X-ray imaging device

Abstract

To easily perform X-ray imaging regardless of the posture of an inspection object.SOLUTION: The X-ray imaging apparatus includes a turning arm that is rotatable around a predetermined axis, an X-ray irradiation unit, an X-ray detection unit, and a robot arm that adjusts a position of the turning arm with respect to an inspection target, the robot arm includes a plurality of joints, and the joints include at least a distal end side joint that is disposed at a distal end portion and is rotatable around the predetermined axis and a position adjustment joint that is disposed closer to a base side than a disposition position of the distal end side joint and is rotatable around an axis intersecting a vertical direction. A portion of the robot arm closer to the distal end than the position adjustment joint is displaced about the axis of the position adjustment joint, and the predetermined axis of the turning arm is inclined with respect to the vertical direction.SELECTED DRAWING: Figure 1

Description

Technical Field

[0005]

[0001] The present invention relates to an X-ray imaging apparatus.

Background Art

[0002] Conventionally, as a dental X-ray imaging apparatus, there is one capable of at least one of CT imaging and panoramic tomography. This conventional X-ray imaging apparatus includes an X-ray irradiation unit that irradiates an object to be examined with X-rays, and an X-ray detection unit that detects the X-rays transmitted through the object to be examined. The X-ray irradiation unit and the X-ray detection unit are arranged on a swing arm. The swing arm is supported so as to be able to move up and down. In addition, a subject holding device including a chin rest is installed in the dental X-ray imaging apparatus. At the time of X-ray imaging, the jaw of the subject is placed on the chin rest, and the head of the subject is fixed by the subject holding device. Such an X-ray imaging apparatus is disclosed in, for example, Patent Document 1. <000001​​​​​​​​​​​​​​​​​​​​​​​​​​

[0006] This invention was made to solve the above problems and aims to provide an X-ray imaging apparatus that can easily perform X-ray imaging regardless of the posture of the subject being examined. The subject being examined includes corpses. [Means for solving the problem]

[0007] To achieve the above objective, an X-ray imaging apparatus according to one aspect of the present invention is an X-ray imaging apparatus capable of X-ray imaging in at least one of CT imaging mode and panoramic tomography mode, comprising: a swivel arm that is rotatable around a predetermined axis and has a predetermined axis between a predetermined direction between one end perpendicular to the predetermined axis and the other end opposite to the first end; an X-ray irradiation unit disposed at one end of the swivel arm for irradiating an object to be examined with X-rays; an X-ray detection unit disposed at the other end of the swivel arm, facing the X-ray irradiation unit in a predetermined direction with the object to be examined in between, for detecting X-rays that have passed through the object to be examined; and a robot arm supported by a base, with the swivel arm attached to its tip opposite to the base, which adjusts the position of the swivel arm relative to the object to be examined by movement. The robot arm has a plurality of joints. The joints include at least a tip-side joint disposed at the tip of the robot arm and rotatable around a predetermined axis, and a position adjustment joint disposed on the base side of the robot arm than the position of the tip-side joint and rotatable around an axis intersecting the vertical direction. The swivel arm is attached to the tip joint, and as the tip joint rotates around a predetermined axis, the swivel arm rotates together with the tip joint around a predetermined axis. When the position of the swivel arm is adjusted relative to the object being inspected, the position adjustment joint is driven, causing the portion of the robot arm closer to the tip than the position adjustment joint to be displaced around the axis of the position adjustment joint, and the predetermined axis of the swivel arm to tilt with respect to the vertical. [Effects of the Invention]

[0008] In this invention, X-ray imaging can be easily performed regardless of the posture of the person being examined. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram of an X-ray imaging apparatus according to an embodiment. [Figure 2] This diagram shows the positional relationship between the rotating arm of the X-ray imaging device and the object being examined (specifically, the patient's head) according to the embodiment. [Figure 3] This is a block diagram of an X-ray imaging apparatus according to an embodiment. [Figure 4] This figure shows the positional relationship between the rotating arm of the X-ray imaging apparatus according to the embodiment and the subject in an abnormal posture. [Figure 5] This diagram shows the state in which a predetermined axis of the swivel arm of an X-ray imaging apparatus according to an embodiment is tilted with respect to the vertical direction. [Figure 6] This figure shows the movement trajectory of the swivel arm when X-ray imaging is performed in CT mode without using a robotic arm. [Figure 7] This figure shows the movement trajectory of the swivel arm when X-ray imaging is performed in CT imaging mode using an X-ray imaging device according to the embodiment. [Figure 8] This figure illustrates the deformation of the swivel arm of an X-ray imaging apparatus according to an embodiment when a predetermined axis of the swivel arm is parallel to the vertical direction. [Figure 9] This figure illustrates the deformation of the swivel arm when a predetermined axis of the swivel arm of an X-ray imaging apparatus according to an embodiment is tilted with respect to the vertical direction. [Figure 10] This figure illustrates the deformation of the swivel arm when a predetermined axis of the swivel arm of an X-ray imaging apparatus according to an embodiment is tilted with respect to the vertical direction. [Figure 11] This figure illustrates the experimental conditions for confirming the effects obtained with the configuration of the embodiment. [Figure 12] This figure schematically shows X-ray images from an experiment to confirm the effects obtained with the configuration of the embodiment. [Figure 13] This figure shows the experimental results obtained to confirm the effects obtained with the configuration of the embodiment (Example 1). [Figure 14] This is a diagram showing the experimental results obtained to confirm the effects achieved by the configuration of the embodiment (Example 2). [Figure 15] This is a diagram showing the experimental results obtained to confirm the effects achieved by the configuration of the embodiment (Comparative Example).

Mode for Carrying Out the Invention

[0010] <Overall Configuration of the X-ray Imaging Apparatus> As shown in FIG. 1, the X-ray imaging apparatus 100 of the present embodiment is installed on a substantially flat floor surface FL. The X-ray imaging apparatus 100 has the vertical direction perpendicular to the floor surface FL as the up-down direction. Of the X-ray imaging apparatus 100, the side on the floor surface FL side is the lower side of the X-ray imaging apparatus 100. The up-down direction of the X-ray imaging apparatus 100 corresponds to the vertical direction.

