X-ray imaging apparatus and automatic control method for X-ray aperture opening.

Abstract

This technology provides an automatic setting of the illumination range that maximizes the effective image-receiving surface of the FPD, regardless of the FPD size. [Solution] The X-ray imaging apparatus comprises an X-ray irradiation unit including an X-ray tube and an X-ray diaphragm, an imaging table equipped with a storage unit for housing an X-ray detector, and a processor for controlling the X-ray irradiation unit. The processor has an automatic opening control function that detects the size of the X-ray detector and the distance between the X-ray tube and the X-ray detector, and automatically adjusts the opening of the X-ray diaphragm to match the size of the X-ray detector based on the detection results.

Description

Technical Field

[0001] The present invention relates to an X-ray imaging apparatus, and particularly to a control technique for an X-ray aperture.

Background Art

[0002] An X-ray imaging apparatus arranges an X-ray detector at a position facing an X-ray source that irradiates X-rays with a subject sandwiched therebetween, and performs imaging. The X-ray source is provided with an X-ray tube connected to a high-voltage generator, an X-ray aperture that determines the irradiation range of the X-rays irradiated from the X-ray tube, and an aperture motor that opens and closes the X-ray aperture. The X-ray aperture usually includes a pair of aperture blades that open and close in two orthogonal directions, for example, two directions of the vertical direction and the horizontal direction, and by driving the aperture motor to adjust the distance between the pair of blades (the opening degree of the aperture), the irradiation range (irradiation field) is adjusted.

[0003] At the time of imaging, an inspector or a doctor (collectively referred to as a user) operates an operation button on an operation panel installed near the X-ray source or a portable operation panel to adjust the distance (SID) between the X-ray source and the X-ray detector, the opening degree of the aperture, etc., and adjusts so that the X-ray irradiation range determined by the SID and the opening degree of the aperture substantially coincides with the X-ray detector. In the case of oblique incidence imaging in which X-rays are irradiated on the subject obliquely, the X-ray irradiation range is adjusted in consideration of the angle of the X-ray tube. Although there are various types of X-ray detectors, an FPD (Flat Panel Detector) that is versatile for both general imaging (also simply referred to as imaging) for acquiring still images and fluoroscopy for acquiring moving images is widely used.

[0004] In adjusting the X-ray irradiation field, in fluoroscopy mode imaging, it is defined as a standard that the X-ray irradiation field does not exceed the range of the X-ray detector, and the strictness of adjusting the opening degree of the aperture blades is high. Also, it is preferable that the entire imaging surface of the X-ray detector (FPD) can be used for the X-ray irradiation field, and it is desirable to secure the maximum irradiation field within the limits of the irradiation field.

[0005] Conventionally, the aperture opening is adjusted by the user via the control panel as described above, which is time-consuming and burdensome for the user. To address this problem, Patent Document 1 discloses a technology for automatically controlling the X-ray aperture, which involves the user specifying the dimensions of the irradiation field on the radiation detection surface, and then calculating the aperture amount from the specified irradiation field dimensions and adjusting the aperture accordingly. Specifically, it describes how, by inputting the position and size of the film, which is the X-ray detector, the aperture value (opening) is calculated using this information and the separately input distance between sensor tubes (SID), and the irradiation field is controlled to achieve the calculated aperture value.

[0006] Furthermore, Patent Document 2 discloses a technique for controlling the collimator drive mechanism (aperture adjustment mechanism) so that radiation is irradiated only within the incident range of the FPD based on information about the incident range and projection distance. Specifically, it describes that when the shooting mode is set, the incident range and shooting distance predetermined according to the shooting conditions are read out, the collimator opening (aperture opening) is calculated, and the collimator is controlled based on that. Furthermore, Patent Document 3 discloses a method for adjusting the aperture and cropping the resulting image when taking oblique-infrared X-ray images, in which the direction of X-ray irradiation is tilted relative to the imaging position of the subject. However, Patent Document 3 does not mention automatic control of the aperture. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2005-31323 [Patent Document 2] Japanese Patent Publication No. 2015-26313 [Patent Document 3] Japanese Patent Publication No. 2008-36314 [Overview of the Initiative]

[0008] The technologies described in Patent Documents 1 and 2 control the aperture assuming a constant size for the film or FPD, and therefore cannot accommodate the various FPDs currently in use, which have diverse sizes and effective image-receiving surface sizes. Furthermore, the technology described in Patent Document 2 determines the illumination field range based on a predetermined incident range, which still leaves the user with the problem of having to adjust the position of the FPD itself. Furthermore, there is a possibility that a different FPD than the one intended for use may be mistakenly set on the imaging table, in which case the illumination field may exceed the size of the FPD, but conventional technology cannot handle such cases.

[0009] The present invention aims to provide a technology that can automatically set the illumination range that maximizes the effective image-receiving surface of an FPD, regardless of the size of the FPD. [Means for solving the problem]

[0010] This invention detects the size and position of the X-ray detector while it is set in the housing, calculates the opening of the X-ray aperture (opening of the aperture blades) using the detected information, and automatically determines the irradiation field corresponding to the FPD.

[0011] In other words, the X-ray imaging apparatus of the present invention comprises an X-ray irradiation unit including an X-ray tube and an X-ray diaphragm, an imaging table equipped with a storage unit for housing an X-ray detector, and a processor for controlling the X-ray irradiation unit, wherein the processor has an automatic opening control function that detects the size of the X-ray detector and the distance between the X-ray tube and the X-ray detector, and automatically adjusts the opening of the X-ray diaphragm to match the size of the X-ray detector based on the detection results.

[0012] Furthermore, the present invention relates to an automatic control method for the X-ray aperture opening of an X-ray imaging apparatus comprising an X-ray irradiation unit including an X-ray tube and an X-ray aperture, and an imaging table equipped with a storage unit for housing an X-ray detector, and is characterized by including the steps of detecting the size of the X-ray detector housed in the storage unit and the distance between the X-ray tube and the X-ray detector, and calculating an X-ray aperture opening corresponding to the size of the X-ray detector using the detected size of the X-ray detector and the distance between the X-ray tube and the X-ray detector, and automatically controlling the X-ray aperture to achieve the calculated X-ray aperture opening. [Effects of the Invention]

[0013] According to the present invention, the size, position, or orientation of the X-ray detector is detected while it is housed in the storage unit, and the irradiation range is determined using the detected information, thereby eliminating the need for user adjustment and maximizing the effective imaging surface of the X-ray detector. [Brief explanation of the drawing]

