CN115078415A - Computed tomography apparatus - Google Patents

Abstract

The invention provides a computed tomography apparatus, which can obtain three-dimensional data of an object to be checked without moving or rotating a checking table and set soft limit based on the three-dimensional data. The computer tomography apparatus of the present invention includes: an inspection table (1) on which an object (W) to be inspected is placed and which is provided so as to be movable in a horizontal direction and rotatable; a radiation source (2) for irradiating a subject (W) with a radiation beam; a detector (3) which is disposed opposite to the radiation source (2) with the subject (W) therebetween and outputs a perspective image of the subject (W); a three-dimensional information acquisition unit (4) which is provided above the inspection table (1) and acquires three-dimensional information of the object (W) to be inspected while the inspection table (1) is stopped; and a soft limit setting unit (94) that sets an area in which the object (W) can approach the radiation source (2) or the detector (3) based on the three-dimensional information.

Description

Computed tomography apparatus

Technical Field

Embodiments of the present invention relate to a Computed Tomography (CT) apparatus.

Background

The computed tomography apparatus includes: a radiation source that irradiates, for example, an X-ray beam as radiation; and a detector disposed opposite to the radiation source and detecting the X-ray beam. An examination table on which an object to be examined is placed is provided between the radiation source and the detector, and a perspective image from all directions is obtained by one rotation of the examination table while the object is irradiated with the X-ray beam. A computed tomography image (cross-sectional image) of the object is obtained by reconstructing the fluoroscopic image.

When imaging an object, the imaging position of the object is adjusted by moving the examination table on which the object is placed in the horizontal direction between the radiation source and the detector. Furthermore, the examination table is rotated when the computed tomography images are acquired. At this time, the object may collide with the radiation source or the detector due to the movement or rotation of the examination table.

In order to avoid such a collision, it is known to set an accessible region called a soft limit (soft limit). By setting such soft limits, the object to be examined can be prevented from colliding with the radiation source or the detector in advance. The soft limit may be manually set, but there is a possibility that the setting data is erroneously input, and thus, for example, as in patent document 1 or patent document 2, the soft limit is automatically set based on three-dimensional data acquired from the object to be inspected.

[ Prior art documents ]

[ patent document ]

[ patent document 1] Japanese patent laid-open No. 2007-078557

[ patent document 2] Japanese patent laid-open No. 2009-294047

Disclosure of Invention

[ problems to be solved by the invention ]

However, in these conventional techniques, in order to acquire three-dimensional data of an object to be inspected, it is necessary to move or rotate the inspection table in the horizontal direction while the object to be inspected is placed thereon. Such movement or rotation of the examination table takes time, and the object does not necessarily collide with the radiation source or the detector until the soft limit is set due to the movement of the examination table at this time. In addition, as a method of setting soft limits without moving or rotating the examination table, it is conceivable to acquire data of the object to be examined from an optical camera image provided above the examination table, but in this case, height information of the object to be examined cannot be acquired, and thus, this method is not sufficient as three-dimensional data for setting soft limits.

In order to solve the above-described problems, an object of the present embodiment is to provide a computed tomography apparatus capable of acquiring three-dimensional data of an object to be examined without moving or rotating an examination table and setting a soft limit based on the three-dimensional data.

[ means for solving problems ]

The computer tomography apparatus of the embodiment includes the following structure.

(1) An inspection table on which an object to be inspected is placed, and which is provided so as to be movable and rotatable in a horizontal direction.

(2) And a radiation source for irradiating the object with a radiation beam.

(3) And a detector which is provided opposite to the radiation source with the object interposed therebetween and outputs a perspective image of the object.

(4) And a three-dimensional information acquisition unit provided above the inspection table and configured to acquire three-dimensional information of the inspection object while the inspection table is stopped.

(5) And a soft limit setting unit that sets a region in which the object can approach the radiation source or the detector, based on the three-dimensional information.

The computer tomography apparatus according to the embodiment includes the following configuration.

(1) An inspection table on which an object to be inspected is placed, and which is provided so as to be movable and rotatable in a horizontal direction.

(2) And a radiation source for irradiating the object with a radiation beam.