[0011] In the present embodiment, the installation location of the X-ray imaging apparatus 100 is the substantially flat floor surface FL, but it is not limited thereto. For example, the X-ray imaging apparatus 100 may be installed on an inclined surface inclined with respect to the floor surface FL, the X-ray imaging apparatus 100 may be installed on a wall surface erected in the up-down direction, or the X-ray imaging apparatus 100 may be installed so as to be suspended from the ceiling. Further, the X-ray imaging apparatus 100 may be made transportable by installing it on a cart or the like.

[0012] The X-ray imaging apparatus 100 is for dental use. The X-ray imaging apparatus 100 performs X-ray imaging with the jaw and facial region of the human body as the inspection target. The inspection target is a living body. However, the inspection target may be a cadaver. The X-ray imaging apparatus 100 can perform X-ray imaging on a subject in a normal posture such as a standing posture and a sitting posture. Here, the X-ray imaging apparatus 100 can further perform X-ray imaging on a subject in an unusual posture that is not a normal posture such as a semi-sitting posture and a lying posture. In other words, the unusual posture is a posture in which the upper body of the subject is inclined with respect to the vertical direction.

[0013] As shown in FIGS. 1 and 2, the X-ray imaging apparatus 100 includes an X-ray irradiation unit 1 and an X-ray detection unit 2. The X-ray irradiation unit 1 and the X-ray detection unit 2 are arranged to face each other with the jaw and face of the subject as the inspection object interposed therebetween. In FIG. 2, the part above the subject's neck (the part including the head and the jaw and face, etc.) is schematically shown by a broken line and denoted by the symbol H. In the following description, the part H above the subject's neck is simply referred to as the head H.

[0014] The X-ray irradiation unit 1 irradiates the subject with X-rays. In other words, the X-ray irradiation unit 1 emits X-rays toward the X-ray detection unit 2. The X-ray irradiation unit 1 is composed of an X-ray tube, a collimator, etc. The collimator regulates the spread of X-rays.

[0015] The X-ray detection unit 2 detects the X-rays that have been irradiated by the X-ray irradiation unit 1 and passed through the subject. The X-ray detection unit 2 is composed of a flat panel detector, etc. The flat panel detector receives the irradiation of the X-rays that have passed through the subject.

[0016] The X-ray imaging apparatus 100 includes a swivel arm 3. The X-ray irradiation unit 1 and the X-ray detection unit 2 are arranged on the swivel arm 3. In FIG. 1, the swivel arm 3 attached to the robot arm 4 described later is illustrated, and in FIG. 2, the swivel arm 3 is illustrated alone. Note that the external shape of the swivel arm 3 shown in FIGS. 1 and 2 (that is, the exterior cover of the swivel arm 3) is an example, and the external shape of the swivel arm 3 is not particularly limited.

[0017] The swivel arm 3 is composed of a metal frame such as aluminum. At least a part of the frame constituting the swivel arm 3 is covered with an exterior cover. In the following description, the frame constituting the swivel arm 3 is referred to as an arm frame.

[0018] The swivel arm 3 is rotatable about a predetermined axis AX. The swivel arm 3 is rotatably supported about the predetermined axis AX by the robot arm 4 described later.

[0019] The pivot arm 3 has its longitudinal direction in a predetermined direction PD (see Figure 2) perpendicular to the predetermined axis AX when viewed from the axial direction of the predetermined axis AX. One end 3a of the pivot arm 3 in the predetermined direction PD and the other end 3b opposite to the one end 3a in the predetermined direction PD rotate around the predetermined axis AX. That is, the predetermined axis AX is located between the predetermined direction PD of the pivot arm 3 and the one end 3a and the other end 3b. The X-ray irradiation unit 1 is located at one end 3a of the pivot arm 3. The X-ray detection unit 2 is located at the other end 3b of the pivot arm 3.

[0020] During X-ray imaging, it is necessary to hold the portion of the swivel arm 3 between one end 3a and the other end 3b in a predetermined direction PD at a distance from the subject's head H (specifically, the top of the head) in the axial direction of a predetermined axis AX. At this time, the swivel arm 3 is held so as to straddle the subject's head H (specifically, the top of the head). As a result, the X-ray irradiation unit 1 and the X-ray detection unit 2 face each other in the predetermined direction PD, with the subject's maxillofacial region in between.

[0021] The X-ray imaging apparatus 100 is equipped with a robotic arm 4. The swivel arm 3 is attached to the robotic arm 4. The robotic arm 4 adjusts the position of the swivel arm 3 to match the position of the patient's maxillofacial region. Through this position adjustment by the robotic arm 4, the X-ray irradiation unit 1 and the X-ray detection unit 2 are held facing each other in a predetermined direction PD, with the patient's maxillofacial region in between.

[0022] In this case, if the subject is healthy, they can be asked to move in accordance with the position of the swivel arm 3 during X-ray imaging. In this case, for example, the position between the swivel arm 3 and the subject's maxillofacial region can be adjusted simply by moving the swivel arm 3 vertically to match the subject's body shape (height and sitting height, etc.).

[0023] However, there are cases where the subject cannot assume a normal posture. In other words, there are cases where the subject can only assume an abnormal posture such as a semi-sitting posture, a supine posture, or a standing posture with a bent waist. In these cases, simply moving the swivel arm 3 in the vertical direction is not sufficient to align the swivel arm 3 with the subject's maxillofacial region. When the subject is in an abnormal posture, it is necessary to tilt the predetermined axis AX, which is the rotation axis of the swivel arm 3, with respect to the vertical direction.

