JP2012200463A - Alignment adjustment method, alignment measurement method, alignment tool, and x-ray ct apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method allowing precise alignment measurement of X-ray CT (Computed Tomography) apparatus.SOLUTION: This method includes steps of: installing an optical mirror 511 such that the optical mirror 511 rotates integrally with a gantry rotation part 11 near the rotational axis GA of the rotation part 11; adjusting a tilt of the mirror 511 such that a reflection surface of the mirror 511 becomes parallel with a rotation plane of the rotation part 11 based on a change of the track of reflected light 612 by the mirror 511 when irradiating a light beam 61 having directivity to the mirror 511 and turning the rotation part 11; horizontally irradiating the light beam 61 to the mirror 511, and comparing the tracks of incident light 611 and the reflected light 612 to obtain a tilt angle of the rotation part 11; horizontally irradiating the light beam 61 to the mirror 511 such that the track vertically overlaps the center line (a moving direction) of a top plate 21 of a photographic table 2; comparing the track of the incident light 611 to the mirror 511, and the track of the reflected light 612 or the moving direction of the top plate 21 to obtain positional relation between the rotation plane of the rotation part 11 and the moving direction of the top plate 21.

Description

  The present invention relates to an alignment adjustment method and alignment measurement method for an X-ray CT (Computed Tomography) apparatus, an alignment jig suitable for these methods, and an X-ray CT apparatus.

  The scanning gantry and the imaging table of the X-ray CT apparatus are required to have high alignment accuracy so that an appropriate tomographic image can be obtained. In particular, in an X-ray CT apparatus, a PET-CT apparatus, and the like used for a treatment plan such as radiotherapy, it is necessary to match the coordinate system of the imaging space with the treatment apparatus, and extremely high accuracy is required.

  Conventionally, as a method for measuring the alignment accuracy of an X-ray CT apparatus, a dedicated phantom in which, for example, a wire having a diameter of about 0.5 mm or a plurality of steel balls is arranged in the same slice plane is used. A method of photographing and observing the appearance of a steel ball or wire in the obtained tomographic image is known (see, for example, Patent Document 1 and FIG. 3).

JP 2008-148964 A

  However, this method cannot detect a position shift smaller than the slice thickness of the tomographic image and has insufficient resolution, so that the verticality of the scan plane (ISO plane) of the gantry cannot be measured accurately. The accuracy cannot be measured accurately.

  Under such circumstances, an alignment measurement method that can accurately measure the alignment accuracy of an X-ray CT apparatus and an alignment adjustment method that can accurately perform alignment adjustment are desired.

  The invention of the first aspect includes a step of installing a mirror in the vicinity of the rotation axis of the rotation unit of the scanning gantry so as to rotate integrally with the rotation unit, and light having directivity toward the mirror. When the rotating unit is rotated while irradiating a beam, the reflecting surface of the mirror is parallel to the rotating surface of the rotating unit based on the change in the trajectory of the reflected light of the light beam by the mirror. Adjusting the tilt of the mirror, and adjusting the tilt angle of the rotating unit based on the trajectory of the reflected light from the mirror of the light beam irradiated horizontally toward the mirror. An alignment adjustment method for an X-ray CT apparatus provided is provided.

  According to a second aspect of the invention, in the first aspect, the step of adjusting the tilt angle of the rotating unit is a step of adjusting the rotating surface of the rotating unit to be perpendicular to a horizontal plane. Provided is an alignment adjustment method for a line CT apparatus.

  According to a third aspect of the invention, in the step of adjusting the tilt angle of the rotating unit, the height of the trajectory of the incident light to the mirror of the light beam irradiated horizontally toward the mirror, and the light beam There is provided an X-ray CT alignment adjustment method according to the second aspect, which is a step of adjusting the height of the orbit of reflected light by a mirror to coincide.

According to a fourth aspect of the invention, there is provided a step of installing the mirror in the vicinity of the rotation axis of the rotation unit of the scanning gantry so as to rotate integrally with the rotation unit, and irradiating the mirror with a light beam having directivity. The mirror so that the reflecting surface of the mirror is parallel to the rotating surface of the rotating unit based on the change in the trajectory of the reflected light of the light beam when the rotating unit is rotated while rotating the rotating unit. And a step of adjusting a tilt of the light beam, a trajectory of light incident on the mirror horizontally irradiated toward the mirror, and a trajectory of reflected light of the light beam by the mirror are viewed in a vertical direction. Adjusting the position of at least one of the scanning gantry and the light source of the light beam to overlap,
There is provided an alignment adjustment method for an X-ray CT apparatus comprising a step of adjusting a position and / or inclination of an imaging table with reference to a trajectory of a light beam irradiated toward the mirror.

