11] The processor, The information regarding the body thickness is notified by an alarm device, correcting the imaging conditions defined by the tube voltage and the tube current time product in response to an input instruction received by the operation device; 10. The radiation irradiation device according to claim 9. [Additional Note 12] an optical camera attached to the radiation source for generating an optical image including the object; A display device that displays the optical image; and Further equipped with the radiation source has a collimator for limiting an irradiation field of the radiation; The processor causes one or both of the center position of the radiation and the irradiation field to be superimposed on the optical image. 12. The radiation irradiation device according to claim 1. [Additional Note 13] When the processor has collimator aperture information, the processor determines the size of the irradiation field on the optical image based on the collimator aperture information. 13. The radiation irradiation device according to claim 12. [Additional Note 14] When the processor does not have the collimator opening information, the processor determines the size of the irradiation field on the optical image based on the collimator opening information associated with the imaging menu. 13. The radiation irradiation device according to claim 12. [Explanation of symbols]

[0105] 2 Radiography system 10 Radiation irradiation equipment 11 Electronic Cassette 12 Console 14 Bogie section 15 Radiation source 16 Irradiation switch 17 wheels 18 Beds 18A Top plate 19 First Arm 20 Second Arm 21 Radiation tube 22 Collimator 23 Radiation source control device 24 Tube voltage generator 25 Cassette storage section 26 Handle 30 Camera Unit 31 Monitor 32 Distance measuring camera 32A Distance Image 32B 3D point cloud 33 Optical Camera 33A Optical image 40 CPU 41 Memory 41A Operation Program 42 Communication I / F 43 Display 44 Input Devices 50 Acquisition Department 51 Data conversion section 52 Body Thickness Calculation Section 52A SSD calculation part 52B SID calculation section 52C Difference calculation section 53 Shooting condition determination unit 54 Noise removal processing section 60 Icons 61~63 physique 64 marks 70 Cuboid 71 Section 80 irradiation fields 90 frames A0,A1,A2 Optical axis BT body thickness C0 center position F0 Radiation focus F1,F2 camera focus FOV field of view H Subject O Origin P closest point R Radiation S Field

Claims

1. A radiation source that irradiates a target object with radiation; a distance measurement camera attached to the radiation source, the distance measurement camera including the object within a field of view, and generating a distance image in which each pixel value represents a distance; A processor; Equipped with The processor converts the distance image into a three-dimensional point cloud, and calculates a distance from the radiation focus to the object based on the converted three-dimensional point cloud. Radiation irradiation equipment.

2. The processor, searching for a closest point, which is a point closest to the radiation focus, among the three-dimensional point cloud along the irradiation direction of the radiation from the radiation focus; calculating a distance from the radiation focus to the closest point detected by the search; The radiation irradiation device according to claim 1 .

3. The processor, a rectangular parallelepiped extending from the radiation focal point in an irradiation direction of the radiation is set; searching for a closest point, which is a point closest to the radiation focus, from among the three-dimensional point group included in the rectangular parallelepiped; calculating a distance from the radiation focus to the closest point detected by the search; The radiation irradiation device according to claim 1 .

4. The object is a specimen, the processor calculates a first distance, the first distance being a distance from the radiation focal point to a surface of the object; The radiation irradiation device according to claim 1 .

5. the target object is a surface of a member that is in contact with an object to be examined and that is disposed at a position farther from the radiation source than the object to be examined, the processor calculates a second distance, the second distance being a distance from the radiation focal point to a surface of the member. The radiation irradiation device according to claim 1 .

6. The member is a bed, an imaging table, or a radiation image detector. The radiation irradiation device according to claim 5 .

7. The processor, creating a histogram using a group of points included in an area centered on the center position of the radiation from among the three-dimensional point group, with the number of points as a first axis and the coordinates of the points related to the irradiation direction of the radiation as a second axis; calculating the second distance by determining the coordinate value at which the number of points is maximum in the histogram; The radiation irradiation device according to claim 5 .

8. The processor changes the size of the region according to the size of the surface of the member. The radiation irradiation device according to claim 7.

9. the target object includes an object to be examined and a surface of a member with which the object to be examined is in contact and which is disposed at a position farther from the radiation source than the object to be examined; The processor, calculating a first distance which is a distance from the radiation focal point to a surface of the object, and calculating a second distance which is a distance from the radiation focal point to a surface of the member; A difference between the first distance and the second distance is calculated as a body thickness of the subject. The radiation irradiation device according to claim 1 .

10. The processor corrects an imaging condition defined by a tube voltage and a tube current time product based on the body thickness. The radiation irradiation device according to claim 9.

11. The processor, The information regarding the body thickness is notified by an alarm device, correcting the imaging conditions defined by the tube voltage and the tube current time product in response to an input instruction received by the operation device; The radiation irradiation device according to claim 9.

12. an optical camera attached to the radiation source for generating an optical image including the object; A display device that displays the optical image; and Further equipped with the radiation source has a collimator for limiting an irradiation field of the radiation; The processor causes one or both of the center position of the radiation and the irradiation field to be superimposed on the optical image. The radiation irradiation device according to claim 1 .

13. When the processor has collimator aperture information, the processor determines the size of the irradiation field on the optical image based on the collimator aperture information. The radiation irradiation device according to claim 12.

14. When the processor does not have the collimator opening information, the processor determines the size of the irradiation field on the optical image based on the collimator opening information associated with the imaging menu. The radiation irradiation device according to claim 12.

15. A radiation source that irradiates a target object with radiation; a distance measurement camera attached to the radiation source, the distance measurement camera including the object within a field of view, and generating a distance image in which each pixel value represents a distance; A method for operating a radiation irradiation device comprising: converting the distance image into a three-dimensional point cloud, and calculating a distance from the radiation focus to the object based on the converted three-dimensional point cloud; A method for operating a radiation irradiation device, comprising the steps of:

16. A radiation source that irradiates a target object with radiation; a distance measurement camera attached to the radiation source, the distance measurement camera including the object within a field of view, and generating a distance image in which each pixel value represents a distance; An operation program for operating a radiation irradiation device comprising: converting the distance image into a three-dimensional point cloud, and calculating a distance from the radiation focus to the object based on the converted three-dimensional point cloud; An operating program that causes a processor to execute a process including the steps of:

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