[0024] Therefore, in this embodiment, a multi-joint robot arm having multiple joints (axes) is used as the robot arm 4. The number of axes of the robot arm 4 is not particularly limited. For example, a 6-axis robot arm can be used as the robot arm 4. In the following description, we will assume that the robot arm 4 is a 6-axis robot arm. However, the number of axes of the robot arm 4 may be 7 or more axes, or 5 or less axes.

[0025] The robot arm 4 is supported by a base 40 on the floor surface FL. The robot arm 4 is erected relative to the base 40. The swivel arm 3 is attached to the end of the robot arm 4 on the side opposite to the base 40.

[0026] The robot arm 4 is a combination of multiple links. The robot arm 4 has multiple joints (specifically, joints 41 to 46, which will be described later) to connect the links. Each of the multiple joints has a built-in motor (not shown), and the corresponding motor is driven to rotate. This allows the robot arm 4 to perform actions such as turning, rotating, bending, and twisting.

[0027] The robot arm 4 is a 6-axis robot arm. Therefore, the robot arm 4 has joints 41, 42, 43, 44, 45, and 46. The joints 41, 42, 43, 44, 45, and 46 are arranged in this order from the base 40 side to the tip side of the robot arm 4. Also, the joints 41, 42, 43, 44, 45, and 46 correspond to the first axis A1, second axis A2, third axis A3, fourth axis A4, fifth axis A5, and sixth axis A6, respectively. The joints 41, 42, 43, 44, 45, and 46 are each rotatable around their corresponding axis.

[0028] Joint 41 is located closer to the base 40 of the robot arm 4 than the other joints 42-46. In the following description, joint 41 may be referred to as the base-side joint 41 to distinguish it from the other joints 42-46.

[0029] The first axis A1, which corresponds to the base joint 41, is parallel to the vertical direction. By rotating the base joint 41 around the first axis A1, the robot arm 4 as a whole is rotated around the first axis A1.

[0030] Joint 46 is located at the tip of the robot arm 4. That is, the robot arm 4 has joint 46 as its tip. The swivel arm 3 is attached to joint 46. Joint 46 corresponds to the "tip-side joint". In the following description, joint 46 will be referred to as the tip-side joint 46 to distinguish it from the other joints 41 to 45.

[0031] The sixth axis A6, which corresponds to the tip-side joint 46, coincides with a predetermined axis AX. That is, the tip-side joint 46 is rotatable around the predetermined axis AX. The swivel arm 3 is attached to the tip-side joint 46. This allows the swivel arm 3 to rotate around the predetermined axis AX.

[0032] Joints 42 to 45 are each positioned on the base 40 side of the robot arm 4, relative to the position of the tip joint 46. Specifically, joints 42 to 45 are each positioned between the base joint 41 and the tip joint 46 of the robot arm 4.

[0033] Here, joints 42 to 45 are each rotatable around an axis intersecting the vertical direction. In this configuration, joints 42 to 45 each correspond to "position adjustment joints".

[0034] The second axis A2, which corresponds to joint 42, is parallel to one of the horizontal directions perpendicular to the vertical direction (i.e., the direction perpendicular to the plane of the paper in Figure 1). By displacing joint 42 around the second axis A2, the portion of the robot arm 4 closer to the tip of joint 42 is displaced around the second axis A2. For example, by displacing joint 42 around the second axis A2, the predetermined axis AX of the swivel arm 3 can be tilted relative to the vertical direction, starting from a state where the predetermined axis AX is parallel to the vertical direction.

[0035] The third axis A3, which corresponds to joint 43, is parallel to one direction in the horizontal direction, similar to the second axis A2. By displacing joint 43 around the third axis A3, the portion of the robot arm 4 closer to the tip of joint 43 is displaced around the third axis A3. By displacing joint 43 around the third axis A3, the predetermined axis AX of the swivel arm 3 can be tilted relative to the vertical direction, starting from a state where the predetermined axis AX is parallel to the vertical direction.

[0036] The fourth axis A4, which corresponds to joint 44, is perpendicular to the axial directions of the second axis A2 and the third axis A3. The axial direction of the fourth axis A4, which corresponds to joint 44, changes depending on the rotation angles of joints 42 and 43. By displacing joint 44 around the fourth axis A4, the portion of the robot arm 4 closer to the tip of joint 44 is displaced around the fourth axis A4. Starting from a state where the predetermined axis AX of the swivel arm 3 is parallel to the vertical and the fourth axis A4 is inclined with respect to the vertical, displacing joint 44 around the fourth axis A4 makes it possible to make the predetermined axis AX inclined with respect to the vertical.

[0037] The fifth axis A5, which corresponds to joint 45, is parallel to one direction in the horizontal direction, similar to the second axis A2 and the third axis A3. By displacing joint 45 around the fifth axis A5, the portion of the robot arm 4 closer to the tip of joint 45 is displaced around the fifth axis A5. By displacing joint 45 around the fifth axis A5, the predetermined axis AX of the swivel arm 3 can be tilted relative to the vertical direction, starting from a state where the predetermined axis AX is parallel to the vertical direction.

[0038] As shown in Figure 3, the X-ray imaging apparatus 100 includes a control device 5. The control device 5 includes processing circuits such as a CPU and an ASIC. The control device 5 also includes storage devices such as RAM, ROM, SSD, and HDD.

[0039] The control device 5 controls the X-ray imaging performed by the X-ray irradiation unit 1 and the X-ray detection unit 2. The control device 5 performs various image processing on the images obtained from the X-ray imaging and generates output images from the images.

[0040] The control device 5 controls the robot arm 4 and makes it operate appropriately. Specifically, the control device 5 controls each motor (not shown) of joints 41 to 46.

[0041] The control device 5 performs processing related to X-ray imaging according to the imaging mode. For example, imaging modes include panoramic tomography mode and CT imaging mode.

[0042] In panoramic tomography mode, the control device 5 moves the swivel arm 3 so that the X-ray irradiation unit 1 and X-ray detection unit 2 trace a trajectory along the shape of the patient's dental arch, while performing X-ray imaging with the X-ray irradiation unit 1 and X-ray detection unit 2. In panoramic tomography mode, the swivel arm 3 rotates around a predetermined axis AX and moves in a direction perpendicular to the predetermined axis AX.