[0014] [Figure 1] Diagram showing an overall overview of the X-ray imaging system. [Figure 2] Block diagram of one embodiment of an X-ray imaging apparatus [Figure 3] A diagram showing an example of an X-ray aperture. [Figure 4] Diagram showing the operation flow of an X-ray imaging device. [Figure 5] This diagram shows an example of a tray for housing an X-ray detector. [Figure 6] Diagram showing an example of the control panel display screen. [Figure 7] A diagram illustrating the structure of the tray that houses the FPD and the FPD size detection. [Figure 8] Diagram illustrating SID in supine and standing radiography. [Figure 9] Diagram illustrating the calculation of aperture opening in Embodiment 1 [Figure 10] A diagram showing the relationship between an encoder indicating the amount of aperture movement, the aperture opening, and the illumination field. [Figure 11] This figure shows an example of a table used to control the aperture opening. [Figure 12] Flowchart of the opening control of the X-ray aperture in Embodiment 1 [Figure 13] Diagram for explaining a modification of Embodiment 1 [Figure 14] Diagram for explaining the adjustment of the X-ray aperture in the modification

Mode for Carrying Out the Invention

[0015] Hereinafter, embodiments of the X-ray imaging apparatus of the present invention will be described with reference to the drawings. First, referring to FIGS. 1 and 2, an overall overview of the X-ray imaging apparatus of the present embodiment will be described.

[0016] As shown in FIG. 1, the X-ray imaging apparatus 1 includes an X-ray irradiation unit 10 including an X-ray tube 12 and an X-ray aperture 13, an imaging table (20, 30) for supporting a subject, and an X-ray tube drive mechanism unit 50 for moving the X-ray irradiation unit 10 (X-ray tube 12) in three orthogonal directions of X, Y, and Z and a rotational direction. The imaging table includes a supine imaging table 20 having a top plate 21 for laying the subject and a standing imaging table 30 for performing standing imaging, and each has a storage unit for storing an X-ray detector, usually an FPD 40, for detecting X-rays irradiated from the X-ray tube 12 and transmitted through the subject. In the following description, the X-ray detector is referred to as FPD 40.

[0017] The X-ray imaging apparatus 1 is also provided with an operation unit 60 and a console 80 (also referred to as an operation desk) for an operator to operate the X-ray irradiation unit 10 and the X-ray tube drive mechanism unit 50. The operation unit 60 is attached to the X-ray irradiation unit 10 and can move independently of the X-ray tube 12 and the like. The console 80 is installed in an operation room shielded from the imaging room where the X-ray irradiation unit 10 and the like are arranged.

[0018] Furthermore, the X-ray imaging apparatus 1 is connected to a processor 70 that controls the high-voltage generation unit 15 (FIG. 2) connected to the X-ray tube to control imaging and performs processes necessary for image generation using the information on the transmitted X-rays detected by the FPD 40. The processor 70 may be housed in the console 80 or may be installed at a location separate from the X-ray imaging apparatus 1.

[0019] The configuration of the X-ray irradiation unit 10 is similar to that of a typical X-ray irradiation unit, and as shown in Figure 2, it includes an X-ray tube 12 for irradiating the subject with X-rays, an X-ray diaphragm 13 for setting the X-ray irradiation area for the subject, an irradiation lamp 14 for confirming the area irradiated by the X-ray diaphragm 13 in visible light, and a support 11 for supporting the X-ray tube 12 and the X-ray diaphragm 13, etc.

[0020] As shown in Figure 3, the X-ray diaphragm 13 is equipped with a pair of diaphragm blades (X-axis diaphragm) 131 that open and close in the X-axis direction and a pair of diaphragm blades (Y-axis diaphragm) 132 that open and close in the Y-axis direction, in order to limit the irradiation field of the X-rays irradiated from the X-ray tube 12 in two axes (X-axis direction and Y-axis direction). These are driven by motors 133 and 134, respectively, and the amount of drive can be read by a potentiometer or encoders 135 and 136. In the following description, an encoder will be used as a representative device for reading the amount of motor drive, but known devices such as potentiometers and encoders can be used. The pair of X-axis diaphragms 131 and the pair of Y-axis diaphragms 132 are configured to open and close by moving the blades symmetrically from the center of the diaphragm, but the pair of blades may be configured to move independently.

[0021] The encoder value is sent to the processor 70, which then obtains information about the opening degree of the X-ray diaphragm. In this embodiment, the motor of the X-ray diaphragm is controlled by a control signal from the processor 70, thereby controlling the opening degree of the X-ray diaphragm. The control of the opening degree of the X-ray diaphragm 13 by the processor 70 will be described in detail in the embodiments described later.

[0022] As shown in Figure 1, the supine imaging table 20 comprises a tabletop 21 and a support base 22. In one embodiment, the support base 22 has a structure that can be extended and retracted in the Z direction, allowing the height of the tabletop 21 to be adjusted. The tabletop 21 is also movable in the X-axis and Y-axis directions relative to the support base 22, allowing the position of the subject lying on the tabletop 21 to be finely adjusted in the X-axis and Y-axis directions relative to the X-ray tube 12. The position of the tabletop 21 is detected by a position sensor (not shown), and the detected position information of the tabletop 21 is sent to a processor.

[0023] A tray 25 (Figure 2) for storing FPDs 40 is installed between the support base 22 and the top plate 21. The tray 25 has a storage space that can accommodate multiple types of FPDs, sized to fit the largest FPD. Various FPDs are fixed in place by, for example, inserting the left end of the FPD along the left edge of the storage space until the tip touches the end of the storage space. The tray 25 is equipped with a sensor that identifies the type of FPD stored inside, and the sense signal detected by the sensor is sent to the processor 70. The processor 70 can determine the type (size) of the FPD from the signal from the sensor. The sensor may consist of multiple photosensors, for example, or information representing the size and type of the FPD may be labeled on a side of the FPD 40 that does not affect the image-receiving surface, and the size may be read by attaching an optical reading device such as a camera or barcode reader to the side of the tray 25, or a mechanism may be used to read the size of the FPD 40 from the mechanical connection state between the FPD 40 and the tray 25. The specific structures of the tray 25 and the sensor 41 will be described in detail in the embodiments described later.

[0024] The standing imaging table 30 is also equipped with a storage compartment (not shown) for housing the FPD 40, and the storage compartment is equipped with a sensor (not shown) that detects the size of the stored FPD 40, similar to the tray 25 described above. The sense signal from the sensor installed in the storage compartment of the standing imaging table 30 is also sent to the processor 70.

