CT device

Abstract

To provide a CT device with which it is possible to acquire the three-dimensional data of a test object without having to move or rotate an inspection table and set a soft limit on the basis of this three-dimensional data.SOLUTION: The CT device comprises: an inspection table 1 provided so as to be movably and rotatably in the horizontal direction, on which a test object W is placed; a radiation source 2 for irradiating the test object W with a radiation beam; a detector 3 for outputting a transparent image of the test object W and provided facing the radiation source 2 across the test object W; a three-dimensional information acquisition unit 4 provided upward of the inspection table 1, for acquiring the three-dimensional information of the test object W while the inspection table 1 remains halted; and a soft limit setting unit 94 for setting, on the basis of the three-dimensional information, a region which the test object W is approachable to the radiation source 2 or the detector 3.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Embodiments of the present invention relate to a CT apparatus.

Background Art

[0002] A CT apparatus includes a radiation source that irradiates, for example, an X-ray beam as radiation, and a detector that is provided opposite to the radiation source and detects the X-ray beam. Between the radiation source and the detector, an examination table on which an object to be examined is placed is provided. While the object to be examined is irradiated with the X-ray beam, the examination table rotates once, and a fluoroscopic image from all directions can be obtained. By reconstructing this fluoroscopic image, a CT image (cross-sectional image) of the object to be examined can be obtained.

[0003] When imaging an object to be examined, the imaging position of the object to be examined is adjusted by horizontally moving the examination table on which the object to be examined is placed between the radiation source and the detector. Also, when acquiring a CT image, the examination table is rotated. At this time, there is a risk that the object to be examined may collide with the radiation source or the detector due to the movement or rotation of the examination table.

[0004] In order to avoid such collisions, it is known to set an approachable area called a soft limit. By setting such a soft limit, it is possible to avoid in advance the object to be examined from colliding with the radiation source or the detector. The soft limit can be set manually, but there is a risk of misinputting the setting data. Therefore, it is often automatically set based on three-dimensional data acquired from the object to be examined, as in Patent Document 1 or 2, for example.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

[0006] However, even with these conventional technologies, it was necessary to move or rotate the inspection table horizontally with the object under inspection on it in order to acquire three-dimensional data of the object under inspection. Such movement or rotation of the inspection table is time-consuming, and there was a risk that the object under inspection might collide with the radiation source or detector before the soft limit could be set. As a method for setting the soft limit without moving or rotating the inspection table, it is conceivable to acquire data of the object under inspection from an optical camera image mounted above the inspection table, but in this case, it is not possible to obtain height information of the object under inspection, and therefore the three-dimensional data is insufficient for setting the soft limit.

[0007] This embodiment aims to solve the above problems by providing a CT scanner that can acquire three-dimensional data of an object to be inspected without moving or rotating the inspection table, and can set a soft limit based on this three-dimensional data. [Means for solving the problem]

[0008] The CT apparatus of this embodiment has the following configuration. (1) An inspection table on which the object to be inspected is placed and which is movable and rotatable in the horizontal direction. (2) A radiation source that irradiates the object to be inspected with a radiation beam. (3) A detector provided opposite the radiation source with the object to be inspected in between, which outputs a translucent image of the object to be inspected. (4) A three-dimensional information acquisition unit provided above the inspection table, which acquires three-dimensional information of the object to be inspected while the inspection table is stopped. (5) A soft limit setting unit that sets an area in which the object to be inspected can approach the radiation source or the detector based on the three-dimensional information. (6) An imaging position calculation unit that calculates an imaging position in the region where the detector can acquire a translucent image of the object to be inspected at the maximum magnification, based on the three-dimensional information of the object to be inspected, the region, and predetermined parameters. (7) The inspection table is, The radiation source and the detector are moved horizontally in a direction that aligns them. The object to be inspected is moved to the imaging position.