  The invention of the fifth aspect is a step of adjusting the position and / or inclination of the imaging table so that the moving direction of the top plate in the imaging table is parallel to the reference light beam trajectory. An alignment adjustment method for an X-ray CT apparatus according to a fourth aspect is provided.

  According to the sixth aspect of the invention, in the step of adjusting the tilt of the mirror, the trajectory of the reflected light of the light beam irradiated toward the mirror is constant regardless of the rotation of the rotating portion. An alignment adjustment method for an X-ray CT apparatus according to the first to fifth aspects is provided.

  A seventh aspect of the invention is a method of installing a mirror in the vicinity of a rotation axis of a rotation unit of a scanning gantry so as to rotate integrally with the rotation unit, and irradiating a light beam having directivity toward the mirror The mirror so that the reflecting surface of the mirror is parallel to the rotating surface of the rotating unit based on the change in the trajectory of the reflected light of the light beam when the rotating unit is rotated while rotating the rotating unit. An X-ray CT apparatus comprising: a step of adjusting a tilt of the rotating portion; and a step of obtaining a tilt angle of the rotating unit based on a trajectory of a reflected light beam of the light beam irradiated horizontally toward the mirror. An alignment measurement method is provided.

  According to an eighth aspect of the invention, there is provided a step of installing the mirror in the vicinity of the rotation axis of the rotation unit of the scanning gantry so as to rotate integrally with the rotation unit, and irradiating the mirror with a light beam having directivity. The mirror so that the reflecting surface of the mirror is parallel to the rotating surface of the rotating unit based on the change in the trajectory of the reflected light of the light beam when the rotating unit is rotated while rotating the rotating unit. Adjusting the inclination of the light beam, irradiating the light beam toward the mirror horizontally and so that the trajectory overlaps the center line of the imaging table when viewed in the vertical direction, and the light beam to the mirror An X-ray CT apparatus comprising: a step of determining a positional relationship between a rotating surface of the rotating unit and a moving direction of the top plate on the imaging table based on an incident light trajectory and a reflected light trajectory by the mirror How to measure alignment To provide.

  The ninth aspect of the invention is the step of installing the mirror in the vicinity of the rotation axis of the rotating portion of the scanning gantry so as to rotate integrally with the rotating portion, and irradiating the mirror with a light beam having directivity. The mirror so that the reflecting surface of the mirror is parallel to the rotating surface of the rotating unit based on the change in the trajectory of the reflected light of the light beam when the rotating unit is rotated while rotating the rotating unit. And a step of adjusting a tilt of the light beam, a trajectory of light incident on the mirror horizontally irradiated toward the mirror, and a trajectory of reflected light of the light beam by the mirror are viewed in a vertical direction. The positional relationship between the rotating surface of the rotating unit and the moving direction of the top plate on the imaging table, based on the step of adjusting the position of the light beam source so as to overlap, and the trajectory of the light beam irradiated toward the mirror Process Providing an alignment measurement method of X-ray CT apparatus.

  The invention of a tenth aspect provides an alignment measurement method for an X-ray CT apparatus according to any one of the first to ninth aspects, wherein the light beam is a laser (LASER) light.

  An eleventh aspect of the invention is a mirror unit having a mirror, a tilt adjusting mechanism of a reflecting surface of the mirror, a base unit on which the mirror unit is installed, and a rotating unit of a scanning gantry. An X-ray CT apparatus, wherein the mirror portion is disposed so as to be positioned in the vicinity of the rotation axis of the rotating portion when the base portion is attached to the rotating portion. An alignment jig is provided.

  The invention of the twelfth aspect provides an X-ray CT apparatus comprising a rotating portion of a scanning gantry having a mounted portion to which a base portion of the alignment jig of the eleventh aspect is attached.

  The invention of the thirteenth aspect provides an X-ray CT apparatus in which the tilt angle of the rotating part of the scanning gantry is adjusted using the alignment adjustment method of any one of the first to third aspects. To do.

  The invention of the fourteenth aspect provides an X-ray CT apparatus in which the position and / or inclination of the imaging table is adjusted using the alignment adjustment method of the fourth aspect or the fifth aspect.

  According to the invention of the above aspect, a mirror is installed in the vicinity of the rotation axis of the rotating part of the scanning gantry, and the reflection surface of the mirror can be adjusted with accuracy so as to be parallel to the rotation surface. The light beam irradiated on the mirror or its reflected light can be used as an accurate reference surface or reference line for alignment. As a result, it is possible to precisely measure the alignment accuracy of the X-ray CT apparatus and perform alignment adjustment with high accuracy.