[0025] The X-ray tube drive mechanism 50 includes a horizontal movement mechanism (X-axis drive mechanism and Y-axis drive mechanism) such as a rail 55, a vertical movement mechanism (Z-axis drive mechanism) not shown, and a rotation mechanism, with part or all of the vertical movement mechanism and the rotation mechanism being incorporated into the X-ray irradiation unit 10. The X-ray tube drive mechanism 50 equipped with such a mechanism can freely move and support the X-ray tube 12 in three axial directions: the axis direction of the subject placed on the top plate 21, i.e., the longitudinal direction of the top plate 21 (X-axis direction), the short direction of the top plate 21 perpendicular to the X-axis direction (Y-axis direction), and the direction perpendicular to the surface of the top plate 21, perpendicular to the X and Y axes (hereinafter referred to as the Z-axis direction). Furthermore, the X-ray tube 12 can be rotated around the Y-axis, for example, the irradiation direction of the X-rays emitted from the X-ray tube 12 can be rotated by any angle (for example, within a range of ±180 degrees) between the vertical and horizontal directions.

[0026] The X-ray tube drive mechanism 50 is also equipped with sensors 51 (X-axis sensor, Y-axis sensor, Z-axis sensor, and rotation sensor) that detect movement (amount of movement) in each direction. Although not shown in the figures, the sensors 51 may also include a sensor that detects the position of the support 11 of the X-ray tube 12. In addition to mechanical sensors such as encoders, known sensors such as acceleration sensors, optical or magnetic sensors can be used as sensors 51. The sense signals from these sensors 51 are also sent to the processor 70.

[0027] As shown in Figure 1, the control unit 60 is equipped with an operating handle 61, which allows the operator to move and rotate the X-ray tube drive mechanism 50 of the X-ray irradiation unit 10 along each axis. In addition to the operating handle 61, the control unit 60 is equipped with an operation panel 62 for the operator to input information necessary for imaging and for this information to be displayed to the operator. The console 80, like the control unit 60, is equipped with various buttons (not shown) necessary for imaging, a GUI, and a display device (display panel 82) that displays the acquired X-ray images. The operator inputs information such as whether the imaging is performed in a supine or standing position (information on imaging position), the imaging mode, whether it is general radiography (imaging mode) or fluoroscopy (fluoroscopy mode) (mode information), and imaging conditions via the console 80 (display panel 82). Imaging conditions include, for example, X-ray intensity, X-ray irradiation rate, field of view, SID (distance between the X-ray tube 12 and the FPD image receiving surface).

[0028] The control panel 62 and the display panel 82 of the console 80 are complementary means of receiving input such as instructions, selections, and value settings from the operator. It is possible to input the same items from both, but the control panel 62 installed in the imaging room is mainly used by the operator to confirm information entered from the console 80, and to perform adjustments after preparation for imaging and to start irradiation. In the following explanation, unless otherwise specified, the operation of the control panel 62 will be described as representative of the operation of the control panel 62, but this also includes cases where the same operation is performed via the display panel 82.

[0029] The processor 70 controls the X-ray imaging apparatus and performs calculations and processing necessary for image generation. Its configuration is not particularly limited, but it can be composed of one or more hardware components or a combination of hardware and a program. The type of hardware is not limited; for example, the processor may be composed of a CPU (Central Processing Unit), an MPU (Micro Processing Unit), a programmable logic device such as an FPGA (Field Programmable Gate Array), a dedicated circuit for executing specific processing such as an ASIC (Application Specific Integrated Circuit), a GPU (Graphic Processing Unit), or an NPU (Neural Processing Unit). Furthermore, the type of hardware may be a combination of different types of hardware. When multiple hardware components are configured to execute one or more processes of a processor, these multiple hardware components may reside in physically separate devices or in the same device.

[0030] When the processor 70 is implemented as a combination of hardware and a program, the program may be firmware or software such as microcode. Alternatively, the program may be, for example, a group of program modules, and each of its functions may be implemented by a processor configured to perform its respective function. The program may also be program code or multiple code segments stored in one or more non-temporary computer-readable media (e.g., storage media or other storage).

[0031] In the embodiment shown in Figure 2, the processor 70 includes an irradiation control unit 71 that controls the timing of X-ray irradiation from the X-ray tube 12, an aperture control unit 73 that controls the opening degree of the X-ray aperture 13, a display control unit 74 that controls the display of the operation panel 62 and the display panel 82, and an image processing unit 72 that receives X-ray transmission signals from the X-ray detector (FPD 40) and performs X-ray image generation, storage, and display. The functions of the processor 70 are not limited to those shown in Figure 2, and it is possible to implement some of them in a processing unit other than the X-ray imaging device 1, or to add other functions not shown in Figure 2.

[0032] Next, we will explain the general operation of the X-ray imaging apparatus with the configuration described above.

[0033] Figure 4 shows the workflow when shooting in fluoroscopic mode. First, the operator places the FPD 40 in the tray 25 and sets it on the supine imaging table 20, lays the subject 100 on the tabletop 21 so that the imaging area of ​​the subject 100 is positioned on the FPD 40, and inputs information such as the surgical procedure (supine or standing), tube voltage, tube current, imaging distance (SID), and irradiation field range via the console 80 (S101). Then, the operator operates the X-ray tube drive mechanism 50 to position the X-ray tube 12 in a predetermined position. The predetermined position is usually the position where the direction of X-ray irradiation is vertical and the irradiation center coincides with the center of the FPD 40 (predetermined range). The position of the FPD 40 is detected by registering its center position coordinates in advance and matching them with the position coordinates obtained from the drive mechanism in the X-axis, Y-axis, and Z-axis directions. In this embodiment, the FPD 40 is assumed to be fixed to the supine imaging table 20.

[0034] After the imaging preparation is complete and the fluoroscopy mode is set (S102), the processor 70 starts controlling the X-ray diaphragm opening (S103). The control of the X-ray diaphragm opening may be selectable between automatic control to obtain the maximum irradiation field and manual control mode to follow manual operation of the opening. When automatic control of the diaphragm opening is started (S102), the diaphragm control unit 73 reads the orientation and size of the FPD 40 stored in the tray 25 based on the sense signals from the sensors in the tray 25 (S103). The diaphragm control unit 73 also obtains the position of the X-ray tube 12 based on the sense signals from each sensor 51 of the X-ray tube drive mechanism unit 50, calculates the position from the X-ray tube 12 to the image-receiving surface of the FPD 40 (SID), and calculates the opening of the X-ray diaphragm using the FPD size and SID (S105). In the control to obtain maximum irradiation, the opening is calculated so that the X-ray irradiation field matches the image-receiving surface (maximum area) of the FPD.