[0009] Furthermore, the CT apparatus of this embodiment has the following configuration. (1) An inspection table on which the object to be inspected is placed and which is movable and rotatable in the horizontal direction. (2) A radiation source that irradiates the object to be inspected with a radiation beam. (3) A detector provided opposite the radiation source with the object to be inspected in between, which outputs a translucent image of the object to be inspected. (4) A mirror that reflects one side of the object being inspected. (5) A three-dimensional information acquisition unit provided opposite the mirror with the object to be inspected in between, which captures images of both the other side of the object to be inspected and the one side of the object to be inspected reflected in the mirror while the inspection table is stopped, and acquires three-dimensional information of the object to be inspected. (6) A soft limit setting unit that sets an area in which the object to be inspected can approach the radiation source or the detector based on the three-dimensional information. (7) An imaging position calculation unit that calculates an imaging position in the region where the detector can acquire a transparent image of the object to be inspected at the maximum magnification, based on the three-dimensional information of the object to be inspected, the region, and predetermined parameters. (8) The inspection table is, The radiation source and the detector are moved horizontally in a direction that aligns them. The object to be inspected is moved to the imaging position.

[0011] ( 1 ) A three-dimensional information display unit that displays the object to be inspected in two or three orthogonal directions based on the three-dimensional information of the object to be inspected, an ROI designation unit that designates a region of interest for the object to be inspected displayed on the three-dimensional information display unit, and based on the three-dimensional information of the object to be inspected, the region of interest and predetermined parameters, In the aforementioned region, the detector is at the maximum magnification. The aforementioned area of ​​interest Perspective images can be obtainedIt further includes an imaging position calculation unit that calculates an imaging position, and the inspection table moves the region of interest to the imaging position.

[0012] ( 2 ) It further includes a fluoroscopic image display unit that displays the fluoroscopic image, and the fluoroscopic image display unit displays the region superimposed on the fluoroscopic image.

Brief Description of the Drawings

[0013] [Figure 1] It is a schematic diagram showing a CT apparatus according to the first embodiment. [Figure 2] ]>It is a functional block diagram showing a control unit according to the first embodiment. [Figure 3] It is a diagram showing a soft limit according to the first embodiment. [Figure 4] It is a diagram for explaining the movement of the test object W by the XY mechanism according to the first embodiment. [Figure 5] It is a diagram for explaining the calculation of the imaging position according to the first embodiment. [Figure 6] It is a diagram for explaining the setting of the ROI according to the first embodiment. [Figure 7] It is a diagram for explaining the movement of the test object W by the XY mechanism when setting the ROI according to the first embodiment. [Figure 8] It is a diagram for explaining the calculation of the imaging position when setting the ROI according to the first embodiment. [Figure 9] It is a diagram showing the soft limit and the ROI superimposed and displayed on the fluoroscopic image according to the first embodiment. [Figure 10] It is a flowchart showing the operation of the CT apparatus according to the first embodiment. [Figure 11] It is a schematic diagram showing a CT apparatus according to the second embodiment.

Modes for Carrying Out the Invention

[0014] [1. First Embodiment] [1-1. Configuration of the Embodiment] The configuration of the CT apparatus according to the embodiment will be described below with reference to Figures 1 to 4. The CT apparatus 100 irradiates the object to be inspected W with radiation and detects the radiation that has passed through the object to be inspected W. Based on this detection result, the CT apparatus 100 generates a CT image of the object to be inspected W. As shown in Figure 1, the CT apparatus 100 comprises an inspection table 1 on which the object to be inspected W is placed on its upper surface, a radiation source 2 and a detector 3 for capturing a fluoroscopic image of the object to be inspected W, and a three-dimensional information acquisition unit 4 provided above the object to be inspected W to acquire three-dimensional information of the object to be inspected W. Furthermore, the CT apparatus 100 comprises an inspection table 1, a radiation source 2, a detector 3, a control unit 9 for controlling the operation of the three-dimensional information acquisition unit 4, and a fluoroscopic image display unit M that displays the fluoroscopic image and the soft limit S described later superimposed on it.

[0015] The inspection table 1 is a table having a mounting surface on which the object to be inspected W is placed. The inspection table 1 includes a moving mechanism 11 for moving the mounting surface in a direction parallel or perpendicular to the mounting surface, a rotating mechanism 12 for rotating the mounting surface around the perpendicular direction as an axis, and an XY mechanism 13 for moving the object to be inspected W on the mounting surface in a direction parallel to the mounting surface.

[0016] The moving mechanism 11 can be, for example, a ball screw mechanism driven by a servo motor. That is, the moving mechanism 11 moves the object to be inspected W together with the mounting surface of the inspection table 1 in a direction parallel or perpendicular to the mounting surface of the inspection table 1 by the drive of the servo motor.

