X-ray imaging apparatus

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]

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

[0002] Conventionally, dental X-ray imaging devices are capable of at least one of CT imaging and panoramic tomography. These conventional X-ray imaging devices include an X-ray irradiation unit that irradiates an object with X-rays and an X-ray detection unit that detects X-rays that have passed through the object. The X-ray irradiation unit and the X-ray detection unit are disposed on a swivel arm. The swivel arm is supported so that it can be raised and lowered. The dental X-ray imaging device also includes a subject support device that includes a chin rest. During X-ray imaging, the subject's chin is placed on the chin rest, and the subject's head is fixed by the subject support device. Such an X-ray imaging device is disclosed, for example, in Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-188610 Summary of the Invention [Problem to be solved by the invention]

[0004] Previously, when taking an X-ray, the subject had to move and place their chin on the chin rest of the X-ray machine. The subject's head was also adjusted to a suitable position for imaging using a head fixation device. However, if the subject is able to maintain a normal posture, such as sitting or standing, it is easy for them to move and place their chin on the chin rest, and assume a suitable position for imaging.

[0005] However, some patients are unable to assume a normal posture. In such cases, it is difficult for the patient to move and place their chin on the chin rest, making it difficult to take an X-ray or obtain images suitable for diagnosis.

[0006] The present invention has been made to solve the above-mentioned problems, and aims to provide an X-ray imaging device that can easily perform X-ray imaging regardless of the posture of the subject, including a corpse. [Means for solving the problem]

[0007] To achieve the above object, one aspect of the present invention provides an X-ray imaging apparatus capable of performing X-ray imaging in at least one of a CT imaging mode and a panoramic tomography imaging mode, the X-ray imaging apparatus comprising: a rotating arm rotatable about a predetermined axis and having the predetermined axis between one end in a predetermined direction perpendicular to the predetermined axis and another end opposite the one end; an X-ray irradiation unit disposed at one end of the rotating arm and irradiating X-rays onto an object to be examined; an X-ray detection unit disposed at the other end of the rotating arm, facing the X-ray irradiation unit in the predetermined direction across the object to be examined, and detecting X-rays transmitted through the object to be examined; and a robot arm supported by a base, the rotating arm attached to a tip end opposite the base side, and operable to adjust the position of the rotating arm relative to the object to be examined. The robot arm has multiple joints. The joints include at least a tip joint disposed at the tip of the robot arm and rotatable about the predetermined axis; and a position adjustment joint disposed on the robot arm closer to the base than the tip joint and rotatable about an axis intersecting the vertical direction. The swivel arm is attached to the tip-side joint, and when the tip-side joint rotates about a predetermined axis, the swivel arm rotates together with the tip-side joint about the predetermined axis. When the position adjustment joint is driven to adjust the position of the swivel arm relative to the inspection object, the part of the robot arm that is closer to the tip than the position adjustment joint is displaced about the axis of the position adjustment joint, and the predetermined axis of the swivel arm is tilted with respect to the vertical direction. [Effects of the Invention]

