X-RAY CT APPARATUS, METHOD OF ALIGNING PHANTOM, AND PHANTOM RETAINING TOOL

Abstract

The present invention comprises a top plate 31 for placing a cylindrical phantom 100, an X-ray tube 22 that generates X-rays, an X-ray detector 23 that detects X-rays transmitted through the phantom 100 placed on a top plate 31, a supporting body drive part 25 that rotates the X-ray tube 22 and X-ray detector 23, a tomographic image data generating part 60 that generates tomographic image data on the phantom 100 based on a results of detecting X-rays by the X-ray detector 23, a calculation processing part 80 that calculates displacement of the cylinder axis J of the phantom 100 relative to the center of rotation (center of scan) by the supporting body drive part 25, based on the tomographic image data, and the angle of gradient of the cylinder axis J relative to the normal direction (direction of slice) of the rotation plane of said rotation, and a monitor 5 that displays the calculated results.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic perspective view showing the appearance of the composition of a cylindrical phantom to evaluate the performance of X-ray CT apparatus. FIG. 1B is a schematic cross-section diagram showing the shape of a cross-section of a cylindrical phantom for performance evaluation of X-ray CT apparatus.

FIG. 2 is a schematic perspective view showing an example the appearance of the composition of the first embodiment of X-ray CT apparatus related to the invention.

FIG. 3 is a schematic block diagram showing an example of the internal composition of the first embodiment of X-ray CT apparatus related to the invention.

FIG. 4 is a schematic block diagram showing an example of the composition of the control system of the first embodiment of X-ray CT apparatus related to the invention.

FIG. 5A shows an outline of a tomographic image, based on tomographic image data of the phantom generated by the tomographic image generation part of the first embodiment of X-ray CT apparatus related to the invention. FIG. 5B shows an outline of a tomographic image, based on the partial tomographic image data corresponding to the case of the phantom extracted by the case extraction part in the first embodiment of X-ray CT apparatus related to the invention.

FIG. 6 is a schematic diagram for describing an example of selection modes for three different points on the partial tomographic image data by a circle center calculation part of the first embodiment of X-ray CT apparatus related to the invention.

FIG. 7 is a schematic diagram for describing an example of selection modes for four different points on the partial tomographic image data by an ellipse center calculation part of the first embodiment of X-ray CT apparatus related to the invention.

FIG. 8 is a flow chart showing an example of the action of the first embodiment of X-ray CT apparatus related to the invention.

FIG. 9 is a schematic perspective view showing the phantom positioned in the gradient in a modified example 3 of the first embodiment of X-ray CT apparatus related to the invention.

FIG. 10A is a schematic diagram showing a tomographic image of the phantom in the first slice position of the modified example 3 of the first embodiment of X-ray CT apparatus related to the invention. FIG. 10B is a schematic diagram showing a tomographic image in the second slice position of the modified example 3 of the first embodiment of X-ray CT apparatus related to the invention.

FIG. 11 is a schematic diagram showing an example of the composition of a maintenance system that performs maintenance of X-ray CT apparatus related to the invention.

FIG. 12 is a flow chart showing an example of the action of the second embodiment of X-ray CT apparatus related to the invention.

FIG. 13 is a schematic perspective view showing an example of the appearance of the composition of the third embodiment of X-ray CT apparatus related to the invention.

FIG. 14 is a schematic side-view showing an example of the composition of the phantom retaining tool of the third embodiment of X-ray CT apparatus related to the invention.

FIG. 15 is a schematic block diagram showing an example of the composition of the control system of the third embodiment of X-ray CT apparatus related to the invention.

FIG. 16 is a flow chart showing an example of the action of the third embodiment of X-ray CT apparatus related to the invention.

Claims

1. An X-ray CT apparatus, comprising: a top plate on which a phantom with a cylindrical housing is placed;an X-ray generator;an X-ray detector for X-rays transmitted through the phantom placed on the top plate;a rotational drive unit rotating said X-ray generator and said X-ray detector;a tomographic image data generator for generating tomographic image data for the phantom, based on the results of detecting X-rays by the X-ray detector;a calculation unit calculating information regarding displacement of the phantom relative from the center of rotation by the rotational drive unit, based on the generated tomographic image data; anda display device displaying information for alignment of the phantom, based on the calculated information regarding the displacement.

2. An X-ray CT apparatus, comprising: a top plate on which a phantom with a cylindrical housing is placed;an X-ray generator;an X-ray detector for X-rays transmitted through the phantom placed on the top plate;a rotational drive unit rotating said X-ray generator and said X-ray detector;a tomographic image data generator for generating tomographic image data for the phantom, based on the results of detecting X-rays by the X-ray detector;a calculation unit calculating information regarding displacement of the phantom relative from the center of rotation by the rotational drive unit, based on the generated tomographic image data; anda top plate drive unit moving the top plate to align the cylinder axis of the phantom with the center of rotation, based on the calculated information regarding the displacement.

