Radiography apparatus, radiationography method, and program

Abstract

To automatically optimize the relative positioning of a tube and an object.SOLUTION: The radiation imaging apparatus 1 includes an optical camera (optical camera 18) that captures an optical image, a first changing unit (first changing unit 19) that changes a relative position between a tube and a subject, and a determination unit (control unit 11) that determines whether relative positioning between the tube and the subject is good or bad based on a plurality of optical images.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a radiation imaging apparatus, a radiation imaging method, and a program. [Background Art]

[0002] Conventionally, a user such as an imaging technician manually positions a tube and a subject to perform radiation imaging. In recent years, radiation imaging apparatuses that automatically position the tube relative to the subject have begun to be developed.

[0003] Patent Document 1 describes that an optical camera integrally configured with the tube is used to image a subject, and positioning determination is performed as to whether the relative positional relationship between the tube and the subject is correct. Patent Document 2 describes that an optical camera is used to capture an image of a subject once, and positional information between the tube and the subject is acquired, among other things. [Prior Art Documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Unexamined Patent Publication No. 2012-24399 [Patent Document 2] Japanese Unexamined Patent Publication No. 2023-102361 [Summary of the Invention] [Problem to be Solved by the Invention]

[0005] In Patent Document 1, when it is determined that the relative positional relationship between the tube and the subject is incorrect, an inspection technician repositions the subject. By the way, when a radiation imaging apparatus automatically repositions the tube, it is necessary not only to acquire correctness information of the relative positional relationship, but also to acquire the relative positional information between the tube and the subject as a displacement amount. However, Patent Document 2 describes taking a picture using an optical camera only once, and does not necessarily allow for the accurate acquisition of positional information between the tube and the subject as a displacement amount.

[0006] Therefore, the objective of the present invention is to automatically optimize the relative positioning of the light tube and the subject. [Means for solving the problem]

[0007] To solve the above problems, the radiography apparatus of the present invention is An optical camera that captures an optical image of the subject, The relative positions of the light tube and the subject are Automatically The first means of making the change, A determination unit that determines the relative positioning of the tube and the subject based on a plurality of optical images, Equipped with, The relative positioning of the tube and the subject is achieved by repeating the process of changing the relative position of the tube and the subject using the first changing means, and determining whether the positioning is good or bad based on the optical image captured by the optical camera at the position after the change in the relative position of the tube and the subject, until the determination unit determines that the positioning is good.

[0008] Furthermore, the radiography method of the present invention is An optical camera that captures an optical image of the subject, The relative positions of the light tube and the subject are Automatically The first means of making the change, A radiographic imaging method using a radiographic imaging apparatus equipped with, The process includes a determination step of determining the relative positioning of the tube and the subject based on a plurality of optical images, The method includes a positioning step of performing relative positioning between the tube and the subject by repeating the change of the relative position between the tube and the subject by said first changing means and the determination of whether the positioning is acceptable based on the optical image captured at the position after the change of the relative position between the tube and the subject until said determination step determines that the positioning is acceptable.

[0009] Also, the program of the present invention is The subject an optical camera that captures an optical image, a tube, The aforementioned first changing means for changing the relative position of the subject, causes a computer of a radiation imaging apparatus comprising a plurality of The aforementioned based on optical images The aforementioned the tube and The aforementioned a determination unit that determines whether the relative positioning of the subject is acceptable, The process of changing the relative position of the tube and the subject using the first changing means, and determining whether the positioning is good or bad based on the optical image taken at the position after the change in the relative position of the tube and the subject, is repeated until the determination unit determines that the positioning is good. a positioning unit that performs relative positioning between the tube and the subject, to function as

Effects of the Invention

[0010] According to the present invention, the relative positioning between the tube and the subject can be automatically further optimized.

Brief Description of Drawings

[0011] [Figure 1] It is a schematic configuration diagram showing the radiation imaging apparatus of the present embodiment. [Figure 2] It is a schematic configuration diagram showing the radiation imaging apparatus of the present embodiment. [Figure 3] It is a schematic configuration diagram showing the radiation imaging apparatus of the present embodiment. [Figure 4] It is a schematic configuration diagram showing the radiation imaging apparatus of the present embodiment. [Figure 5] It is a block diagram showing the configuration of the radiation imaging apparatus. [Figure 6] It is a flowchart representing positioning determination processing. [Figure 7] It is a flowchart illustrating positioning determination processing. MODE FOR CARRYING OUT THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, various technically preferable limitations are added to the embodiments described below for carrying out the present invention. Therefore, the technical scope of the present invention is not limited to the following embodiments and illustrated examples.