[0008] According to the present invention, X-ray imaging can be easily performed regardless of the posture of the subject being examined. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram of an X-ray imaging apparatus according to an embodiment. [Figure 2] 1 is a diagram showing the positional relationship between a rotary arm of an X-ray imaging apparatus according to an embodiment and an object to be examined (specifically, the head of a subject). [Figure 3] 1 is a block diagram of an X-ray imaging apparatus according to an embodiment. [Figure 4] 1 is a diagram showing the positional relationship between a rotating arm of an X-ray imaging apparatus according to an embodiment and a subject in an unusual posture. [Figure 5] 1 is a diagram showing a state in which a predetermined axis of a rotation arm of an X-ray imaging apparatus according to an embodiment is tilted relative to the vertical direction. [Figure 6] FIG. 10 is a diagram showing the movement trajectory of a rotating arm when X-ray imaging is performed in CT imaging mode in a configuration that does not use a robot arm. [Figure 7] 10A and 10B are diagrams showing the movement locus of a rotary arm when X-ray imaging is performed in a CT imaging mode by the X-ray imaging apparatus according to the embodiment. [Figure 8] 10A and 10B are diagrams for explaining deformation of a swivel arm when a predetermined axis of the swivel arm of the X-ray imaging apparatus according to the embodiment is parallel to the vertical direction. [Figure 9] 10A and 10B are diagrams for explaining deformation of the rotating arm when a predetermined axis of the rotating arm of the X-ray imaging apparatus according to the embodiment is tilted with respect to the vertical direction. [Figure 10] 10A and 10B are diagrams for explaining deformation of the rotating arm when a predetermined axis of the rotating arm of the X-ray imaging apparatus according to the embodiment is tilted with respect to the vertical direction. [Figure 11] FIG. 10 is a diagram for explaining experimental conditions for confirming the effects obtained by the configuration of the embodiment. [Figure 12] 10A and 10B are diagrams showing X-ray images taken in an experiment to confirm the effects obtained by the configuration of the embodiment. [Figure 13] FIG. 1 is a diagram showing the results of an experiment conducted to confirm the effects obtained by 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 a 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 device 100 includes an X-ray irradiator 1 and an X-ray detector 2. The X-ray irradiator 1 and the X-ray detector 2 are arranged to face each other across the maxillofacial region of a subject as an examination target. In FIG. 2, the portion of the subject above the neck (including the head, maxillofacial region, etc.) is schematically shown by a dashed line and is designated by the symbol H. In the following description, the portion H above the neck of the subject will be simply referred to as the head H.

[0014] The X-ray irradiator 1 irradiates the subject with X-rays. In other words, the X-ray irradiator 1 emits X-rays toward the X-ray detector 2. The X-ray irradiator 1 is composed of an X-ray tube, a collimator, etc. The collimator restricts the spread of the 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 have passed through the subject. The X-ray detection unit 2 is composed of a flat panel detector and the like. The flat panel detector is irradiated with the X-rays that have passed through the subject.

[0016] The X-ray imaging device 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. FIG. 1 illustrates the swivel arm 3 attached to a robot arm 4, which will be described later, and FIG. 2 illustrates the swivel arm 3 alone. Note that the external shape of the swivel arm 3 (i.e., the exterior cover of the swivel arm 3) shown in FIGS. 1 and 2 is an example, and the external shape of the swivel arm 3 is not particularly limited.

[0017] The swivel arm 3 is made of a metal frame such as aluminum. At least a portion of the frame that constitutes the swivel arm 3 is covered with an exterior cover. In the following description, the frame that constitutes the swivel arm 3 will be referred to as an arm frame.

[0018] The swivel arm 3 is rotatable about a predetermined axis AX. The swivel arm 3 is supported by a robot arm 4 (described later) so as to be rotatable about the predetermined axis AX.

[0019] When viewed from the axial direction of the predetermined axis AX, the longitudinal direction of the rotating arm 3 is a predetermined direction PD (see FIG. 2) perpendicular to the predetermined axis AX. One end 3a of the rotating 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. In other words, the predetermined axis AX is located between the one end 3a and the other end 3b of the rotating arm 3 in the predetermined direction PD. The X-ray irradiation unit 1 is disposed at the one end 3a of the rotating arm 3. The X-ray detection unit 2 is disposed at the other end 3b of the rotating arm 3.

[0020] During X-ray imaging, it is necessary to hold the portion of the rotating arm 3 between one end 3a and the other end 3b in the predetermined direction PD with a gap in the axial direction of the predetermined axis AX relative to the subject's head H (specifically, the parietal region). At this time, the rotating arm 3 is held so as to straddle the subject's head H (specifically, the parietal region). 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 device 100 includes a robot arm 4. The swivel arm 3 is attached to the robot arm 4. The robot arm 4 adjusts the position of the swivel arm 3 to match the position of the maxillofacial region of the subject. By adjusting the position using the robot arm 4, the X-ray irradiation unit 1 and the X-ray detection unit 2 are held so as to face each other in a predetermined direction PD with the maxillofacial region of the subject in between.