[0043] In CT scanning mode, the control device 5 moves the swivel arm 3 so that the X-ray irradiation unit 1 and X-ray detection unit 2 rotate around the imaging center of the patient (specifically, the center of the area to be scanned within the patient) as the pivot point, while performing X-ray imaging with the X-ray irradiation unit 1 and X-ray detection unit 2.

[0044] The X-ray imaging apparatus 100 also includes an operation unit 51 and a display unit 52. The operation unit 51 receives settings and instructions related to X-ray imaging from the operator. The display unit 52 displays output images based on the images obtained from X-ray imaging.

[0045] The control device 5 may be a personal computer (PC). In this case, the operation unit 51 is a hardware keyboard and pointing device, etc. The display unit 52 is a PC display.

[0046] However, it is not limited to this. The control device 5 may be a dedicated device for controlling the X-ray imaging apparatus 100. Alternatively, the control device 5 may be divided into a device for controlling X-ray imaging by the X-ray irradiation unit 1 and the X-ray detection unit 2 (including image processing of the image obtained by X-ray imaging) and a device for controlling the robot arm 4.

[0047] <Adjusting the position of the swivel arm> The condition of the subjects varies. For example, as shown in Figure 4, some subjects may only be able to undergo the examination in an unconventional posture. As an example, Figure 4 illustrates a subject in a semi-sitting posture, which is an unconventional posture. In Figure 4, the subject is denoted by the symbol S.

[0048] If the subject is in an abnormal posture, moving the pivot arm 3 vertically from a state where its predetermined axis AX is parallel to the vertical direction will not allow the position of the pivot arm 3 to be properly aligned with the position of the subject's maxillofacial region. Similarly, moving the pivot arm 3 horizontally from a state where its predetermined axis AX is parallel to the vertical direction will not allow the position of the pivot arm 3 to be properly aligned with the position of the subject's maxillofacial region.

[0049] Therefore, if the subject is in an abnormal posture, the control device 5 controls the robot arm 4 so that the predetermined axis AX of the swivel arm 3 is tilted with respect to the vertical direction. The robot arm 4 tilts the predetermined axis AX of the swivel arm 3 with respect to the vertical direction by driving (i.e., rotating) at least one of the joints 42 to 45. Note that the predetermined axis AX of the swivel arm 3 being tilted with respect to the vertical direction means that the predetermined axis AX is not parallel to the vertical direction. In other words, the predetermined axis AX of the swivel arm 3 being tilted with respect to the vertical direction includes the state in which the predetermined axis AX is parallel to the horizontal direction and the state in which it is tilted more than that.

[0050] When performing X-ray imaging on the subject shown in Figure 4, for example, the robot arm 4 operates to transition from the state shown in Figure 1 to the state shown in Figure 5. At this time, the robot arm 4 drives at least one (for example, all) of the joints 42-45, which serve as position adjustment joints. This causes the predetermined axis AX of the swivel arm 3 to tilt with respect to the vertical. In other words, the robot arm 4 tilts the predetermined axis AX of the swivel arm 3 with respect to the vertical by displacing the tip end of the robot arm 4 around the axis of the position adjustment joint.

[0051] In this embodiment, as described above, the swivel arm 3 is attached to the robot arm 4 having the position adjustment joints (joints 42 to 45). When the subject is in an abnormal posture, when adjusting the position of the swivel arm 3 with respect to the jaw and face of the subject (that is, the inspection target), the position adjustment joint is driven, so that the portion of the robot arm 4 on the tip side of the position adjustment joint is displaced around the axis of the position adjustment joint, and the predetermined axis AX, which is the rotation axis of the swivel arm 3, tilts with respect to the vertical direction.

[0052] Thereby, even when the subject is in an abnormal posture, the position of the swivel arm 3 can be appropriately adjusted to the position of the jaw and face of the subject. As a result, X-ray imaging of a subject in an abnormal posture can be easily performed. That is, X-ray imaging can be easily performed regardless of the posture of the subject. If X-ray imaging of a subject in an abnormal posture can be easily performed, there is no need to prepare a dedicated device for performing X-ray imaging of a subject in an abnormal posture.

[0053] From the perspective of the subject, since there is no need to move the body during X-ray imaging, the examination can be received comfortably. From the perspective of the operator of X-ray imaging, even when the subject is in an abnormal posture, the position of the swivel arm 3 with respect to the jaw and face of the subject can be quickly adjusted, so the convenience is good.

[0054] Also, in this embodiment, as described above, four of the joints 42 to 45 are installed on the robot arm 4 as position adjustment joints. That is, the robot arm 4 has a plurality of position adjustment joints. Thereby, the position of the swivel arm 3 with respect to the jaw and face of the subject can be finely adjusted.

[0055] <Operation in CT imaging mode> The operation of the robot arm 4 during X-ray imaging in CT mode will be described below with reference to Figures 6 and 7. Figure 6 corresponds to a conventional configuration, and Figure 7 corresponds to the configuration of this embodiment. Figures 6 and 7 are schematic diagrams showing the positional relationship between the swivel arm 3 (i.e., the X-ray irradiation unit 1 and the X-ray detection unit 2) and the patient's head H when viewed from the axial direction of a predetermined axis AX.

[0056] In Figures 6 and 7, the outline of the subject's head H is schematically shown with a dashed line. In Figures 6 and 7, the subject's maxillofacial region, which is the subject to be photographed, is located within the area enclosed by the dashed line. In other words, the subject's imaging center is located within the area enclosed by the dashed line. In Figures 6 and 7, the position of the black circle labeled Pc corresponds to the imaging center.

[0057] In CT scanning mode, the swivel arm 3 needs to be moved so that the X-ray irradiation unit 1 and the X-ray detection unit 2 rotate around the patient's imaging center as the pivot point, when viewed from the axial direction of a predetermined axis AX. In Figures 6 and 7, the respective rotation directions of the X-ray irradiation unit 1 and the X-ray detection unit 2 are indicated by arrows D.