It is a figure which shows an example of the scanning gantry and imaging | photography table used as the object of alignment adjustment. It is a flowchart (flowchart) of the alignment adjustment method of a X-ray CT apparatus. It is a figure which shows the imaging | photography table by which the centerline was marked on the cradle (cradle). It is a figure which shows the scanning gantry and imaging table which were temporarily placed. It is a figure which shows an example of a mirror jig. It is a figure which shows the structural drawing of a mirror part. It is a figure for demonstrating the process of irradiating a laser beam toward a mirror. It is a figure for demonstrating the process of adjusting the inclination of a mirror. It is FIG. (1) for demonstrating the process of adjusting the tilt angle of a rotation part. It is FIG. (2) for demonstrating the process of adjusting the tilt angle of a rotation part. It is FIG. (1) for demonstrating the process of aligning the rotating surface of a rotation part, and a laser beam. It is FIG. (2) for demonstrating the process of aligning the rotating surface of a rotation part, and a laser beam. It is FIG. (1) for demonstrating the process of adjusting the arrangement | positioning of an imaging | photography table on the basis of a laser beam. It is FIG. (2) for demonstrating the process of adjusting arrangement | positioning of an imaging | photography table on the basis of a laser beam. It is a flowchart of the alignment measuring method of a X-ray CT apparatus. It is a figure for demonstrating the process of calculating | requiring the adjustment error of the tilt angle of a rotation part. It is a figure for demonstrating the process of aligning a laser beam with respect to a cradle. It is a figure for demonstrating the process of calculating | requiring the adjustment error of the azimuth | direction of the imaging | photography table with respect to a scanning gantry. It is a figure for demonstrating the process of calculating | requiring the adjustment error of the inclination in the vertical surface direction of an imaging table.

  Embodiments of the invention will be described below.

(First embodiment)
An alignment adjustment method for the X-ray CT apparatus according to the present embodiment will be described. In the following description, illustration of the operation console that is not directly related to the alignment of the X-ray CT apparatus is omitted.

  FIG. 1 is a diagram illustrating an example of a scanning gantry and an imaging table that are objects of alignment adjustment.

  As shown in FIG. 1, the scanning gantry 1 includes a rotating unit 11 having an X-ray tube and an X-ray detector, a rotation support unit (not shown) that rotatably supports the rotating unit 11, and a tilt of the rotating unit 11. And a tilt angle adjusting mechanism (not shown) for adjusting the angle. The rotating unit 11 includes a stage 111 to which various members can be attached at the periphery of the opening.

  Here, it is assumed that the tilt angle condition of the scanning gantry 1 is variable. However, in the case of a non-variable type, it is assumed that the tilt angle condition remains set to 0 degrees. do it.

  As shown in FIG. 1, the imaging table 2 includes a cradle 21, a cradle support part 22 that supports the cradle so as to be movable in the longitudinal direction, and an elevating part 23 that raises and lowers the cradle support part 22. The elevating unit 23 includes an inclination adjustment mechanism (not shown) for adjusting the inclination of the imaging table 2 in the vertical plane direction (front-rear direction).

The targets for alignment adjustment in the present embodiment are as follows.
(1) When the tilt angle condition of the scanning gantry 1 is set to 0 degrees, the rotating surface 11p of the rotating unit 11 of the scanning gantry 1 is parallel to the vertical direction (perpendicular to the horizontal plane).
(2) When the tilt angle condition of the scanning gantry 1 is set to 0 degree, the moving direction of the cradle 21 of the imaging table 2 is perpendicular to the rotation surface 11p of the rotating unit 11 of the scanning gantry 1 (on the rotation axis). (Parallel to).
(3) The rotation axis of the rotation unit 11 of the scanning gantry 1 and the movement axis of the cradle 21 of the imaging table 2 are coincident when viewed from above (as viewed in the vertical direction).

  FIG. 2 is a flowchart of the alignment adjustment method of the X-ray CT apparatus.

  In step S1, as a preparation for alignment adjustment, the tilt angle condition of the scanning gantry 1 is set to 0 degree, and the center line is marked on the cradle 21 of the imaging table 2. This center line overlaps the movement axis of the cradle 21 when viewed from above. If these preparations have already been performed when the X-ray CT apparatus is carried in, the operation of this step is omitted.

