X-ray imaging apparatus and control program thereof

Abstract

Provided is an X-ray imaging apparatus for performing slot imaging upon moving an X-ray tube (5) from one end side (5a) to the other end side (5c) with respect to the body axis direction of a subject (M), the X-ray imaging apparatus comprising: a drive control unit for controlling movement of the X-ray tube (5) and an X-ray detector (7); a reception unit for receiving the setting of the position of a first end (7a) of the X-ray detector (7), the first end (7a) being one end of the range of movement of the X-ray detector (7), with respect to the body axis direction of the subject (M); and a slit image generation unit for generating a plurality of slit-form X-ray images by sequentially irradiating the X-ray detector (7) with X-rays while moving the X-ray tube (5) from a first position (5a) at one end side (5a) in the body axis direction to a second position (5d) at the other end side (5c) in the body axis direction, the drive control unit performing control for displacing the position of an X-ray irradiation field on the X-ray detector (7) toward the other end side (5c) in a state in which the X-ray detector (7) is positioned at the first end part (7a).

Description

X-ray imaging device and its control program

[0001] The present invention relates to an X-ray imaging apparatus and a control program therefor.

[0002] In medical settings, there are cases where a single X-ray image (long image) is taken of a long range in the body axis direction of a subject, such as the entire spine or the entire length of a lower limb. In this case, due to the specifications of X-ray detectors, it is difficult to take such a long image with a single X-ray irradiation. Therefore, a long image is obtained by taking multiple slit-shaped X-ray images (slit images) along the body axis direction of the subject, each of which has a relatively short length in the body axis direction, and then stitching these multiple slit images together in the body axis direction to reconstruct the long image.

[0003] Methods for capturing multiple slit images along the body axis direction of a subject include the following: As a first method, as shown in Fig. 25 , the position of the X-ray tube 103 in the body axis direction is fixed, and the X-ray detector 105 is moved along the body axis of the subject from the position indicated by the dotted line to the position indicated by the solid line, while the X-ray tube 103 is rotated in accordance with the position of the X-ray detector 105 to change the X-ray irradiation angle, thereby capturing multiple slit images. This first method is also called a long-length imaging method, and is mainly used in general X-ray imaging devices.

[0004] 26, a second method for capturing multiple slit images is to translate the X-ray tube 103 and the X-ray detector 105 at the same speed along the body axis of the subject, and continuously irradiate X-rays from the X-ray tube 103 onto an area limited to a short strip (slit) shape along the body axis of the X-ray detector 105, thereby capturing multiple slit images. This second method is also called a slot imaging method, and is mainly used in X-ray television systems (XTV systems) capable of X-ray fluoroscopy and X-ray imaging (see, for example, Patent Document 1).

[0005] In the first method described above, the X-ray irradiation angles of the multiple slit images acquired are different. Therefore, image distortion due to the difference in X-ray irradiation angles occurs in the long image obtained by reconstruction. Figure 27 shows a long image F1 capturing the entire spine using the first method. In the long image F1, the vertebra Sa captured in the center is an image obtained by irradiating X-rays from the X-ray tube 103 toward the X-ray detector 105 at a substantially perpendicular angle, and therefore has very little image distortion. On the other hand, the vertebrae Sb and Sc captured at the ends of the long image F1 are images obtained by irradiating X-rays from the X-ray tube 103 toward the X-ray detector 105 at an oblique angle, and therefore have significant image distortion. Image distortion in the long image F1 tends to be particularly large in the image at one end or the other end.

[0006] On the other hand, in the second method, each slit image is acquired by irradiating X-rays from the X-ray tube 103 toward the X-ray detector 105 at the same angle, approximately perpendicular to the X-ray tube 103. Therefore, by using the second method, image distortion in the reconstructed long image is significantly reduced. Figure 28 shows a long image F2 capturing the entire spine using the second method. Not only the vertebra Ka captured in the center of the long image F2, but also the vertebra Kb and vertebra Kc captured at the ends of the long image F2 are images obtained by irradiating X-rays from the X-ray tube 103 toward the X-ray detector 105 at an approximately perpendicular angle. Therefore, the images of the vertebrae Ka to Kc all have very little distortion. Therefore, using the second method, slot imaging, enables more accurate diagnosis. Therefore, configurations for acquiring long images using slot imaging have been proposed not only for XTV systems but also for general X-ray imaging devices (e.g., Non-Patent Document 1).

[0007] JP 2016-214362 A

[0008] Shigeji Ichikawa, Kanan Kumagai, Yasutaka Sato, Takashi Nonaka, Yutaka Nakamura, "A new approach to quantitative calculation of contrast in slot scan images," Journal of the Japanese Society of Radiological Technologists 2020. Vol.67 no.813 14-21(694-701)

[0009] However, the conventional example having such a configuration has the following problems.

[0010] XTV systems are relatively large devices, and the range of movement of the X-ray detector in the body axis direction of the subject is wide. This allows for a wide range of long images to be captured using the slot imaging method. On the other hand, in X-ray imaging devices for general X-ray imaging, it is difficult to ensure a sufficient range of movement of the X-ray detector in the body axis direction due to reasons such as the relatively small size of the table that houses the X-ray detector. As a result, there is a concern that the range of long images that can be captured using the slot imaging method with a general X-ray imaging device will be narrower than the range of long images that can be captured using the slot imaging method with a conventional XTV system.

[0011] In the conventional configuration disclosed in Patent Document 1, to widen the capture range of a long image, the collimator aperture is increased when capturing slit images at the ends of the capture range of the long image. In other words, by increasing the collimator aperture, the capture range of the slit image at the ends of the capture range of the long image is widened in the body axis direction of the subject. As a result, the range of the long image can be widened. However, with this configuration disclosed in Patent Document 1, particularly large distortion occurs in the slit image captured at the ends of the long image. In other words, by widening the capture range of the slit image, the image reflected at the ends of the slit image is obtained by irradiating X-rays from the X-ray tube 103 at an angle oblique to the X-ray detector 105, resulting in significant image distortion. Therefore, it is difficult to reduce distortion in the long image while widening the capture range of the long image.

[0012] The present invention has been made in consideration of the above circumstances, and aims to provide an X-ray imaging device and a control program therefor that can capture a longer image with a wider range using the slot imaging method and capture longer images with less distortion.

[0013] In order to achieve the above object, the present invention has the following configuration: That is, a first aspect of the present invention includes an X-ray tube that irradiates a subject with X-rays, an X-ray detector that is disposed opposite the X-ray tube and detects X-rays that have passed through the subject, a collimator that forms a slit-shaped X-ray irradiation field by limiting an irradiation area of ​​the X-rays irradiated from the X-ray tube, an X-ray tube driver that moves the X-ray tube in the body axis direction of the subject, a detector driver that moves the X-ray detector in the body axis direction of the subject, a drive controller that controls movement of the X-ray tube driver and the detector driver, a reception unit that receives setting of a first end position that is one end of a movement range of the X-ray detector in the body axis direction of the subject, and a control unit for controlling the drive controller. and a long image reconstruction unit that reconstructs a long X-ray image by connecting the slit-shaped X-ray images generated by the slit image generation unit in the body axis direction of the subject, while moving the X-ray tube from a first position at one end side in the body axis direction to a second position at the other end side in the body axis direction under control of the drive control unit, wherein the drive control unit controls to displace the position of the X-ray irradiation field on the X-ray detector in a direction from the one end side to the other end side with the X-ray detector positioned at the first end position.

[0014] A second aspect of the present invention includes an X-ray tube that irradiates a subject with X-rays, an X-ray detector that is disposed opposite the X-ray tube and detects X-rays that have passed through the subject, a collimator that forms a slit-shaped X-ray irradiation field by limiting an irradiation area of ​​the X-rays irradiated from the X-ray tube, an X-ray tube driver that moves the X-ray tube in the body axis direction of the subject, a detector driver that moves the X-ray detector in the body axis direction of the subject, a drive controller that controls movement of the X-ray tube driver and the detector driver, a reception unit that receives setting of a first end position that is one end of a movement range of the X-ray detector in the body axis direction of the subject, and a control unit that controls the drive controller to move the X-ray tube from a first position at one end side in the body axis direction to a second position at the other end side in the body axis direction. a slit image generating unit that sequentially irradiates the X-ray detector with X-rays to generate multiple slit-shaped X-ray images while moving the X-ray detector to a different position, and a long image reconstructing unit that reconstructs a long X-ray image by connecting the slit-shaped X-ray images generated by the slit image generating unit in the body axis direction of the subject, wherein the control program is configured to cause a computer to execute a process of displacing the position of the X-ray irradiation field on the X-ray detector in a direction from the one end side to the other end side while the X-ray detector is positioned at the first end position in the slit image generating step of generating the multiple slit-shaped X-ray images by the slit image generating unit.

[0015] According to a first aspect of the present invention and a control program according to a second aspect, the X-ray imaging apparatus includes a drive control unit that controls movement of the X-ray tube and the X-ray detector, a slit image generation unit that moves the X-ray tube from a first position at one end of the body axis of the subject to a second position at the other end while sequentially irradiating the X-ray detector with X-rays to generate a plurality of slit-shaped X-ray images, and a long image reconstruction unit that reconstructs a long X-ray image by connecting the slit-shaped X-ray images in the body axis direction of the subject. The drive control unit is configured to control the displacement of the position of the X-ray irradiation field of the X-ray detector in a direction from the one end to the other end when the X-ray detector is located at the first end.

[0016] In this configuration, while the X-ray detector is positioned at a first end, which is one end of the X-ray detector's range of movement, the position of the X-ray irradiation field on the X-ray detector is controlled to be displaced from one end to the other end. In this case, the range captured by each slit-shaped X-ray image is longer than in conventional methods in which slit-shaped X-ray images are captured while maintaining the position of the X-ray irradiation field on the X-ray detector, by the distance by which the X-ray irradiation field is displaced toward the other end of the subject. As a result, even when using an X-ray detector with a relatively short movable range, the capture range of long images can be widened. Therefore, the range in which long images can be captured using the slot imaging method can be expanded using a relatively small device, such as an X-ray imaging device for general X-ray imaging. Furthermore, each slit-shaped X-ray image is captured with the X-ray irradiation field limited in the body axis direction of the subject. In this case, distortion occurring in the slit-shaped X-ray image can be reduced, thereby enabling long images with a wide capture range and less distortion to be acquired.