[0058] In CT imaging mode, when viewed from the axial direction of a predetermined axis AX, the imaging center of the patient is located on the side of the X-ray detection unit 2 rather than the center of the predetermined direction PD between the X-ray irradiation unit 1 and the X-ray detection unit 2.

[0059] Conventionally, as shown in the configuration in Figure 6, the predetermined axis AX was positioned on the X-ray detection unit 2 side of the center between the X-ray irradiation unit 1 and the X-ray detection unit 2 in a predetermined direction PD, when viewed from the axial direction of the predetermined axis AX, thereby approximately aligning the subject's imaging center with the predetermined axis AX. In the configuration shown in Figure 6, by rotating the swivel arm 3 around the predetermined axis AX, the X-ray irradiation unit 1 and the X-ray detection unit 2 rotate with the subject's imaging center as the pivot point.

[0060] Here, the X-ray irradiation unit 1 is heavier than the X-ray detection unit 2. For example, the weight of the X-ray irradiation unit 1 is 8 kg to 10 kg, which is 3 to 4 times the weight of the X-ray detection unit 2.

[0061] In this case, with the configuration shown in Figure 6, the distance L between the predetermined axis AX and the center of gravity G of the swivel arm 3 in the predetermined direction PD is large, resulting in a larger moment of inertia than when the predetermined axis AX and the center of gravity G coincide. As a result, a greater rotational force is required to rotate the swivel arm 3. If the rotational force is insufficient, the swivel arm 3 cannot be rotated properly, and X-ray imaging cannot be performed properly.

[0062] Therefore, in the configuration shown in Figure 6, a reduction gear using gears or belts is used. This allows for the output of a large rotational force, enabling the swivel arm 3 to rotate properly.

[0063] On the other hand, in this embodiment, the swivel arm 3 is supported (transported) by the robot arm 4. The robot arm 4 has limitations on its payload capacity and moment of inertia. Therefore, it is necessary to reduce the weight of the swivel arm 3 and minimize its moment of inertia.

[0064] Therefore, in this embodiment, the configuration shown in Figure 7 is adopted. In the configuration shown in Figure 7, the predetermined axis AX of the swivel arm 3, which is the sixth axis A6 of the robot arm 4, and the imaging center of the subject are offset, and the predetermined axis AX approaches the center of gravity G of the swivel arm 3. This makes it possible to reduce the moment of inertia.

[0065] Specifically, in this embodiment, as shown in Figure 7, the predetermined axis AX of the swivel arm 3 is located on the X-ray irradiation unit 1 side (corresponding to "one side" as described in claim 3) of the X-ray detection unit 2 side, which is heavier than the X-ray irradiation unit 1 side, relative to the center of the predetermined direction PD of the swivel arm 3. The imaging center of the patient is located on the X-ray detection unit 2 side (corresponding to "the other side opposite to one side" as described in claim 3) of the X-ray detection unit 2 side, which is lighter than the X-ray irradiation unit 1 side, relative to the predetermined axis AX of the swivel arm 3. In other words, the predetermined axis AX of the swivel arm 3 is located on the X-ray irradiation unit 1 side relative to the imaging center of the patient. To put it another way, the position of the predetermined axis AX of the swivel arm 3 is shifted toward the X-ray irradiation unit 1 side relative to the imaging center of the patient. This makes it possible to reduce the distance between the position of the predetermined axis AX and the center of gravity position G in the predetermined direction PD. That is, the moment of inertia can be reduced.

[0066] Here, the smaller the distance between the predetermined axis AX and the center of gravity G in the predetermined direction PD, the smaller the moment of inertia. For this reason, to reduce the moment of inertia, it is most preferable that the position of the predetermined axis AX and the center of gravity G coincide. Therefore, for example, the configuration is such that the position of the predetermined axis AX and the center of gravity G coincide (including approximate coincidence) when viewed from the axial direction of the predetermined axis AX. In this configuration, the distance between the position of the predetermined axis AX and the center of gravity G in the predetermined direction PD is 0. As a result, the moment of inertia when the swivel arm 3 rotates around the predetermined axis AX can be reduced.

[0067] Note that the center of gravity position G of the swivel arm 3 is not the center of gravity position of the swivel arm 3 alone. The center of gravity position G of the swivel arm 3 is the center of gravity position of the swivel arm 3 when the X-ray irradiation unit 1 and the X-ray detection unit 2 are positioned on the swivel arm 3. In other words, the center of gravity position G of the swivel arm 3 is the center of gravity position of the X-ray imaging unit when viewed from the axial direction of a predetermined axis AX. The X-ray imaging unit is a unit obtained by positioning the X-ray irradiation unit 1 and the X-ray detection unit 2 on the swivel arm 3 (i.e., a unit including the X-ray irradiation unit 1, the X-ray detection unit 2, and the swivel arm 3).

[0068] However, if the predetermined axis AX of the swivel arm 3 is positioned on the side of the X-ray irradiation unit 1 that is closer to the patient's imaging center, simply rotating the swivel arm 3 around the predetermined axis AX will not cause the X-ray irradiation unit 1 and the X-ray detection unit 2 to rotate around the patient's imaging center as the rotation center.

[0069] Therefore, when the X-ray imaging mode is set to CT imaging mode, as shown in Figure 7, the robot arm 4 rotates the swivel arm 3 around a predetermined axis AX while rotating the tip-side joint 46 around the imaging center of the patient. In Figure 7, the state before rotation is shown in the upper figure, and the state after the start of rotation (i.e., during rotation) is shown in the lower figure. In the lower figure of Figure 7, the swivel arm 3 before rotation (i.e., the X-ray irradiation unit 1, the X-ray detection unit 2, and the joint 46) is shown by a dashed line. Also in the lower figure of Figure 7, the direction of rotation of the swivel arm 3 around the predetermined axis AX (i.e., the direction of rotation of the tip-side joint 46 around the sixth axis A6) is indicated by arrow D1, and the direction of rotation of the tip-side joint 46 that rotates around the imaging center of the patient is indicated by arrow D2.