[0022] If the subject is a healthy person, during X-ray imaging, the subject can move to match the position of the rotating arm 3. In this case, for example, simply by moving the rotating arm 3 in the vertical direction to match the subject's body shape (height, sitting height, etc.), it is possible to align the rotating arm 3 with the subject's maxillofacial region.

[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 abnormal postures such as a semi-sitting posture, a recumbent posture, or a bent-over standing posture. In such cases, simply moving the swivel arm 3 in the vertical direction cannot 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, relative to the vertical direction.

[0024] Therefore, in this embodiment, a multi-joint robot arm having a plurality of 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 six-axis robot arm can be used as the robot arm 4. In the following description, it is assumed that the robot arm 4 is a six-axis robot arm. However, the number of axes of the robot arm 4 may be seven or more, or five or less.

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

[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 rotates when driven by the corresponding motor. This allows the robot arm 4 to perform movements such as turning, rotating, bending, and twisting.

[0027] The robot arm 4 is a six-axis robot arm. Therefore, the joints of the robot arm 4 include 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 of the robot arm 4 toward the tip end side. The joints 41, 42, 43, 44, 45, and 46 correspond to the first axis A1, the second axis A2, the third axis A3, the fourth axis A4, the fifth axis A5, and the sixth axis A6, respectively. The joints 41, 42, 43, 44, 45, and 46 are rotatable around the corresponding axes.

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

[0029] The first axis A1 corresponding to the base-side joint 41 is parallel to the vertical direction. The base-side joint 41 rotates around the first axis A1, thereby causing the robot arm 4 to pivot as a whole around the first axis A1.

[0030] The joint 46 is disposed at the tip of the robot arm 4. That is, the robot arm 4 has the joint 46 as its tip. The swivel arm 3 is attached to the joint 46. The joint 46 corresponds to the "tip side joint." In the following description, the 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 corresponding to the tip side joint 46 coincides with the 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] The joints 42 to 45 are each disposed closer to the base 40 than the tip-side joint 46 of the robot arm 4. Specifically, the joints 42 to 45 are each disposed between the base-side joint 41 and the tip-side joint 46 of the robot arm 4.

[0033] Here, each of the joints 42 to 45 is rotatable around an axis that intersects with the vertical direction. In this configuration, each of the joints 42 to 45 corresponds to a "position adjustment joint."

[0034] The second axis A2 corresponding to the 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 FIG. 1). By displacing the joint 42 about the second axis A2, the portion of the robot arm 4 that is closer to the tip end than the joint 42 is displaced about the second axis A2. For example, by displacing the joint 42 about the second axis A2 from a state in which the predetermined axis AX of the swivel arm 3 is parallel to the vertical direction, the predetermined axis AX can be tilted with respect to the vertical direction.

[0035] The third axis A3 corresponding to the joint 43 is parallel to one horizontal direction, similar to the second axis A2. By displacing the joint 43 about the third axis A3, the portion of the robot arm 4 that is closer to the tip end than the joint 43 is displaced about the third axis A3. By displacing the joint 43 about the third axis A3 from a state in which the predetermined axis AX of the swivel arm 3 is parallel to the vertical direction, the predetermined axis AX can be tilted with respect to the vertical direction.

[0036] The fourth axis A4 corresponding to the 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 corresponding to the joint 44 changes depending on the rotation angles of the joints 42 and 43. By displacing the joint 44 about the fourth axis A4, the portion of the robot arm 4 that is closer to the tip than the joint 44 is displaced about the fourth axis A4. From a state in which the predetermined axis AX of the swivel arm 3 is parallel to the vertical direction and the fourth axis A4 is tilted with respect to the vertical direction, by displacing the joint 44 about the fourth axis A4, the predetermined axis AX can be tilted with respect to the vertical direction.