[0017] 1 is a front view illustrating the overall configuration of an X-ray imaging apparatus according to a first embodiment; FIG. 2 is a longitudinal sectional view illustrating the configuration of a collimator according to the first embodiment; FIG. 3 is a functional block diagram of an X-ray imaging apparatus according to the first embodiment; FIG. 4 is a diagram illustrating slot imaging using an X-ray imaging apparatus according to the first embodiment; (a) is a diagram illustrating an imaging area of ​​a slit image, and (b) is a diagram illustrating a long image reconstructed by joining slit images; (b) is a schematic diagram illustrating the operation of an X-ray tube and an X-ray detector in a state where only a first drive controller is operating in the first embodiment; (c) is a schematic diagram illustrating the operation of an X-ray tube and an X-ray detector in a state where only a second drive controller is operating in the first embodiment; (d) is a schematic diagram illustrating the operation of an X-ray tube and an X-ray detector in a state where both a first drive controller and a second drive controller are operating in the first embodiment; (e) is a diagram illustrating general X-ray imaging performed using an X-ray imaging apparatus according to the first embodiment; (f) is a diagram illustrating the position of an X-ray irradiation field in general X-ray imaging according to the first embodiment; (g) is a diagram illustrating step S3 of slot imaging according to the first embodiment; (h) is a diagram illustrating the position of an X-ray irradiation field in step S3 of slot imaging according to the first embodiment; (i) is a diagram illustrating step S4F of slot imaging according to the first embodiment; (ii) is a diagram illustrating step S4G of slot imaging according to the first embodiment. 1 is a diagram for explaining a change in the position of the X-ray radiation field in step S4F of slot imaging according to the first embodiment. FIG. 2 is a diagram for explaining a change in the position of the X-ray radiation field in step S4G of slot imaging according to the first embodiment. FIG. 3 is a diagram for explaining step S4A of slot imaging according to the second embodiment. FIG. 4 is a diagram for explaining step S4B of slot imaging according to the second embodiment. FIG. 5 is a diagram for explaining step S4C of slot imaging according to the second embodiment. FIG. 6 is a diagram for explaining a change in the position of the X-ray radiation field in step S4A of slot imaging according to the second embodiment. FIG. 7 is a diagram for explaining a change in the position of the X-ray radiation field in step S4C of slot imaging according to the second embodiment. FIG. 8 is a diagram for explaining a change in the position of the X-ray radiation field in step S4P of slot imaging according to the third embodiment. FIG. 9 is a diagram for explaining step S4P of slot imaging according to the third embodiment. FIG. 10 is a diagram for explaining step S4Q of slot imaging according to the third embodiment.FIG. 1 is a diagram for explaining the operation of an X-ray tube and an X-ray detector in conventional slot imaging; FIG. 2 is a diagram for explaining the operation of acquiring a long image using conventional long imaging; FIG. 3 is a diagram for explaining the operation of acquiring a long image using conventional slot imaging; FIG. 4 is a schematic diagram of a long image acquired by conventional long imaging; FIG. 5 is a schematic diagram of a long image acquired by conventional slot imaging. First embodiment

[0018] A first embodiment of the present invention will be described below with reference to the drawings.

[0019] <Explanation of Overall Configuration> As shown in Fig. 1, the X-ray imaging apparatus 1 according to the first embodiment includes a tabletop 3, an X-ray tube 5, and an X-ray detector 7. The tabletop 3 is on which the subject M is placed, and is supported by a base 4 disposed on the floor surface. In this embodiment, the tabletop 3 is configured to be horizontally movable in the x direction (the longitudinal direction of the tabletop 3) and the y direction (the lateral direction of the tabletop 3). In this embodiment, the subject M is placed on the tabletop 3 so that the body axis direction of the subject M is aligned with the x direction, as shown in Fig. 1.

[0020] The X-ray tube 5 is suspended by a suspension support 9 and irradiates X-rays onto the subject M. The suspension support 9 hangs down from the ceiling T via rails 11 and a ceiling running section 13. The suspension support 9 is extendable and retractable in the z-direction, which is the vertical direction. The extension and contraction of the suspension support 9 allows the X-ray tube 5 to move back and forth in the z-direction.

[0021] The rail 11 extends in the x direction along the ceiling T. The ceiling travel section 13 is connected to the X-ray tube drive section 15 via the inside of the rail 11, etc. The X-ray tube drive section 15 is equipped with a drive member, for example, a motor. The X-ray tube drive section 15 moves the ceiling travel section 13 back and forth in the x direction along the rail 11. When the X-ray tube drive section 15 is activated, the ceiling travel section 13 moves in the x direction, and the X-ray tube 5 is configured to be able to move back and forth in the x direction.

[0022] The X-ray detector 7 is built into the base 4 and detects X-rays emitted from the X-ray tube 5 and converts them into an electrical signal. That is, the X-ray detector 7 is disposed opposite the X-ray tube 5 across the top board 3. An example of the X-ray detector 7 is an FPD (Flat Panel Detector). The X-ray tube 5 and the X-ray detector 7 constitute an imaging system. An example of the length Lf of one side of the X-ray detector 7 is 14 inches or 17 inches.

[0023] In addition to the X-ray detector 7, the base 4 also has built-in rails 17 and a detector drive unit 19. The rails 17 extend in the x direction and support the X-ray detector 7. The detector drive unit 19 has a drive member, such as a motor. The detector drive unit 19 moves the X-ray detector 7 back and forth in the x direction along the rails 17. In FIG. 1 , the movable range of the X-ray detector 7 in the x direction is indicated by the symbol Lp. By providing a mechanism for moving the X-ray tube 5 and X-ray detector 7 back and forth in the x direction in this way, the X-ray imaging device 1 is configured to be capable of slot imaging in addition to general X-ray imaging.

[0024] A collimator 21 is disposed below the X-ray tube 5. As shown in FIG. 2 , the collimator 21 includes two plate-shaped shielding plates 23 arranged in the x direction. Each of the shielding plates 23 is made of a material that blocks X-rays, an example of which is lead. In this embodiment, each of the pair of shielding plates 23 is configured to move in mirror symmetry in the x direction with respect to the central axis S of the X-rays 8 irradiated from the focal point 6 of the X-ray tube 5.

[0025] The spread of X-rays 8 emitted from the X-ray focal point 6 is restricted to a pyramidal shape by each of the shielding plates 23. The X-rays 8 that pass through the openings formed by each of the shielding plates 23 are then irradiated onto the subject M. That is, the position and range of the irradiation range (X-ray irradiation field) of the X-rays 8 are adjusted by opening and closing each of the shielding plates 23 to adjust the openings. In this embodiment, the collimator 21 restricts the X-ray irradiation field to a rectangular shape with the x direction as the short side.

[0026] The shielding plates 23 are not limited to being configured to move in mirror symmetry, but may be configured to move independently. The number of shielding plates 23 included in the collimator 21 may be changed as appropriate. As an example, a configuration may be given in which, in addition to a pair of shielding plates 23 that move vertically in the x direction, a pair of shielding plates 23 that move horizontally in the y direction is included.

[0027] 3, the X-ray imaging apparatus 1 includes a main controller 25, an input unit 27, a display unit 29, and a storage unit 31. The main controller 25 includes an information processing unit such as a central processing unit (CPU). The main controller 25 controls various components of the X-ray imaging apparatus 1, such as the X-ray tube 5 and the X-ray detector 7.

[0028] The main controller 25 includes an X-ray irradiation controller 33, a reception unit 34, a collimator controller 35, an image processor 37, and a drive controller 39. The X-ray irradiation controller 33 is provided before the X-ray tube 5, and controls the X-ray irradiation time and the tube voltage and tube current applied to the X-ray tube 5, thereby controlling the dose of X-rays irradiated from the X-ray tube 5 and the timing of X-ray irradiation. The reception unit 34 receives various information, such as instructions input by the operator through the input unit 27, and transmits the information to each component.

[0029] The collimator control unit 35 controls the opening and closing movement of each of the shielding plates 23 provided in the collimator 21. That is, the collimator control unit 35 controls the range and shape of the X-ray irradiation field relative to the X-ray detector 7.

[0030] The image processing unit 37 is provided after the X-ray detector 7, and generates various X-ray images based on the X-ray detection signal output from the X-ray detector 7. The X-ray images generated by the image processing unit 37 include X-ray images generated by general X-ray photography, strip-shaped X-ray images (slit images) generated by slot photography, and long X-ray images (long images) formed by joining together the slit images.

[0031] The image processing unit 37 includes a slit image generating unit 41 and a long image reconstructing unit 43. When performing slot imaging, the slit image generating unit 41 generates a slit image for each imaging region aligned in the body axis direction of the subject M (x direction in this embodiment). The long image reconstructing unit 43 is provided after the slit image generating unit 41, and reconstructs a long image by connecting a series of slit images generated by the slit image generating unit 41 in the body axis direction of the subject M.

[0032] An example of the imaging region in slot imaging is shown in each diagram in Fig. 4. In slot imaging according to this embodiment, a plurality of elongated rectangular X-ray images, i.e., slit images, are acquired, with the short side extending in the x-direction, which is the body axis direction of the subject M. These slit images are then joined together in the body axis direction of the subject M to reconstruct a single elongated image.

[0033] 4A, regions R1 to Rn of the subject M arranged in parallel in the x-direction are imaged by the imaging operation of the X-ray imaging device 1. Of the regions R1 to Rn, region R1 located at the uppermost position (head side) in the body axis direction of the subject M is irradiated with X-rays to generate a slit image P1.

[0034] The slit image capturing position is then moved downward in order, and the operation of irradiating X-rays to generate slit images is repeated, until finally X-rays are irradiated onto region Rn located at the bottom (toward the foot) to generate slit image Pn. As a result of performing a total of n X-ray captures in this manner, a total of n slit images P1 to Pn are generated. The length of each of the slit images P1 to Pn in the x-direction is defined as the slit width Lh. As an example, the slit width Lh is approximately 2 cm to 6 cm.

[0035] Then, by stitching the slit images P1 to Pn together in the body axis direction (x direction) of the subject M, a long image Q of the long region W, which is the region of interest, is reconstructed, as shown in FIG. 4B. Note that the head side of the subject M corresponds to one end of the subject in this embodiment, and the foot side of the subject M corresponds to the other end of the subject in this embodiment.

[0036] The drive control unit 39 performs overall control of the X-ray tube drive unit 15 and the detector drive unit 19. That is, the drive control unit 39 controls the position of the X-ray tube 5 in the x direction and the position of the X-ray detector 7 in the x direction. The drive control unit 39 includes a first drive control unit 45 and a second drive control unit 47. The first drive control unit 45 and the second drive control unit 47 are control circuits used in slot imaging, and are independently controlled by the drive control unit 39. That is, in slot imaging using the X-ray imaging apparatus 1, the drive control unit 39 is configured to control the X-ray tube drive unit 15 and the detector drive unit 19 by appropriately operating one or both of the first drive control unit 45 and the second drive control unit 47.

[0037] The first drive control unit 45 performs overall control over the X-ray tube drive unit 15 and the detector drive unit 19 so that drive forces are applied to the X-ray tube 5 and the X-ray detector 7 such that the X-ray tube 5 and the X-ray detector 7 move at the same speed in the x direction. That is, when the operation of the first drive control unit 45 of the first drive control unit 45 and the second drive control unit 47 is controlled to be on, the X-ray tube 5 and the X-ray detector 7 move at the same speed in the x direction. In other words, when the second drive control unit 47 does not operate but the first drive control unit 45 operates in the drive control unit 39, the drive control unit 39 controls the X-ray tube drive unit 15 and the detector drive unit 19 so that the X-ray tube 5 and the X-ray detector 7 move in the x direction while maintaining their relative positional relationship.

[0038] The second drive controller 45 controls the operation of the X-ray tube driver 15 of the X-ray tube driver 15 and the detector driver 19. That is, the second drive controller 45 controls the X-ray tube driver 15 of the X-ray tube 5 and the X-ray detector 7 so as to apply a driving force to the X-ray tube 5 that moves it in the x direction. The direction of the driving force applied to the X-ray tube 5 by the second drive controller 45 is the direction from the imaging start position to the imaging end position in slot imaging. In this embodiment, the direction x2 from the head side to the foot side of the subject M corresponds to the direction from the slot imaging start position to the imaging end position. That is, when the first drive controller 45 does not operate but the second drive controller 47 operates in the drive controller 39, the drive controller 39 controls the X-ray tube driver 15 and the detector driver 19 so that the X-ray detector 7 does not move but the X-ray tube 5 moves in the x2 direction.