(3) And a detector which is provided opposite to the radiation source with the object interposed therebetween and outputs a perspective image of the object.

(4) And a mirror for reflecting one side surface of the object to be inspected.

(5) And a three-dimensional information acquisition unit that is provided opposite the mirror with the inspection object interposed therebetween, and that captures images of both the other side surface of the inspection object and the one side surface of the inspection object reflected on the mirror with the inspection table stopped, thereby acquiring three-dimensional information of the inspection object.

(6) And a soft limit setting unit that sets a region in which the object can approach the radiation source or the detector, based on the three-dimensional information.

The computed tomography apparatus of the embodiment may also further include the following structure.

(1) Further comprising: and an imaging position calculation unit that calculates an imaging position suitable for imaging the object based on the three-dimensional information of the object, the region, and a predetermined parameter, and the examination table moves the object to the imaging position.

(2) Further comprising: 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 Region of Interest (ROI) specifying unit that specifies a Region of Interest for the object displayed on the three-dimensional information display unit; and an imaging position calculation unit that calculates an imaging position suitable for imaging the region of interest based on the three-dimensional information of the object, the region of interest, and a predetermined parameter, and the examination table moves the region of interest to the imaging position.

(3) Further comprising: and a fluoroscopic image display unit that displays the fluoroscopic image, wherein the fluoroscopic image display unit displays the region superimposed on the fluoroscopic image.

Drawings

Fig. 1 is a schematic view showing a computed tomography apparatus according to a first embodiment.

Fig. 2 is a functional block diagram showing a control unit according to the first embodiment.

Fig. 3 is a diagram showing soft limiting of the first embodiment.

Fig. 4 is a diagram illustrating movement of the object W by the XY mechanism according to the first embodiment.

Fig. 5 is a diagram illustrating calculation of the imaging position according to the first embodiment.

Fig. 6 is a diagram illustrating setting of an ROI according to the first embodiment.

Fig. 7 is a diagram illustrating movement of the object W by the XY mechanism when setting the ROI according to the first embodiment.

Fig. 8 is a diagram illustrating calculation of the imaging position when setting the ROI according to the first embodiment.

Fig. 9 is a diagram showing soft limits and ROIs superimposed on a fluoroscopic image according to the first embodiment.

Fig. 10 is a flowchart showing the operation of the computed tomography apparatus according to the first embodiment.

Fig. 11 is a schematic view showing a computer tomography apparatus according to the second embodiment.

[ description of symbols ]

100: computed tomography apparatus

1: inspection table

11: moving mechanism

12: rotating mechanism

2: radiation source

3: detector

4: three-dimensional information acquisition unit

5: mirror with mirror head

9: control unit

91: mechanism control unit

92: radiation source control unit

93: image processing unit

931: acquisition unit

932: correction part

933: reconstruction unit

94: soft limit setting unit

95: imaging position calculation unit

96: ROI setting unit

961: three-dimensional information display unit

962: ROI designating unit

M: perspective image display unit

S: soft limit

W: object to be inspected

Detailed Description

[1. first embodiment ]

[1-1. Structure of embodiment ]

Hereinafter, the configuration of the computer tomography apparatus according to the embodiment will be described with reference to fig. 1 to 4. The computed tomography apparatus 100 irradiates the object W with radiation and detects radiation transmitted through the object W. The computed tomography apparatus 100 generates a computed tomography image of the object W based on the detection result. As shown in fig. 1, the computed tomography apparatus 100 includes: an inspection table 1 on which an object to be inspected W is placed; a radiation source 2 and a detector 3 for capturing a perspective image of an object W; and a three-dimensional information acquisition unit 4 provided above the object W to acquire three-dimensional information of the object W. Further, the computed tomography apparatus 100 includes: a control unit 9 for controlling the operations of the examination table 1, the radiation source 2, the detector 3, and the three-dimensional information acquisition unit 4; and a fluoroscopic image display unit M for displaying the fluoroscopic image and a soft limit S described later in a superimposed manner.