[0017] The rotating mechanism 12 is mounted on the moving mechanism 11 and is an actuator that includes a drive source such as a motor. The rotating mechanism 12 rotates the mounting surface of the inspection table 1 around an axis perpendicular to the mounting surface. This rotation allows for imaging of the object to be inspected W from all directions to acquire fluoroscopic images, and CT images to be reconstructed from these fluoroscopic images.

[0018] The XY mechanism 13 is mounted on the rotation mechanism 12 and can use, for example, a ball screw mechanism driven by a servo motor. The XY mechanism 13 moves the object to be inspected W on the mounting surface of the inspection table 1. In other words, instead of moving the object to be inspected W together with the rotation axis of the inspection table 1 (the rotation axis of the mounting surface) as with the moving mechanism 11, the XY mechanism 13 moves the object to be inspected W on the mounting surface without changing the position of this rotation axis. This makes it possible to move the object to be inspected W to the center of the mounting surface of the inspection table 1. In this way, the moving mechanism 11 and the XY mechanism 13 can each move the object to be inspected W in a direction parallel to the mounting surface independently.

[0019] The radiation source 2 irradiates the object W under inspection with a radiation beam. The radiation beam is a beam of radiation that expands in a pyramidal shape with the focal point as its apex. The radiation source 2 is, for example, an X-ray tube, and the radiation is, for example, X-rays. The detector 3 is positioned opposite the radiation source 2, with the inspection table 1 and the object W under inspection in between, and detects the two-dimensional distribution of radiation intensity that has been attenuated according to the radiation transmission path, and outputs a fluoroscopic image to the image processing unit 93 and the fluoroscopic image display unit M, which will be described later. The detector 3 is, for example, composed of a flat panel detector (FPD).

[0020] The three-dimensional information acquisition unit 4 is, for example, a three-dimensional measuring instrument or a 3D camera. As a 3D camera, for example, a ToF (Time of Flight), stereo, or structured illumination type can be used. The three-dimensional information acquisition unit 4 can acquire not only external appearance information of the object being imaged, but also distance information to the object being imaged. The three-dimensional information acquisition unit 4 is installed above the inspection table 1 and, with the inspection table 1 stopped, images the object to be inspected W placed on the inspection table 1 and acquires the three-dimensional information of the object to be inspected W. More precisely, the inspection table 1 is first imaged without the object to be inspected W on it, and the three-dimensional information of the object to be inspected W is acquired as the difference between this image and the image taken with the object to be inspected W on the inspection table 1. The three-dimensional information acquisition unit 4 outputs the acquired three-dimensional information of the object to be inspected W to the soft limit setting unit 94, the imaging position calculation unit 95, and the ROI setting unit 96, which will be described later.

[0021] As shown in Figure 2, the control unit 9 includes a mechanism control unit 91 that controls the movement mechanism 11 and rotation mechanism 12 of the inspection table 1, a radiation source control unit 92 that controls the radiation source 2, an image processing unit 93 that corrects and reconstructs the fluoroscopic image acquired from the detector 3 to generate a CT image, a soft limit setting unit 94 that sets a soft limit S based on the three-dimensional information of the object to be inspected W acquired from the three-dimensional information acquisition unit 4, an imaging position calculation unit 95 that calculates an appropriate imaging position for imaging the object to be inspected W, and an ROI setting unit 96 that displays the object to be inspected W in two or three orthogonal directions based on the three-dimensional information acquired by the three-dimensional information acquisition unit 4 and sets a region of interest (hereinafter referred to as ROI) in the object to be inspected W in this displayed image.

[0022] The control unit 9 consists of a computer and a driver circuit. The computer consists of storage such as an HDD or SSD, RAM, a CPU, etc. An input unit (not shown) is connected to the control unit 9, and the user controls the various components of the CT device 100 via this input unit.

[0023] The mechanism control unit 91 can move and rotate the object to be inspected W placed on the inspection table 1 by controlling the movement mechanism 11, rotation mechanism 12, and XY mechanism 13 of the inspection table 1. In particular, the mechanism control unit 91 in this embodiment controls the movement and rotation of the inspection table 1 so that the object to be inspected W does not fall beyond the soft limit S set by the soft limit setting unit 94.

[0024] The radiation source control unit 92 controls the radiation source 2 to irradiate the object under inspection W with a radiation beam. This allows a fluoroscopic image of the object under inspection W to be acquired from the detector 3, which is positioned opposite the radiation source 2 with the object under inspection W in between.