[0039] When performing slot imaging, the drive control unit 39 can change the control pattern for the X-ray tube drive unit 15 and the detector drive unit 19 by turning on one or both of the first drive control unit 45 and the second drive control unit 47. Here, the control patterns that can be executed by the drive control unit 39 will be described with reference to Figures 5 to 7.

[0040] First, a first control pattern by the drive control unit 39 will be described. In the first control pattern, the first drive control unit 45 in the drive control unit 39 is turned on, while the second drive control unit 47 is turned off. Fig. 5 is a diagram showing the operations of the X-ray tube 5 and the X-ray detector 7 when the drive control unit 39 controls the X-ray tube drive unit 15 and the detector drive unit 19 in the first control pattern.

[0041] 5 , the X-ray tube 5 moves in the x direction from the position indicated by the reference symbol 5a to the position indicated by the reference symbol 5b, and at the same time, the X-ray detector 7 moves in the x direction from the position indicated by the reference symbol 7a to the position indicated by the reference symbol 7b. At this time, the moving speed of the X-ray tube 5 and the moving speed of the X-ray detector 7 are equal, so the distance Na that the X-ray tube 5 moves in the x direction is equal to the distance Nb that the X-ray detector 7 moves in the x direction. Therefore, when only the first drive control unit 45 operates, the position of the range (X-ray irradiation field) in the X-ray detector 7 where X-rays 8 are irradiated from the X-ray tube 5 does not change.

[0042] That is, while the X-ray detector 7 moves from position 7a to position 7b, the position of the X-ray irradiation field L on the detection surface of the X-ray detector 7 remains the same. In Fig. 5 , the X-ray irradiation field L is always located in the center of the X-ray detector 7. In this way, by operating the first drive controller 45 of the first drive controller 45 and the second drive controller 47, the X-ray tube 5 and the X-ray detector 7 can be moved in the x direction at the same speed without displacing the position of the X-ray irradiation field L on the X-ray detector 7. The first control pattern corresponds to a control pattern in which the X-ray tube 5 and the X-ray detector 7 are moved in the x direction without displacing the position of the X-ray irradiation field L on the X-ray detector 7.

[0043] Next, a second control pattern by the drive control unit 39 will be described. In the second control pattern, the second drive control unit 47 in the drive control unit 39 is turned on, while the first drive control unit 45 is turned off. Fig. 6 is a diagram showing the operations of the X-ray tube 5 and the X-ray detector 7 when the drive control unit 39 controls the X-ray tube drive unit 15 and the detector drive unit 19 in the second control pattern.

[0044] When the drive control unit 39 controls the X-ray tube drive unit 15 and the detector drive unit 19 using the second control pattern, the detector drive unit 19 is not controlled by the second drive control unit 47 and therefore does not apply a drive force in the x direction to the X-ray detector 7. As a result, the X-ray detector 7 does not move in the x direction. On the other hand, the X-ray tube drive unit 15 is controlled by the second drive control unit 47 and applies a drive force to the X-ray tube 5 in a direction from the start position of slot imaging to the end position of imaging. As a result, the X-ray tube 5 moves in the x direction (x2 direction) from the start position of slot imaging to the end position of imaging.

[0045] At this time, the position of the X-ray detector 7 is fixed, while the X-ray tube 5 moves from the position indicated by the dotted line 5a to the position indicated by the solid line 5c. As a result, the position of the X-ray irradiation field L on the detection surface of the X-ray detector 7 moves in the x2 direction according to the moving distance Nc of the X-ray tube 5. In FIG. 6 , the X-ray irradiation field L is displaced from the center of the X-ray detector 7 to the other end of the X-ray detector 7 (the right side in the figure). In this way, by operating the second drive controller 47 of the first drive controller 45 and the second drive controller 47, the position of the X-ray irradiation field L on the X-ray detector 7 can be displaced in the x2 direction. That is, when the drive controller 39 controls the X-ray tube driver 15 and the detector driver 19 using the second control pattern, the position of the X-ray detector 7 does not change, but the X-ray tube 5 moves in the x2 direction. As a result, the position of the X-ray irradiation field L on the X-ray detector 7 is displaced in the x2 direction. The second control pattern corresponds to a control pattern in which the position of the X-ray irradiation field L on the X-ray detector 7 is displaced in the x2 direction while the position of the X-ray detector 7 is fixed.

[0046] Next, a third control pattern by the drive control unit 39 will be described. In the third control pattern, the drive control unit 39 controls both the first drive control unit 45 and the second drive control unit 47 to be in the on state. Fig. 7 is a diagram showing the operations of the X-ray tube 5 and the X-ray detector 7 when the drive control unit 39 controls the X-ray tube drive unit 15 and the detector drive unit 19 in the third control pattern.

[0047] When the first drive control unit 45 and the second drive control unit 47 are controlled to be in the on state, the X-ray detector 7 receives only the drive force caused by the first drive control unit 45 and moves in the x direction from the position indicated by reference symbol 7a to the position indicated by reference symbol 7b. On the other hand, the X-ray tube 5 receives the drive force caused by the second drive control unit 47 in addition to the drive force caused by the first drive control unit 45 and moves in the x direction from the position indicated by reference symbol 5a to the position indicated by reference symbol 5d.

[0048] The distance traveled by the X-ray detector 7 in Fig. 7 is the same as the distance traveled by the X-ray detector 7 in Fig. 5. That is, the distance traveled by the X-ray detector 7 in Fig. 7 is Nb. Meanwhile, unlike the state shown in Fig. 5, the X-ray tube 5 in the state shown in Fig. 7 is subjected to driving forces from both the first drive control unit 45 and the second drive control unit 47. Therefore, the distance traveled by the X-ray tube 5 in Fig. 7, Nd, is the sum of the distance traveled by the X-ray tube 5 in Fig. 5, Na, and the distance traveled by the X-ray tube 5 in Fig. 6.

[0049] As a result, the distance Nd traveled by the X-ray tube 5 in Fig. 7 is longer than the distance Nb traveled by the X-ray detector 7 in Fig. 7. That is, when both the first drive control unit 45 and the second drive control unit 47 in the drive control unit 39 are in the on state, the movement speed of the X-ray tube 5 in the x2 direction is faster than the movement speed of the X-ray detector 7 in the x2 direction. As a result, the relative position of the X-ray tube 5 with respect to the X-ray detector 7 is displaced in the x2 direction, and the position of the X-ray irradiation field L on the X-ray detector 7 gradually displaces in the x2 direction.

[0050] As an example, if the first drive control unit 45 applies a drive force to each of the X-ray tube drive unit 15 and the detector drive unit 19 such that the X-ray tube 5 and the X-ray detector 7 move in the x2 direction at a speed of 10 cm per second, and the second drive control unit 47 applies a drive force to the X-ray tube drive unit 15 such that the X-ray tube 5 moves in the x2 direction at a speed of 2 cm per second, then by controlling the first drive control unit 45 and the second drive control unit 47 to be in the on state, the X-ray detector 7 moves in the x2 direction at a speed of 10 cm per second, while the X-ray tube 5 moves in the x2 direction at a speed of 12 cm per second. Therefore, the position of the X-ray irradiation field L on the X-ray detector 7 displaces in the x2 direction at a speed of 2 cm per second.

[0051] In this way, when the drive control unit 39 controls the X-ray tube drive unit 15 and the detector drive unit 19 using the third control pattern, the X-ray detector 7 moves in the x2 direction at a relatively low speed, while the X-ray tube 5 moves in the x2 direction at a relatively high speed. The third control pattern corresponds to a control pattern in which the X-ray tube 5 and the X-ray detector 7 are each moved in the x2 direction while displacing the position of the X-ray irradiation field L on the X-ray detector 7 in the x2 direction.

[0052] The input unit 27 is used to input instructions from the operator regarding the operation of the X-ray imaging apparatus 1, and the main control unit 25 performs various controls in accordance with the instructions input by the surgeon to the input unit 27. Examples of operation devices arranged in the input unit 27 include a keyboard input panel, a touch input panel, a mouse, and a switch. One example of an instruction input to the input unit 27 is an instruction to set the range over which the X-ray detector 7 moves in the x direction in slot imaging. Information related to the instructions input to the input unit 27 is received by a receiving unit 34 in the main control unit 25.

[0053] The display unit 29 displays various information related to the X-ray imaging apparatus 1, various parameter information related to X-ray imaging, or X-ray images generated by the image processing unit 37. Examples of the display unit 29 include a liquid crystal monitor or a high-precision display.

[0054] The storage unit 31 writes and stores various X-ray images generated by the image processing unit 37, information related to image processing by the image processing unit 37, and various information related to the operation of the X-ray imaging device 1. The stored information is read out as needed and output to the display unit 29 and the like via the main control unit 25. The storage unit 31 is configured with a storage medium such as a non-volatile memory.

[0055] <Operation of General X-ray Imaging> Here, the operation of performing X-ray imaging using the X-ray imaging device 1 will be described. In this embodiment, the X-ray imaging device 1 is configured to be able to capture general X-ray images using general X-ray imaging and long X-ray images using slot imaging. Therefore, first, the operation of performing general X-ray imaging using the X-ray imaging device 1 will be described. Figure 8 shows the state in which general X-ray imaging is performed using the X-ray imaging device 1, with the chest of the subject M being the region of interest.

[0056] When general X-ray imaging is performed, the drive control unit 39 controls the X-ray tube driving unit 15 and the detector driving unit 19 to appropriately move the X-ray tube 5 and the X-ray detector 7. Under the control of the drive control unit 39, the imaging system consisting of the X-ray tube 5 and the X-ray detector 7 moves to the position shown by the solid line in Fig. 8 according to the position of the region of interest. In this general X-ray imaging, the chest of the subject M is assumed to be the region of interest.

[0057] When the positions of the imaging systems are adjusted by the drive control unit 39, the collimator control unit 35 adjusts the range of the X-ray irradiation field by appropriately moving the shielding plate 23 of the collimator 21. In general X-ray imaging, the collimator control unit 35 controls the X-ray irradiation field so that it is a relatively wide range. As shown in Fig. 9, control is performed so that the entire surface of the X-ray detector 7 becomes the X-ray irradiation field L. That is, in general X-ray imaging according to this embodiment, the width of the X-ray irradiation field L in the x direction corresponds to the width Lf of the X-ray detector 7 in the x direction.

[0058] Once the position of the imaging system and the range of the X-ray irradiation field have been adjusted, X-rays 8 are emitted from the X-ray tube 5, and the X-rays 8 that have passed through the subject M are detected by the X-ray detector 7. The image processing unit 37 generates an X-ray image B1 of a general size with the chest as the region of interest based on the X-ray detection signal output from the X-ray detector 7. The generated X-ray image B1 is displayed on the display unit 29 and stored in the memory unit 31. The operator uses the generated X-ray image B1 to make a diagnosis using general X-ray photography.

[0059] <Operation of Slot Imaging> Next, an operation of performing slot imaging using the X-ray imaging device 1 will be described. The operator operates the input unit 27 in advance to set the movement range of the X-ray detector 7 during slot imaging. That is, the operator sets one end position (first end position) and the other end position (second end position) in the x direction for the range of movement of the X-ray detector 7 during slot imaging. In this embodiment, the movement range of the X-ray detector 7 during slot imaging is set to the movable range Lp. In this embodiment, the imaging end position Gn corresponds to the first end of the movement range of the X-ray detector 7. Note that the movement range of the X-ray detector 7 is not limited to the movable range Lp, as long as it is included in the movable range Lp of the X-ray detector 7.