The inspection table 1 is a table having a mounting surface on which an object to be inspected W is mounted. The examination table 1 comprises: a moving mechanism 11 for moving the mounting surface in a direction parallel to the mounting surface or in a direction perpendicular to the mounting surface; a rotation mechanism 12 for rotating the mounting surface about the vertical direction; and an XY mechanism 13 for moving the object W on the mounting surface in a direction parallel to the mounting surface.

The moving mechanism 11 may be a ball screw mechanism driven by a servo motor (servo motor), for example. That is, the moving mechanism 11 moves the object W together with the mounting surface in a direction parallel to the mounting surface of the inspection table 1 or in a direction perpendicular to the mounting surface of the inspection table 1 by driving the servo motor.

The rotation mechanism 12 is provided on the movement mechanism 11, and is an actuator including a drive source such as a motor. The rotation mechanism 12 rotates the mounting surface about an axis perpendicular to the mounting surface of the inspection table 1. By this rotation, the object W is imaged in all directions to acquire perspective images, and a computed tomography image is reconstructed from these perspective images.

The XY mechanism 13 is provided on the rotation mechanism 12, and a ball screw mechanism driven by a servomotor, for example, can be used. The XY mechanism 13 moves the object W on the mounting surface of the inspection stage 1. In other words, the object W is not moved together with the rotation axis (rotation axis of the mounting surface) of the inspection table 1 as in the moving mechanism 11, but is moved on the mounting surface without changing the position of the rotation axis. This allows the object W to be inspected to move to the center of the mounting surface of the inspection stage 1. In this way, the moving mechanism 11 and the XY mechanism 13 can move the object W in the direction parallel to the mounting surface independently of each other.

The radiation source 2 irradiates a radiation beam to the object W. The radiation beam is a beam of radiation that is enlarged in a pyramid shape with the focal point as the apex. The radiation source 2 is, for example, an X-ray tube, and the radiation is, for example, X-rays. The detector 3 is disposed opposite the radiation source 2 with the examination table 1 and the object W interposed therebetween, detects a two-dimensional distribution of radiation intensity weakened by a transmission path of radiation, and outputs a fluoroscopic image to an image processing unit 93 and a fluoroscopic image display unit M, which will be described later. The Detector 3 includes, for example, a Flat Panel Detector (FPD).

The Three-dimensional information acquiring unit 4 is, for example, a Three-dimensional measuring instrument or a Three-dimensional (3D) camera. As the 3D camera, for example, a Time of Flight (ToF) system, a stereo (stereo) system, and a structured light illumination (structured illumination) system can be used. The three-dimensional information acquisition section 4 may acquire distance information from the photographic subject in addition to appearance information of the photographic subject. The three-dimensional information acquisition unit 4 is provided above the inspection table 1, and images the object W placed on the inspection table 1 in a state where the inspection table 1 is stopped, and acquires three-dimensional information of the object W. Strictly speaking, the inspection table 1 in which the object W is not placed is imaged in advance, and three-dimensional information of the object W is acquired as a difference from the imaging in which the object W is placed on the inspection table 1. The three-dimensional information acquiring unit 4 outputs the acquired three-dimensional information of the object W to be inspected to a soft limit setting unit 94, an imaging position calculating unit 95, and an ROI setting unit 96, which will be described later.

As shown in fig. 2, the control unit 9 includes: a mechanism control unit 91 for controlling the moving mechanism 11 and the rotating mechanism 12 of the inspection stage 1; a radiation source control unit 92 for controlling the radiation source 2; an image processing unit 93 that corrects and reconstructs a fluoroscopic image acquired from the detector 3 to generate a computed tomography image; a soft limit setting unit 94 that sets a soft limit S based on the three-dimensional information of the object W acquired from the three-dimensional information acquiring unit 4; an imaging position calculation unit 95 for calculating an imaging position suitable for imaging the test object W; and an ROI setting unit 96 that displays the object 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 display image of the object W.

The control unit 9 includes a computer and a driver circuit. The computer includes a storage (storage) such as a Hard Disk Drive (HDD) or a Solid State Drive (SSD), a Random Access Memory (RAM), a Central Processing Unit (CPU), and the like. An input unit, not shown, is connected to the control unit 9, and the user causes the control unit 9 to control the respective components of the computed tomography apparatus 100 via the input unit.