[0037] The fifth axis A5 corresponding to the joint 45 is parallel to one horizontal direction, similar to the second axis A2 and the third axis A3. By displacing the joint 45 about the fifth axis A5, the portion of the robot arm 4 that is closer to the tip end than the joint 45 is displaced about the fifth axis A5. By displacing the joint 45 about the fifth axis A5 from a state in which the predetermined axis AX of the swivel arm 3 is parallel to the vertical direction, the predetermined axis AX can be tilted with respect to the vertical direction.

[0038] 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, and storage devices such as a RAM, a ROM, an SSD, and an HDD.

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

[0040] The control device 5 controls the robot arm 4 to appropriately operate the robot arm 4. That is, the control device 5 controls the motors (not shown) of the joints 41 to 46.

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

[0042] In the panoramic tomography mode, the control device 5 performs X-ray photography using the X-ray irradiation unit 1 and the X-ray detection unit 2 while moving the rotating arm 3 so that the X-ray irradiation unit 1 and the X-ray detection unit 2 trace trajectories that follow the shape of the subject's dental arch. In the panoramic tomography mode, the rotating arm 3 rotates around a predetermined axis AX while moving in a direction perpendicular to the predetermined axis AX.

[0043] In the CT imaging mode, the control device 5 performs X-ray imaging using the X-ray irradiation unit 1 and the X-ray detection unit 2 while moving the rotating arm 3 so that the X-ray irradiation unit 1 and the X-ray detection unit 2 rotate around the imaging center of the subject (specifically, the center of the area of ​​the subject to be imaged).

[0044] The X-ray imaging apparatus 100 also includes an operation unit 51 and a display unit 52. The operation unit 51 accepts settings and instructions related to X-ray imaging from an operator. The display unit 52 displays an output image based on an image obtained by 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, a pointing device, etc. The display unit 52 is a PC display.

[0046] However, the present invention is not limited to this. The control device 5 may be a dedicated device for controlling the X-ray imaging device 100. The control device 5 may also be separated 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 images obtained by X-ray imaging), and a device for controlling the robot arm 4.

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

[0048] When the subject is in an abnormal posture, even if the swivel arm 3 is moved vertically from a state in which the predetermined axis AX of the swivel arm 3 is parallel to the vertical direction, the position of the swivel arm 3 and the position of the subject's maxillofacial region cannot be properly aligned. Also, even if the swivel arm 3 is moved horizontally from a state in which the predetermined axis AX of the swivel arm 3 is parallel to the vertical direction, the position of the swivel arm 3 and the position of the subject's maxillofacial region cannot be properly aligned.

[0049] Therefore, when 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 a state in which the predetermined axis AX is parallel to the horizontal direction and a state in which it is tilted further than that.

[0050] When performing X-ray imaging on the subject shown in Fig. 4, for example, the robot arm 4 operates to transition from the state shown in Fig. 1 to the state shown in Fig. 5. At this time, the robot arm 4 drives at least one (for example, all) of the joints 42 to 45 serving as position adjustment joints. This causes the predetermined axis AX of the swivel arm 3 to tilt with respect to the vertical direction. That is, the robot arm 4 tilts the predetermined axis AX of the swivel arm 3 with respect to the vertical direction by displacing the tip side of the robot arm 4 beyond the position adjustment joint 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] As a result, 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 adjustment of the swivel arm 3 with respect to the jaw and face of the subject can be performed finely.

[0055] <Operation in CT imaging mode> The operation of the robot arm 4 during X-ray imaging in CT imaging 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. Also, Figures 6 and 7 are each diagrams that schematically show the positional relationship between the rotating arm 3 (i.e., the X-ray irradiation unit 1 and the X-ray detection unit 2) and the subject's head H when viewed from the axial direction of a predetermined axis AX.

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

[0057] In the CT imaging mode, it is necessary to move the rotary arm 3 so that the X-ray irradiation unit 1 and the X-ray detection unit 2 rotate around the center of the subject's imaging as the rotation center when viewed from the axial direction of the predetermined axis AX. In Figures 6 and 7, the rotation directions of the X-ray irradiation unit 1 and the X-ray detection unit 2 are indicated by arrows D.