[0060] When slot imaging is started, first, the X-ray tube 5 and the X-ray detector 7 are each moved to an imaging start position (step S1). That is, under the control of the drive control unit 39, the X-ray tube 5 and the X-ray detector 7 are each moved to the positions indicated by solid lines, as shown in FIG. 10 . The imaging start position of the X-ray tube 5 is indicated by reference symbol E1 in FIG. 10 . The imaging start position of the X-ray detector 7 is indicated by reference symbol G1 in FIG. 10 . As shown in FIG. 11 , the imaging start position E1 of the X-ray tube 5 is adjusted so that the position of the X-ray irradiation field L relative to the X-ray detector 7 moving to imaging start position G1 becomes position T1. Position T1 of the X-ray irradiation field L corresponds to one end of the X-ray detector 7 (in the direction indicated by arrow x1).

[0061] When the X-ray tube 5 and the X-ray detector 7 are moved to their respective imaging start positions, the range of the X-ray irradiation field L is adjusted (step S2). That is, the collimator control unit 35 moves the shielding plates 23 closer to each other in accordance with the preset value of the slit width Lh, thereby restricting the irradiation field of the X-rays 8 in the x direction. Under the control of the collimator control unit 35, the X-ray irradiation field L in the X-ray detector 7 is restricted to a slit shape that extends in the y direction and has a width in the x direction of the slit width Lh, as shown in FIG.

[0062] After the range of the X-ray irradiation field L is adjusted, the first slit image is captured (step S3). That is, as shown in Fig. 10, X-rays 8 are irradiated from the X-ray tube 5, which is moving to an imaging start position E1, to the X-ray detector 7, which is moving to an imaging start position G1. The X-rays 8 pass through a region R1 of the subject M and are incident on the region of the X-ray irradiation field L shown in Fig. 11, i.e., a region on one end side of the X-ray detector 7. An X-ray detection signal output from the X-ray detector 7 is transmitted to the image processing unit 37. A slit image generation unit 41 provided in the image processing unit 37 generates a rectangular slit image P1 whose length in the x direction is the slit width Lh, based on the X-ray detection signal.

[0063] After the slit image P1 is generated, slit images P2 to Pn are captured while moving each of the imaging systems in the x2 direction (step S4). In step S4, the drive controller 39 controls the X-ray tube driver 15 and the detector driver 19 to move the X-ray tube 5 in the x2 direction from the imaging start position E1 to the imaging end position En, and to move the X-ray detector 7 in the x2 direction from the imaging start position G1 to the imaging end position Gn. In this embodiment, the imaging end position Gn of the X-ray detector 7 corresponds to the end of the movable range Lp of the X-ray detector 7 on the x2 direction side. The imaging start position G1 of the X-ray detector 7 corresponds to the end of the movable range Lp of the X-ray detector 7 on the x1 direction side.

[0064] Then, in step S4, each time the position of the X-ray irradiation field L relative to the subject M moves in the x2 direction by a distance equivalent to the slit width Lh, the X-ray tube 5 repeats the irradiation of X-rays 8 under the control of the X-ray irradiation controller 33. The slit image generator 41 generates slit images P2 to Pn whose length in the x direction is the slit width Lh, based on each of the X-ray detection signals output from the X-ray detector 7.

[0065] In step S4, the state in which the X-ray tube 5 irradiates the X-rays 8 substantially perpendicularly to the X-ray detector 7 is maintained. That is, an X-ray tube rotation control unit (not shown) moves the X-ray tube 5 from the imaging start position E1 to the imaging end position En while maintaining the orientation of the X-ray tube 5 substantially perpendicular to the X-ray detector 7. Then, while the X-ray tube 5 is being moved from the imaging start position E1 to the imaging end position En, the X-rays 8 are irradiated from the X-ray tube 5 to the X-ray detector 7, and slit images P1 to Pn are acquired.

[0066] Step S4 according to the first embodiment is divided into two stages, step S4F and step S4G, depending on the manner in which the X-ray tube 5 and the X-ray detector 7 move in the x2 direction. In step S4F, the X-ray tube 5 is moved in the x2 direction while the X-ray detector 7 is moved in the x2 direction from the imaging start position G1 to the imaging end position Gn. In step S4G, when the X-ray detector 7 reaches the imaging end position Gn, which is the end of the movable range Lp, the X-ray tube 5 is further moved in the x2 direction while the X-ray detector 7 is stopped. The operations in each of steps S4F and S4G will be described below.

[0067] <Explanation of Step S4F> Figure 12 shows the operation of the X-ray tube 5 and X-ray detector 7 in step S4F. In step S4F, the drive control unit 39 controls the X-ray tube drive unit 15 and the detector drive unit 19, so that the X-ray detector 7 moves in the x2 direction from the imaging start position G1 to the imaging end position Gn, and the X-ray tube 5 moves from the imaging start position E1 to the imaging position Ek. Each time the position of the X-ray irradiation field L with respect to the subject M moves in the x2 direction a distance equivalent to the slit width Lh, irradiation of X-rays 8 is repeated to generate slit images P1 to Pk. Figure 12 shows the state in which X-rays 8 are irradiated from the X-ray tube 5, which has moved to the imaging position Ek, to the X-ray detector 7, which has moved to the imaging end position Gn, to generate slit image Pk.

[0068] In step S4F, the drive control unit 39 controls the first drive control unit 45 and the second drive control unit 47 to the ON state to move the imaging system. In other words, in step S4F, the drive control unit 39 controls the X-ray tube drive unit 15 and the detector drive unit 19 using the third control pattern. That is, as shown in Fig. 7 , the drive control unit 39 executes control so that the movement speed of the X-ray tube 5 in the x2 direction is faster than the movement speed of the X-ray detector 7 in the x2 direction. That is, the distance Lk from the imaging start position E1 to the imaging position Ek, which corresponds to the distance moved by the X-ray tube 5 in step S4F, is longer than the distance L1 from the imaging start position G1 to the imaging end position Gn, which corresponds to the distance moved by the X-ray detector 7 in step S4F.

[0069] In step S4F, the movement speed of the X-ray tube 5 in the x2 direction is faster than the movement speed of the X-ray detector 7 in the x2 direction. Therefore, as the X-ray tube 5 moves from the imaging start position E1 to the imaging position Ek, the position of the X-ray irradiation field L on the X-ray detector 7 is displaced in the x2 direction from position T1 to position Tk, as shown in Fig. 14. As the X-ray tube 5 moves to the imaging position Tk while irradiating X-rays 8, and the X-ray detector 7 moves to the imaging end position Gn, the process proceeds from step S4F to step S4G.

[0070] 13 shows the operation of the X-ray tube 5 and X-ray detector 7 in step S4G. In step S4G, the X-ray detector 7 remains at the imaging end position Gn, while the X-ray tube 5 moves from the imaging position Ek to the imaging end position En. Each time the position of the X-ray irradiation field L with respect to the subject M moves in the x2 direction by a distance equivalent to the slit width Lh, irradiation of X-rays 8 is repeated to generate a slit image.

[0071] In step S4G, the drive control unit 39 controls the first drive control unit 45 to be in the OFF state and the second drive control unit 47 to be in the ON state to move the imaging system. In other words, in step S4G, the drive control unit 39 controls the X-ray tube drive unit 15 and the detector drive unit 19 using the second control pattern. As a result, the operations of the X-ray tube 5 and the X-ray detector 7 become as shown in Fig. 6. That is, in step S4G, the X-ray tube 5 is controlled to move in the x2 direction, while the X-ray detector 7 is controlled not to move in the x2 direction.

[0072] Thus, in step S4G, by using a control pattern in which the first drive control unit 45 is controlled to be in the OFF state while the second drive control unit 47 is controlled to be in the ON state, the X-ray tube 5 moves in the x2 direction from the imaging position E3 to the imaging end position En as shown in FIG. 13, while the X-ray detector 7 remains at the imaging end position Gn. As a result, the position of the X-ray irradiation field L on the X-ray detector 7 displaces in the x2 direction from position T2 to position Tn as shown in FIG. 15. In this embodiment, position Tn of the X-ray irradiation field L corresponds to the end on the other end side (the direction indicated by arrow x2) of the X-ray detector 7. In step S4G, while the position of the X-ray irradiation field L on the X-ray detector 7 is displaced from position T2 to position Tn, irradiation of X-rays 8 is repeated to capture slit images Pk to Pn.

[0073] The slit image generator 41 generates slit images Pk-Pn, each having a length in the x-direction equal to the slit width Lh, based on each of the X-ray detection signals output from the X-ray detector 7. Fig. 13 shows the state in which X-rays 8 are irradiated from the X-ray tube 5, which has moved to the imaging end position En, to the X-ray detector 7, which has moved to the imaging end position Gn, to generate the final slit image Pn. The generation of the slit image Pn completes the process of step S4G. The completion of all of the processes of steps S4F and S4G completes the process of step S4 according to the first embodiment.

[0074] In the first embodiment, it is preferable that the speed at which the X-ray tube 5 moves in the x2 direction in step S4 is constant, and that the speed at which the X-ray detector 7 moves in the x2 direction is also controlled to be constant. That is, the distance that the X-ray detector 7 moves from the imaging start position G1 to the imaging end position Gn in step S4F is defined as L1, and the distance that the X-ray tube 5 moves from the imaging start position E1 to the imaging position Ek in step S4F is defined as L2. In this case, it is preferable that the ratio of the moving speed V1 of the X-ray detector 7 to the moving speed V2 of the X-ray tube 5 in step S4F is set to be equal to the ratio of the distance L1 to the distance L2. It is also preferable that the X-ray tube 5 moves from the imaging position Ek to the imaging end position En while maintaining the moving speed V2 in step S4G. By keeping the moving speeds of the X-ray tube 5 and the X-ray detector 7 constant in step S4, it is possible to avoid a situation in which the subject M experiences psychological stress due to changes in the moving speed of the X-ray detector 7 or the X-ray tube 5.

[0075] After capturing the slit images P1 to Pn, a long image is reconstructed (step S5). That is, the data of the slit images P1 to Pn generated by the slit image generation unit 41 is transmitted from the slit image generation unit 41 to the long image reconstruction unit 43. The long image reconstruction unit 43 reconstructs a single long image Q by stitching together the multiple slit images P1 to Pn generated for the long region W in the x direction. The reconstructed long image Q is displayed on the display unit 29 and stored in the storage unit 31. In this way, by performing steps S1 to S5, a single long image Q that displays an X-ray image of the long region W is acquired, completing the slot imaging. The operator uses the generated long image Q to make a diagnosis using the slot imaging.

[0076] In the X-ray imaging apparatus 1 according to the first embodiment, when slit images P1 to Pn are captured during slot imaging, the X-ray tube 5 is further advanced in the x2 direction with the X-ray detector 7 positioned at the first end of the movable range Lp (the imaging end position Gn in this embodiment). At this time, the position of the X-ray detector 7 in the x direction is maintained, while the X-ray tube 5 moves in the x2 direction, displacing the position of the X-ray irradiation field L on the X-ray detector 7 in the x2 direction. That is, in the slit image acquisition process in step S4, the position of the X-ray irradiation field L is displaced in the x2 direction with the X-ray detector 7 reaching the imaging end position Gn. As a result, the movement distance L2 of the X-ray tube 5 is longer than the movement distance L1 of the X-ray detector 7 by the distance Lg by which the X-ray irradiation field L is displaced in the x2 direction.