[0013] <Overall Configuration of Radiation Imaging Apparatus 1> First, a schematic configuration of the radiation imaging apparatus 1 according to the present embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a schematic configuration diagram of the radiation imaging apparatus 1 as viewed from the side. FIG. 2 is a schematic configuration diagram of the radiation imaging apparatus 1 as viewed from above. The radiation imaging apparatus 1 includes a support column 2 and a structure 3 movably fixed to the support column 2. The structure 3 includes a first movement mechanism 1001 that moves the structure 3 in the vertical direction as shown in FIG. 1 or in a rotational direction around the support column 2 as shown in FIG. 2. The structure 3 includes a tube 16, an FPD (Flat Panel Detector) 17, an optical camera 18 and the like, which will be described later. The tube 16, the FPD 17, and the optical camera 18 are each movable relative to a subject 4 in up-down, front-back, left-right, and rotational directions (tilt directions relative to the subject 4). The tube 16 includes a second movement mechanism 1002 that moves the tube 16 in up-down, front-back, left-right, and rotational directions. The FPD 17 includes a third movement mechanism 1003 that moves the FPD 17 in up-down, front-back, left-right, and rotational directions. The third movement mechanism 1003 moves the FPD 17 to a position facing the tube 16 in accordance with movement of the tube 16. The optical camera 18 includes a fourth movement mechanism 1004 that moves the optical camera 18 in up-down, front-back, left-right, and rotational directions. In the radiography apparatus 1 shown in Figures 1 and 2, the tube 16 and the optical camera 18 are integrated and can be moved as a single unit. Furthermore, the tube 16 and the optical camera 18 may be separate components and movable, as shown in the radiography apparatus 5 in Figures 3 and 4. The first moving mechanism 1001, the second moving mechanism 1002, and the third moving mechanism 1003 are operated under the control of the control unit 11, which will be described later. As a result, the structure 3, the tube 16, and the FPD 17 are automatically moved relative to the subject 4, thereby automatically positioning the tube 16 relative to the subject 4.

[0014] <Components of the radiography apparatus 1> Next, the various components of the radiography apparatus 1 in this embodiment will be described using Figure 5. Figure 5 is a block diagram showing the configuration of the radiography apparatus 1. As shown in Figure 5, the radiography apparatus 1 includes a control unit 11, an operation unit 12, a display unit 13, a communication unit 14, a storage unit 15, a light tube 16, an FPD 17, an optical camera 18, a first modification unit 19, a second modification unit 110, and the like.

[0015] The control unit 11 is composed of a CPU (Central Processing Unit), RAM (Random Access Memory), etc. The CPU of the control unit 11 reads system programs and various processing programs stored in the memory unit 15 in response to input from the operation unit 12 and loads them into the RAM. The CPU of the control unit 11 executes various processes according to the loaded programs.

[0016] The control unit 11 functions as a determination unit that determines the quality of the relative positioning between the tube and the subject based on multiple optical images. The multiple optical images include not only multiple optical images captured as still images, but also multiple frame images captured as video. Multiple optical images are optical images taken at different shooting positions or angles. Furthermore, multiple optical images may also include optical images taken at different fields of view. Decision-making based on multiple optical images includes cases where a decision is made multiple times based on a single optical image, and cases where a decision is made multiple times based on multiple optical images.

[0017] The control unit 11 functions as a positioning unit that performs relative positioning of the light tube and the subject based on the determination result of the determination unit. Positioning involves moving the optical camera and tube first, and then determining the position at the location where good positioning is determined after the movement (Figure 6; positioning determination process), or moving the tube to the location where good positioning is determined (Figure 7; positioning determination process). Positioning is performed using various analytical models, such as machine learning models. The analysis model is assumed to have been pre-trained, with the input information being an optical image of subject 4 captured by the optical camera 18, and the output information being the relative positional information of the tube 16 and subject 4. Specifically, the relative positional information of the tube 16 and subject 4 refers to the direction and / or amount of deviation from the correct positioning. At least the direction of deviation is to be output. The positional information of the tube 16 and the optical camera 18 can be obtained from the operation information of the first moving mechanism 1001, the second moving mechanism 1002, and the fourth moving mechanism 1004, which move the tube 16 and the optical camera 18. Furthermore, the optical images input to the analysis model are not limited to one; multiple images may be used. One example of an analysis method is for the control unit 11 to estimate the position and posture of a person from an optical image (Japanese Patent Publication No. 2018-206321).