The mechanism controller 91 can move and rotate the object W placed on the inspection stage 1 by controlling the moving mechanism 11, the rotating mechanism 12, and the XY mechanism 13 of the inspection stage 1. In particular, the mechanism control unit 91 of the present embodiment controls the movement and rotation of the inspection table 1 so that the object W does not exceed the soft limit S set by the soft limit setting unit 94.

The radiation source controller 92 controls the radiation source 2 to irradiate the object W with a radiation beam. This makes it possible to acquire a fluoroscopic image of the object W from the detector 3 disposed opposite to the radiation source 2 with the object W interposed therebetween.

The image processing unit 93 includes: an acquisition unit 931 for acquiring various data such as offset data (offset data) and gain data (gain data) from the detector 3; a correcting unit 932 for correcting the fluoroscopic image based on the various data; and a reconstruction unit 933 for reconstructing the corrected perspective image. For reconstruction, a computed tomography image is generated by filtering and Back-projecting (Back Projection) each corrected fluoroscopic image using, for example, a Filtered Back Projection (FBP) method of FeldKamp (FeldKamp).

The soft limit setting unit 94 sets the soft limit S based on the three-dimensional information of the object W acquired from the three-dimensional information acquiring unit 4. The soft limit S is a region where the object W can approach the radiation source 2 or the detector 3. In other words, the soft limit S is a region where the object W does not collide with the radiation source 2 or the detector 3. The soft limit S of the present embodiment is set around the rotation axis of the examination table 1. The setting of the soft limit S will be described in detail below with reference to fig. 3.

The soft limit setting unit 94 sets a cylindrical region including the object W based on the three-dimensional information of the object W acquired from the three-dimensional information acquiring unit 4. In the plan view of fig. 3, the cylindrical region is a circumscribed circle of the object W to be inspected. Assuming that the radius of the circumscribed circle is r1 and the distance from the center of the circumscribed circle to the rotation axis of the mounting surface of the inspection table 1 is r2, the radius of the outer circumferential path of the object W when rotated is r1+ r 2. The radius r1+ r2 plus the distance β of the margin portion is the radius of the soft limit S. The distance β of the margin portion can be arbitrarily set. As the setting of the height direction of the soft limit S, for example, the following setting may be used: the distance β of the margin portion is added to the height of the inspection object W obtained based on the three-dimensional information of the inspection object W. In this way, the soft limit setting unit 94 sets the soft limit S around the rotation axis of the examination table 1. Further, 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.

By setting the soft limit S, the accessible moving distance md1 of the examination table 1 to the radiation source 2 is obtained by the following equation. 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

Similarly, the accessible moving distance md2 of the examination table 1 to the detector 3 is obtained by the following equation. In the equation, FDD is the distance from the focal point of the radiation source 2 to the examination table 1.

md2 ═ f (FDD-FCD) - (radius of soft Limit S)

＝(FDD－FCD)－(r1+r2)－β

The imaging position calculation unit 95 calculates an imaging position suitable for imaging the object W based on the three-dimensional information of the object W acquired from the three-dimensional information acquisition unit 4, the soft limit S, and a predetermined parameter. The predetermined parameters include various parameters such as the height of the mounting surface of the examination table 1 with respect to the radiation source 2, the imaging range of the detector 3, and the magnification of the fluoroscopic image. The imaging position suitable for imaging the object W is, for example, a position at which the detector 3 can acquire a fluoroscopic image of the object W at the maximum magnification in the accessible movement range defined by the soft limit S. The calculation of the imaging position will be described in detail below with reference to fig. 4 and 5.

First, the imaging position calculation unit 95 acquires the center position of the circumscribed circle of the object W and the center position of the rotation axis of the inspection table 1 based on the three-dimensional information of the object W. The imaging position calculation unit 95 outputs the information to the mechanism control unit 91. Thus, as shown in fig. 4, the mechanism control unit 91 moves the object W to be inspected by the XY mechanism 13 so that the center position of the circumscribed circle of the object W is aligned with the center position of the rotation axis of the inspection table 1.