[0077] The length of the long region W in the x direction is equal to the movement distance L2 of the X-ray tube 5 in step S4. Therefore, the length of the long region W in the x direction can be made longer than the movement distance L1 of the X-ray detector 7 by the distance Lg by which the X-ray irradiation field L is displaced in the x2 direction. That is, in the X-ray imaging device 1 according to the first embodiment, the captureable range of the long image Q in the x direction can be made longer by the distance Lg compared to the maximum distance the X-ray detector 7 can move in the x direction. Therefore, even in an X-ray device in which the base 4 is short in the x direction and the movement range of the X-ray detector 7 is narrow, slot imaging that can acquire a long image Q that displays an X-ray image of a wider range is possible.

[0078] Furthermore, in slot imaging in the first embodiment, the length in the x-direction of the X-ray irradiation field of each of the slit images P1 to Pn is limited to the slit width Lh. That is, the entire area of ​​the slit images P1 to Pn reflects an image obtained by irradiating the X-ray detector 7 with light from the X-ray tube 5 approximately perpendicularly in the x-direction. Therefore, image distortion is significantly suppressed not only in the center but also at the edges of each of the slit images P1 to Pn, and distortion of the long image Q obtained by reconstruction is also suppressed. Therefore, the imaging range of the long image Q can be wider, and distortion of the image reflected in the long image Q can be avoided.

[0079] In the first embodiment, in the process of capturing slit images P1 to Pn while moving the X-ray tube 5 from the imaging start position E1 to the imaging end position En (step S4), the drive control unit 39 controls the movement of the imaging system in accordance with the third control pattern or the second control pattern. Therefore, the position of the X-ray irradiation field L on the X-ray detector 7 continues to move in the x2 direction in step S4.

[0080] In this case, the time at which X-rays 8 are incident on each pixel constituting the X-ray detector 7 is dispersed, thereby preventing residual charges caused by the incidence of X-rays 8 from being generated unevenly in one part of the X-ray detector 7. This prevents noise from being generated unevenly in one part of the X-ray image due to uneven residual charges. In step S4, the moving speed V1 of the X-ray detector 7 is constant, and the moving speed V2 of the X-ray tube 5 is also constant. This prevents blurring of the slit images P1 to Pn caused by changes in the moving speed V1 or V2. Second embodiment

[0081] Next, a second embodiment of the present invention will be described. Note that the same components as those in the X-ray imaging apparatus 1 described in the first embodiment are denoted by the same reference numerals, and only different components will be described in detail.

[0082] The X-ray imaging apparatus 1 according to the first embodiment and the X-ray imaging apparatus 1A according to the second embodiment share the same components as those shown in Figures 1 to 3. However, they differ in the pattern in which the drive control unit 39 controls the on / off of the first drive control unit 45 and the second drive control unit 47 in step S4.

[0083] In step S4 in the first embodiment, two control patterns are switched between. That is, in step S4F, the drive control unit 39 controls the first drive control unit 45 and the second drive control unit 47 to be on. Then, in step S4G, the drive control unit 39 controls the first drive control unit 45 to be off, while controlling the second drive control unit 47 to be on. On the other hand, in the second embodiment, the drive control unit 39 switches between three control patterns in sequence in step S4.

[0084] In other words, step S4 according to the second embodiment is further divided into three steps (steps S4A, S4B, and S4C) depending on the control pattern performed by the drive control unit 39. Therefore, a description of the components of the X-ray imaging apparatus 1A according to the second embodiment will be omitted, and only the parts of the series of operations for performing slot imaging that differ from those of the first embodiment will be described in detail.

[0085] Slot imaging using the X-ray imaging apparatus 1A according to the second embodiment is the same as that according to the first embodiment in steps S1 to S3. That is, in step S1, the X-ray tube 5 is moved to imaging start position E1, and the X-ray detector 7 is moved to imaging start position G1, as shown in FIG. 10 . In step S2, the range of the X-ray irradiation field L is adjusted so that the X-ray irradiation field L is shaped like a slit whose length in the x-direction is equal to the slit width Lh. In step S3, as shown in FIG. 10 , X-rays 8 are irradiated from the X-ray tube 5, which has been moved to imaging start position E1, to the X-ray detector 7, which has been moved to imaging start position G1, to capture a slit image P1.

[0086] Once slit image P1 is generated and step S3 is completed, step S4 begins, in which slit images P2 to Pn are captured. Step S4 according to the second embodiment is divided into three stages: step S4A, in which the head side of the elongated region W of the subject M is captured; step S4B, in which the central portion of the elongated region W is captured; and step S4C, in which the foot side of the elongated region W of the subject M is captured. First, the operation of step S4A will be described. FIG. 19 is a diagram illustrating the change in position of the X-ray irradiation field L in step S4A, and FIG. 16 is a diagram illustrating the operation of the X-ray imaging apparatus 1A in step S4A.

[0087] <Explanation of Step S4A> In step S4A, as shown in Fig. 16, the X-ray tube 5 of the imaging system is moved in the x2 direction to capture a slit image of the head side of the subject M. That is, in step S4A, the drive controller 39 controls only the second drive controller 47 of the first drive controller 45 and the second drive controller 47 to be on. As a result, the operations of the X-ray tube 5 and the X-ray detector 7 are as shown in Fig. 6. That is, in step S4A, the X-ray tube 5 is controlled to move in the x2 direction, while the X-ray detector 7 is controlled not to move in the x2 direction.

[0088] In this way, in step S4A, by using a control pattern that controls only the second drive control unit 47 to be in the on state, the X-ray tube 5 moves in the x2 direction from the imaging start position E1 to the imaging position E2 as shown in Fig. 16, while the X-ray detector 7 remains at the imaging start position G1. As a result, the position of the X-ray irradiation field L on the X-ray detector 7 moves in the x direction from position T1 to position T2. ​​Position T2 is a predetermined position on the X-ray detector 7, and is determined in advance before slot imaging is performed.

[0089] 16 and 19, the present embodiment will be described by taking an example in which position T2 is the central portion of the X-ray detector 7. Furthermore, the imaging position E2 to which the X-ray tube 5 moves in step S4A is determined in advance according to the position T2 of the X-ray irradiation field L. That is, the imaging position E2 is determined in advance as a position where the position of the X-ray irradiation field L with respect to the X-ray detector 7 remaining at the imaging start position G1 is position T2.

[0090] When step S4A starts, the drive control unit 39 controls the first drive control unit 45 to be turned off and controls only the second drive control unit 47 to be turned on, thereby moving the X-ray tube 5 of the imaging system from position E1 to position E2. Then, a slit image is captured while the X-ray tube 5 is moved from position E1 to position E2. In other words, every time the position of the X-ray irradiation field L with respect to the subject M moves in the x2 direction by a distance equivalent to the slit width Lh, the X-ray tube 5 repeatedly irradiates X-rays 8 under the control of the X-ray irradiation control unit 33.

[0091] The slit image generator 41 generates slit images P2 to Pa, each having a slit width Lh in the x-direction, based on each of the X-ray detection signals output from the X-ray detector 7. FIG. 16 shows a state in which the X-ray tube 5, which has moved to imaging position E2, irradiates X-rays 8 onto the X-ray detector 7, which remains at imaging start position G1, to generate a slit image Pa. As described above, in step S4A, while the X-ray detector 7 remains at the end of the movable range Lp (imaging start position G1), the position of the X-ray irradiation field L on the X-ray detector 7 is displaced in the x2 direction to capture a slit image. When the X-ray tube 5 moves to imaging position E2, step S4A of step S4 is completed.

[0092] <Explanation of Step S4B> When step S4A is completed, the process of step S4B is started. FIG. 17 is a diagram illustrating the operation of the X-ray imaging apparatus 1A in step S4B. In step S4B, as shown in FIG. 17, the X-ray tube 5 and the X-ray detector 7 are synchronously moved in the x2 direction to capture a slit image of the central portion of the long region. That is, in step S4B, the drive control unit 39 controls only the first drive control unit 45 out of the first drive control unit 45 and the second drive control unit 47 to be on. As a result, the operation of the X-ray tube 5 and the X-ray detector 7 becomes the state shown in FIG. 5. That is, in step S4B, the X-ray tube 5 and the X-ray detector 7 are controlled to move in the x2 direction at the same speed.

[0093] 17 , the X-ray tube 5 moves in the x2 direction from the imaging position E2 to the imaging position E3, while the X-ray detector 7 moves from the imaging start position G1 to the imaging end position Gn. In step S4B, the moving speed of the X-ray tube 5 is the same as the moving speed of the X-ray detector 7. Therefore, the distance that the X-ray tube 5 moves from the imaging position E2 to the imaging position E3 in step S4B is equal to the distance L1 that the X-ray detector 7 moves from the imaging start position G1 to the imaging end position Gn in step S4B.

[0094] In step S4B, the X-ray tube 5 and the X-ray detector 7 move in the x2 direction at the same speed, so there is no change in the relative position of the X-ray tube 5 with respect to the X-ray detector 7. As a result, while the X-ray detector 7 moves from the imaging start position G1 to the imaging end position Gn, the position of the X-ray irradiation field L on the X-ray detector 7 does not change from position T2. ​​Note that the imaging position E3 of the X-ray tube 5 is determined in advance as an imaging position where the position of the X-ray irradiation field L with respect to the X-ray detector 7 moving to the imaging end position Gn becomes position T2.

[0095] When step S4B starts, the drive control unit 39 controls the second drive control unit 47 to be OFF and the first drive control unit 45 to be ON. Then, the X-ray tube 5 and the X-ray detector 7 are moved in the x2 direction at the same speed to capture a slit image. That is, every time the position of the X-ray irradiation field L relative to the subject M moves in the x2 direction a distance equivalent to the slit width Lh, the X-ray tube 5 repeatedly irradiates X-rays 8 under the control of the X-ray irradiation control unit 33.

[0096] The slit image generator 41 generates slit images Pa to Pg, each having a slit width Lh as its length in the x-direction, based on each of the X-ray detection signals output from the X-ray detector 7. Fig. 17 shows a state in which X-rays 8 are irradiated from the X-ray tube 5, which has moved to the imaging position E3, to the X-ray detector 7, which has moved to the imaging start position Gn, to generate a slit image Pg. When the X-ray tube 5 moves to the imaging position E3 and the slit image Pg is generated, step S4B of step S4 is completed.

[0097] <Explanation of Step S4C> When step S4B is completed, the process of step S4C is started. Fig. 18 is a diagram for explaining the operation of the X-ray imaging apparatus 1A in step S4C, and Fig. 20 is a diagram for explaining the change in the position of the X-ray irradiation field L in step S4C.

[0098] In step S4C, as shown in Fig. 18, the X-ray tube 5 of the imaging system is moved in the x2 direction to capture a slit image of the foot side of the subject M. That is, in step S4C, similar to step S4A, the drive control unit 39 controls only the second drive control unit 47 of the first drive control unit 45 and the second drive control unit 47 to be on. As a result, the operations of the X-ray tube 5 and the X-ray detector 7 are as shown in Fig. 6. That is, in step S4C, the X-ray tube 5 is controlled to move in the x2 direction, while the X-ray detector 7 is controlled not to move in the x2 direction.

[0099] In this way, in step S4C, by using a control pattern that controls only the second drive control unit 47 to be in the on state, the X-ray tube 5 moves in the x2 direction from the imaging position E3 to the imaging end position En as shown in Fig. 18, while the X-ray detector 7 remains at the imaging end position Gn. As a result, the position of the X-ray irradiation field L on the X-ray detector 7 moves in the x2 direction from position T2 to position Tn as shown in Fig. 20.