[0018] The operation unit 12 has a touch panel or the like, with transparent electrodes arranged in a grid pattern to cover the surface of the display unit 13. The operation unit 12 is configured to be operable by an operator. The operation unit 12 also outputs various signals to the control unit 11 based on the operations performed by the operator.

[0019] The display unit 13 is composed of monitors such as LCDs (Liquid Crystal Displays) and CRTs (Cathode Ray Tubes). The display unit 13 displays information according to the instructions of the display signals input from the control unit 11.

[0020] The communication unit 14 transmits and receives data from various devices, including the FPD 17, via wired or wireless communication. Wireless communication methods include wireless LAN (Local Area Network), Bluetooth, and infrared communication. Other wireless communication methods may also be used, and the unit may support multiple wireless communication methods. In addition to the FPD17, the various devices include RIS (Radiology Information Systems), electronic medical record systems, and PACS (Picture Archiving and Communication Systems).

[0021] The storage unit 15 is composed of non-volatile semiconductor memory, a hard disk, or the like. The storage unit 15 stores data such as various programs executed by the control unit 11, parameters necessary for processing by the programs, or processing results.

[0022] The tube 16 (radiation source) is driven by a drive unit (not shown). The drive unit is a circuit that drives the tube 16. The drive unit and the tube 16 are connected by a cable. The light tube 16 irradiates the subject 4 with radiation. Radiation is, for example, X-rays.

[0023] The FPD 17 is positioned opposite the tube 16 with the subject 4 in between, and generates an electric charge corresponding to the radiation emitted from the tube 16 and transmitted through the subject 4. The generated electric charge is then read out as image data.

[0024] The optical camera 18 is an optical camera that photographs the subject 4 and captures optical images. In addition to taking still images, the optical camera 18 can also continuously photograph the subject 4 to capture optical images as moving images in video format.

[0025] The first modification unit 19 is composed of a first movement mechanism 1001 and / or a second movement mechanism 1002. The first modification unit 19 changes the relative position between the light tube 16 and the subject 4 by moving the light tube 16. The first modification unit 19 can acquire position information of the light tube 16 from the operation information of the first moving mechanism 1001 and / or the second moving mechanism 1002.

[0026] The second modification unit 110 is composed of the first movement mechanism 1001 and / or the fourth movement mechanism 1004. The second modification unit 110 changes the relative position between the optical camera 18 and the subject 4 by moving the optical camera 18. The second modification unit 110 can acquire positional information of the optical camera 18 from the operation information of the first movement mechanism 1001 and / or the fourth movement mechanism 1004. Furthermore, if the tube 16 and the optical camera 18 are integrated, the first modification unit 19 also functions as the second modification unit 110.

[0027] <Positioning Determination Process Case 1> Next, the positioning determination process in this embodiment will be explained using Figure 6. The positioning determination process determines whether the position of the light tube 16 relative to the subject 4 is correct or incorrect, and automatically positions the light tube 16 relative to the subject 4. The positioning determination process shown in Figure 6 is a process performed in a radiography apparatus 1 in which the tube 16 and optical camera 18 are integrated. The default movement amount of the light tube 16, as described later, is entered by the user using the operation unit 12 and stored in the memory unit 15.

[0028] First, the control unit 11 controls the optical camera 18 and acquires a first optical image of the subject 4 from the optical camera 18 (step S1). Note that the first optical image is not limited to one image, but may be multiple images. If multiple images are to be acquired, the control unit 11 controls various movement mechanisms to change the position of the optical camera 18 and acquire multiple first optical images.

[0029] Next, the control unit 11 analyzes the first optical image using the analysis model (step S2). The control unit 11 obtains the direction of displacement and / or the amount of displacement. The control unit 11 obtains at least the direction of displacement. The displacement directions include vertical, horizontal, left-right, and tilt (rotation) directions relative to the subject 4, as well as combinations of these directions.