Next, the imaging position calculation unit 95 calculates an imaging position where the distance β between the object W and the margin enters the radiation beam and the fluoroscopic image of the object W is at the maximum magnification and within the accessible movement range defined by the soft limit S, in a state where the circumscribed center position of the object W and the rotation axis of the examination table 1 are concentric. Further, the upper limit of the maximum magnification may be defined based on the predetermined parameter. The imaging position calculation unit 95 outputs the imaging position to the mechanism control unit 91. As a result, as shown in fig. 5, the mechanism control unit 91 moves the circumscribed center position of the test object W to the imaging position calculated by the imaging position calculation unit 95 by the movement mechanism 11. At this time, since r2 is 0, the soft limit S set around the rotation axis of the examination table 1 shown in fig. 5 is smaller than that shown in fig. 4.

The ROI setting unit 96 includes a three-dimensional information display unit 961 and an ROI specification unit 962. The three-dimensional information display unit 961 includes, for example, liquid crystal or organic Electroluminescence (EL), and displays the object W in two or three orthogonal directions based on the three-dimensional information of the object W acquired from the three-dimensional information acquisition unit 4. In the following description, the following cases are assumed: the object W to be inspected is displayed in three directions, i.e., two mutually orthogonal directions parallel to the placing surface of the inspection table 1 and one direction orthogonal to the two directions.

Here, when the direction in which the radiation source 2 and the detector 3 are arranged is an X direction, a direction parallel to the placement surface of the examination table 1 and orthogonal to the X direction is a Y direction, and a direction orthogonal to the X direction and the Y direction is a Z direction, the object W is displayed in three orthogonal directions of the Z direction (XY plane), the X direction (YZ plane), and the Y direction (XZ plane), as shown in fig. 6.

The ROI designating unit 962 designates an ROI on the object W displayed on the three-dimensional information display unit 961. Specifically, as shown in fig. 6, a circular or rectangular ROI is specified for the object W in each of the XY plane, the YZ plane, and the XZ plane. Thus, the ROI is designated as a cylindrical region. That is, the ROI is designated as a three-dimensional region.

In this way, when the ROI is set in the subject W by the ROI setting unit 96, the imaging position calculation unit 95 calculates an imaging position suitable for imaging the region in which the ROI is set. The calculation of the imaging position when the ROI is set will be described in detail below with reference to fig. 7 and 8.

First, the imaging position calculation unit 95 acquires the center position of the ROI set on the object W and the center position of the rotation axis of the examination table 1 based on the three-dimensional information of the object W and the ROI. The imaging position calculation unit 95 outputs the information to the mechanism control unit 91. Thus, as shown in fig. 7, the mechanism control unit 91 moves the object W to be inspected by the XY mechanism 13 so that the center position of the ROI set on the object W is aligned with the center position of the rotation axis of the inspection table 1.

Next, the imaging position calculation unit 95 calculates an imaging position at which the ROI set on the object W enters the radiation beam and at which the fluoroscopic image of the ROI is at the maximum magnification and within the accessible movement range defined by the soft limit S, in a state in which the center position of the ROI set on the object W and the rotation axis (in plan view) of the examination table 1 are concentric. Further, the upper limit of the maximum magnification may be defined based on the predetermined parameter. The imaging position calculation unit 95 outputs the imaging position to the mechanism control unit 91. Thus, as shown in fig. 8, the mechanism control unit 91 moves the center position of the ROI set on the object W to the imaging position calculated by the imaging position calculation unit 95 by the movement mechanism 11.

The fluoroscopic image display unit M includes, for example, a liquid crystal, an organic EL, or the like, and displays a fluoroscopic image of the object W acquired by the detector 3 and the soft limit S set by the soft limit setting unit 94 in a superimposed manner as shown in fig. 9. Furthermore, when the ROI setting unit 96 sets the ROI, the fluoroscopic image display unit M may display the ROI superimposed on the fluoroscopic image. In the fluoroscopic image display unit M, the ROI set by the ROI setting unit 96 is displayed at a corresponding position and magnification on the fluoroscopic image.