3. An X-ray CT apparatus, comprising: a phantom retaining unit retaining a phantom with a cylindrical housing on a top plate;an X-ray generator;an X-ray detector for X-rays transmitted through the retained phantom;a rotational drive unit rotating said X-ray generator and said X-ray detector;a tomographic image data generator for generating tomographic image data for the phantom, based on the results of detecting X-rays by the X-ray detector;a calculation unit calculating information regarding displacement of the phantom relative from the center of rotation by the rotational drive unit, based on the generated tomographic image data; anda phantom drive unit moving the phantom to align the cylinder axis of the retained phantom with the center of rotation, based on the calculated information regarding the displacement.

4. The X-ray CT apparatus according to any one of claims 1 to 3, further comprising a storage device storing, in advance, the coordinates of the center of rotation by the rotation drive unit,wherein the calculation unit comprises:an extraction unit for extracting partial tomographic image data corresponding to the housing of the phantom from the tomographic image data generated by the tomographic image data generator;a circle center calculation unit calculating the coordinates of the center of a circle passing through three different points in the extracted partial tomographic image data; anda displacement calculation unit calculating displacement of the cylinder axis of the phantom relative to the center of rotation, based on the calculated coordinates of the center of the circle and the stored coordinates of the center of rotation.

5. The X-ray CT apparatus according to any one of claims 1 to 3, further comprising a storage device storing, in advance, coordinates of the center of rotation by the rotation drive unit, wherein the calculation unit comprises:an extraction unit extracting partial tomographic image data corresponding to the housing of the phantom from tomographic image data generated by the tomographic image data generator;an ellipse center calculation unit calculating the coordinates of the center of an ellipse passing through four different points in the extracted partial tomographic image data; anda displacement calculation unit calculating displacement of the cylinder axis of the phantom relative to the center of rotation, based on the calculated coordinates of the center of the ellipse and the stored coordinates of the center of rotation.

6. The X-ray CT apparatus according to claim 5, comprising: an error calculation unit calculating the error of different multiple points in the partial tomographic image data extracted by the extraction unit relative to the circle;a determination unit determining whether the calculated error exceeds a predetermined value; andan alarm information output device outputting alarm information when the error was determined to exceed the predetermined value.

7. The X-ray CT apparatus according to claim 6, comprising: an error calculation unit calculating the error of different multiple points in the partial tomographic image data extracted by the extraction unit relative to the ellipse;a determination unit determining whether the calculated error exceeds a predetermined value; andan alarm information output device outputting alarm information when the error was determined to exceed the predetermined value.

8. An X-ray CT apparatus, comprising: a top plate on which a phantom with a cylindrical housing is placed;an X-ray generator;an X-ray detector for X-rays transmitted through the phantom placed on the top plate;a rotational drive unit rotating said X-ray generator and said X-ray detector;a tomographic image data generator for generating tomographic image data for the phantom, based on the results of detecting X-rays by the X-ray detector;a calculation unit calculating the angle of gradient of the cylinder axis of the phantom relative to the normal direction of the rotation plane of rotation by the rotational drive unit, based on the generated tomographic image data; anda display device displaying information for alignment of the phantom, based on the calculated angle of gradient.

9. An X-ray CT apparatus, comprising: a top plate on which a phantom with a cylindrical housing is placed;an X-ray generator;an X-ray detector for X-rays transmitted through the phantom placed on the top plate;a rotational drive unit rotating said X-ray generator and said X-ray detector;a tomographic image data generator for generating tomographic image data for the phantom, based on the results of detecting X-rays by the X-ray detector;a calculation unit calculating the angle of gradient of the cylinder axis of the phantom relative to the normal direction of the rotation plane of rotation by the rotational drive unit, based on the generated tomographic image data; anda gradient drive unit tilting the X-ray generator and the X-ray detector integrally, based on the calculated angle of gradient, so as to align the normal direction of the rotation plane with the cylinder axis of the phantom.

10. An X-ray CT apparatus, comprising: a phantom retaining unit retaining a phantom with a cylindrical housing on a top plate;an X-ray generator;an X-ray detector for X-rays transmitted through the retained phantom;a rotational drive unit rotating said X-ray generator and said X-ray detector;a calculation unit calculating the angle of gradient of the cylinder axis of the phantom relative to the normal direction of the rotation plane of rotation by the rotational drive unit, based on the results of detecting X-rays by the X-ray detector; anda phantom gradient drive unit tilting the phantom, based on the calculated angle of gradient, so as to align the cylinder axis of the phantom with the normal direction of the rotation plane.