  FIG. 3 is a diagram for explaining a process of marking the center line on the cradle of the imaging table. In this example, as shown in FIG. 3, lines CL indicating the center line of the cradle 21 are marked at both ends in the longitudinal direction of the cradle 21. Thereby, the center line and moving direction of the cradle 21 can be visually confirmed using the line CL as a mark. The line CL may be previously marked or printed on the cradle 21 at the stage of manufacturing the cradle 21.

  In step S2, the scanning gantry 1 and the imaging table 2 are temporarily arranged.

  FIG. 4 is a diagram for explaining a process of temporarily arranging the scanning gantry and the imaging table. In this example, as shown in FIG. 4, the rotation axis GA of the scanning gantry 1 and the center line TA of the cradle 21 of the imaging table 2 are roughly overlapped when viewed in the vertical direction, and between the scanning gantry 1 and the imaging table 2. Is temporarily placed on the floor 9 such that the scanning gantry 1 and the imaging table 2 become a predetermined distance. Here, the vertical direction is the y direction, and the horizontal direction parallel to the rotation surface 11p of the rotating unit 11 is the x direction, and the direction z is perpendicular to the x direction and the y direction.

  In step S <b> 3, the mirror jig 5 is attached to the rotating part 11 of the scanning gantry 1.

  FIG. 5 is a diagram illustrating an example of a mirror jig. As shown in FIG. 5, the mirror jig 5 includes a mirror part 51, a base part 52 on which the mirror part 51 is installed, and an attachment part 53 for attaching the base part 52 to the rotating part 11.

  The base portion 52 has a rectangular plate shape as a whole, and holes for fixing the bolts to the stage 111 of the rotating portion 11 with bolts are formed as attachment portions 53 at both ends in the longitudinal direction. . The base portion 52 is formed so that the center in the longitudinal direction of the base portion 52 and the rotation axis GA overlap when attached to the rotating portion 11. In addition, a mirror portion 51 is installed at the center portion of the base portion 52 in the longitudinal direction. That is, when the base unit 52 is attached to the rotating unit 11 and the rotating unit 11 is rotated, the base unit 52 and the mirror unit 51 rotate integrally with the rotating unit 11, and the mirror unit 52 is located at substantially the same position in the vicinity of the rotation axis GA. Rotate with.

  FIG. 6 shows an enlarged structural view of the mirror portion in the mirror jig. As shown in FIG. 6, the mirror unit 51 includes an optical mirror 511, a substantially rectangular plate member 512, a plurality of screws 513, and a plurality of springs 514. A mirror 511 is attached to the center of the front surface of the plate member 512. In addition, holes 515 that penetrate the plate surface are formed at three corners of the four corners of the plate member 512. Screws 513 are inserted into the respective holes 515 from the front side of the plate member 512, and helical springs 514 are fitted on the back side of the plate member 512 so as to cover the screws 513 penetrating the plate member 512. ing. The spring 514 may be a plurality of disc springs. Screw holes 521 corresponding to these three screws 513 are formed on the front plate surface of the base portion 52. On the inner side surfaces of these screw holes 521, screw grooves that fit into the threads of the screws 513 are formed. The three screws 513 are turned into the screw holes 521 of these base portions 52. With such a configuration, the plate member 512, the three screws 513, and the three springs 514 function as an inclination adjustment mechanism for the reflecting surface 511p of the mirror 511. That is, the inclination of the reflection surface 511p of the mirror 511 can be arbitrarily adjusted by turning the respective screws 513 to change the inclination of the plate surface of the plate member 512 with respect to the mirror portion 511.

  The stage 111 of the rotating part 11 is provided with a hole as the attached part 112 at a position corresponding to the hole as the attaching part 53 formed at both ends in the longitudinal direction of the base part 52 of the mirror jig 5. Yes. The hole of the attachment part 53 and the hole of the attachment part 112 are fixed by tightening with a nut through a bolt.

  Here, the attaching portion 53 and the attached portion 112 are examples, and are not limited to such an attaching mechanism.

  In step S4, the laser beam 61 is irradiated toward the mirror 511.

  FIG. 7 is a diagram for explaining a process of irradiating a laser beam toward the mirror. In this example, a laser marking device (laser level) 6 is used as the light source of the laser beam 61. The laser marking device 6 can irradiate a cross-line laser beam in which the horizontal line and the vertical line intersect in one horizontal direction regardless of the inclination of the main body, and is suitable for alignment. Light source. In this example, as shown in FIG. 7, the laser marking device 6 is placed behind the temporarily placed cradle 21 at a position slightly off in the horizontal direction from the center line TA of the cradle 21. It is installed at almost the same height as the rotation axis GA. Then, a laser beam 61 is emitted from the laser marking device 6 toward the center of the mirror 511.