[0025] The image processing unit 93 includes an acquisition unit 931 that acquires various data such as offset data and gain data from the detector 3, a correction unit 932 that corrects the fluoroscopic image based on this various data, and a reconstruction unit 933 that reconstructs the corrected fluoroscopic image. For reconstruction, for example, the FeldKamp FBP method is used, and a CT image is generated by performing filtering and back projection on each corrected fluoroscopic image.

[0026] The soft limit setting unit 94 sets the soft limit S based on the three-dimensional information of the object under inspection W acquired from the three-dimensional information acquisition unit 4. The soft limit S is the region in which the object under inspection W can approach the radiation source 2 or the detector 3. In other words, the soft limit S is the region in which the object under inspection W is not likely to collide with the radiation source 2 or the detector 3. In this embodiment, the soft limit S is set around the rotation axis of the inspection table 1. The setting of the soft limit S will be described in detail below with reference to Figure 3.

[0027] The soft limit setting unit 94 sets a cylindrical region encompassing the object to be inspected W based on the three-dimensional information of the object to be inspected W acquired from the three-dimensional information acquisition unit 4. In the top view of Figure 3, this cylindrical region is the circumscribed circle of the object to be inspected W. If the radius of this circumscribed circle is r1 and the distance from the center of this circumscribed circle to the rotation axis of the mounting surface of the inspection table 1 is r2, then the radius of the outer trajectory when the object to be inspected W is rotated is r1 + r2. The distance obtained by adding a margin distance β to this radius r1 + r2 is the radius of the soft limit S. The margin distance β can be set arbitrarily. For setting the height of the soft limit S, for example, the height of the object to be inspected W obtained based on the three-dimensional information of the object to be inspected W plus the margin distance β can be used. In this way, the soft limit setting unit 94 sets the soft limit S around the rotation axis of the inspection table 1. Furthermore, the soft limit setting unit 94 outputs the soft limit S to the imaging position calculation unit 95 and the fluoroscopic image display unit M.

[0028] The distance md1 that the examination table 1 can move to in proximity to the radiation source 2 can be determined by the following formula, based on the setting of the soft limit S. In the formula, FCD is the distance from the focal point of the radiation source 2 to the center of the rotation axis of the examination table 1, and α is the distance from the focal point of the radiation source 2 to the window. md1 = FCD - α - (radius of soft limit S) =FCD-α-(r1+r2)-β

[0029] Similarly, the distance md2 that the examination table 1 can move to in proximity to the detector 3 can be calculated using the following formula. In the formula, FDD is the distance from the focal point of the radiation source 2 to the examination table 3. md2 = (FDD - FCD) - (radius of soft limit S) =(FDD-FCD)-(r1+r2)-β

[0030] The imaging position calculation unit 95 calculates an imaging position suitable for imaging the object under inspection W based on the three-dimensional information of the object under inspection W acquired from the three-dimensional information acquisition unit 4, the soft limit S, and predetermined parameters. The predetermined parameters are various parameters such as the height of the mounting surface of the inspection table 1 relative to the radiation source 2, the imaging range of the detector 3, and the magnification ratio of the fluoroscopic image. An imaging position suitable for imaging the object under inspection W is, for example, a position within the proximity movement range defined by the soft limit S in which the detector 3 can acquire a fluoroscopic image of the object under inspection W at the maximum magnification ratio. The calculation of the imaging position will be explained in detail below with reference to Figures 4 and 5.

[0031] First, the imaging position calculation unit 95 obtains the center position of the circumscribed circle of the object W under inspection and the center position of the rotation axis of the inspection table 1 based on the three-dimensional information of the object W under inspection. The imaging position calculation unit 95 outputs this information to the mechanism control unit 91. As a result, as shown in Figure 4, the mechanism control unit 91 moves the object W under inspection to the XY mechanism 13 so that the center position of the circumscribed circle of the object W under inspection aligns with the center position of the rotation axis of the inspection table 1.