[1-2. effects of embodiments ]

The setting of soft limits, the calculation of imaging positions, and the generation of a computed tomography image according to the present embodiment will be described with reference to a flowchart of fig. 10.

(1) Setting of soft limits

The three-dimensional information acquiring unit 4 acquires three-dimensional information of the object W in a state where the examination table 1 is stopped, and outputs the three-dimensional information to the soft limit setting unit 94, the imaging position calculating unit 95, and the ROI setting unit 96 (step S01). The soft limit setting unit 94 sets the soft limit S around the rotation axis of the examination table 1 based on the three-dimensional information of the object W acquired from the three-dimensional information acquiring unit 4 (step S02). The soft limit S can be set, for example, based on the center position of the circumscribed circle of the inspection object W in plan view, the center position of the rotation axis of the inspection table 1, and the distance of the margin portion. The soft limit S defines the accessible moving distance of the object W.

(2) Calculation of shooting 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 acquired from the soft limit setting unit 94 and the soft limit S acquired from the soft limit setting unit 94. Note that here, ROI is not set (NO in step S03).

First, the imaging position calculation unit 95 acquires the center position of the circumscribed circle of the object W and the center position of the rotation axis of the inspection table 1 based on the three-dimensional information of the object W. The imaging position calculation unit 95 outputs the information to the mechanism control unit 91, and the mechanism control unit 91 moves the object W to be inspected by the XY mechanism 13 so that the center position of the circumscribed circle of the object W is aligned with the center position of the rotation axis of the inspection table 1. Next, the imaging position calculation unit 95 calculates an imaging position where the distance β between the object W and the margin enters the radiation beam and the fluoroscopic image of the object W is at the maximum magnification and within the accessible movement range defined by the soft limit S, in a state where the circumscribed center position of the object W and the rotation axis of the examination table 1 are concentric (step S04-1).

Further, the imaging position is output to the mechanism control unit 91 by the imaging position calculation unit 95, and the mechanism control unit 91 controls the movement mechanism 11 to move the circumscribed center of the object W to the imaging position (step S05). Then, the process proceeds to step S06 described later.

Next, a case of setting ROI will be described (YES in step S03). When the ROI is set by the ROI designating unit 962 for the object W displayed on the three-dimensional information display unit 961, the imaging position calculating unit 95 calculates the imaging position of the object W based on the ROI.

First, the imaging position calculation unit 95 acquires the center position of the ROI set on the object W and the center position of the rotation axis of the examination table 1 based on the three-dimensional information of the object W and the ROI. The imaging position calculation unit 95 outputs the information to the mechanism control unit 91, and the mechanism control unit 91 moves the object W through the XY mechanism 13 so that the center position of the ROI set on the object W is aligned with the center position of the rotation axis of the examination table 1. Next, the imaging position calculation unit 95 calculates an imaging position at which the ROI set on the object W enters the radiation beam and at which the fluoroscopic image of the ROI has the maximum magnification and is within the accessible movement range defined by the soft limit S, in a state in which the center position of the ROI set on the object W and the rotation axis of the examination table 1 are concentric with each other (step S04-2). Then, the process proceeds to step S05, and further to step S06.

(3) Generation of computed tomography images

After the examination table 1 is moved to the imaging position, the detector 3 acquires a fluoroscopic image of the object W to be examined or the ROI set on the object W to be examined in all directions by simultaneously performing the rotation of the examination table 1 under the control of the mechanism control unit 91 and the irradiation of the radiation beam by the radiation source 2 under the control of the radiation source control unit 92 (step S06). The corrector 932 of the image processor 93 performs the correction process on the fluoroscopic image, and the reconstructor 933 reconstructs the corrected fluoroscopic image, thereby generating a computed tomography image (step S07).

[1-3. effects of the embodiment ]

(1) In the present embodiment, the soft limit setting unit 94 sets the soft limit S based on the three-dimensional information of the object W acquired by the three-dimensional information acquiring unit 4. This makes it possible to set the soft limit S without moving or rotating the examination table 1 in a troublesome manner. Further, since the soft limit S is set based on the three-dimensional information, the effective soft limit S can be set also in the height direction of the object W.