11. The X-ray CT apparatus according to any one of claims 8 to 10, wherein the calculation unit comprises: an extraction unit extracting partial tomographic image data corresponding to the housing of the phantom from the tomographic image data generated by the tomographic image data generator;a radius calculation unit calculating both the horizontal radius and the vertical radius of the ellipse passing through four different points in the extracted partial tomographic image data; anda gradient angle calculation unit calculating the angle of gradient, based on the calculated horizontal radius and vertical radius of the ellipse.

12. The X-ray CT apparatus according to claim 8, wherein: the tomographic image data generator generates multiple tomographic image data in different slice positions of the phantom;the calculation unit specifies the gradient direction of the cylinder axis of the phantom relative to the normal direction of the rotation plane, based on the generated multiple tomographic image data;the display device displays the specified gradient direction together with the angle of gradient.

13. The X-ray CT apparatus according to claim 9, wherein: the tomographic image data generator generates multiple tomographic image data in different slice positions of the phantom;the calculation unit specifies the gradient direction of the cylinder axis of the phantom relative to the normal direction of the rotation plane, based on the generated multiple tomographic image data;the gradient drive unit performs the integral tilting based on the specified gradient direction and the angle of gradient.

14. The X-ray CT apparatus according to the claim 10, wherein: the tomographic image data generator generates multiple tomographic image data in different slice positions of the phantom;the calculation unit specifies the gradient direction of the cylinder axis of the phantom relative to the normal direction of the rotation plane, based on the generated multiple tomographic image data;the phantom gradient drive unit tilts the phantom, based on the specified gradient direction and the angle of gradient.

15. The X-ray CT apparatus according to any one of claims 12 to 14, the calculation unit comprising: a extraction unit extracting partial tomographic image data corresponding to the housing of the phantom from all of the multiple tomographic image data generated by the tomographic image data generator; andan ellipse center calculation unit calculating the coordinates of the center of a ellipse passing through four different points with regard to all of the extracted multiple partial tomographic image data;wherein the calculation unit specifies the gradient direction, based on the calculated multiple coordinates of the center of the ellipses and slice positions of the multiple tomographic image data.

16. An X-ray CT apparatus, comprising: a top plate on which a phantom with a cylindrical housing is placed;an X-ray generator;an X-ray detector for X-rays transmitted through the phantom placed on the top plate;a rotational drive unit rotating said X-ray generator and said X-ray detector;a storage device storing, in advance, coordinates of the center of rotation by the rotation drive unit;a tomographic image data generator for generating tomographic image data for the phantom, based on the results of detecting X-rays by the X-ray detector;an extraction unit extracting partial tomographic image data corresponding to the housing of the phantom from the generated tomographic image data;a circle center calculation unit calculating the coordinates of the center of a circle passing through three different points in the extracted partial tomographic image data;a first displacement calculation unit calculating displacement of the cylinder axis of the phantom relative to the center of rotation, based on the calculated coordinates of the center of the circle and the stored coordinates of the center of rotation;an error calculation unit calculating error of different multiple points in the extracted partial tomographic image data relative to the circle;a determination unit determining whether the calculated error exceeds a predetermined value;an ellipse center calculation unit calculating the coordinates of the center of a ellipse passing through four different points in the extracted partial tomographic image data when the error was determined to exceed the predetermined value;a second displacement calculation unit calculating displacement of the cylinder axis of the phantom relative to the center of rotation, based on the calculated coordinates of the center of the ellipse and the stored coordinates of the center of rotation;a radius calculation unit calculating both the horizontal radius and the vertical radius of the ellipse when the error was determined to exceed the predetermined value;a gradient angle calculation unit calculating the angle of gradient of the cylinder axis of the phantom relative to the normal direction of the rotation plane of the rotation, based on the calculated horizontal radius and vertical direction; anda display device displaying the displacement calculated by the first displacement calculation unit when the error was determined not to exceed the predetermined value by the determination unit, and displaying the displacement calculated by the second displacement calculation unit and the angle of gradient calculated by the gradient angle calculation unit when the error was determined to exceed the predetermined value.