[0032] Next, the imaging position calculation unit 95 calculates an imaging position such that the circumscribed center of the object under inspection W is concentric with the rotation axis of the inspection table 1, the object under inspection W or a margin of distance β enters the radiation beam, the fluoroscopic image of the object under inspection W is at the maximum magnification, and it is within the close-movement range defined by the soft limit S. The upper limit of the maximum magnification may be defined based on the predetermined parameters mentioned above. The imaging position calculation unit 95 outputs this imaging position to the mechanism control unit 91. As a result, as shown in Figure 5, the mechanism control unit 91 moves the circumscribed center of the object under inspection W to the imaging position calculated by the imaging position calculation unit 95 using the movement mechanism 11. Since r2=0 at this time, the soft limit S, which is set around the rotation axis of the inspection table 1 as shown in Figure 5, is smaller than that in Figure 4.

[0033] The ROI setting unit 96 includes a three-dimensional information display unit 961 and an ROI designation unit 962. The three-dimensional information display unit 961 includes, for example, a liquid crystal or organic EL, and displays the object to be inspected W in two or three orthogonal directions based on the three-dimensional information of the object to be inspected W acquired from the three-dimensional information acquisition unit 4. In the following description, the object to be inspected W will be displayed in three directions: two directions parallel to the mounting surface of the inspection table 1 and mutually orthogonal, and one direction orthogonal to these two directions.

[0034] Here, if we define the direction in which the radiation source 2 and the detector 3 are aligned as the X direction, the direction parallel to the mounting surface of the inspection table 1 and perpendicular to the X direction as the Y direction, and the direction perpendicular to both the X and Y directions as the Z direction, then the object under inspection W is represented in three orthogonal directions: the Z direction (XY plane), the X direction (YZ plane), and the Y direction (XZ plane), as shown in Figure 6.

[0035] The ROI designation unit 962 designates an ROI for the object W under inspection displayed on the three-dimensional information display unit 961. Specifically, as shown in Figure 6, a circular or rectangular ROI is designated for the object W under inspection in the XY plane, YZ plane, and XZ plane, respectively. As a result, the ROI is designated as a cylindrical region. In other words, the ROI is designated as a three-dimensional region.

[0036] As described above, when an ROI is set on the object W under inspection by the ROI setting unit 96, the imaging position calculation unit 95 calculates an imaging position suitable for imaging the area where the ROI is set. The calculation of the imaging position when an ROI is set will be explained in detail below with reference to Figures 7 and 8.

[0037] First, the imaging position calculation unit 95 obtains the center position of the ROI set on the object W and the rotation axis center position of the inspection table 1 based on the three-dimensional information and ROI of the object W to be inspected. The imaging position calculation unit 95 outputs this information to the mechanism control unit 91. As a result, as shown in Figure 7, the mechanism control unit 91 moves the object W to be inspected using the XY mechanism 13 so that the center position of the ROI set on the object W aligns with the rotation axis center position of the inspection table 1.

[0038] Next, the imaging position calculation unit 95 calculates an imaging position such that the center position of the ROI set on the object under inspection W is concentric with the rotation axis of the inspection table 1 (in a top view), the ROI set on the object under inspection W enters the radiation beam, the fluoroscopic image of the ROI is at the maximum magnification, and it is within the close-movement range defined by the soft limit S. The upper limit of the maximum magnification may be defined based on the predetermined parameters mentioned above. The imaging position calculation unit 95 outputs this imaging position to the mechanism control unit 91. As a result, as shown in Figure 8, the mechanism control unit 91 moves the center position of the ROI set on the object under inspection W to the imaging position calculated by the imaging position calculation unit 95 using the moving mechanism 11.

[0039] The fluoroscopic image display unit M includes, for example, a liquid crystal or organic EL display, and as shown in Figure 9, it displays the fluoroscopic image of the object W under inspection acquired by the detector 3 and the soft limit S set by the soft limit setting unit 94 superimposed on it. Furthermore, if the ROI setting unit 96 sets an ROI, the fluoroscopic image display unit M can also superimpose and display the ROI on the fluoroscopic image. In the fluoroscopic image display unit M, the ROI set by the ROI setting unit 96 is displayed at the corresponding position and magnification on the fluoroscopic image.

[0040] [1-2. Operation of the Embodiment] The setting of the soft limit, calculation of the imaging position, and generation of the CT image in this embodiment will be explained with reference to the flowchart in Figure 10.