(2) In the present embodiment, the imaging position calculating unit 95 can calculate an imaging position suitable for imaging the test object W based on the three-dimensional information of the test object W and the soft limit S. This enables the object W to be moved to the following imaging positions, for example: the detector 3 can acquire a fluoroscopic image of the object W at the maximum magnification within the accessible movement range defined by the soft limit S.

(3) In the present embodiment, the ROI designating unit 962 designates an ROI for the object W displayed on the three-dimensional information display unit 961. Since the object W is displayed in the three-dimensional information display portion 961 in the orthogonal three directions, the ROI may be designated as a three-dimensional region in the same manner as the object W. The imaging position calculation unit 95 can calculate the imaging position in consideration of the ROI which is the three-dimensional region, and thus can move the object W to the imaging position, for example, as follows: the detector 3 can acquire a fluoroscopic image of an ROI set on the object W at the maximum magnification within the accessible movement range defined by the soft limit S.

(4) In the present embodiment, the fluoroscopic image of the object W and the soft limit S are superimposed and displayed on the fluoroscopic image display unit M. Thus, the user can visually recognize the range of the soft limit S with respect to the inspection object W.

[2. second embodiment ]

[2-1. Structure ]

A configuration of the computed tomography apparatus 100 according to the present embodiment will be described with reference to fig. 11. The basic structure of the second embodiment is the same as that of the first embodiment. Hereinafter, only the differences from the first embodiment will be described, and the same portions as those of the first embodiment will be denoted by the same reference numerals, and detailed description thereof will be omitted.

In the computed tomography apparatus 100 according to the present embodiment, as shown in fig. 11, the three-dimensional information acquisition unit 4 is provided in the vicinity of the radiation source 2, for example, directly above, rather than above the examination table 1. The computed tomography apparatus 100 of the present embodiment further includes a mirror 5. The mirror 5 is provided above the detector 3 so as to reflect the back surface (surface on the side facing the detector 3) of the test object W when viewed from the three-dimensional information acquisition unit 4 side. That is, the three-dimensional information acquisition unit 4 can capture an image of the back surface of the subject W via the mirror 5, except for the front surface (surface on the side facing the radiation source 2) of the subject W.

The imaging of the back surface of the test object W by the three-dimensional information acquisition unit 4 will be described in detail. The three-dimensional information acquisition unit 4 can obtain an equation representing the plane of the mirror 5 by acquiring position information of a plurality of not-shown marks provided on the mirror 5. The distance information from the three-dimensional information acquisition unit 4 to the back surface of the test object W can be calculated from the plane equation and the position information of the back surface of the test object W reflected by the mirror 5. That is, the three-dimensional information acquisition unit 4 can calculate the positional information of the back surface of the test object W via the mirror 5. Thus, the three-dimensional information acquiring unit 4 can acquire the three-dimensional information of the object W based on the front surface of the object W directly imaged and the back surface of the object W indirectly imaged. The above-mentioned technique is described in detail in, for example, "shape measurement using a mirror surface obtained by a three-dimensional measuring instrument" (report on study by information technology research institute of mons prefecture (11), pages 30 to 34, 2009).

[2-2. Effect ]

The setting of the soft limit S, the calculation of the imaging position, and the generation of the computed tomography image in the present embodiment are basically the same as those in the first embodiment, and therefore, the description thereof is omitted.

[2-3. Effect ]

In the present embodiment, the three-dimensional information acquisition unit 4 is provided directly above the radiation source 2. In the first embodiment, when the object W is configured as an umbrella, the shadow portion of the umbrella cannot be imaged. Therefore, when the ROI is specified as a three-dimensional region with respect to the object W, a problem such as data missing may occur, and it is necessary to supplement the missing portion with a cylinder having a bottom surface that is a circumscribed circle of the object W in a plan view, for example. However, in the present embodiment, since the three-dimensional information acquisition unit 4 and the mirror 5 provided directly above the radiation source 2 perform imaging, such a problem does not occur.