[0100] When step S4C starts, the drive control unit 39 controls the first drive control unit 45 to be in the OFF state, while controlling the second drive control unit 47 to be in the ON state. Then, a slit image is captured while only the X-ray tube 5 of the imaging system is moved in the x2 direction. That is, every time the position of the X-ray irradiation field L with respect to the subject M moves in the x2 direction a distance equivalent to the slit width Lh, the X-ray tube 5 repeatedly irradiates X-rays 8 under the control of the X-ray irradiation control unit 33.

[0101] The slit image generator 41 generates slit images Pg-Pn, each having a slit width Lh in the x-direction, based on each X-ray detection signal output from the X-ray detector 7. FIG. 18 shows the state in which X-rays 8 are irradiated from the X-ray tube 5, which has moved to the imaging end position En, to the X-ray detector 7, which has moved to the imaging end position Gn, to generate the final slit image Pn. Thus, in step S4C, while the X-ray detector 7 remains at the end of the movable range Lp (imaging end position Gn), the position of the X-ray irradiation field L on the X-ray detector 7 is displaced in the x2 direction to capture a slit image. The process of step S4C is completed when slit image Pn is generated. The process of step S4A, step S4B, and step S4C are all completed, thereby completing step S4 according to the second embodiment.

[0102] Once step S4 is completed and slit images P1 to Pn are generated, a long image is reconstructed (step S5). The operation of step S5 according to the second embodiment is the same as that of the first embodiment. That is, data on slit images P1 to Pn is transmitted from slit image generation unit 41 to long image reconstruction unit 43, which then reconstructs a single long image Q by stitching together the multiple slit images P1 to Pn generated for the long region W in the x direction. Once long image Q is acquired, the series of operations related to slot imaging is completed.

[0103] In the second embodiment, a control pattern is appropriately switched between one in which the second drive control unit 47 is controlled to be on to displace the position of the X-ray irradiation field L on the X-ray detector 7 in the x2 direction, and another in which the first drive control unit 45 is controlled to be on to move the X-ray tube 5 and the X-ray detector 7 in the x2 direction at the same speed. That is, in the second embodiment, the control pattern by the drive control unit 39 is appropriately switched between the first control pattern shown in Fig. 5 and the second control pattern shown in Fig. 6. Then, while switching the control pattern of the drive control unit 39, the X-ray irradiation field L with respect to the subject M is moved in the x2 direction to intermittently irradiate X-rays 8, and slit images P1 to Pn are captured.

[0104] In steps S4A and S4C, only the X-ray tube 5 is moved in the x2 direction while the X-ray detector 7 remains at the end of the movable range Lp. That is, in steps S4A and S4C, the position of the X-ray irradiation field L relative to the subject M is displaced in the x2 direction without moving the X-ray detector 7. Therefore, compared to the distance L1 moved by the X-ray detector 7 in step S4B, the length of the elongated region W in the x direction can be increased by the amount of the displacement of the X-ray irradiation field L in the x2 direction in steps S4A and S4C. Therefore, in the X-ray imaging apparatus 1A according to the second embodiment, as in the first embodiment, the effect of widening the range of the elongated region W can be obtained even if the movable range of the X-ray detector 7 is narrow. Third embodiment

[0105] Next, a third embodiment of the present invention will be described. The X-ray imaging apparatus 1 according to the first embodiment and the X-ray imaging apparatus 1B according to the third embodiment share the same components as those shown in Figures 1 to 3. Furthermore, slot imaging using the X-ray imaging apparatus 1B according to the third embodiment shares steps S1 to S3 and step S5 with the first embodiment.

[0106] However, the difference is the pattern in which the drive control unit 39 controls the on / off of the first drive control unit 45 and the second drive control unit 47 in step S4. In the third embodiment, the drive control unit 39 switches between two control patterns in sequence in step S4. In other words, step S4 in the third embodiment is further divided into two steps (steps S4P and S4Q) depending on the control pattern performed by the drive control unit 39. Therefore, the process of step S4 in the step photography in the third embodiment, which differs from the other embodiments, will be described in detail.

[0107] When steps S1 to S3 are completed and the slit image P1 is generated, step S4 is started. Step S4 according to the third embodiment is divided into two stages: step S4P for imaging the head side of the subject M in the long region W, and step S4Q for imaging the region W from the center of the subject M to the foot side.

[0108] First, the operation in step S4P will be described. Fig. 21 is a diagram illustrating the change in the position of the X-ray irradiation field L in step S4P, and Fig. 22 is a diagram illustrating the operation of the X-ray imaging apparatus 1B in step S4P. Note that the imaging start position E1 of the X-ray tube 5, the imaging end position En of the X-ray tube 5, the imaging start position G1 of the X-ray detector 7, and the imaging end position Gn of the X-ray detector 7 are assumed to be the same positions as in other embodiments.

[0109] <Explanation of Step S4P> In step S4P, as shown in Fig. 22, the X-ray tube 5 of the imaging system is moved in the x2 direction to capture a slit image of the head side of the subject M. That is, in step S4P, the drive controller 39 controls only the second drive controller 47 of the first drive controller 45 and the second drive controller 47 to be on. As a result, the operations of the X-ray tube 5 and the X-ray detector 7 are as shown in Fig. 6. That is, in step S4P, the X-ray tube 5 is controlled to move in the x2 direction, while the X-ray detector 7 is controlled not to move in the x2 direction.

[0110] 22 , the X-ray tube 5 moves in the x2 direction from the imaging start position E1 to the imaging position E4, while the X-ray detector 7 remains at the imaging start position G1. As a result, the position of the X-ray irradiation field L on the X-ray detector 7 moves in the x direction from the position T1 to the position Tn. The imaging position E4 of the X-ray tube 5 corresponds to the position of the X-ray tube 5 where the X-ray irradiation field L is at the position Tn for the X-ray detector 7 remaining at the imaging start position G1.

[0111] When step S4P starts, the drive control unit 39 controls the first drive control unit 45 to be turned off and controls only the second drive control unit 47 to be turned on, thereby moving the X-ray tube 5 of the imaging system from the imaging start position E1 to the imaging position E4. Then, while moving the X-ray tube 5 from the imaging start position E1 to the imaging position E4, a slit image is captured. In other words, every time the position of the X-ray irradiation field L with respect to the subject M moves in the x2 direction by a distance equivalent to the slit width Lh, the X-ray tube 5 repeatedly irradiates X-rays 8 under the control of the X-ray irradiation control unit 33.

[0112] The slit image generator 41 generates slit images P2 to Pe, each having a slit width Lh in the x-direction, based on each X-ray detection signal output from the X-ray detector 7. FIG. 22 shows a state in which the X-ray tube 5, which has moved to imaging position E4, irradiates X-rays 8 onto the X-ray detector 7, which remains at imaging start position G1, to generate a slit image Pe. Thus, in step S4P, while the X-ray detector 7 remains at the end of the movable range Lp (imaging start position G1), the position of the X-ray irradiation field L on the X-ray detector 7 is displaced in the x2 direction to capture a slit image. That is, in the third embodiment, the imaging start position G1, which is the end of the movable range Lp in the x1 direction, corresponds to the first end position in the present invention. The X-ray tube 5 moves to imaging position E4, completing step S4P of step S4 according to the third embodiment.

[0113] <Explanation of Step S4Q> When step S4P is completed, the process of step S4Q is started. FIG. 23 is a diagram illustrating the operation of the X-ray imaging apparatus 1B in step S4Q. In step S4Q, as shown in FIG. 23, the X-ray tube 5 and the X-ray detector 7 are moved in the x2 direction at the same speed to capture a slit image. That is, in step S4Q, the drive control unit 39 controls only the first drive control unit 45 of the first drive control unit 45 and the second drive control unit 47 to be in the on state. That is, the control pattern of the drive control unit 39 in step S4P corresponds to the second control pattern shown in FIG. 6, and the control pattern of the drive control unit 39 in step S4Q corresponds to the first control pattern shown in FIG. 5.

[0114] In step S4Q, a control pattern in which only the first drive control unit 45 is controlled to be in the on state causes the X-ray tube 5 to move in the x2 direction from the imaging position E4 to the imaging end position En, while the X-ray detector 7 moves from the imaging start position G1 to the imaging end position Gn, as shown in Fig. 23. The distance that the X-ray tube 5 moves from the imaging position E4 to the imaging end position En in step S4Q is equal to the distance L1 that the X-ray detector 7 moves from the imaging start position G1 to the imaging end position Gn in step S4Q.

[0115] In step S4Q, the X-ray tube 5 and the X-ray detector 7 move in the x2 direction at the same speed, so there is no change in the relative position of the X-ray tube 5 with respect to the X-ray detector 7. As a result, while the X-ray detector 7 moves from the imaging start position G1 to the imaging end position Gn, the position of the X-ray irradiation field L on the X-ray detector 7 does not change from position Tn.

[0116] When step S4Q starts, the drive control unit 39 controls the second drive control unit 47 to be OFF and the first drive control unit 45 to be ON. Then, the X-ray tube 5 and the X-ray detector 7 are moved in the x2 direction at the same speed to capture a slit image. That is, each time the position of the X-ray irradiation field L relative to the subject M moves in the x2 direction a distance equivalent to the slit width Lh, the X-ray tube 5 repeatedly irradiates X-rays 8 under the control of the X-ray irradiation control unit 33.

[0117] The slit image generator 41 generates slit images Pe to Pn, each having a length in the x-direction equal to the slit width Lh, based on each X-ray detection signal output from the X-ray detector 7. FIG. 23 shows a state in which X-rays 8 are irradiated from the X-ray tube 5, which has moved to the imaging end position En, to the X-ray detector 7, which has moved to the imaging start position Gn, to generate a slit image Pn. When the X-ray tube 5 moves to the imaging end position En and the slit image Pn is generated, step S4Q of step S4 is completed. When steps S4P and S4Q are all completed, step S4 according to the third embodiment is completed. After step S4 is completed and slit images P1 to Pn are generated, a long image Q is reconstructed in step S5, completing the series of operations related to slot imaging.

[0118] In the third embodiment, similarly to the second embodiment, a first control pattern is appropriately switched between, in which the first drive control unit 45 is controlled to be in the ON state to move the X-ray tube 5 and the X-ray detector 7 in the x2 direction at the same speed, and a second control pattern is controlled to be in the ON state to displace the position of the X-ray irradiation field L in the x2 direction on the X-ray detector 7. Then, while switching the control pattern, the X-ray irradiation field L with respect to the subject M is moved in the x2 direction to intermittently irradiate X-rays 8, thereby capturing slit images P1 to Pn.

[0119] In step S4P, only the X-ray tube 5 is moved in the x2 direction without moving the X-ray detector 7, so the position of the X-ray irradiation field L relative to the subject M is displaced in the x2 direction. Therefore, compared to the distance L1 moved by the X-ray detector 7 in step S4Q, the length of the elongated region W in the x direction can be made longer by the length by which the X-ray irradiation field L is displaced in the x2 direction in step S4P. Therefore, in the X-ray imaging apparatus 1A according to the third embodiment, as in the first embodiment, the effect of widening the range of the elongated region W can be obtained even if the movable range of the X-ray detector 7 is narrow.