[0041] (1) Setting the soft limit The three-dimensional information acquisition unit 4 acquires three-dimensional information of the object under inspection W while the inspection table 1 is stopped, and outputs it to the soft limit setting unit 94, the imaging position calculation unit 95, and the ROI setting unit 96 (step S01). The soft limit setting unit 94 sets a soft limit S around the rotation axis of the inspection table 1 based on the three-dimensional information of the object under inspection W acquired from the three-dimensional information acquisition unit 4 (step S02). The soft limit S can be set, for example, from the center position of the circumscribed circle of the object under inspection W in a top view, the center position of the rotation axis of the inspection table 1, and a margin of error. This soft limit S defines the distance over which the object under inspection W can move.

[0042] (2) Calculation of imaging position The imaging position calculation unit 95 calculates an imaging position suitable for the detector 3 to image the object W, based on the three-dimensional information of the object W obtained from the soft limit setting unit 94 and the soft limit S obtained from the soft limit setting unit 94. Note that no ROI is set in this case (NO in step S03).

[0043] First, the imaging position calculation unit 95 obtains the center position of the circumscribed circle of the object W under inspection and the center position of the rotation axis of the inspection table 1 based on the three-dimensional information of the object W under inspection. The imaging position calculation unit 95 outputs this information to the mechanism control unit 91, and the mechanism control unit 91 moves the object W under inspection using the XY mechanism 13 so that the center position of the circumscribed circle of the object W under inspection aligns with the center position of the rotation axis of the inspection table 1. Next, the imaging position calculation unit 95 calculates an imaging position such that, with the center position of the circumscribed circle of the object W under inspection concentric with the rotation axis of the inspection table 1, the object W under inspection or a margin of distance β enters the radiation beam, the fluoroscopic image of the object W under inspection is at maximum magnification, and it is within the close-movement range defined by the soft limit S (step S04-1).

[0044] Furthermore, the imaging position calculation unit 95 outputs this imaging position to the mechanism control unit 91, which then controls the movement mechanism 11 to move the circumscribed center of the object under inspection W to this imaging position (step S05). After this, the process proceeds to step S06, which will be described later.

[0045] Next, we will explain the case where an ROI is set (YES in step S03). When an ROI is set for the object under inspection W displayed on the three-dimensional information display unit 961 using the ROI designation unit 962, the imaging position calculation unit 95 calculates the imaging position of the object under inspection W according to this ROI.

[0046] First, the imaging position calculation unit 95 obtains the center position of the ROI set on the object W and the rotation axis center position of the inspection table 1 based on the three-dimensional information of the object W and the ROI. The imaging position calculation unit 95 outputs this information to the mechanism control unit 91, and the mechanism control unit 91 moves the object W using the XY mechanism 13 so that the center position of the ROI set on the object W aligns with the rotation axis center position of the inspection table 1. Next, the imaging position calculation unit 95 calculates an imaging position such that the center position of the ROI set on the object W is concentric with the rotation axis of the inspection table 1, the ROI set on the object W enters the radiation beam, the fluoroscopic image of the ROI is at maximum magnification, and it is within the proximity movement range defined by the soft limit S (step S04-2). After this, the process proceeds to step S05 described above, and then to step S06.

[0047] (3) Generation of CT images After moving the examination table 1 to the imaging position, the detector 3 acquires fluoroscopic images of the object under inspection W or the ROI set on the object under inspection W from all directions by simultaneously rotating the examination table 1 under the control of the mechanism control unit 91 and irradiating with a radiation beam from the radiation source 2 under the control of the radiation source control unit 92 (step S06). The correction unit 32 of the image processing unit 93 performs correction processing on these fluoroscopic images, and the reconstruction unit 933 further reconstructs these corrected fluoroscopic images to generate a CT image (step S07).

[0048] [1-3. Effects of the Embodiment] (1) In this embodiment, the soft limit setting unit 94 sets the soft limit S based on the three-dimensional information of the object to be inspected W acquired by the three-dimensional information acquisition unit 4. This makes it possible to set the soft limit S without the need to move or rotate the inspection table 1. Furthermore, since the soft limit S is set based on three-dimensional information, an effective soft limit S can also be set in the height direction of the object to be inspected W.

[0049] (2) In this embodiment, the imaging position calculation unit 95 can calculate an imaging position suitable for imaging the object under inspection W based on the three-dimensional information of the object under inspection W and the soft limit S. This makes it possible to move the object under inspection W to an imaging position in which the detector 3 can acquire a translucent image of the object under inspection W at the maximum magnification within the proximity movement range defined by the soft limit S.