[0058] In the CT imaging mode, X-ray imaging is performed in a state where the center of the subject's imaging is located closer to the X-ray detection unit 2 than the center between the X-ray irradiation unit 1 and the X-ray detection unit 2 in the specified direction PD, as viewed from the axial direction of the specified axis AX.

[0059] Therefore, conventionally, as seen from the axial direction of the predetermined axis AX, the predetermined axis AX is positioned closer to the X-ray detection unit 2 than the center between the X-ray irradiator 1 and the X-ray detection unit 2 in the predetermined direction PD, so that the imaging center of the subject and the predetermined axis AX are approximately aligned, as in the configuration shown in Fig. 6. In the configuration shown in Fig. 6, by rotating the swivel arm 3 around the predetermined axis AX, the X-ray irradiator 1 and the X-ray detection unit 2 rotate around the imaging center of the subject.

[0060] Here, the X-ray irradiator 1 is heavier than the X-ray detector 2. For example, the weight of the X-ray irradiator 1 is 8 kg to 10 kg, which is three to four times the weight of the X-ray detector 2.

[0061] In this case, in the configuration shown in Figure 6, the distance L between the position of the predetermined axis AX and the position of the center of gravity G of the swivel arm 3 in the predetermined direction PD is large, so the moment of inertia is larger than when the predetermined axis AX and the position of the center of gravity G are aligned. As a result, a larger 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] For this reason, a reducer using gears, belts, etc. is used in the configuration shown in Fig. 6. This makes it possible to output a large rotational force, allowing the swivel arm 3 to rotate appropriately.

[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 the weight it can carry and the moment of inertia. Therefore, it is necessary to reduce the weight and moment of inertia of the swivel arm 3.

[0064] Therefore, this embodiment employs the configuration shown in Fig. 7. In the configuration shown in Fig. 7, the predetermined axis AX of the rotating arm 3, which is the sixth axis A6 of the robot arm 4, is shifted from the center of imaging of the subject, and the predetermined axis AX approaches the center of gravity G of the rotating arm 3. This reduces the moment of inertia.

[0065] Specifically, in this embodiment, as shown in FIG. 7 , the predetermined axis AX of the swivel arm 3 is located closer to the X-ray irradiator 1 side (corresponding to "one side" in claim 3) than the center of the swivel arm 3 in the predetermined direction PD, which is the heavier side of the X-ray irradiator 1 or the X-ray detection unit 2. The imaging center of the subject is located closer to the X-ray detection unit 2 side (corresponding to "the other side opposite to the one side" in claim 3) than the predetermined axis AX of the swivel arm 3. In other words, the predetermined axis AX of the swivel arm 3 is located closer to the X-ray irradiator 1 than the imaging center of the subject. In other words, the position of the predetermined axis AX of the swivel arm 3 is shifted toward the X-ray irradiator 1 with respect to the imaging center of the subject. This reduces the distance between the position of the predetermined axis AX and the center of gravity G in the predetermined direction PD. In other words, the moment of inertia can be reduced.

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

[0067] It should be noted that the position of the center of gravity G of the swivel arm 3 is not the position of the center of gravity of the swivel arm 3 alone. The position of the center of gravity G of the swivel arm 3 is the position of the center of gravity of the swivel arm 3 when the X-ray irradiation unit 1 and the X-ray detection unit 2 are arranged on the swivel arm 3. In other words, the position of the center of gravity G of the swivel arm 3 is the position of the center of gravity of the X-ray imaging unit when viewed from the axial direction of the predetermined axis AX. The X-ray imaging unit is a unit obtained by arranging 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, when the predetermined axis AX of the swivel arm 3 is positioned closer to the X-ray irradiation unit 1 than the center of the subject's imaging, 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 center of the subject's imaging.