[0035] Next, the aperture control unit 73 controls the motors of each axis of the X-ray aperture 13 so that the calculated aperture opening is achieved (S106). After the X-ray aperture 13 is adjusted to match the size of the FPD image receiving surface, when a technician or doctor (hereinafter referred to as the operator) operates the irradiation button on the control panel 62 (S107), the irradiation control unit 71 receives the operation and controls the high voltage generator 15 to irradiate the FPD 40 with X-rays (S108). The image processing unit 72 receives a signal corresponding to the transmitted X-rays from the FPD 40 and generates and saves an image (S109). If automatic aperture control is not selected, the manually adjusted aperture opening is maintained, and when the irradiation button is operated (S107), irradiation (S108) and image acquisition (S109) are performed. When automatic adjustment is completed, the display control unit 74 may display on the control panel 62 that the aperture adjustment is complete and that irradiation is possible. In that case, the operator checks the display and then presses the irradiation button.

[0036] According to this embodiment, when the X-ray aperture 13 is automatically controlled in fluoroscopy mode, the processor 70 reads the size of the FPD 40 based on the sense signal from the tray 25 (storage section) that houses the FPD 40, and uses the size information and SID information to calculate the irradiation field that makes maximum use of the image-receiving surface of the FPD 40. The processor 70 automatically controls the opening of the X-ray aperture to achieve the calculated irradiation field.

[0037] This allows operators to maximize the image-receiving surface of FPDs of various sizes while reducing the effort required to adjust the aperture opening.

[0038] Based on the above embodiments, a specific embodiment of controlling the X-ray aperture will be described. In the following embodiments, configurations that overlap with the above embodiments will be shown in Figures 1 to 3, and their explanations will be omitted or simplified.

[0039] <Embodiment 1> The X-ray diaphragm control of this embodiment is characterized by having a configuration that allows setting an automatic control mode for automatically controlling the X-ray diaphragm and a manual control mode for manually adjusting the irradiation field according to the irradiation field size (Feature 1).

[0040] The automatic control mode is a control system in which the processor 70 automatically detects the size (including orientation) of the FPD and adjusts the aperture of the X-ray diaphragm to match the maximum area of ​​the FPD's image-receiving surface. In automatic control mode, for example, even if the SID is changed by moving the examination table up or down during automatic control, the aperture opening is automatically adjusted so that the irradiation field expands or contracts to match the FPD's image-receiving surface. In manual control mode, the operator manually adjusts the aperture opening or adjusts the SID, etc., by moving the examination table up and down or left and right with a fixed aperture opening to achieve the desired irradiation field. In manual control mode, if the aperture opening that follows the desired irradiation field cannot be achieved by moving the examination table, the processor 70 performs a control to disable X-ray irradiation.

[0041] Furthermore, a feature of the aperture control in this embodiment is that information for the operator to confirm the status during aperture control, as well as information related to whether or not illumination is permitted, is presented via the control panel (Feature 2).

[0042] The following describes the specific configuration required to achieve these features. Figure 5 shows the details of the control unit by the processor 70 involved in aperture opening control. As shown in the figure, in addition to the irradiation control unit 71, aperture control unit 73, and display control unit 74 shown in Figure 2, the processor 70 includes an aperture opening calculation unit 75, an FPD detection unit 76, an SID calculation unit 77, a body position determination unit 78 that determines the shooting position based on information (such as surgical procedure information) input from the console 80 regarding whether the shooting is in a supine or standing position, and a mode determination unit 79 that determines whether the console 80 is in shooting mode or fluoroscopy mode. The functions of each part of the processor 70 will be described in detail below.

[0043] When the automatic control mode is set as the aperture opening control mode described above, the aperture control unit 73 acquires necessary information from the aperture opening calculation unit 75, FPD detection unit 76, SID calculation unit 77, body position determination unit 78, and mode determination unit 79, and controls the automatic control mode. The aperture control unit 73 also compares the size of the FPD detected by the FPD detection unit 76 with the illumination field determined by the aperture opening calculated by the aperture opening calculation unit 75, and passes information such as whether illumination is possible to the display control unit 74. Details of the aperture control unit 73 and each part involved in aperture control will be described later.

[0044] The display control unit 74 primarily controls the display related to the aperture opening (aperture opening display control unit), detects button operations on the operation panel 62 (button operation detection unit), and displays the operation buttons (button display control unit).

[0045] The aperture opening display control unit controls the display of information that should be presented to the operator, such as an indication that automatic control mode is in place and an indication that illumination is possible or not. The button operation detection unit detects button operations performed by the operator and passes the corresponding processing to the processor (aperture control unit 73). When a button is operated and the corresponding processing is performed, the button display control unit performs processing such as changing the display appearance of the button, for example, the color and brightness of the button, or the color of the button frame.

[0046] Figure 6 shows an example of the display screen of the operation panel 62 controlled by the display control unit 74. As shown in the figure, the operation panel has several buttons (GUI), including mode selection buttons 621 and 622 for selecting either the imaging mode or the fluoroscopy mode, position selection buttons 623 and 624 for selecting whether the patient is lying down or standing, start buttons 625 and 626 for instructing the start of fluoroscopy or imaging, and a button 627 (shown as the "MAX" button in the figure) for selecting automatic setting of the X-ray aperture, as well as a display area 628 for displaying surgical procedure information and conditions input from the console 80. In the example shown, the size of the FPD and the irradiation field size are displayed in the display area 628.

[0047] As described above, the X-ray diaphragm control in this embodiment allows for the setting of an automatic control mode that automatically controls the X-ray diaphragm to match the maximum area of ​​the FPD's image-receiving surface, and a manual control mode in which the operator manually adjusts the diaphragm to match the irradiation field size. In the example of the control panel shown in Figure 6, when the operator presses the "MAX" button 627, the automatic control mode is turned "ON" and the automatic control described later begins. Pressing the "MAX" button 627 again turns the automatic control mode "OFF", and the current opening is maintained. A separate button for disabling the automatic control mode may also be provided.

[0048] The display control unit 74 detects the operation of each button by the operator and sends the detected results to the processor 70. For example, the results of operation of the mode selection buttons 621 and 622, which select between shooting mode and X-ray mode, are sent to the mode determination unit 79, the results of operation of the position selection buttons 623 and 624 are sent to the position determination unit 78, and the result of operation of the "MAX" button 627 is sent to the aperture opening calculation unit 75. In addition, when the "MAX" button 627 is operated, the display control unit 74 displays on the operation panel 62 that the automatic aperture opening control function has been turned ON. The method of display is not particularly limited, but for example, the color of the frame of the operated button or the brightness or color of the button itself may be changed. For other buttons as well, the display of the operation buttons may be controlled so that it is clear which button has been operated and which process is in the "ON" state.