[0120] <Effects of the Configuration of the Embodiment> (Item 1) The X-ray imaging device (1) according to this embodiment includes an X-ray tube (5) that irradiates a subject (M) with X-rays, an X-ray detector (7) that is disposed opposite the X-ray tube and that detects X-rays that have passed through the subject, a collimator (21) that forms a slit-shaped X-ray irradiation field (L) by limiting an irradiation area of ​​the X-rays irradiated from the X-ray tube, an X-ray tube driver (15) that moves the X-ray tube in the body axis direction of the subject, a detector driver (19) that moves the X-ray detector in the body axis direction of the subject, a drive controller (39) that controls movement of the X-ray tube driver and the detector driver, and a reception unit ( a slit image generating unit (41) that sequentially irradiates the X-ray detector with X-rays to generate a plurality of slit-shaped X-ray images while moving the X-ray tube from a first position (E1) at one end side in the body axis direction to a second position (En) at the other end side in the body axis direction under the control of the drive control unit; and a long image reconstructing unit (43) that reconstructs a long X-ray image (Q) by connecting the slit-shaped X-ray images generated by the slit image generating unit in the body axis direction of the subject, wherein the drive control unit (39) is configured to perform control to displace the position of the X-ray irradiation field in the X-ray detector in a direction from the one end side to the other end side with the X-ray detector positioned at the first end position.

[0121] The X-ray imaging apparatus described in paragraph 1 includes a reception unit that receives setting of a first end position, which is one end of a movement range of an X-ray detector in a body axis direction of a subject, a drive control unit that controls movement of the X-ray tube and the X-ray detector, a slit image generation unit that moves the X-ray tube from a first position at one end side of the body axis direction of the subject to a second position at the other end side while sequentially irradiating the X-ray detector with X-rays to generate a plurality of slit-shaped X-ray images, and a long image reconstruction unit that connects the slit-shaped X-ray images in the body axis direction of the subject to reconstruct a long X-ray image. The drive control unit is configured to control, with the X-ray detector located at the first end position, to displace the position of the X-ray irradiation field of the X-ray detector in a direction from one end side to the other end side.

[0122] Here, the effects of the X-ray imaging apparatus according to this embodiment will be described in comparison with a conventional configuration. When capturing multiple slit images in conventional slot imaging, as shown in FIG. 24 , drive control is performed to move the X-ray tube 103 and the X-ray detector 105 in the body axis direction of the subject at the same speed while maintaining the X-ray irradiation direction of the X-ray tube 103. All slit images are captured while moving the X-ray tube 103 and the X-ray detector 105 at the same speed. The captured slit images are then joined together to reconstruct a long image. That is, in conventional slot imaging, when capturing all slit images, the distance N1 that the X-ray tube 103 moves from the imaging start position H1 to the imaging end position Hn is equal to the distance N2 that the X-ray detector 105 moves from the imaging start position J1 to the imaging end position Jn. In other words, in conventional slot imaging, the X-ray tube 103 and the X-ray detector 105 are always moved at the same speed while capturing slit images.

[0123] In such conventional slot radiography, the movement distance N1 of the X-ray tube 103 and the movement distance N2 of the X-ray detector 105 are the same, so the movement distance of the X-ray irradiation field relative to the subject M is also equal to the movement distance N2 of the X-ray detector 105. The length of a long image in the subject's body axis direction is the sum of the movement distance of the X-ray irradiation field and the slit width. Since the slit width in slot radiography is short, the length of a long image that can be acquired in the conventional configuration is approximately the same as the movement distance N2 of the X-ray detector 105.

[0124] Such conventional slot imaging is generally performed using an X-ray TV system 100 as shown in FIG. 24 . The X-ray TV system 100 is a relatively large device, and in a configuration in which an image is taken of a subject in a supine position, for example, the base BS incorporating the X-ray detector 105 is also configured to be long in the x direction. Therefore, the X-ray TV system 100 makes it easy to ensure a sufficient range of movement of the X-ray detector 105, and therefore the range of movement of the X-ray detector 105 can be widened. Therefore, even in a configuration in which the X-ray tube 103 and the X-ray detector 105 are moved at the same speed in the body axis direction of the subject to capture a slit image, the X-ray TV system 100 can capture a long image that is wide in the body axis direction of the subject.

[0125] However, in X-ray imaging devices for general X-ray imaging, there is a relatively strong need to reduce the footprint of the X-ray imaging device, so the movable range of the X-ray detector is relatively short. In conventional slot imaging, the upper limit of the length of a long image is approximately the same as the movable range Lp of the X-ray detector. Therefore, when conventional slot imaging is performed on a conventional X-ray imaging device for general X-ray imaging, the upper limit of the length of the long image that can be obtained is shortened. Therefore, it is difficult to capture a long image that is wide in the body axis direction of a subject using a conventional X-ray imaging device for general X-ray imaging.

[0126] On the other hand, the X-ray imaging apparatus described in paragraph 1 includes, in addition to the first drive control unit 45 that moves the X-ray tube 5 and the X-ray detector 7 in the x2 direction at the same speed, a second drive control unit 47 that applies a drive force to the X-ray tube 5 of the X-ray tube 5 and the X-ray detector 7 to move it in the x2 direction. Then, with the X-ray detector 7 located at the first end position, the position of the X-ray irradiation field L on the X-ray detector 7 is displaced in the x2 direction.

[0127] In this case, the range over which each slit-shaped X-ray image is captured, i.e., the range of the long region W, is longer by the distance Lg by which the position of the X-ray irradiation field L is displaced in the x2 direction, compared to the conventional method of capturing slit-shaped X-ray images while maintaining the position of the X-ray irradiation field on the X-ray detector. As a result, even when using an X-ray detector with a relatively short movable range, the capturing range of the long image Q can be widened. Therefore, slot imaging that captures long images over a wide range can be performed using a relatively small device, such as an X-ray imaging device for general X-ray imaging.

[0128] Furthermore, each of the X-ray images P1 to Pn is captured with the X-ray irradiation range in the body axis direction of the subject being limited to a short range. By limiting the range of the X-ray irradiation field in the body axis direction of the subject, an image obtained by irradiating X-rays from the X-ray tube 5 to the X-ray detector 7 in a direction approximately perpendicular to the entire area of ​​the X-ray images P1 to Pn is displayed. Therefore, each of the X-ray images P1 to Pn is an image with little distortion. As a result, image distortion can be significantly reduced in the reconstructed long image.

[0129] (2) In the X-ray imaging device described in 1, the drive control unit is configured to, during the period in which the X-ray tube moves from the first position to the second position, always sequentially displace the position of the X-ray irradiation field in the X-ray detector from the one end side to the other end side, while causing the slit image generation unit to generate the slit-shaped X-ray image.

[0130] According to the X-ray imaging device described in paragraph 2, during the period in which the X-ray tube moves from the first position to the second position, the position of the X-ray irradiation field in the X-ray detector is sequentially displaced from one end to the other end in the body axis direction of the subject, while the slit image generation unit generates a slit-shaped X-ray image.

[0131] In this case, the imaging range of a long image can be widened by the distance the position of the X-ray irradiation field is displaced toward the other end of the subject's body axis compared to the moving distance of the X-ray detector. Furthermore, since the moving speed of the X-ray tube and the moving speed of the X-ray detector can be kept constant during the period in which a slit-shaped X-ray image is captured, it is possible to avoid a situation in which blurring occurs in the X-ray image due to changes in the moving speed of the X-ray tube or the X-ray detector when capturing the slit-shaped X-ray image. It is also possible to avoid a situation in which the subject is subjected to psychological stress due to changes in the moving speed of the X-ray tube or the X-ray detector.

[0132] Furthermore, since the position of the X-ray irradiation field in the X-ray detector is displaced at a constant speed, it is possible to prevent a portion of the X-ray detector from being irradiated with X-rays for a long period of time. In other words, it is possible to prevent the X-ray detector from being irradiated with X-rays unevenly. As a result, it is possible to prevent the residual charge in the X-ray detector from being unevenly generated and the quality of the X-ray image from being reduced.

[0133] (Item 3) The X-ray imaging apparatus according to item 1 further comprises an input unit that is operated by an operator and inputs an instruction to set the position of the first end.

[0134] According to the X-ray imaging device described in paragraph 3, by including an input unit, the position of the first end can be set by inputting an instruction from the operator to the input unit. In this case, the position of the first end within the movement range of the X-ray detector can be appropriately set at the discretion of the operator. Therefore, the operation of widening the imaging range of the long image can be performed quickly and appropriately.

[0135] (4) In the X-ray imaging apparatus described in the 1st paragraph, the position of the first end is a position at one end of a movable range of the X-ray detector.

[0136] According to the X-ray imaging device described in paragraph 4, the position of the first end is one end of the movable range of the X-ray detector. With this configuration, the movable range of the X-ray detector is further increased, and therefore the imaging range of the long image can be further increased.

[0137] (Item 5) A control program according to this embodiment includes an X-ray tube that irradiates a subject with X-rays, an X-ray detector that is disposed opposite the X-ray tube and detects X-rays that have passed through the subject, a collimator that forms a slit-shaped X-ray irradiation field by limiting an irradiation area of ​​X-rays irradiated from the X-ray tube, an X-ray tube driver that moves the X-ray tube in the body axis direction of the subject, a detector driver that moves the X-ray detector in the body axis direction of the subject, a drive controller that controls movement of the X-ray tube driver and the detector driver, a reception unit that receives setting of a first end position that is one end of a movement range of the X-ray detector in the body axis direction of the subject, and a drive controller that controls the X-ray tube to move from a first position at one end in the body axis direction to a second position in the body axis direction. a slit image generating unit that sequentially irradiates the X-ray detector with X-rays to generate a plurality of slit-shaped X-ray images while moving the X-ray detector to a second position at the other end of the X-ray detector, and a long image reconstructing unit that connects the slit-shaped X-ray images generated by the slit image generating unit in the body axis direction of the subject to reconstruct a long X-ray image; and a control program that causes a computer to execute a series of processes to control an X-ray imaging apparatus that includes: a slit image generating unit that sequentially irradiates the X-ray detector with X-rays to generate a plurality of slit-shaped X-ray images while moving the X-ray detector to a second position at the other end of the X-ray detector; and a long image reconstructing unit that connects the slit-shaped X-ray images generated by the slit image generating unit in the body axis direction of the subject to reconstruct a long X-ray image. In the slit image generating step of generating the plurality of slit-shaped X-ray images by the slit image generating unit, the control program is configured to cause the computer to execute a process of displacing the position of the X-ray irradiation field on the X-ray detector in a direction from the one end side to the other end side while the X-ray detector is positioned at the position of a first end.

[0138] According to the control program described in paragraph 5, the computer is configured to execute a process of displacing the position of the X-ray irradiation field 7 on the X-ray detector 7 in the x2 direction, which is the direction of progression of the slot imaging, while the X-ray detector 7 is positioned at the first end of the X-ray detector 7 in the body axis direction of the subject.

[0139] In this case, the range over which each slit-shaped X-ray image is captured, i.e., the range of the long region W, is longer by the distance Lg by which the position of the X-ray irradiation field L is displaced in the x2 direction, compared to the conventional method of capturing slit-shaped X-ray images while maintaining the position of the X-ray irradiation field on the X-ray detector. As a result, even when using an X-ray detector with a relatively short movable range, the capturing range of the long image Q can be widened. Therefore, slot imaging that captures long images over a wide range can be performed using a relatively small device, such as an X-ray imaging device for general X-ray imaging.

[0140] (Item 6) Furthermore, in the control program described in Item 5, the slit image generating step is configured to cause a computer to execute a process of generating the slit-shaped X-ray image by the slit image generating unit while always sequentially displacing the position of the X-ray irradiation field in the X-ray detector from the one end side to the other end side during the period in which the X-ray tube is moved from the first position to the second position.