[0069] Therefore, when the X-ray imaging mode is the CT imaging mode, as shown in FIG. 7, the robot arm 4 rotates the swivel arm 3 about the predetermined axis AX while rotating the distal joint 46 about the imaging center of the subject. In FIG. 7, the upper diagram shows the state before the rotation, and the lower diagram shows the state after the rotation starts (i.e., during the rotation). In the lower diagram of FIG. 7, the swivel arm 3 before the rotation (i.e., the X-ray irradiation unit 1, the X-ray detection unit 2, and the joint 46) is shown by a dashed dotted line. In the lower diagram of FIG. 7, the rotation direction of the swivel arm 3 about the predetermined axis AX (i.e., the rotation direction of the distal joint 46 about the sixth axis A6) is indicated by arrow D1, and the rotation direction of the distal joint 46 rotating about the imaging center of the subject is indicated by arrow D2.

[0070] In this embodiment, by making the robot arm 4 perform the above-described operations, it is possible to properly rotate the X-ray irradiation unit 1 and the X-ray detection unit 2 even in a configuration in which the rotary arm 3 is supported (i.e., transported) by the robot arm 4. In other words, it is possible to properly perform X-ray imaging in the CT imaging mode.

[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. Here, the robot arm 4 has a limit on the weight it can carry. Therefore, if the swivel arm 3 is too heavy, the robot arm 4 cannot operate appropriately. Therefore, it is preferable to reduce the weight of the swivel arm 3. However, if the rigidity of the swivel arm 3 is reduced as a result of reducing the weight of the swivel arm 3, the swivel arm 3 becomes more susceptible to deformation.

[0072] In particular, in a configuration in which the predetermined axis AX of the swivel arm 3 is tilted relative to the vertical direction, the swivel arm 3 is prone to deformation due to 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. This will be explained in detail below with reference to Figs. 8 to 10. In Figs. 8 to 10, the direction of gravity is indicated by a hollow arrow, and the direction of deformation of the swivel arm 3 is indicated by a dashed arrow.

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

[0074] On the other hand, when the predetermined axis AX of the swivel arm 3 is tilted with respect to the vertical direction, the state shown in Fig. 9 or the state shown in Fig. 10 occurs. In the state shown in Fig. 9, the X-ray irradiation unit 1 is positioned below and the X-ray detection unit 2 is positioned above, so the portion of the swivel arm 3 on the X-ray irradiation unit 1 side deforms in a direction away from the portion on the X-ray detection unit 2 side. In the state shown in Fig. 10, the X-ray irradiation unit 1 is positioned above and the X-ray detection unit 2 is positioned below, so the portion of the swivel arm 3 on the X-ray irradiation unit 1 side deforms in a direction approaching the portion 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 direction makes the swivel arm 3 more susceptible to deformation.

[0075] This improves the rigidity and reduces the weight of the swivel arm 3 (specifically, the arm frame). To achieve both improved rigidity and reduced weight for the swivel arm 3, the arm frame may be made of aluminum casting that has been improved in rigidity and reduced in weight through optimization techniques such as topology optimization. Alternatively, the arm frame may be made of an aluminum honeycomb structure.

[0076] This makes it possible to suppress deformation of the swivel arm 3 in a configuration in which the predetermined axis AX of the swivel arm 3 is inclined relative to the vertical direction. That is, it is possible to suppress deviation of the positional relationship between the X-ray irradiation unit 1 and the X-ray detection unit 2.

[0077] Here, the results of an experiment that confirmed the effect of suppressing deviation in the positional relationship between the X-ray irradiation unit 1 and the X-ray detection unit 2 will be described.

[0078] In Example 1, an aluminum casting with improved rigidity and reduced weight achieved through topology optimization was used as the swivel arm 3. In Example 2, an aluminum honeycomb structure was used as the swivel arm 3. In the comparative example, a sheet metal frame with no improved rigidity was used as the swivel arm 3.