  In step S <b> 5, the inclination of the mirror 511 is adjusted so that the reflection surface 511 p of the mirror 511 is parallel to the rotation surface 11 p of the rotation unit 11. That is, the rotating unit 11 is rotated while irradiating the laser beam 61 horizontally toward the mirror 511, and the inclination of the mirror 511 is adjusted so that the trajectory of the reflected light 612 from the mirror 511 does not change.

  FIG. 8 is a diagram for explaining a process of adjusting the tilt of the mirror. In this example, as shown in FIG. 8, a shielding plate 7 that blocks the reflected light 612 is installed in the vicinity of the laser marking device 6, and a cross line 613 of the reflected light 612 appears on the plate surface of the shielding plate 7. To. Next, the rotating unit 11 is rotated about 180 °, and the movement of the position of the cross line 613 is observed. Then, the tilt of the mirror 511 is adjusted so that the position of the cross line 613 does not change even when the rotating unit 11 is rotated. Thereby, the reflecting surface 511p of the mirror 511 is accurately adjusted in parallel to the rotating surface 11p of the rotating unit 11.

  In step S <b> 6, the tilt angle of the rotating unit 11 is adjusted based on the reflected light 612 from the mirror 511.

  9 and 10 are diagrams for explaining the process of adjusting the tilt angle of the rotating unit. In this example, as shown in FIGS. 9 and 10, the orbit of the incident light 611 on the mirror 511 of the laser light 61 irradiated toward the mirror 511 and the reflected light 612 of the laser light 61 reflected by the mirror 511. Observe the orbit. Then, the tilt angle of the rotating unit 11 is adjusted so that both of these trajectories coincide with each other in the vertical direction, that is, the trajectory of the reflected light 612 is horizontal as in the incident light 611. For example, a shielding plate 7 that blocks the reflected light 612 is installed in the vicinity of the laser marking device 6. Then, the height position of the cross line 613 of the reflected light 612 that appears on the plate surface of the shielding plate 7 is adjusted so as to coincide with the height position of the laser emission port 62 of the laser marking device 6. When these height positions coincide with each other, the reflecting surface 511p of the mirror 511 is parallel to the vertical direction, and the rotating surface 11p of the rotating unit 11 is also parallel to the vertical direction. Thereby, the tilt angle of the rotating unit 11 when the tilt angle condition of the scanning gantry 1 is set to 0 degree is accurately adjusted so as to be true 0 degree parallel to the vertical direction.

  In step S7, the rotating surface 11p of the rotating unit 11 and the laser beam 61 are aligned.

  11 and 12 are diagrams for explaining a process of aligning the rotating surface of the rotating unit and the laser beam. In this example, as shown in FIGS. 11 and 12, the laser marking device 6 is moved behind the cradle 21 of the temporarily placed imaging table 2 to a position that substantially overlaps the center line TA of the cradle 21. The laser beam 61 is irradiated toward the mirror 511. Then, the arrangement of the laser marking device 6 is finely adjusted so that the trajectory of the incident light 611 of the laser light 61 on the mirror 511 and the trajectory of the reflected light 612 of the laser light 61 reflected by the mirror 511 overlap. The arrangement of the scanning gantry 1 or the arrangement of both the scanning gantry 1 and the laser marking device 6 may be finely adjusted. Thereby, the rotating surface 11p of the rotating part 11 and the orbit of the laser beam 61 are adjusted with high accuracy so as to intersect perpendicularly.

  In step S8, the arrangement of the imaging table 2 is adjusted based on the laser beam 61. That is, the position of the imaging table 2, the orientation in the horizontal plane direction, and the vertical plane direction (front-rear direction) so that the trajectory of the laser beam 61 irradiated toward the mirror 511 and the moving direction of the cradle 21 are parallel to each other. Adjust the tilt.

  13 and 14 are diagrams for explaining a process of adjusting the arrangement of the imaging table with reference to the laser beam. In this example, as shown in FIG. 13, the position of the imaging table 2 and the azimuth in the horizontal plane direction are adjusted so that the trajectory of the laser light 61 and the line CL indicating the center line TA marked on the cradle 21 coincide with each other. .

  Further, as shown in FIG. 14, a shielding plate 7 that blocks the laser beam 61 is placed on the rear part of the cradle 21. Then, the inclination in the vertical plane direction of the imaging table 2 is adjusted so that the height position of the cross line 613 that appears on the plate surface of the shielding plate 7 with respect to the cradle 21 does not change even if the cradle 21 is moved.

  Thereby, the rotation surface 11p of the rotation part 11 and the moving direction of the cradle 21 of the imaging table 2 are adjusted with high accuracy so as to intersect perpendicularly.