[0050] (3) In this embodiment, the ROI designation unit 962 can be used to designate an ROI for the object under inspection W displayed on the three-dimensional information display unit 961. Since the object under inspection W is displayed in three orthogonal directions by the three-dimensional information display unit 961, the ROI can also be designated as a three-dimensional region, similar to the object under inspection W. The imaging position calculation unit 95 can calculate the imaging position considering the ROI as such a three-dimensional region. For example, within the proximity movement range defined by the soft limit S, the object under inspection W can be moved to an imaging position in which the detector 3 can acquire a fluoroscopic image of the ROI set on the object under inspection W at the maximum magnification.

[0051] (4) In this embodiment, the transparent image display unit M can display the transparent image of the object to be inspected W and the soft limit S superimposed on each other. This allows the user to visually recognize the range of the soft limit S relative to the object to be inspected W.

[0052] [2. Second Embodiment] [2-1. Structure] The configuration of the CT apparatus 100 in this embodiment will be described with reference to Figure 11. The second embodiment has the same basic configuration as the first embodiment. In the following, only the differences from the first embodiment will be described, and the same reference numerals will be used for parts that are the same as in the first embodiment, and detailed descriptions will be omitted.

[0053] In the CT scanner 100 of this embodiment, as shown in Figure 11, the three-dimensional information acquisition unit 4 is not located above the examination table 1, but rather near the radiation source 2, for example, directly above it. The CT scanner 100 of this embodiment further includes a mirror 5. The mirror 5 is positioned above the detector 3 so as to reflect the back surface of the object under inspection W (the surface facing the detector 3) as viewed from the three-dimensional information acquisition unit 4 side. That is, the three-dimensional information acquisition unit 4 can image the back surface of the object under inspection W (the surface facing the radiation source 2) as well as the back surface of the object under inspection W via the mirror 5.

[0054] The imaging of the back surface of the object under inspection W by the three-dimensional information acquisition unit 4 will be explained in detail. The three-dimensional information acquisition unit 4 can obtain an equation representing the plane of the mirror 5 by acquiring positional information of multiple markers (not shown) provided on the mirror 5. From this plane equation and the positional information of the back surface of the object under inspection W reflected in the mirror 5, the distance information from the three-dimensional information acquisition unit 4 to the back surface of the object under inspection W can be calculated. In other words, the three-dimensional information acquisition unit 4 can calculate the positional information of the back surface of the object under inspection W via the mirror 5. As a result, the three-dimensional information acquisition unit 4 can acquire three-dimensional information of the object under inspection W from the surface of the object under inspection W, which is directly imaged, and the back surface of the object under inspection W, which is indirectly imaged. For more details on this technology, see, for example, "Shape Measurement Using a Mirror Surface with a Three-Dimensional Measuring Instrument" (Gifu Prefectural Institute of Information Technology Research Report (11), pp. 30-34, 2009).

[0055] [2-2. Effect] The setting of the soft limit S, the calculation of the imaging position, and the generation of the CT image in this embodiment are basically the same as in the first embodiment, so we will omit the explanation.

[0056] [2-3. Effects] In this embodiment, the three-dimensional information acquisition unit 4 is located directly above the radiation source 2. In the first embodiment, if the object under inspection W had an umbrella-like structure, it was not possible to image the part of the umbrella that was in the shade. As a result, when specifying an ROI as a three-dimensional region for the object under inspection W, problems such as data loss may occur, and it was necessary to compensate for this missing portion with, for example, a cylinder whose base is the circumscribed circle of the object under inspection W in a top view. However, in this embodiment, imaging is performed by the three-dimensional information acquisition unit 4 and mirror 5 located directly above the radiation source 2, so such problems do not occur.

[0057] [3. Other Embodiments] While several embodiments of the present invention have been described herein, these embodiments are presented as examples and are not intended to limit the scope of the invention. The embodiments described above can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the scope of the invention. These embodiments and their variations are included within the scope and essence of the invention, as well as within the scope of the claims and its equivalents.