[0049] The aperture control unit 73 includes an aperture opening determination unit 731 that receives sense signals from the X-axis aperture sensor 131 and the Y-axis aperture sensor 132 and determines the aperture opening for the X-axis aperture and the Y-axis aperture, respectively. The aperture control unit 73 sends the aperture opening determination information determined by the aperture opening determination unit 731 to the display control unit 74, which displays it on the operation panel 62, for example, in the display area 628.

[0050] Furthermore, the aperture control unit 73 determines whether illumination is possible or not based on the aperture opening determined by the aperture opening determination unit 731, sends the determination result to the display control unit 74, and displays whether illumination is possible or not on the operation panel 62. The determination of whether illumination is possible or not is made by comparing the size of the FPD 40 with the illumination field determined by the aperture opening calculated by the aperture opening calculation unit 75. If the FPD size > illumination field size or the FPD size = illumination field size, illumination is possible; if the FPD size < illumination field size, illumination is not possible. The method of displaying whether illumination is possible or not is not particularly limited, but for example, the "MAX" button 627 can be activated when illumination is possible and deactivated when illumination is not possible, the color of the frame surrounding the "MAX" button 627 can be changed to a warning color (e.g., gray), or the illumination is possible or not can be displayed as text information in the display area 628, etc.

[0051] The FPD detection unit 76 includes a detection unit for detecting the FPD of the supine imaging table 20 and a detection unit for detecting the FPD of the standing imaging table 30. It receives sense signals from sensors for FPD detection provided on the supine imaging table 20 and the standing imaging table 30, respectively, and detects whether or not the FPD 40 is positioned in an appropriate location on the supine imaging table 20 or the standing imaging table 30.

[0052] As an example of FPD detection, the configuration of the tray 25 installed on the supine imaging table 20, and the size and orientation of the FPD 40 will be described. For simplicity, the case where size A (17 inches x 17 inches) and size B (17 inches x 14 inches) are used as the FPD 40 will be described.

[0053] As shown in Figure 7(a), the tray 25 has a roughly rectangular shape, and multiple photosensors (sensors 1 to 3 in the figure) are provided along two adjacent sides of the rectangle. These sensors are arranged so that the spacing between sensor 1 and sensor 2, and between sensor 2 and sensor 3, is less than 17 inches and greater than 14 inches. As a result, as shown in Figure 7(b), when a size A FPD 40 is inserted, all three sensors are covered by the FPD 40, and sense signals are emitted from all three sensors. Also, as shown in Figure 7(c), when a size B FPD 40 is inserted horizontally, only sensor 1 is covered by the FPD 40, and a sense signal is emitted from this sensor. When a size B FPD 40 is inserted vertically towards the left side of the tray 25 (Figure 7(d)), the two sensors, sensors 1 and 2, located along the left side, are covered by the FPD 40, and sense signals are generated from both sensors.

[0054] The aperture control unit 73 can determine from the number of sense signals received that there are four states ((a) to (d)), including the presence or absence of an FPD, as shown in the table below Figure 7, and can determine what size FPD is placed in the tray 25 and in what orientation. Guides can be provided in the tray 25 so that FPDs with different aspect ratios (for example, an FPD of size B) are all inserted towards the left side of the tray 25, thereby ensuring reliable detection of size and orientation. Figure 7 shows a configuration for distinguishing between two different sizes of FPDs, but by increasing the number of sensors and appropriately setting the sensor spacing based on the size of the FPD 40, it is possible to distinguish between multiple sizes. Also, the sensor arrangement in Figure 7 is for detecting the size when the FPD 40 is placed towards the left (or right) edge of the tray 25, but it is also possible to arrange the sensors so that the size can be detected when the FPD 40 is placed in the center of the tray 25.

[0055] The SID calculation unit 77 calculates the SID using the surgical procedure information input to the patient position determination unit 78 and the position of the X-ray tube 12 and the set FPD detected by the sensor 51 of the drive mechanism unit 50 (including a sensor that detects the position of the support 11 of the X-ray tube 12). The surgical procedure information includes information on whether the imaging is performed in a supine or standing position. In the case of supine imaging as shown in the upper part of Figure 8, the SID calculation unit 77 calculates the distance between the FPD image receiving surface installed on the supine imaging table and the X-ray tube 12 as the SID. In the case of standing imaging as shown in the lower part of Figure 8, the SID is calculated as the distance between the FPD image receiving surface installed on the standing imaging table and the X-ray tube 12.

[0056] The aperture opening calculation unit 75 calculates a target value for the aperture opening, for example, an aperture angle that yields an illumination field that closely matches the size of the FPD image receiving surface, based on the SID calculated by the SID calculation unit 77, the surgical procedure information and fluoroscopy mode information input via the operation panel 62 or console 80, and the information input by operating the buttons on the operation panel. The aperture opening is calculated for both the X-axis aperture and the Y-axis aperture (X-axis aperture opening calculation unit, Y-axis aperture opening calculation unit).

[0057] The specific method for calculating the aperture opening will be explained using Figure 9. In this embodiment, the aperture opening is normalized, and the normalized value is adjusted to match the actual SID (distance between the X-ray tube 12 and the FPD image receiving surface) to calculate the aperture opening that makes the irradiation field most closely match the FPD image receiving surface. Note that Figure 8 shows the case where the aperture opening is calculated for one of the X and Y axes for simplicity of explanation.

[0058] As shown on the left side of Figure 9, let amax be the aperture opening when the aperture is fully open, and let Amax be the field size when the SID is 1m. Since amax is a fixed value determined by the X-ray aperture, Amax is also a predetermined value. If the ratio of Amax to amax is taken as the standard value, and the actual set SID value is D, and the size of the image receiving surface of the FPD40 used is W, then the aperture opening a that achieves an illumination field matching the maximum width of the image receiving surface is calculated by the following equation (1). [Mathematics 1] a = [amax / Amax] × [W / D] (1)

[0059] Specifically, the aperture opening calculation unit 75 calculates the aperture opening a using D (value of SID) calculated by the SID calculation unit 77 and the size W of the image receiving surface determined by the size of the FPD 40 detected by the FPD detection unit 76, and sends it to the aperture control unit 73.