  According to such an alignment adjustment method of the X-ray CT apparatus, an optical mirror 511 is installed in the vicinity of the rotation axis GA of the rotation unit 11 of the scanning gantry 1, and the reflection surface 511p of the mirror 511 is connected to the rotation surface 11p. It can be adjusted with high accuracy so as to be parallel, and the incident light 611 on the mirror 511 or the reflected light 612 of the laser beam 61 irradiating the reflecting surface 511p of the mirror 511 or the mirror 511 can be changed to It can be used as a reference line. As a result, alignment adjustment of the X-ray CT apparatus can be performed precisely.

(Second embodiment)
An alignment measurement method of the X-ray CT apparatus according to this embodiment will be described.

  FIG. 15 is a flowchart of the alignment measurement method of the X-ray CT apparatus.

  In step T1, as in step S2, the tilt angle condition of the scanning gantry 1 is set to 0 degree, and the center line TA of the cradle 21 is marked.

  In step T2, the mirror jig 5 is attached to the rotating portion 11 of the scanning gantry 1 as in step S3.

  In step T3, similarly to step S4, the laser beam 61 is irradiated toward the mirror 511.

  In step T4, as in step S5, the tilt of the mirror 511 is adjusted based on the reflected light 612 from the mirror 511 when the rotating unit 11 is rotated, and the reflecting surface 511p of the mirror 511 is made parallel to the rotating surface 11p. .

  In Step T5, an adjustment error of the tilt angle of the rotating unit 11 is obtained based on the reflected light 612 from the mirror 511.

  For example, how much the orbit of the reflected light 612 of the laser beam 61 reflected by the mirror 511 is shifted in the vertical direction with respect to the orbit of the incident light 611 of the laser beam 61 irradiated horizontally toward the mirror 511. Ask what they are. Then, based on the obtained deviation amount, the number of times the rotation surface 11p of the rotation unit 11 when the tilt angle condition of the scanning gantry 1 is set to 0 degrees is displaced from the vertical surface by an angle is obtained.

  FIG. 16 is a diagram for explaining a process for obtaining an adjustment error of the tilt angle of the rotating unit. In this example, as shown in FIG. 16, a shielding plate 7 that blocks the reflected light 612 is provided in the vicinity of the laser marking device 6. Then, a distance Δy1 in the vertical direction between the position of the cross line 613 of the reflected light 612 that appears on the plate surface of the shielding plate 7 and the position of the laser emission port 62 of the laser marking device 6 is obtained. Then, using the following relational expression, the vertical surface of the rotating surface 11p is obtained from the obtained distance Δy1 and the distance from the reflecting surface 511p of the mirror 511 to the plate surface of the shielding plate 7, that is, the optical path length b1 of the reflected light 612. Find the deviation angle α from. This deviation angle α becomes an adjustment error of the tilt angle of the rotating unit 11.

  Δy1≈b1 · sin2α (Formula 1)

  In step T6, the laser beam 61 is aligned with the cradle 21.

  FIG. 17 is a diagram for explaining a process of aligning the laser beam with the cradle. In this example, as shown in FIG. 17, the laser marking device 6 is moved to a position behind the cradle 21 so as to substantially overlap the center line of the cradle 21, and the laser beam 61 is irradiated toward the mirror. Then, the position of the laser marking device 6 and the direction in the horizontal plane direction are set so that the orbit of the incident light 611 on the mirror 511 of the laser beam 61 and the center line TA of the cradle 21 overlap when viewed in the vertical direction. Make fine adjustments. Thereby, the orbit of the laser beam 61 and the moving direction of the cradle 21 overlap when viewed in the vertical direction.

  In step T7, an adjustment error of the orientation of the imaging table 2 with respect to the scanning gantry 1 is obtained based on the reflected light 612 from the mirror 511.

  For example, with respect to the trajectory of the laser beam 61 irradiated horizontally toward the mirror 511 and the trajectory of the incident light 611 on the mirror 511, how much the trajectory of the reflected light 612 of the laser beam 61 by the mirror 511 is in the horizontal direction. Find out if it is off. Then, based on the obtained deviation amount, how many times the orientation of the imaging table 2 in the horizontal plane direction deviates from the direction perpendicular to the rotation surface 11p of the rotation unit 11 is obtained.