[0141] According to the control program described in paragraph 6, in the slit image generation process, the position of the X-ray irradiation field in the X-ray detector is constantly shifted sequentially from one end to the other end in the subject's body axis direction, while the computer executes a process of generating a slit-shaped X-ray image using the slit image generation unit.

[0142] In this case, the imaging range of a long image can be widened by the distance the position of the X-ray irradiation field is displaced toward the other end of the subject's body axis compared to the moving distance of the X-ray detector. Furthermore, since the moving speed of the X-ray tube and the X-ray detector can be kept constant during the period in which a slit-shaped X-ray image is captured, it is possible to avoid a situation in which blurring of the X-ray image occurs due to changes in the moving speed of the X-ray tube or the X-ray detector during the slit image generation process. Furthermore, it is also possible to avoid a situation in which the subject is subjected to psychological stress due to changes in the moving speed of the X-ray tube or the X-ray detector.

[0143] Furthermore, since the position of the X-ray irradiation field on the X-ray detector is displaced at a constant speed in the slit image generation process, it is possible to prevent X-rays from being irradiated onto a portion of the X-ray detector for a long period of time. That is, it is possible to prevent X-rays from being irradiated onto the X-ray detector unevenly when capturing a series of slit images. As a result, it is possible to prevent residual charges from being generated unevenly in the X-ray detector, which would otherwise degrade the quality of the long image.

[0144] (Item 7) In the control program described in Item 5, the position of the first end is one end position of a movable range of the X-ray detector.

[0145] According to the control program described in paragraph 7, the position of the first end is one end of the movable range of the X-ray detector. With this configuration, the movable range of the X-ray detector is further increased, and therefore the imaging range of the long image can be further increased.

[0146] <Other Embodiments> The embodiments disclosed herein are illustrative in all respects and are not limiting. The scope of the present invention includes the claims and all modifications within the meaning and scope of the claims. For example, the present invention can be modified as follows.

[0147] (1) In the first embodiment described above, an example has been described in which the X-ray tube 5 is moved to an imaging start position E1 in step S1 and the first slit image P1 is captured at the imaging start position E1. However, the present invention is not limited to this. That is, in step S1, the X-ray tube 5 may be moved to a predetermined position E0 away from the imaging start position E1 in the x1 direction, and after step S2, the X-ray tube 5 may be moved from the predetermined position E0 in the x2 direction. The moment the X-ray tube 5 passes the imaging start position E1, step S3 may be started to capture the first slit image P1. In this case, the speed of the X-ray tube 5 when capturing each of the slit images P1 to Pn can be made equal, thereby significantly reducing differences in the visibility of each slit image due to differences in the moving speed of the X-ray tube 5.

[0148] (2) In the first embodiment described above, the first drive control unit 45 and the second drive control unit 47 are always kept on while the X-ray tube 5 is moved from the imaging start position E1 to the imaging end position En. However, the first drive control unit 45 and the second drive control unit 47 may be kept on during part of the movement from the imaging start position E1 to the imaging end position En. That is, in the process of capturing slit images P1 to Pn, if the second drive control unit 47 is on while the X-ray detector 7 is located at either end of the movement range of the X-ray detector 7, it is possible to obtain the effect of making the length of the long image Q longer than the movement distance L1 of the X-ray detector 7, in accordance with the distance Lg by which the position of the X-ray irradiation field L on the X-ray detector 7 is displaced in the x2 direction by the second drive control unit 47.

[0149] (3) In the second embodiment described above, the position T2 to which the X-ray irradiation field L is moved in step S4A is set to the central portion of the X-ray detector 7. However, the position T2 is not limited to the central portion. In other words, the position T2 can be set to any region of the X-ray detector 7 in step S4A.

[0150] (4) In the third embodiment described above, the operation of turning on the second drive control unit 47 is performed when the X-ray detector 7 is moved to the imaging start position G1, i.e., the end on the head side of the subject M. However, this is not limiting. That is, the second drive control unit 47 may be controlled to be turned on when the X-ray detector 7 is moved to the imaging end position Gn, thereby displacing the position of the X-ray irradiation field L on the X-ray detector 7 from position T1, which is the end on the x1 direction, to position Tn, which is the end on the x2 direction. In such a modified embodiment, the imaging end position Gn corresponds to the first end in the present invention. In other words, the timing for displacing the position of the X-ray irradiation field L relative to the X-ray detector 7 in the x2 direction is not limited to the timing for capturing a slit image of the foot side of the subject M, but may be the timing for capturing an image of the head side of the subject M or another part of the subject M.

[0151] Furthermore, if the position of the X-ray irradiation field L relative to the X-ray detector 7 is displaced in the x2 direction (the direction of progression of slot imaging) while the X-ray detector 7 is positioned at one end of the movement range in slot imaging, the position before the displacement is not limited to position T1 but can be set to any region on the X-ray detector 7. Furthermore, the position after the displacement is not limited to position Tn but can be set to any region on the X-ray detector 7.

[0152] (5) In the above-described embodiments, an example has been described in which slot imaging is performed with the subject M in a supine position placed on the tabletop 3. However, the configurations of the embodiments can also be applied to a configuration in which slot imaging is performed with the subject M in an upright position. Furthermore, the X-ray imaging device 1 is not limited to an X-ray device for general X-ray imaging, and the configurations of the embodiments can be applied to an X-ray device used for any X-ray imaging.

[0153] (6) In each of the above-described embodiments, the first drive control unit 45 and the second drive control unit 47 are exemplified to explain a configuration in which the control pattern by the drive control unit 39 becomes the third control pattern or a configuration in which the control pattern is switched between the first control pattern and the second control pattern. Therefore, the drive control unit 39 is not limited to a configuration including multiple control units, i.e., the first drive control unit 45 and the second drive control unit 47. One example of the drive control unit 39 is a configuration in which the drive control unit 39 executes a single program to switch the control pattern for the X-ray tube drive unit 15 and the detector drive unit 19 from the first control pattern to the second control pattern when the X-ray detector 7 is located at one end of its movement range during slot imaging. Another example of the drive control unit 39 is a configuration in which the drive control unit 39 does not include the first drive control unit 45 and the second drive control unit 47, but includes a single control unit that executes the third control pattern during slot imaging.

[0154] The drive control unit 39 controls the X-ray tube drive unit 15 and the detector drive unit 19 using the second control pattern or the third control pattern, thereby displacing the position of the X-ray irradiation field L on the X-ray detector 7 in the x2 direction. Therefore, even with this configuration, the position of the X-ray irradiation field L relative to the X-ray detector 7 can be displaced in the x2 direction when the X-ray detector 7 is positioned at one end of the movement range for slot imaging.

[0155] (7) In the above-described embodiments, the direction x2 from the head side to the foot side of the subject M corresponds to the direction from the start position of slot imaging to the end position of imaging (the direction of travel in slot imaging). However, this is not limiting. That is, the direction x1 from the foot side to the head side of the subject M may correspond to the direction from the start position of slot imaging to the end position of imaging. In this case, the drive control unit 39 controls the X-ray tube 5 to move in the x1 direction while the X-ray detector 7 is positioned at one end of its range of movement in slot imaging. By this control, the position of the X-ray irradiation field L on the X-ray detector 7 can be displaced in the direction of travel in slot imaging while the X-ray detector 7 is positioned at one end of its range of movement in slot imaging.

[0156] DESCRIPTION OF SYMBOLS 1 X-ray imaging device 3 Top plate 4 Base 5 X-ray tube 6 X-ray focal point 7 X-ray detector 15 X-ray tube driving unit 19 Detector driving unit 21 Collimator 25 Main control unit 27 Input unit 29 Display unit 31 Memory unit 33 X-ray irradiation control unit 35 Collimator control unit 37 Image processing unit 39 Drive control unit 41 Slit image generation unit 43 Long image reconstruction unit 45 First drive control unit 47 Second drive control unit

Claims

1. An X-ray tube which irradiates an object with X-rays; an X-ray detector which is disposed opposite the X-ray tube and detects X-rays which have passed through the object; a collimator which forms a slit-shaped X-ray irradiation field by limiting an irradiation area of ​​the X-ray irradiated from the X-ray tube; an X-ray tube drive unit which moves the X-ray detector in the direction of the object's body axis; a detector drive unit which moves the X-ray detector in the direction of the object's body axis; a drive control unit which controls the movement of the X-ray tube drive unit and the detector drive unit; a reception unit which receives a setting of a first end position which is one end of a movement range of the X-ray detector in the direction of the object's body axis; and a slit image generation unit which generates a plurality of slit-shaped X-ray images by sequentially irradiating the X-ray detector with X-rays under the control of the drive control unit. an X-ray imaging device comprising: a long image reconstruction unit that connects the slit-shaped X-ray images generated by the slit image generation unit in the body axis direction of the subject to reconstruct a long X-ray image; and the drive control unit is configured to control the displacement of the position of the X-ray irradiation field in the X-ray detector in a direction from the one end side to the other end side while the X-ray detector is positioned at the first end position.

2. An X-ray imaging device as described in claim 1, wherein the drive control unit is configured to, during the period in which the X-ray tube moves from the first position to the second position, constantly displace the position of the X-ray irradiation field in the X-ray detector from the one end side to the other end side, while causing the slit image generation unit to generate the slit-shaped X-ray image.

3. An X-ray imaging apparatus according to claim 1, further comprising an input section that is operated by an operator and that inputs an instruction to set the position of the first end section.

4. An X-ray imaging apparatus according to claim 1, wherein the position of the first end is one end position of a movable range of the X-ray detector.

5. An X-ray tube for irradiating an object with X-rays, an X-ray detector disposed opposite to the X-ray tube and detecting X-rays transmitted through the object, a collimator for forming a slit-shaped X-ray irradiation field by restricting an irradiation area of ​​the X-rays irradiated from the X-ray tube, an X-ray tube drive unit for moving the X-ray tube in the body axis direction of the object, a detector drive unit for moving the X-ray detector in the body axis direction of the object, a drive control unit for controlling the movement of the X-ray tube drive unit and the detector drive unit, and a slit image generating unit that sequentially irradiates X-rays to the X-ray detector while moving the X-ray tube from a first position at one end side of the body axis direction to a second position at the other end side of the body axis direction under the control of the drive control unit, and generates a plurality of slit-shaped X-ray images by connecting the slit-shaped X-ray images generated by the slit image generating unit in the body axis direction of the subject to reconstruct a long X-ray image, wherein the control program is configured to cause a computer to execute a series of processes for controlling an X-ray imaging apparatus comprising: a receiving unit that receives setting of a first end position, which is one end of a moving range of an X-ray detector; a slit image generating unit that sequentially irradiates X-rays to the X-ray detector while moving the X-ray tube from a first position at one end side of the body axis direction to a second position at the other end side of the body axis direction under the control of the drive control unit, and a long image reconstructing unit that connects the slit-shaped X-ray images generated by the slit image generating unit in the body axis direction of the subject to reconstruct a long X-ray image, with the X-ray detector located at the first end position.

6. A control program as claimed in claim 5, configured to cause a computer to execute a process in the slit image generating step of generating the slit-shaped X-ray image by the slit image generating unit while always sequentially displacing the position of the X-ray irradiation field in the X-ray detector from the one end side to the other end side during the period in which the X-ray tube is moved from the first position to the second position.

7. A control program according to claim 5, wherein the position of the first end is one end position of a movable range of the X-ray detector.