[0060] The aperture control unit 73 controls the X-axis aperture and Y-axis aperture using the aperture opening value calculated by the aperture opening calculation unit 75, and controls the aperture opening to achieve a predetermined illumination field size. In controlling the aperture opening, the current positions of the X-axis aperture and Y-axis aperture are read from encoders, etc., and the motors 133 and 134 of the X-axis aperture 131 and Y-axis aperture 132 are controlled so that the X-axis aperture and Y-axis aperture move to the position where the aperture opening is the calculated opening. This control can be achieved by creating a table in advance that shows the relationship between the readings of encoders 135 and 136 and the aperture opening, and the relationship between the aperture opening and illumination field size for each SID, and then determining the aperture position (reading value) according to the SID from the table.

[0061] The relationship between the encoder and the aperture opening is as shown in Figure 10(a) when the aperture opening changes from fully closed to fully open. When this is shown in relation to the illumination field Amax at SID=1m, the graph is shown in Figure 10(b). When SID is greater than 1m, the illumination field widens, and for example at SID=1.4m, it changes as shown in Figure 10(c). An example of a table used for aperture control, created based on this relationship, is shown in Figure 11. The example shown defines the relationship between the illumination field size and the aperture opening, and the relationship between the aperture opening and the encoder reading, for three SIDs (SID=1m, 1.2m, and 1.4m). Here, for simplicity of explanation, only the aperture in the uniaxial direction is shown, but similar tables are prepared for the X and Y biaxial directions.

[0062] The aperture opening is calculated using linear interpolation with two adjustment points from the table in Figure 11. Specifically, the value when the aperture is fully closed on the image surface at SID=1m (adjustment point 1) and the value when it is fully open (adjustment point 2) are used for linear interpolation to determine the aperture opening that results in the maximum illumination size W determined by the FPD size. For example, if the aperture on the image surface is 20cm at SID=1m, the aperture on the image surface will be 40cm at SID=2m. Therefore, the aperture opening is halved to maintain an aperture of 20cm on the image surface even at SID=2m. Using such a table enables simple control. In the above example, linear interpolation was used, but instead of using discrete values ​​from the table, the aperture opening was calculated from the table values ​​based on the FPD size. However, values ​​(or coefficients based on SID=1m) can be predetermined for each SID.

[0063] Next, an example of the X-ray aperture control flow of the X-ray imaging apparatus of this embodiment, based on the above-described configuration, will be explained with reference to Figure 12. Here, as an example, the case in which imaging is performed on a supine imaging table will be explained.

[0064] First, prior to imaging, surgical procedure information and imaging conditions are entered via the console 80 (Figure 4, S101). Then, the imaging site of the subject is positioned at the imaging location, the X-ray tube 12 is moved to the imaging site, and it is confirmed that the center of the FPD set on the imaging table and the X-ray tube 12 are facing each other, and control of the fluoroscopy mode is started (S111).

[0065] Control of the fluoroscopy mode begins after the preparation for imaging is complete. The processor 70 reads the mode information input from the console 80 or the control panel 62, and the mode determination unit 79 determines that it is in fluoroscopy mode. Subsequently, when the "MAX" button 627 on the control panel 62 is operated, the processor 70 starts the X-ray diaphragm control function (control of the automatic control mode) (S200). If the "MAX" button 627 is not operated, the automatic control mode is not entered, and the operator manually adjusts the irradiation field.

[0066] When the automatic control mode is activated (S200), the position determination unit 78 reads information about the patient's position from, for example, the surgical procedure information input from the console 80, and determines whether the patient is lying down or standing (S112). The processor 70 calculates the SID and detects the FPD according to this determination result.

[0067] As shown in Figure 8, in the case of supine imaging, the FPD detection unit 76 receives a sense signal from the FPD sensor 41 of the supine imaging table 20 and determines the presence or absence of the FPD, as well as the size and orientation of the FPD (S114). In the case of standing imaging, the FPD detection unit 76 uses the sense signal from the FPD sensor of the standing imaging table to determine the size of the FPD, etc. The size and other characteristics are determined from the number and arrangement of the photosensors that have emitted a sense signal, as explained with reference to Figure 6. The size of the FPD determined by the FPD sensor is displayed by the display control unit 74 on the display area 628 of the operation panel. If the FPD 40 is not set in the predetermined position, an alert may be issued, such as by displaying a message on the operation panel 62.

[0068] The SID calculation unit 77 obtains position information of the X-ray tube 12 from the sensor 51 for detecting the position of the X-ray tube 12, and uses information from the surgical procedure information (patient position information) to determine whether the imaging table to be used (supine or standing imaging table) is being used to calculate the distance SID from the center of the X-ray tube 12 to the center of the FPD image receiving surface set on the imaging table (S115). Next, the aperture opening calculation unit 75 uses the size of the FPD (size in the X-axis direction and size in the Y-axis direction) detected by the FPD detection unit 76 and the SID calculated by the SID calculation unit 77 to calculate the opening of the X-axis aperture and Y-axis aperture corresponding to the size of the FPD using the aforementioned formula (1) (S116). The aperture control unit 73 uses the aperture opening calculated by the aperture opening calculation unit 75 and the current aperture position determined by the aperture opening determination unit 731 to determine the amount of movement (encoded value) of the X-axis aperture and Y-axis aperture from the table, and controls the aperture drive motor so that the X-axis aperture and Y-axis aperture move by that amount (S117).

[0069] When the processor 70 (aperture control unit 73) determines the illumination field by controlling the aperture opening, it sends this information to the display control unit 74, which displays it on the operation panel 62 (display area 628). Furthermore, it determines whether the calculated illumination field exceeds the size of the detected FPD 40, and if the size of the illumination field is less than or equal to the size of the FPD 40, the display control unit 74 indicates on the operation panel 62 that illumination is possible. For example, it activates the illumination button (transparency start button 626) that was previously inactive.

[0070] When the operator confirms the display on the control panel 62 or activates the irradiation button and operates the irradiation button, the irradiation control unit 71 irradiates the FPD 40 with X-rays (S118). In fluoroscopy mode, X-ray irradiation and fluoroscopic image acquisition are performed for a predetermined time while monitoring that the positional relationship between the X-ray tube 12 and the FPD 40 has not changed (S119). While fluoroscopy mode continues, automatic control is continued while constantly monitoring the change in the distance SID between the X-ray tube 12 and the FPD (image-receiving surface). That is, the processes in steps S113 to S117 are repeated.

[0071] In fluoroscopy mode, if the "MAX" button is not pressed, the X-ray aperture is maintained at the initial or manually set aperture, and fluoroscopy is performed by pressing the fluoroscopy start button (manual aperture control mode). Although not shown in Figure 12, even in manual control mode, the irradiation field is calculated from the set aperture and the calculated SID, and a step is performed to confirm that the calculated irradiation field does not exceed the FPD size, and the irradiation button is deactivated to prevent X-ray irradiation beyond the FPD size.