  FIG. 18 is a diagram for explaining a process for obtaining an adjustment error of the orientation of the imaging table with respect to the scanning gantry. In this example, as shown in FIG. 18, a shielding plate 7 that blocks the reflected light 612 is installed in the vicinity of the laser marking device 6. Then, a horizontal distance Δx1 between the position of the cross line 613 of the reflected light 612 appearing on the plate surface of the shielding plate 7 and the position of the laser emission port 62 of the laser marking device 6 is obtained. Then, using the following relational expression, the obtained distance Δx1 and the distance from the reflecting surface 511p of the mirror 511 to the plate surface of the shielding plate 7, that is, the optical path length b2 of the reflected light 612, are perpendicular to the rotating surface 11p. A deviation angle β in the moving direction of the cradle 21 from the direction is obtained. This deviation angle β becomes an adjustment error of the azimuth in the horizontal plane direction of the imaging table 2 with respect to the scanning gantry 1.

  Δx1≈b2 · sin2β (Formula 2)

  In step T8, the tilt adjustment error in the vertical plane direction of the imaging table 2 is obtained with reference to the laser beam 61 irradiated on the mirror 511.

  For example, it is determined how much the moving direction of the cradle 21 is deviated from the trajectory of the laser beam 61 irradiated toward the mirror 511.

  FIG. 19 is a diagram for explaining a process of obtaining an adjustment error of the tilt in the vertical plane direction of the imaging table. In this example, as shown in FIG. 19, the laser marking device 6 is installed behind the cradle 21, and the shielding plate 7 that blocks the laser light 61 is placed at a predetermined position from the center to the rear of the cradle 21. . Then, the cradle 21 is moved forward by a predetermined distance in the direction approaching the scanning gantry 1. At this time, the movement distance Δy2 in the vertical direction of the height position of the cross line 613 appearing on the plate surface of the shielding plate 7 with respect to the cradle 21 is obtained. Then, the deviation angle γ of the cradle 21 from the horizontal plane is obtained from the predetermined distance b3 that the cradle 21 has moved and the moving distance Δy2 of the cross line 613 of the laser light 61 using the following relational expression. This deviation angle γ becomes an adjustment error of the tilt in the vertical plane direction of the imaging table 2.

  Δy2≈b3 · sinγ (Formula 3)

  According to such an alignment measurement method of the X-ray CT apparatus, an optical mirror 511 is installed in the vicinity of the rotation axis GA of the rotation unit 11 of the scanning gantry 1, and the reflection surface 511p of the mirror 511- is the rotation surface 11p. The reflection light 611 of the mirror 511 or the reflected light 612 of the laser light 61 irradiating the mirror 511 with respect to the reflection surface 511p of the mirror 511 or the reflection light 612 of the mirror 511 can be accurately adjusted. Or as a reference line. As a result, the alignment accuracy of the X-ray CT apparatus can be accurately measured.

  The embodiments of the invention are not limited to the above-described embodiments, and various additions and changes can be made without departing from the spirit of the invention.

  For example, in the above alignment adjustment method and alignment measurement method, the combination of the steps may be changed or the order of the steps may be changed.

  The light applied to the mirror is not limited to laser light, and any light beam having directivity may be used.

  The invention can be applied not only to a general X-ray CT apparatus but also to other apparatuses having a CT function, such as a PET-CT apparatus, an Angio-CT apparatus, a radiotherapy apparatus having a CT function, and the like. .

DESCRIPTION OF SYMBOLS 1 Scanning gantry 11 Rotating part 11p Rotating surface 111 Stage 112 Mounted part 2 Imaging table 21 Cradle 22 Cradle support part 23 Lifting part 5 Mirror jig 51 Mirror part 511 Optical mirror 511p Reflecting surface 512 Plate member 513 Screw 514 Spring 515 Hole 52 Base portion 521 Screw hole 53 Mounting portion 6 Laser marking device 61 Laser light 611 Incident light 612 Reflected light 613 Cross line 62 Outlet 7 Shield plate 9 Floor

Claims (14)