[0030] Next, the control unit 11 determines the direction of movement of the light tube 16 based on the acquired displacement direction (step S3).

[0031] Next, the control unit 11 determines whether it is possible to calculate the amount of movement of the light tube 16 based on the acquisition status of the displacement amount (step S4). If it is possible to calculate it (step S4; YES), the control unit 11 proceeds to step S5 for the positioning determination process. If it is not possible to calculate it (step S4; NO), the control unit 11 proceeds to step S6 for the positioning determination process.

[0032] Next, the control unit 11 calculates the amount of movement of the light tube 16 based on the acquired displacement amount (step S5). If there is an error between the amount of movement acquired by the analysis and the amount of movement in the actual device, the control unit 11 may reflect the error in the displacement amount when calculating the amount of movement.

[0033] Next, the control unit 11 obtains the default movement amount of the light tube 16 from the storage unit 15 (step S6).

[0034] Next, the control unit 11 uses the first modification unit 19 to move the integrated tube 16 and optical camera 18 (step S7).

[0035] First, the control unit 11 controls the optical camera 18 and acquires a second optical image of the subject 4 from the optical camera 18 (step S8). Note that the second optical image is not limited to one image, but may be multiple images. If multiple images are to be acquired, the control unit 11 controls various movement mechanisms to change the position of the optical camera 18 and acquire multiple second optical images.

[0036] Next, the control unit 11 analyzes the second optical image using the analysis model (step S9). The control unit 11 obtains the direction of displacement and / or the amount of displacement. The control unit 11 obtains at least the direction of displacement.

[0037] Next, the control unit 11 determines the positioning of the light tube 16 relative to the subject 4 (step S10). If the amount of displacement is less than a threshold (step S10; YES), the control unit 11 determines that the positioning is good and terminates the positioning determination process. If the amount of displacement is greater than or equal to the threshold, or if the amount of displacement has not been obtained (step S11; NO), the control unit 11 determines that the positioning is not good and proceeds to step S3 of the positioning determination process.

[0038] This allows the tube 16 and optical camera 18, which are integrated into a single unit, to be moved slightly up and down, forward and backward, left and right, and rotated, and the determination process is repeated, thereby automatically optimizing the relative positioning of the tube 16 and the subject 4. Furthermore, since the tilt relative to subject 4 cannot be calculated from a single optical image, this method allows us to calculate the direction of displacement including the tilt, and the amount of displacement including the tilt.

[0039] <Positioning Determination Process Case 2> Next, the positioning determination process in this embodiment will be explained using Figure 7. The positioning determination process shown in Figure 7 is a process in a radiography apparatus 1 in which the tube 16 and optical camera 18 are separate components. The default movement amount of the optical camera 18, described later, is assumed to be input by the user using the operation unit 12 and stored in the memory unit 15. Steps S11 and S12 are the same as steps S1 and S2 in Figure 6, so their explanation is omitted. Steps S20 to S22 are the same as steps S8 to S10 in Figure 6, so their explanation is omitted.

[0040] Next, the control unit 11 determines whether it is possible to calculate the amount of movement of the light tube 16 based on the acquisition status of the displacement amount in step S12 (step S13). If it is possible to calculate it (step S13; YES), the control unit 11 proceeds to step S14 for the positioning determination process. If it is not possible to calculate it (step S13; NO), the control unit 11 proceeds to step S17 for the positioning determination process.

[0041] This section explains the case where the amount of movement of the light tube 16 can be calculated. First, the control unit 11 determines the direction of movement of the light tube 16 based on the acquired displacement direction (step S14). Next, the control unit 11 calculates the amount of movement of the light tube 16 based on the acquired displacement amount (step S15). If there is an error between the amount of movement acquired by the analysis and the amount of movement in the actual device, the control unit 11 may reflect the error in the displacement amount when calculating the amount of movement. Next, the control unit 11 moves the light tube 16 using the first modification unit 19 (step S16). The control unit 11 then proceeds to step S20 to perform the positioning determination process.

[0042] This section explains the case where the amount of movement of the tube 16 cannot be calculated. First, the control unit 11 determines the direction of movement of the optical camera 18 based on the displacement direction of the tube 16 acquired in step S12 (step S17). In other words, the control unit 11 determines the direction of movement of the optical camera 18 in which the amount of movement of the tube 16 can be calculated as the direction of movement. Next, the control unit 11 obtains the default movement amount of the optical camera 18 from the storage unit 15 (step S18). Next, the control unit 11 moves the optical camera 18 using the second modification unit 110 (step S19). The control unit 11 then proceeds to step S20 to perform the positioning determination process.