[0072] As described above, according to this embodiment, the FPD detection unit detects the size and orientation of the FPD, ensuring that the X-ray irradiation range does not extend beyond the image-receiving surface while making maximum use of the size of the image-receiving surface of the actually placed FPD. Furthermore, since this aperture opening is controlled under the control of the processor, the operator's workload and time can be significantly reduced. Furthermore, according to this embodiment, the operator can constantly monitor the status of automatic control via the control panel, prevent erroneous operation, and safely perform fluoroscopy while ensuring the necessary conditions for fluoroscopy.

[0073] The control flow of this embodiment has been explained using supine imaging as an example. However, in the case of standing imaging, the X-ray aperture can be controlled in the same way as in supine imaging, except that the FPD detection uses a sense signal from the FPD sensor of the standing imaging table, and the SID calculation unit 77 calculates the SID based on the standing imaging table. Furthermore, the configuration of the operation panel and the FPD detection unit (tray) exemplified in this embodiment can be modified in various ways.

[0074] Furthermore, in the embodiment described above, the automatic control mode and manual control mode are switched by operating the MAX button (Feature 1), but it is also possible to set the automatic control mode in conjunction with the start of fluoroscopy, and such an embodiment is also included in the present invention. In addition to the configuration for switching between the automatic control mode and manual control mode in this embodiment, the numerical values ​​and judgment results obtained during aperture control are reflected on the display of the operation panel (Feature 2), but it is not essential in the present invention to include both Feature 1 and Feature 2, and an X-ray imaging apparatus equipped with only one of them is also included in the present invention.

[0075] Furthermore, the present invention allows for various modifications to the specific configurations shown in this embodiment, such as a configuration in which a photosensor for detecting the size and orientation (storage direction) of the FPD 40 is provided in the tray 25 that houses the FPD 40, a configuration in which a correspondence (table) with the SID is set in advance for the aperture opening that maximizes the image-receiving surface of the FPD 40, and an automatic control of the aperture opening based on this table, and a configuration in which the irradiation button is activated / deactivated depending on whether irradiation is possible or not. Moreover, it is not essential to have all of these configurations or their variations, and embodiments of X-ray imaging devices equipped with only one or two of them are also possible.

[0076] <Variation> Next, as a modified example of this embodiment, we will describe aperture control when the positional relationship between the X-ray tube 12 and the FPD 40 changes.

[0077] In Embodiment 1, as shown in Figure 13(a), aperture control is performed on the premise that the irradiation direction of the X-rays emitted from the X-ray tube coincides with the line connecting the focal point of the X-ray tube and the center position of the FPD, that is, the X-ray irradiation direction is perpendicular and the center of the X-ray tube 12 and the center of the FPD image receiving surface coincide in the vertical direction. To confirm this premise, for example, before step S115 in Figure 11, the processor may perform a step to determine whether the line connecting the focal point of the X-ray tube 12 and the center position of the X-ray detector coincides with the irradiation direction of the X-rays emitted from the X-ray tube 12, and only when they coincide may the automatic aperture control function be executed.

[0078] Furthermore, if the pair of X-ray diaphragms are equipped with a mechanism that allows each to be adjusted independently, it is possible to control the diaphragm opening in response to cases where the irradiation direction of the X-rays emitted from the X-ray tube 12 does not coincide with the line connecting the focal point of the X-ray tube 12 and the center position of the FPD 40, rather than adding the judgment step described above. In this case, the diaphragm opening is adjusted by moving the pair of diaphragm blades individually. For example, if the positional relationship between the X-ray tube 12 and the FPD 40 is such that one of the X-ray tube 12 and the FPD 40 is shifted in the X-axis direction or the Y-axis direction, as shown in Figure 13(b), and the line connecting their center positions is inclined from the vertical, or if the X-ray irradiation direction is inclined with respect to the vertical in oblique-entry radiography, where X-rays from the X-ray tube 12 are irradiated onto the subject at an oblique angle for imaging, as shown in Figure 13(c), then the pair of diaphragm blades are controlled individually.

[0079] For example, the adjustment in the case of Figure 13(b) is performed as follows. First, the amount of displacement Δx in the parallel direction between the X-ray tube 12 and the FPD 40 is calculated. The amount of displacement can be calculated, for example, by obtaining the position of the X-ray tube 12 (position in the device's coordinate system) from the sense signal from the sensor 51 that detects its position, and using the center position of the top plate 21 and the FPD 40 housed therein in the device's coordinate system as a reference. The center position of the FPD 40 can be calculated from the relationship between the size of the FPD 40 detected by the FPD detection unit 76 and the tray 25 in which the FPD 40 is housed. The amount of displacement of the irradiation field ΔW is equal to this amount of displacement Δx.

[0080] Taking the X-axis aperture as an example, the aperture opening calculation unit 75 first calculates the aperture opening a of the X-axis aperture in the same manner as in Embodiment 1. Next, it increases or decreases the opening (a / 2) of the left and right X-axis aperture blades by the opening Δa corresponding to the displacement Δx in the X-axis direction (displacement ΔW of the irradiation field). That is, for one aperture blade, it subtracts the opening Δa corresponding to the displacement ΔW from half of the X-ray aperture opening a calculated by the aperture opening calculation unit 75, and for the other aperture blade, it adds the opening Δa corresponding to the displacement ΔW to half of the X-ray aperture opening a calculated by the aperture opening calculation unit 75. The aperture opening Δa corresponding to the displacement ΔW can be calculated based on the geometric relationship between the irradiation field W obtained from the X-axis aperture opening a and the irradiation field W+ΔW obtained from the opening a / 2+Δa. In terms of geometric relationships, as shown in Figure 14, the ratio of the irradiation field W / 2 to the aperture a / 2 is the same as the ratio of the irradiation field (W / 2 + ΔW) to (a / 2 + Δa), so Δa can be determined from this relationship.

[0081] In the case of oblique imaging shown in 13(c), the illumination field W, which is determined by the aperture opening calculated based on the size of the FPD 40 (the illumination field that makes maximum use of its image-receiving surface), widens as the illumination angle is tilted. The aperture opening calculation unit 75 adjusts the aperture opening so that the illumination field (W-ΔW) is obtained by subtracting the error ΔW caused by the tilt of the illumination angle from W. In this case as well, ΔW can be calculated from the geometric relationship between the SID and the size of the FPD image-receiving surface and the oblique angle. The amount of adjustment for the illumination field may be calculated in advance for each oblique angle, and these pre-calculated values ​​may be set as adjustment values ​​when performing oblique imaging.