Installing a mirror in the vicinity of the rotation axis of the rotating part of the scanning gantry so as to rotate integrally with the rotating part;
Based on the change in the trajectory of the reflected light by the mirror of the light beam when the rotating unit is rotated while irradiating a light beam having directivity toward the mirror, the reflecting surface of the mirror is Adjusting the tilt of the mirror so as to be parallel to the rotating surface of the rotating part;
An alignment adjustment method for an X-ray CT apparatus, comprising: adjusting a tilt angle of the rotating unit based on a trajectory of light reflected by the mirror of a light beam irradiated horizontally toward the mirror.   2. The alignment adjustment method for an X-ray CT apparatus according to claim 1, wherein the step of adjusting the tilt angle of the rotating unit is a step of adjusting the rotating surface of the rotating unit to be perpendicular to a horizontal plane.   The step of adjusting the tilt angle of the rotating unit includes the height of the trajectory of light incident on the mirror and the height of the trajectory of light reflected by the mirror. The method for adjusting the alignment of X-ray CT according to claim 2, wherein the adjustment is performed so that the values coincide with each other. Installing a mirror in the vicinity of the rotation axis of the rotating part of the scanning gantry so as to rotate integrally with the rotating part;
Based on the change in the trajectory of the reflected light by the mirror of the light beam when the rotating unit is rotated while irradiating a light beam having directivity toward the mirror, the reflecting surface of the mirror is Adjusting the tilt of the mirror so as to be parallel to the rotating surface of the rotating part;
The scanning gantry and the scanning gantry are arranged so that a trajectory of light incident on the mirror and a trajectory of light reflected by the mirror overlaps when viewed in the vertical direction. Adjusting the position of at least one of the light sources of the light beam;
An alignment adjustment method for an X-ray CT apparatus, comprising: adjusting a position and / or an inclination of an imaging table based on a trajectory of a light beam irradiated toward the mirror.   The step of adjusting the position and / or inclination of the imaging table is a step of adjusting so that the moving direction of the top plate on the imaging table is parallel to the trajectory of the reference light beam. Alignment adjustment method for line CT apparatus.   The step of adjusting the tilt of the mirror is a step of adjusting the trajectory of the reflected light of the light beam irradiated toward the mirror to be constant regardless of the rotation of the rotating unit. The alignment adjustment method of the X-ray CT apparatus according to claim 1. Installing a mirror in the vicinity of the rotation axis of the rotating part of the scanning gantry so as to rotate integrally with the rotating part;
Based on the change in the trajectory of the reflected light by the mirror of the light beam when the rotating unit is rotated while irradiating a light beam having directivity toward the mirror, the reflecting surface of the mirror is Adjusting the tilt of the mirror so as to be parallel to the rotating surface of the rotating part;
An alignment measurement method for an X-ray CT apparatus, comprising: obtaining a tilt angle of the rotating unit based on a trajectory of light reflected by the mirror of a light beam irradiated horizontally toward the mirror. Installing a mirror in the vicinity of the rotation axis of the rotating part of the scanning gantry so as to rotate integrally with the rotating part;
Based on the change in the trajectory of the reflected light by the mirror of the light beam when the rotating unit is rotated while irradiating a light beam having directivity toward the mirror, the reflecting surface of the mirror is Adjusting the tilt of the mirror so as to be parallel to the rotating surface of the rotating part;
Irradiating the light beam toward the mirror horizontally and so that the trajectory overlaps the center line of the imaging table when viewed in the vertical direction;
Obtaining a positional relationship between the rotating surface of the rotating unit and the moving direction of the top plate on the imaging table based on the trajectory of the light beam incident on the mirror and the trajectory of reflected light from the mirror; An X-ray CT apparatus alignment measurement method provided. Installing a mirror in the vicinity of the rotation axis of the rotating part of the scanning gantry so as to rotate integrally with the rotating part;
Based on the change in the trajectory of the reflected light by the mirror of the light beam when the rotating unit is rotated while irradiating a light beam having directivity toward the mirror, the reflecting surface of the mirror is Adjusting the tilt of the mirror so as to be parallel to the rotating surface of the rotating part;
A light source of the light beam so that a trajectory of light incident on the mirror and a trajectory of light reflected by the mirror overlaps when viewed in the vertical direction. Adjusting the position of
Alignment measurement of an X-ray CT apparatus comprising a step of determining a positional relationship between a rotating surface of the rotating unit and a moving direction of the top plate on the imaging table with reference to the trajectory of the light beam irradiated toward the mirror Method.   The X-ray CT apparatus alignment measurement method according to claim 1, wherein the light beam is laser light. A mirror section having a mirror and a tilt adjustment mechanism of the reflecting surface of the mirror;
A base part on which the mirror part is installed;
An attachment portion for attaching the base portion to the rotating portion of the scanning gantry,
The X-ray CT apparatus alignment jig, wherein the mirror unit is disposed so as to be positioned in the vicinity of a rotation axis of the rotating unit when the base unit is attached to the rotating unit.   An X-ray CT apparatus comprising: a rotating portion of a scanning gantry having a mounted portion to which a base portion of the alignment jig according to claim 11 is attached.   An X-ray CT apparatus in which the tilt angle of the rotating part of the scanning gantry is adjusted using the alignment adjustment method according to any one of claims 1 to 3.   An X-ray CT apparatus in which the position and / or inclination of the imaging table is adjusted using the alignment adjustment method according to claim 4.

Images