[0043] This allows the optical camera 18 to be moved slightly up and down, forward and backward, left and right, and rotated, and the positioning is repeatedly evaluated. By moving the tube 16 to a position where good positioning is determined, the relative positioning of the tube 16 and the subject 4 can be automatically optimized.

[0044] <Other> In the positioning determination process described above, the position that is first determined to be good positioning in the positioning determination (steps S10, S22) is determined to be the final position, but this example is not limited to this case. For example, the control unit 11 may control various movement mechanisms to change the initial positions of the tube 16 and / or optical camera 18, perform multiple positioning determination processes, and determine the position with the best positioning determination result as the final position. The best positioning determination result means that the amount of deviation is the smallest.

[0045] The above explanation uses optical images acquired by the optical camera 18, but is not limited to this. For example, a radiographic image obtained by exposing the tube 16 to a low dose of radiation may be used. Also, if it is a retake and the subject 4 has not moved between the previous and retakes, the radiographic image from the previous take may be used. Furthermore, the quality determination may be made from a serial signal without using a radiographic image (frame image).

[0046] Furthermore, although the above describes the automatic movement of the tube 16 and / or optical camera 18 by control of the control unit 11, the system is not limited to this. A semi-automatic configuration may be provided in which a mechanism is provided to fix the direction of movement of the tube 16 and / or optical camera 18, the control unit 11 fixes the direction of movement of the tube 16 and / or optical camera 18, and the movement of the tube 16 and / or optical camera 18 is performed manually by the user. The control unit 11 may also show the amount of movement to the user by displaying it on the display unit 13.

[0047] Furthermore, the control unit 11 (determination unit) may determine the shooting conditions using an analysis model (for example, a machine learning model) that takes order information and sensor information (information acquired by the optical camera 18 and / or position information of the tube acquired by the first modification means) as input and outputs shooting conditions such as the conditions for radiation irradiation by the tube 16 and the conditions for radiation accumulation and reading by the FPD 17. This will lead to the determination of optimal shooting conditions. Imaging conditions include, for example, the size of the irradiation field, the position of the tube center, the angle of incidence, and the X-ray irradiation conditions (mAs value, tube voltage, filter type, etc.). For example, the control unit 11 estimates the thickness of the subject from the area information and optical image, and determines the tube voltage, tube current, and irradiation time. For example, the control unit 11 estimates the contour of the region of interest from the site information and optical image and determines the size of the irradiation field. For example, the control unit 11 can accurately determine the position by making fine adjustments to the position of the tube's center and the angle of incidence based on the direction and / or amount of displacement between the tube and the subject, which are obtained from the optical image and the position information of the tube.

[0048] Alternatively, instead of the optical camera 18, a sensor capable of detecting the amount of relative positional shift between the optical tube and the subject, such as a depth camera or a lidar scanner, may be used.

[0049] <Effects> Based on the above, the radiography apparatus 1 comprises an optical camera 18 for capturing optical images, a first changing means (first changing unit 19) for changing the relative position of the tube and the subject, and a determination unit (control unit 11) for determining whether the relative positioning of the tube and the subject is good or bad based on a plurality of optical images, and the relative positioning of the tube and the subject is performed based on the determination result of the determination unit. This allows for automatic and more optimized relative positioning between the tube and the subject.

[0050] Furthermore, the radiography method is a radiography method using a radiography apparatus 1 comprising an optical camera 18 for capturing optical images and a first changing means (first changing unit 19) for changing the relative position of the tube and the subject, and includes a determination step (steps S10, S22) for determining whether the relative positioning of the tube and the subject is good or bad based on a plurality of optical images, and a positioning step (steps S3 to S6, steps S13 to S15) for positioning the tube and the subject relative to each other based on the determination result of the determination step. This allows for automatic and more optimized relative positioning between the tube and the subject.