[0082] As explained above, this modified version allows for automatic control of the aperture opening to match the size of the FPD 40, even when the X-ray tube 12 and the FPD 40 are not directly facing each other. This reduces the tolerance for the operator's alignment accuracy regarding the positional relationship between the X-ray tube 12 and the FPD 40, thereby saving time and effort. Furthermore, by combining the technique disclosed in Patent Document 3, which controls the rotation angle of the aperture blades during oblique entry and applies appropriate trimming to the image, with the method of this embodiment (modified version), it becomes possible to control the aperture opening so that the X-ray irradiation field becomes equal to the size of the FPD image receiving surface, depending on the SID and FPD. [Explanation of Symbols]

[0083] 10: X-ray irradiation unit, 20: Supine imaging table, 30: Standing imaging table, 40: FPD (X-ray detector), 50: X-ray tube drive mechanism, 60: Operation unit, 62: Operation panel, 70: Processor, 71: Irradiation control unit, 72: Image processing unit, 73: Aperture control unit, 74: Display control unit, 75: Aperture opening calculation unit, 76: FPD detection unit, 77: SID calculation unit, 78: Body position determination unit, 79: Mode determination unit, 80: Console

Claims

1. The system comprises an X-ray irradiation unit including an X-ray tube and an X-ray diaphragm, an imaging table with a storage unit for housing an X-ray detector, and a processor for controlling the X-ray irradiation unit. The X-ray imaging apparatus is characterized in that the processor has an automatic opening control function that detects the size of the X-ray detector and the distance between the X-ray tube and the X-ray detector, and automatically adjusts the opening of the X-ray aperture to match the size of the X-ray detector based on the detection results.

2. An X-ray imaging apparatus according to claim 1, The processor controls the X-ray irradiation unit according to either the fluoroscopy mode or the imaging mode. An X-ray imaging apparatus characterized in that it executes the automatic opening control function only when imaging in the aforementioned fluoroscopic mode.

3. An X-ray imaging apparatus according to claim 1, The storage unit is equipped with a sensor for detecting the X-ray detector, The X-ray imaging apparatus is characterized in that the processor determines the size of the X-ray detector using the signal from the sensor.

4. An X-ray imaging apparatus according to claim 3, The sensor includes a plurality of photosensors arranged along the planar direction of the X-ray detector, The X-ray imaging apparatus is characterized in that the processor determines the size of the X-ray detector using the outputs of the plurality of photosensors.

5. An X-ray imaging apparatus according to claim 3, The X-ray irradiation unit is further provided with a drive mechanism that allows it to move in the mutually orthogonal X-axis, Y-axis, and Z-axis directions. The X-ray imaging apparatus is characterized in that the processor detects the distance between the X-ray tube and the X-ray detector using the position of the X-ray tube and the center position of the X-ray detector obtained from the drive mechanism of each axis.

6. An X-ray imaging apparatus according to claim 1, The X-ray imaging apparatus is characterized in that the processor pre-determines the relationship between the distance between the X-ray tube and the X-ray detector and the size of the irradiation field at that distance, using the maximum opening of the X-ray aperture and the irradiation field at a reference value of the distance between the X-ray tube and the X-ray detector, and automatically controls the opening of the X-ray aperture to match the size of the X-ray detector based on this relationship.

7. An X-ray imaging apparatus according to claim 1, The X-ray aperture comprises a pair of left and right aperture blades and a pair of upper and lower aperture blades, and a mechanism for opening and closing the left and right pair or the upper and lower pair of aperture blades symmetrically with respect to the aperture center. The X-ray imaging apparatus is characterized in that the processor determines whether the line connecting the focal point of the X-ray tube and the center position of the X-ray detector coincides with the irradiation direction of the X-rays emitted from the X-ray tube, and executes the automatic opening control function only when they coincide.

8. An X-ray imaging apparatus according to claim 1, The system further includes an operation panel connected to the aforementioned processor for interacting with the user, The X-ray imaging apparatus is characterized in that the processor displays a button (GUI) on the control panel for the user to select the automatic opening degree control function, and executes the automatic opening degree control function when the button on the control panel is operated.

9. An X-ray imaging apparatus according to claim 8, The X-ray imaging apparatus is characterized in that the processor displays on the operation panel at least one of the size of the X-ray detector and the size of the X-ray irradiation field achieved by the automatic opening control function.

10. An X-ray imaging apparatus according to claim 8, The X-ray aperture comprises a pair of left and right aperture blades and a pair of upper and lower aperture blades, and a mechanism for opening and closing the left and right pair or the upper and lower pair of aperture blades symmetrically with respect to the aperture center. The X-ray imaging apparatus is characterized in that the processor activates the opening control button only when the line connecting the focal point of the X-ray tube and the center position of the X-ray detector coincides with the irradiation direction of the X-rays emitted from the X-ray tube.

11. An X-ray imaging apparatus according to claim 1, The X-ray imaging apparatus is characterized in that the imaging table includes at least one of a table for imaging a subject in a supine position and a standing imaging table for imaging a subject in an upright position, and the axis for detecting the distance between the X-ray tube and the X-ray detector is changed for supine and standing imaging.

12. An automatic control method for the opening of an X-ray diaphragm in an X-ray imaging apparatus comprising an X-ray irradiation section including an X-ray tube and an X-ray diaphragm, and an imaging table equipped with a storage section for housing an X-ray detector, The size of the X-ray detector housed in the storage compartment and the distance between the X-ray tube and the X-ray detector are detected. Using the detected size of the X-ray detector and the distance between the X-ray tube and the X-ray detector, the X-ray aperture opening corresponding to the size of the X-ray detector is calculated. An automatic control method for X-ray aperture opening, characterized by automatically controlling the X-ray aperture so that it achieves a calculated X-ray aperture opening.

13. An automatic control method for the X-ray aperture opening according to claim 12, The calculation of the aforementioned X-ray aperture is as follows: An automatic control method for X-ray diaphragm opening, characterized by first calculating the relationship between the distance between the X-ray tube and the X-ray detector and the irradiation field size using the maximum opening of the X-ray diaphragm and the irradiation field at a reference value of the distance between the X-ray tube and the X-ray detector, and then calculating an opening that results in an irradiation size matching the size of the X-ray detector based on this relationship.

14. An automatic control method for the X-ray aperture opening according to claim 13, The relationship between the distance between the X-ray tube and the X-ray detector and the irradiation field size is a table or function used for automatic control of the X-ray aperture opening.

Images