[0070] In this embodiment, by having the robot arm 4 perform the operations described above, the X-ray irradiation unit 1 and the X-ray detection unit 2 can be appropriately rotated even in a configuration where the rotating arm 3 is supported (i.e., transported) by the robot arm 4. In other words, X-ray imaging in CT scanning mode can be performed appropriately.

[0071] <Improved rigidity and weight reduction of the swivel arm> The swivel arm 3 is attached to the robot arm 4 and moves relative to the subject as the robot arm 4 operates. However, the robot arm 4 has a payload limit. Therefore, if the swivel arm 3 is too heavy, the robot arm 4 cannot operate properly. For this reason, it is preferable to reduce the weight of the swivel arm 3. However, if the rigidity of the swivel arm 3 decreases as a result of reducing its weight, the swivel arm 3 becomes more susceptible to deformation.

[0072] In particular, in a configuration where the predetermined axis AX of the swivel arm 3 is tilted with respect to the vertical direction, deformation of the swivel arm 3 is likely to occur due to the low rigidity of the swivel arm 3. When the swivel arm 3 deforms, the positional relationship between the X-ray irradiation unit 1 and the X-ray detection unit 2 shifts. The following will be explained in detail with reference to Figures 8 to 10. In Figures 8 to 10, the direction of gravity is indicated by an open white arrow, and the direction of deformation of the swivel arm 3 is indicated by a dashed arrow.

[0073] As shown in Figure 8, when the predetermined axis AX of the swivel arm 3 is parallel to the vertical direction, even if gravity acts on the X-ray irradiation unit 1 side and the X-ray detection unit 2 side of the swivel arm 3, the positional relationship between the X-ray irradiation unit 1 and the X-ray detection unit 2 is unlikely to shift.

[0074] On the other hand, if the predetermined axis AX of the swivel arm 3 is tilted with respect to the vertical, the state shown in Figure 9 or the state shown in Figure 10 will occur. In the state shown in Figure 9, the X-ray irradiation unit 1 is below and the X-ray detection unit 2 is above, so the part of the swivel arm 3 on the X-ray irradiation unit 1 side deforms in a direction away from the part on the X-ray detection unit 2 side. In the state shown in Figure 10, the X-ray irradiation unit 1 is above and the X-ray detection unit 2 is below, so the part of the swivel arm 3 on the X-ray irradiation unit 1 side deforms in a direction closer to the part on the X-ray detection unit 2 side. In either case, tilting the predetermined axis AX of the swivel arm 3 with respect to the vertical makes the swivel arm 3 more susceptible to deformation.

[0075] Therefore, the rigidity and weight of the swivel arm 3 (specifically, the arm frame) are improved. To achieve both improved rigidity and weight reduction of the swivel arm 3, the arm frame may be constructed from aluminum castings that have been optimized for both rigidity and weight reduction using optimization techniques such as topology optimization. Alternatively, the arm frame may be constructed from an aluminum honeycomb structure.

[0076] This makes it possible to suppress deformation of the pivot arm 3 in a configuration where the predetermined axis AX of the pivot arm 3 is tilted with respect to the vertical direction. In other words, it is possible to suppress misalignment of the positional relationship between the X-ray irradiation unit 1 and the X-ray detection unit 2.

[0077] Here, we will explain the experimental results that confirmed the effect of suppressing the misalignment in the positional relationship between the X-ray irradiation unit 1 and the X-ray detection unit 2.

[0078] In Example 1, an aluminum casting was used as the swivel arm 3, with improved rigidity and reduced weight achieved through topology optimization. In Example 2, an aluminum honeycomb structure was used as the swivel arm 3. In the comparative example, a sheet metal frame without improved rigidity was used as the swivel arm 3.

[0079] Furthermore, in each of Example 1, Example 2, and Comparative Example, as shown in Figure 11, a rod-shaped member 30 extending parallel to a predetermined axis AX was attached to the swivel arm 3 and positioned between the X-ray irradiation unit 1 and the X-ray detection unit 2 in a predetermined direction PD.

[0080] Then, with the pivot arm 3 held so that its predetermined axis AX was parallel to the horizontal direction, the pivot arm 3 was rotated around the predetermined axis AX, and X-ray images were taken at the following rotation angles: when the pivot arm 3 was at the reference angle (0°), when the rotation angle from the reference angle was 90°, when the rotation angle from the reference angle was 180°, and when the rotation angle from the reference angle was 270°.

[0081] The rotation angle of the swivel arm 3 around a predetermined axis AX when the predetermined direction PD of the swivel arm 3 (i.e., the opposing direction between the X-ray irradiation unit 1 and the X-ray detection unit 2) is parallel to the vertical direction and the X-ray irradiation unit 1 is at the top is the reference angle. The rotation angle of the swivel arm 3 around the predetermined axis AX when the swivel arm 3 is rotated 90° in one direction from the reference angle is 90°. The rotation angle of the swivel arm 3 around the predetermined axis AX when the predetermined direction PD of the swivel arm 3 is parallel to the vertical direction and the X-ray irradiation unit 1 is at the bottom (i.e., when the swivel arm 3 is rotated 180° in one direction from the reference angle) is 180°. The rotation angle of the swivel arm 3 around the predetermined axis AX when the swivel arm 3 is rotated 270° in one direction from the reference angle is 270°.

[0082] In X-ray imaging, the rod-shaped member 30 is the object of inspection (i.e., the object of X-ray imaging). X-ray imaging yields an X-ray image XG as shown in Figure 12. In the X-ray image XG shown in Figure 12, the high-density portion corresponds to the image of the rod-shaped member 30. Here, in the X-ray image XG, the direction perpendicular to the extension direction of the rod-shaped member 30 is defined as the X-axis direction, and the extension direction of the rod-shaped member 30 is defined as the Y-axis direction.