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

[0080] Then, while holding the swivel arm 3 so that its predetermined axis AX was parallel to the horizontal direction, the swivel arm 3 was rotated around the predetermined axis AX, and X-ray images were taken when the rotation angle of the swivel arm 3 around the predetermined axis AX was 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 reference angle is the rotation angle of the swivel arm 3 about the 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. The rotation angle of the swivel arm 3 about 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 about 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 about 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 photography, the rod-shaped member 30 is the object of inspection (i.e., the object of X-ray photography). X-ray photography produces an X-ray image XG as shown in FIG. 12. In the X-ray image XG shown in FIG. 12, the portion indicated by high density 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 the 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 is referred to as the tip image TP, and the position of the tip image TP in the X-ray image XG is referred to as the tip position. In addition, the tip position when the rotation angle of the swivel arm 3 around the specified axis AX is the reference angle is referred to as the reference position.

[0084] Note that the shapes of the swivel arm 3 (specifically, the shapes of the arm frames) are different between Example 1, Example 2, and the comparative example. Therefore, the installation positions of the rod-shaped members 30 relative to the swivel arm 3 are also different. Therefore, the reference positions are different between Example 1, Example 2, and the comparative example.

[0085] In the confirmation experiment, the amount of deviation in the positional relationship between the X-ray irradiation unit 1 and the X-ray detection unit 2 was confirmed based on the tip positions when the rotation angle of the swivel arm 3 around the predetermined axis AX was a 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°. It can be said that the smaller the difference between the reference position and other positions, the smaller the deviation in the positional relationship 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). It can be said that the larger the difference between the reference position and other positions, the larger the deviation in the positional relationship 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 confirmation experiment, the amount of deviation between the reference position and other positions was detected in terms of the number of pixels.

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

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

[0088] In Example 2 (see FIG. 14), when the rotation angle of the swivel arm 3 was 90°, the deviation in the X-axis direction from the reference position was 2 pixels, and the deviation 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 deviation in the X-axis direction from the reference position, and the deviation in the Y-axis direction from the reference position was 2 pixels. When the rotation angle of the swivel arm 3 was 270°, the deviation in the X-axis direction from the reference position was 2 pixels, and the deviation 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 aluminum castings that have been made more rigid and lighter through optimization techniques such as topology optimization (Example 1), it is possible to suppress deviations in the positional relationship between the X-ray irradiation unit 1 and the X-ray detection unit 2 (i.e., deformation of the swivel arm 3) even when the predetermined axis AX is tilted with respect to the vertical direction and the swivel arm 3 is rotated around the predetermined axis AX. Furthermore, it was confirmed that by constructing the swivel arm 3 from an aluminum honeycomb structure (Example 2), it is possible to suppress deviations in the positional relationship between the X-ray irradiation unit 1 and the X-ray detection unit 2 (i.e., deformation of the swivel arm 3) even when the predetermined axis AX is tilted with respect to the vertical direction and the swivel arm 3 is rotated around the predetermined axis AX.

[0090] <Robot arm motion correction> In a configuration in which the predetermined axis AX of the swivel arm 3 is tilted relative to the vertical direction, the swivel arm 3 is prone to deformation. When the swivel arm 3 is deformed, the positional relationship between the imaging position (hereinafter simply referred to as the X-ray imaging position) of the X-ray irradiation unit 1 and the X-ray detection unit 2 and the subject's head H is shifted. As a result, the X-ray imaging cannot be performed accurately.

[0091] To prevent such inconveniences from occurring, when the positional relationship between the subject's head H and the X-ray imaging position is displaced due to deformation of the swivel arm 3, the control device 5 causes the robot arm 4 to perform a corrective operation. As the corrective operation, the robot arm 4 performs an operation to offset the displacement of 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 varies depending on the inclination angle of the predetermined axis AX of the swivel arm 3 relative to the vertical direction, and also on the rotation angle around the predetermined axis AX of the swivel arm 3. In other words, the amount of deformation of the swivel arm 3 varies 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 tilt angle and the rotation angle). To perform such control, the control device 5 stores correction information for the corrective operation. The correction information is information that defines the amount of deviation in the positional relationship between the subject's head H and the X-ray imaging position for each posture of the swivel arm 3. The amount of deformation for each posture of the swivel arm 3 can be obtained experimentally (or by simulation).