[3 ] other embodiments ]

In the present specification, a plurality of embodiments of the present invention have been described, but these embodiments are presented as examples and are not intended to limit the scope of the invention. The above-described embodiments may be implemented in other various ways, and various omissions, substitutions, and changes may be made without departing from the scope of the invention. These embodiments and modifications are included in the invention described in the claims and the equivalent range thereof, as well as the scope and gist of the invention.

(1) The three-dimensional information display portion 961 of the embodiment displays the object W in three orthogonal directions, but may display the object W in two orthogonal directions. In this case, since the ROI can be designated from both directions, the ROI can be designated as a three-dimensional region. Further, the shape of the ROI may be set as a cylindrical region in advance. With such a setting, for example, even if the ROI is specified in a rectangular shape from two directions orthogonal to the X direction (YZ plane) and the Y direction (XZ plane), the ROI can be specified as a cylindrical region in the same manner as in fig. 6. The shape of the ROI designated from three directions or the predetermined ROI is not limited to the cylindrical region, and may be a spherical region or a rectangular parallelepiped region.

(2) The three-dimensional information acquisition unit 4 according to the first embodiment is a three-dimensional measuring instrument or a 3D camera, but is not limited thereto, and may be a device using ultrasonic waves or laser light.

(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. If the three-dimensional information of the object W for setting the soft limit S can be acquired, the three-dimensional information acquiring unit 4 may be provided on the detector 3 side, the mirror 5 may be provided on the radiation source 2 side, or any other place.

Claims (7)

1. A computed tomography apparatus comprising:

an inspection table on which an object to be inspected is placed, the inspection table being provided so as to be movable and rotatable in a horizontal direction;

a radiation source that irradiates the subject with a radiation beam;

a detector which is provided opposite to the radiation source with the object interposed therebetween and outputs a perspective image of the object;

a three-dimensional information acquisition unit provided above the inspection stage and configured to acquire three-dimensional information of the inspection object while the inspection stage is stopped; and

and a soft limit setting unit that sets a region in which the object can approach the radiation source or the detector, based on the three-dimensional information.

2. A computed tomography apparatus comprising:

an inspection table on which an object to be inspected is placed, the inspection table being provided so as to be movable and rotatable in a horizontal direction;

a radiation source that irradiates the object with a radiation beam;

a detector which is provided opposite to the radiation source with the object interposed therebetween and outputs a perspective image of the object;

a mirror for reflecting one side surface of the object to be inspected;

a three-dimensional information acquisition unit that is provided opposite to the mirror with the inspection object interposed therebetween, and that acquires three-dimensional information of the inspection object by imaging both the other side surface of the inspection object and the one side surface of the inspection object reflected on the mirror with the inspection table stopped; and

and a soft limit setting unit that sets a region in which the object can approach the radiation source or the detector, based on the three-dimensional information.

3. The computed tomography apparatus of claim 1 or 2, further comprising:

an imaging position calculation unit that calculates an imaging position suitable for imaging the object based on the three-dimensional information of the object, the region, and a predetermined parameter,

the examination table moves the object to be examined to the imaging position.

4. The computed tomography apparatus of claim 1 or 2, further comprising:

a three-dimensional information display unit that displays the object to be inspected in two or three orthogonal directions on the basis of the three-dimensional information of the object to be inspected;

a region-of-interest specifying unit that specifies a region of interest for the object displayed on the three-dimensional information display unit; and

an imaging position calculation unit that calculates an imaging position suitable for imaging the region of interest based on the three-dimensional information of the object, the region of interest, and predetermined parameters,

the examination table moves the region of interest to the recording position.

5. The computed tomography apparatus of claim 1 or 2, further comprising:

a fluoroscopic image display unit for displaying the fluoroscopic image,

the fluoroscopic image display unit displays the region superimposed on the fluoroscopic image.

6. The computed tomography apparatus of claim 3, further comprising:

a fluoroscopic image display unit for displaying the fluoroscopic image,

the fluoroscopic image display unit displays the region superimposed on the fluoroscopic image.

7. The computed tomography apparatus of claim 4, further comprising:

a fluoroscopic image display unit for displaying the fluoroscopic image,

the fluoroscopic image display unit displays the region so as to be superimposed on the fluoroscopic image.

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