[0083] After X-ray imaging, the position of image TP in the X-ray image XG corresponding to the tip 31 of the rod-shaped member 30 was confirmed. The results are shown in Figures 13 to 15. The results of Example 1 are shown in Figure 13, the results of Example 2 are shown in Figure 14, and the results of the comparative example are shown in Figure 15. In the following description, the image TP in the X-ray image XG corresponding to the tip 31 of the rod-shaped member 30 will be referred to as the tip image TP, and the position of the tip image TP within the X-ray image XG will be referred to as the tip position. In addition, the tip position when the rotation angle of the swivel arm 3 around a predetermined axis AX is the reference angle will be referred to as the reference position.

[0084] Note that the shape of the swivel arm 3 (specifically, the shape of the arm frame) differs from that of Example 1, Example 2, and the Comparative Example. Therefore, the installation position of the rod-shaped member 30 relative to the swivel arm 3 also differs from that of the Comparative Example. Consequently, the reference position differs from that of Example 1, Example 2, and the Comparative Example.

[0085] In the verification experiment, the amount of positional deviation between the X-ray irradiation unit 1 and the X-ray detection unit 2 was confirmed based on the tip position of the swivel arm 3 when the rotation angle around a predetermined axis AX was at the reference angle, when the rotation angle from the reference angle was 90°, when the rotation angle from the reference angle was 180°, and when the rotation angle from the reference angle was 270°. The smaller the difference between the reference position and the other positions, the smaller the positional deviation between the X-ray irradiation unit 1 and the X-ray detection unit 2 (i.e., the smaller the deformation of the swivel arm 3). The larger the difference between the reference position and the other positions, the larger the positional deviation between the X-ray irradiation unit 1 and the X-ray detection unit 2 (i.e., the larger the deformation of the swivel arm 3). In the verification experiment, the amount of deviation between the reference position and the other positions was detected in pixels.

[0086] In the comparative example (see Figure 15), when the rotation angle of the swivel arm 3 was 90°, the displacement in the X-axis direction from the reference position was 39 pixels, and the displacement in the Y-axis direction from the reference position was 10 pixels. When the rotation angle of the swivel arm 3 was 180°, the displacement in the X-axis direction from the reference position was 7 pixels, and the displacement in the Y-axis direction from the reference position was 15 pixels. When the rotation angle of the swivel arm 3 was 270°, the displacement in the X-axis direction from the reference position was 46 pixels, and the displacement in the Y-axis direction from the reference position was 7 pixels.

[0087] In Example 1 (see Figure 13), when the rotation angle of the swivel arm 3 was 90°, the displacement in the X-axis and Y-axis directions from the reference position was 1 pixel each. When the rotation angle of the swivel arm 3 was 180°, the displacement in the X-axis direction from the reference position was 1 pixel, and the displacement in the Y-axis direction from the reference position was 2 pixels. When the rotation angle of the swivel arm 3 was 270°, the displacement in the X-axis and Y-axis directions from the reference position was 1 pixel each.

[0088] In Example 2 (see Figure 14), when the rotation angle of the swivel arm 3 was 90°, the displacement in the X-axis direction from the reference position was 2 pixels, and the displacement in the Y-axis direction from the reference position was 1 pixel. When the rotation angle of the swivel arm 3 was 180°, there was no displacement in the X-axis direction from the reference position, and the displacement in the Y-axis direction from the reference position was 2 pixels. When the rotation angle of the swivel arm 3 was 270°, the displacement in the X-axis direction from the reference position was 2 pixels, and the displacement in the Y-axis direction from the reference position was 1 pixel.

[0089] From these results, it was confirmed that by constructing the swivel arm 3 from an aluminum casting with improved rigidity and reduced weight through optimization techniques such as topology optimization (Example 1), even when the predetermined axis AX is tilted with respect to the vertical and the swivel arm 3 is rotated around the predetermined axis AX, the positional relationship between the X-ray irradiation unit 1 and the X-ray detection unit 2 is suppressed (i.e., deformation of the swivel arm 3). Furthermore, it was confirmed that by constructing the swivel arm 3 from an aluminum honeycomb structure (Example 2), even when the predetermined axis AX is tilted with respect to the vertical and the swivel arm 3 is rotated around the predetermined axis AX, the positional relationship between the X-ray irradiation unit 1 and the X-ray detection unit 2 is suppressed (i.e., deformation of the swivel arm 3).

[0090] <Robot arm motion correction> In a configuration where the predetermined axis AX of the swivel arm 3 is tilted with respect to the vertical, the swivel arm 3 is prone to deformation. When the swivel arm 3 deforms, the positional relationship between the imaging position (hereinafter simply referred to as the X-ray imaging position) determined by the X-ray irradiation unit 1 and the X-ray detection unit 2 and the subject's head H shifts. As a result, the inconvenience of not being able to perform accurate X-ray imaging occurs.

[0091] To prevent such problems from occurring, if the positional relationship between the subject's head H and the X-ray imaging position shifts due to deformation of the rotating arm 3, the control device 5 causes the robot arm 4 to perform a corrective operation. As a corrective operation, the robot arm 4 performs an operation to cancel out the shift in the positional relationship between the subject's head H and the X-ray imaging position.

[0092] Here, the amount of deformation of the swivel arm 3 changes depending on the inclination angle of the predetermined axis AX of the swivel arm 3 with respect to the vertical, and also on the rotation angle of the swivel arm 3 around the predetermined axis AX. In other words, the amount of deformation of the swivel arm 3 changes depending on the posture of the swivel arm 3.

[0093] Therefore, the control device 5 controls the corrective operation of the robot arm 4 based on the posture of the swivel arm 3 (i.e., the inclination angle and rotation angle). To perform this control, the control device 5 stores correction information for the corrective operation. The correction information is defined for each posture of the swivel arm 3, specifying the amount of deviation in the positional relationship between the subject's head H and the X-ray imaging position. The amount of deformation for each posture of the swivel arm 3 can be determined experimentally (or through simulation).