[0058] (1) In the above embodiment, the three-dimensional information display unit 961 displays the object under inspection W in three orthogonal directions, but it may also display it in two orthogonal directions. Even in this case, the ROI can be specified from two directions, so the ROI can be specified as a three-dimensional region. It is also possible to set the shape of the ROI to a cylindrical region in advance. In this way, for example, even if the ROI is specified as a rectangle from two orthogonal directions, the X direction (YZ plane) and the Y direction (XZ plane), the ROI can be specified as a cylindrical region, as in Figure 6. Note that the shape of the ROI specified from three directions or the ROI set in advance is not limited to a cylindrical region, but may also be a spherical region or a rectangular parallelepiped region.

[0059] (2) In the first embodiment, the three-dimensional information acquisition unit 4 is a three-dimensional measuring instrument or a 3D camera, but it is not limited to these and can also be a device using ultrasound or laser light.

[0060] (3) In the second embodiment, the three-dimensional information acquisition unit 4 is provided on the radiation source 2 side and the mirror 5 is provided on the detector 3 side, but the system is not limited to this. As long as three-dimensional information of the object W to be inspected for setting the soft limit S can be acquired, the three-dimensional information acquisition unit 4 may be provided on the detector 3 side and the mirror 5 on the radiation source 2 side, or it may be provided anywhere else. [Explanation of symbols]

[0061] 100...CT device 1… Examination table 11...Movement mechanism 12…Rotation mechanism 2…Radiation source 3…Detector 4…Three-dimensional information acquisition section 5...Mirror 9... Control Unit 91... Mechanism Control Unit 92…Radiation Source Control Unit 93…Image Processing Unit 931…Acquisition Department 932... Correction section 933...Reconstruction part 94...Soft limit setting section 95...Image position calculation unit 96…ROI setting section 961...Three-dimensional information display section 962...ROI specification section M...Perspective image display unit S... Soft Limit W...Item under inspection

Claims

1. An inspection table on which the object to be inspected is placed and which is movable and rotatable in the horizontal direction, A radiation source that irradiates the object to be inspected with a radiation beam, A detector is provided facing the radiation source with the object to be inspected in between, and outputs a fluoroscopic image of the object to be inspected. A three-dimensional information acquisition unit is provided above the inspection table and acquires three-dimensional information of the object to be inspected while the inspection table is stopped. A soft limit setting unit sets a region in which the object under inspection can approach the radiation source or the detector based on the three-dimensional information, The system includes an imaging position calculation unit that calculates an imaging position in the region where the detector can acquire a transparent image of the object to be inspected at the maximum magnification, based on the three-dimensional information of the object to be inspected, the region, and predetermined parameters. The examination table is a CT apparatus that moves horizontally in a direction in which the radiation source and the detector are aligned, and moves the object to be examined to the imaging position.

2. An inspection table on which the object to be inspected is placed and which is movable and rotatable in the horizontal direction, A radiation source that irradiates the object to be inspected with a radiation beam, A detector is provided facing the radiation source with the object to be inspected in between, and outputs a fluoroscopic image of the object to be inspected. A mirror that reflects one side of the object to be inspected, A three-dimensional information acquisition unit is provided opposite the mirror, with the object to be inspected in between, and captures images of both the other side of the object to be inspected and the one side of the object reflected in the mirror, while the inspection table is stopped, thereby acquiring three-dimensional information of the object to be inspected. A soft limit setting unit sets a region in which the object under inspection can approach the radiation source or the detector based on the three-dimensional information, The system includes an imaging position calculation unit that calculates an imaging position in the region where the detector can acquire a transparent image of the object to be inspected at the maximum magnification, based on the three-dimensional information of the object to be inspected, the region, and predetermined parameters. The examination table is a CT apparatus that moves horizontally in a direction in which the radiation source and the detector are aligned, and moves the object to be examined to the imaging position.

3. A three-dimensional information display unit that displays the object to be inspected in two or three orthogonal directions based on the three-dimensional information of the object to be inspected, A ROI designation unit for designating a region of interest for the object to be inspected, which is displayed on the three-dimensional information display unit, An imaging position calculation unit calculates an imaging position in the region where the detector can acquire a translucent image of the region of interest at the maximum magnification, based on the three-dimensional information of the object to be inspected, the region of interest, and predetermined parameters. Furthermore, The examination table moves the region of interest to the imaging position. The CT apparatus according to claim 1 or 2.

4. The system further includes a perspective image display unit for displaying the aforementioned perspective image, The perspective image display unit displays the region superimposed on the perspective image. The CT apparatus according to any one of claims 1 to 3.

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