[0051] Furthermore, the program causes the computer of the radiography apparatus 1, which includes an optical camera 18 for capturing optical images and a first modification means (first modification unit 19) for changing the relative position of the tube and the subject, to function as a determination unit (control unit 11) that determines whether the relative positioning of the tube and the subject is good or bad based on a plurality of optical images, and a positioning unit (control unit 11) that performs the relative positioning of the tube and the subject based on the determination result of the determination unit. This allows for automatic and more optimized relative positioning between the tube and the subject.

[0052] Although the present invention has been described in detail based on embodiments above, the present invention is not limited to the above embodiments and can be modified without departing from the spirit of the invention.

[0053] Furthermore, while the above description has disclosed examples in which semiconductor memory and hard disks are used as computer-readable media for the program according to the present invention, the invention is not limited to these examples. Other computer-readable media that can be used include non-volatile memory such as flash memory and portable recording media such as CD-ROMs. Furthermore, a carrier wave can also be used as a medium for providing program data according to the present invention via a communication line. [Explanation of symbols]

[0054] 1. Radiography equipment 5. Radiography equipment 11 Control Unit (Determination Unit, Positioning Unit, Decision Unit) 12 Control section 13 Display section 14 Communications Department 15 Storage section 16 Tube 17 FPD 18 Optical Cameras 19. Section 1 of the Amendments 110 Section 2 of the Amendments 2 pillars 3 structure 4 Subject

Claims

1. An optical camera that captures an optical image of the subject, A first changing means for automatically changing the relative position of the light tube and the subject, A determination unit that determines the quality of the relative positioning of the tube and the subject based on a plurality of optical images, Equipped with, A radiography apparatus that positions the tube and the subject relative to each other by repeating the following steps: changing the relative position of the tube and the subject using the first changing means, and determining whether the positioning is good or bad based on the optical image captured by the optical camera at the position after the change in the relative position of the tube and the subject, until the determination unit determines that the positioning is good.

2. The radiography apparatus according to claim 1, wherein the first modification means is a tube moving means that changes the relative position of the tube and the subject by moving the tube based on the optical image.

3. The determination unit determines the quality of the positioning based on the first optical image captured at the first position by the optical camera, and the first changing means changes the relative positions of the tube and the subject based on the determination result. The radiography apparatus according to claim 1, wherein the determination unit re-determines the quality of the positioning based on a second optical image taken by the optical camera at a second position in which the relative positions of the tube and the subject have been changed.

4. The radiography apparatus according to claim 1, wherein the quality of the relative positioning includes the quality of the position and angle of the tube relative to the subject.

5. The radiography apparatus according to claim 1, further comprising a second changing means for changing the relative position of the optical camera and the subject.

6. The radiography apparatus according to claim 5, wherein the first modification means and the second modification means are a single modification means.

7. It includes a determination unit that determines the shooting conditions for radiography by taking order information and sensor information as input and analyzing it. The radiography apparatus according to claim 1, wherein the sensor information is information acquired by the optical camera and / or information acquired by the first modification means.

8. The radiography apparatus according to claim 7, wherein the imaging conditions include at least one of the following: irradiation field size, position of the tube center, incident angle, and X-ray irradiation conditions.

9. The aforementioned analysis is machine learning, according to the radiography apparatus of claim 7.

10. The radiography apparatus according to claim 8, wherein the X-ray irradiation conditions include at least one of mAs value, tube voltage, and filter type.

11. An optical camera that captures an optical image of the subject, A first changing means for automatically changing the relative position of the light tube and the subject, A radiographic imaging method using a radiographic imaging apparatus equipped with, The process includes a determination step of determining the relative positioning of the tube and the subject based on a plurality of optical images, A radiography method comprising a positioning step for positioning the tube and a subject relative to each other, by repeating the following steps: changing the relative position of the tube and the subject using the first changing means, and determining whether the positioning is good or bad based on the optical image taken at the position after the change in the relative position of the tube and the subject, until the positioning is determined to be good by the determination step.

12. An optical camera that captures an optical image of the subject, A first changing means for changing the relative position of the light tube and the subject, A computer for a radiography device equipped with, A determination unit that determines the quality of the relative positioning of the tube and the subject based on a plurality of optical images. A positioning unit that positions the tube and the subject relative to each other by repeating the following steps: changing the relative position of the tube and the subject using the first changing means, and determining whether the positioning is good or bad based on the optical image taken at the position after the change in the relative position of the tube and the subject, until the determination unit determines that the positioning is good. A program that makes it function as such.

Images