[0094] The control device 5 then corrects the movement of the robot arm 4 based on the correction information. This prevents the positional relationship between the subject's head H and the X-ray imaging position from shifting even if the predetermined axis AX of the swivel arm 3 is tilted with respect to the vertical.

[0095] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the description of the embodiments above, and furthermore, all modifications within the meaning and scope equivalent to the claims are included.

[0096] For example, although the above embodiment described an example of applying the present invention to a dental X-ray imaging device, the present invention can also be applied to X-ray imaging devices for other uses. One example of an X-ray imaging device to which the present invention can be applied is a non-destructive testing device.

[0097] Furthermore, although the above embodiment describes an example where the X-ray irradiation unit is heavier than the X-ray detection unit, the X-ray detection unit may be heavier than the X-ray irradiation unit. Also, although the above embodiment describes an example where the predetermined axis is located on the X-ray irradiation unit side, the predetermined axis may be located on the X-ray detection unit side. Also, although the above embodiment describes an example where the imaging center is located on the X-ray detection unit side, the imaging center may be located on the X-ray irradiation unit side. [Explanation of Symbols]

[0098] 1 X-ray irradiation section 2 X-ray detection unit 3. Swivel Arm 3a One end 3b Other end 4. Robot Arm 5 Control device 40 base 41 Base-side joint (joint) 42, 43, 44, 45 Joints (position adjustment joints) 46. ​​End joint (joint) 100 X-ray imaging equipment AX Predetermined axis PC photography focused PD specified direction

Claims

1. An X-ray imaging device capable of X-ray imaging in at least one of the following modes: CT imaging mode and panoramic tomography mode, A pivot arm that is rotatable around a predetermined axis, and has the predetermined axis between one end in a predetermined direction perpendicular to the predetermined axis and the other end on the opposite side of the predetermined axis, An X-ray irradiation unit is positioned at one end of the aforementioned rotating arm and irradiates the object to be inspected with X-rays, An X-ray detection unit is positioned at the other end of the swivel arm, facing the X-ray irradiation unit in the predetermined direction with the object to be inspected in between, and detecting the X-rays that have passed through the object to be inspected, The robot arm is supported by a base, and the swivel arm is attached to the end opposite to the base, and by moving, it adjusts the position of the swivel arm relative to the object to be inspected. The robot arm has multiple joints, The aforementioned joint includes at least: The robot arm includes a tip-side joint positioned at the tip and rotatable around a predetermined axis, The robot arm includes a position adjustment joint positioned closer to the base than the position of the tip joint, and which is rotatable around an axis intersecting the vertical direction. The swivel arm is attached to the tip joint, and as the tip joint rotates around the predetermined axis, it rotates together with the tip joint around the predetermined axis. When the position of the swivel arm is adjusted relative to the object being inspected, the position adjustment joint is driven, causing the portion of the robot arm closer to the tip than the position adjustment joint to be displaced around the axis of the position adjustment joint, and the predetermined axis of the swivel arm to tilt with respect to the vertical direction. The predetermined axis of the swivel arm is located on the side with the greater weight between the X-ray irradiation unit side and the X-ray detection unit side, rather than the center of the swivel arm in the predetermined direction. The imaging center of the object to be inspected is located on the opposite side of the X-ray irradiation unit side and the X-ray detection unit side from the predetermined axis of the swivel arm, In a CT imaging mode in which the X-ray irradiation unit and the X-ray detection unit move the rotating arm so that they rotate around the imaging center as the pivot point, the robot arm rotates the rotating arm around a predetermined axis while rotating the tip joint around the imaging center, in an X-ray imaging apparatus.

2. The X-ray imaging apparatus according to claim 1, wherein the robot arm has a plurality of position adjustment joints.

3. The X-ray imaging apparatus according to claim 1, wherein, when viewed from the axial direction of the predetermined axis, the center of gravity of the rotating arm when the X-ray irradiation unit and the X-ray detection unit are arranged on the rotating arm coincides with the position of the predetermined axis.

4. An X-ray imaging apparatus capable of performing X-ray imaging in at least one of the CT imaging mode and panoramic tomography mode, A pivot arm that is rotatable around a predetermined axis, and has the predetermined axis between one end in a predetermined direction perpendicular to the predetermined axis and the other end on the opposite side of the predetermined axis, An X-ray irradiation unit is positioned at one end of the aforementioned rotating arm and irradiates the object to be inspected with X-rays, An X-ray detection unit is positioned at the other end of the swivel arm, facing the X-ray irradiation unit in the predetermined direction with the object to be inspected in between, and detecting the X-rays that have passed through the object to be inspected, The robot arm is supported by a base, and the swivel arm is attached to the end opposite to the base, and by moving, it adjusts the position of the swivel arm relative to the object to be inspected. The robot arm has multiple joints, The aforementioned joint includes at least: The robot arm includes a tip-side joint positioned at the tip and rotatable around a predetermined axis, The robot arm includes a position adjustment joint positioned closer to the base than the position of the tip joint, and which is rotatable around an axis intersecting the vertical direction. The swivel arm is attached to the tip joint, and as the tip joint rotates around the predetermined axis, it rotates together with the tip joint around the predetermined axis. When the position of the swivel arm is adjusted relative to the object being inspected, the position adjustment joint is driven, causing the portion of the robot arm closer to the tip than the position adjustment joint to be displaced around the axis of the position adjustment joint, and the predetermined axis of the swivel arm to tilt with respect to the vertical direction. The robot arm is equipped with a control device, If the deformation of the rotating arm causes a shift in the positional relationship between the X-ray irradiation unit and the X-ray detection unit and the object to be inspected, the control device causes the robot arm to perform a correction operation to compensate for the shift in positional relationship. The control device stores correction information defining the amount of deviation in the positional relationship for each posture of the swivel arm, and corrects the movement of the robot arm based on the correction information, in an X-ray imaging apparatus.

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