[0094] Then, the control device 5 corrects the operation of the robot arm 4 based on the correction information. This makes it possible to prevent deviation of the positional relationship between the subject's head H and the X-ray imaging position even if the predetermined axis AX of the swivel arm 3 is tilted with respect to the vertical direction.

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

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

[0097] Furthermore, in the above embodiment, an example was described in which the X-ray irradiator was heavier than the X-ray detector, but the X-ray detector may be heavier than the X-ray irradiator. Furthermore, in the above embodiment, an example was described in which the predetermined axis was located on the X-ray irradiator side, but the predetermined axis may be located on the X-ray detector side. Furthermore, in the above embodiment, an example was described in which the imaging center was located on the X-ray detector side, but the imaging center may be located on the X-ray irradiator 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. Robotic Arm 5. Control device 40 base 41 Base side joint (joint) 42, 43, 44, 45 Joints (position adjustment joints) 46 Tip joint (joint) 100 X-ray equipment AX Predetermined axis PC photography PD specified direction

Claims

1. An X-ray imaging device capable of performing X-ray imaging in at least one of a CT imaging mode and a panoramic tomography imaging mode, a swivel 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 another end opposite to the one end; an X-ray irradiation unit disposed at the one end of the rotary arm and configured to irradiate an object to be inspected with X-rays; an X-ray detection unit that is disposed at the other end of the rotating arm, faces the X-ray irradiation unit in the predetermined direction across the inspection object, and detects the X-rays that have passed through the inspection object; a robot arm that is supported by a base, has the swivel arm attached to a tip end portion on the opposite side to the base side, and operates to adjust the position of the swivel arm relative to the inspection object; the robot arm has a plurality of joints; The joint has at least a tip-side joint disposed at the tip of the robot arm and rotatable around the predetermined axis; a position adjustment joint that is arranged on the robot arm closer to the base than the tip-end joint and is rotatable around an axis that intersects with the vertical direction, the pivot arm is attached to the tip-side joint, and when the tip-side joint rotates around the predetermined axis, the pivot arm rotates together with the tip-side joint around the predetermined axis; an X-ray imaging device in which, when adjusting the position of the swivel arm relative to the object of examination, the position adjustment joint is driven, causing a portion of the robot arm closer to the tip end than the position adjustment joint to be displaced around the axis of the position adjustment joint, and causing the predetermined axis of the swivel arm to tilt with respect to the vertical direction.

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

3. the predetermined axis of the rotating arm is located on one side of the X-ray irradiation unit side or the X-ray detection unit side, which has a greater weight, with respect to the center of the rotating arm in the predetermined direction, an imaging center of the object to be examined is located on the other side of the X-ray irradiation unit side or the X-ray detection unit side, opposite to the one side, of the predetermined axis of the rotary arm; 2. The X-ray imaging device according to claim 1, wherein, in a CT imaging mode in which X-ray imaging is performed by moving the rotary arm so that the X-ray irradiation unit and the X-ray detection unit rotate around the imaging center as a rotation center, the robot arm rotates the rotary arm around the predetermined axis while rotating the tip-end joint around the imaging center.

4. 2. The X-ray imaging device according to claim 1, wherein when viewed in the axial direction of the predetermined axis, the position of the center of gravity of the rotating arm in a state in which 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.

5. a control device for controlling the robot arm, when a positional relationship between an imaging position by the X-ray irradiation unit and the X-ray detection unit and the object of inspection is displaced due to deformation of the rotary arm, the control device causes the robot arm to perform a corrective operation to offset the displacement of the positional relationship; 2. The X-ray imaging apparatus according to claim 1, wherein the control device stores correction information that defines the amount of deviation of the positional relationship for each posture of the rotary arm, and corrects the operation of the robot arm based on the correction information.

Images