17. An X-ray CT apparatus, comprising: a top plate on which a phantom with a cylindrical housing is placed;an X-ray generator;an X-ray detector for X-rays transmitted through the phantom placed on the top plate;a rotational drive unit rotating said X-ray generator and said X-ray detector;a storage device storing, in advance, coordinates of the center of rotation by the rotation drive unit;tomographic image data generator for generating tomographic image data for the phantom, based on the results of detecting X-rays by the X-ray detector;an extraction unit extracting partial tomographic image data corresponding to the housing of the phantom from the generated tomographic image data;a circle center calculation unit calculating the coordinates of the center of a circle passing through three different points in the extracted partial tomographic image data;a first displacement calculation unit calculating displacement of the cylinder axis of the phantom relative to the center of rotation, based on the calculated coordinates of the center of the circle and the stored coordinates of the center of rotation;an error calculation unit calculating error of different multiple points in the extracted partial tomographic image data relative to the circle;a determination unit determining whether the calculated error exceeds a predetermined value;an ellipse center calculation unit calculating the coordinates of the center of a ellipse passing through four different points in the extracted partial tomographic image data when the error was determined to exceed the predetermined value;a second displacement calculation unit calculating displacement of the cylinder axis of the phantom relative to the center of rotation, based on the calculated coordinates of the center of the ellipse and the stored coordinates of the center of rotation;a radius calculation unit calculating both the horizontal radius and the vertical radius of the ellipse when the error was determined to exceed the predetermined value;a gradient angle calculation unit calculating the angle of gradient of the cylinder axis of the phantom relative to the normal direction of the rotation plane of the rotation, based on the calculated horizontal radius and vertical direction;a gradient drive unit tilting the X-ray generator and the X-ray detector integrally, based on the calculated angle of gradient, so as to align the normal direction of the rotation plane with the cylinder axis of the phantom; anda top plate drive unit moving the top plate to align the cylinder axis of the phantom with the center of rotation, based on the displacement calculated by the first displacement calculation unit, when the error was determined not to exceed the predetermined value by the determination unit, and moving the top plate to align the cylinder axis of the phantom with the center of rotation, based on the displacement calculated by the second displacement calculation unit, when the error was determined to exceed the predetermined value.

18. The X-ray CT apparatus according to claim 1 or claim 16, further comprising: a top plate operation device being operated to move the top plate; andunit notifying the position of the top plate operation device with the display by the display device.

19. The X-ray CT apparatus according to claim 8 or claim 16, further comprising: a gradient operation device being operated to tilt said X-ray generator and said X-ray detector integrally; andunit notifying the position of the gradient operation device with the display of the angle of gradient by the display device.

20. A method of aligning the phantom in an X-ray CT apparatus equipped with: a top plate on which a phantom with a cylindrical housing is placed; an X-ray generator; an X-ray detector for X-rays transmitted through the phantom placed on the top plate; a rotational drive unit rotating said X-ray generator and said X-ray detector; and a display device, comprising the steps of: generating tomographic image data for the phantom, based on the results of detecting X-rays by the X-ray detector;calculating information regarding displacement of the phantom relative to the center of rotation by the rotational drive unit, based on the generated tomographic image data; anddisplaying information for alignment of the phantom by the display device, based on the information regarding the calculated displacement.

21. A method of aligning the phantom in an X-ray CT apparatus equipped with: a top plate on which a phantom with a cylindrical housing is placed; an X-ray generator; an X-ray detector for X-rays transmitted through the phantom placed on the top plate; and a rotational drive unit rotating said X-ray generator and said X-ray detector, comprising the steps of: generating tomographic image data for the phantom, based on the results of detecting X-rays by the X-ray detector;calculating information regarding displacement of the phantom relative to the center of rotation by the rotational drive unit, based on the generated tomographic image data; andmoving the top plate to align the cylinder axis of the phantom with the center of rotation, based on information regarding the calculated displacement.

22. A method of aligning the phantom in an X-ray CT apparatus equipped with: a phantom retaining unit retaining a phantom with a cylindrical housing on a top plate; an X-ray generator; an X-ray detector for X-rays transmitted through the retained phantom; and a rotational drive unit rotating said X-ray generator and said X-ray detector, comprising the steps of: generating tomographic image data for the phantom, based on the results of detecting X-rays by the X-ray detector;calculating information regarding displacement of the phantom relative to the center of rotation by the rotational drive unit, based on the generated tomographic image data; andmoving the phantom to align cylinder axis of the retained phantom with the center of rotation, based on the information regarding the calculated displacement.

23. A method of aligning the phantom in an X-ray CT apparatus equipped with: a top plate on which a phantom with a cylindrical housing is placed; an X-ray generator; an X-ray detector for X-rays transmitted through the phantom placed on the top plate; a rotational drive unit rotating said X-ray generator and said X-ray detector; and a display device, comprising the steps of: generating tomographic image data for the phantom, based on the results of detecting X-rays by the X-ray detector;calculating the angle of gradient of the cylinder axis of the phantom relative to the normal direction of the rotation plane of rotation by the rotational drive unit, based on the generated tomographic image data; anddisplaying information for alignment of the phantom by the display device, based on the calculated angle of gradient.

24. A method of aligning the phantom in an X-ray CT apparatus equipped with: a top plate on which a phantom with a cylindrical housing is placed; an X-ray generator; an X-ray detector for X-rays transmitted through the phantom placed on the top plate; and a rotational drive unit rotating said X-ray generator and said X-ray detector, comprising the steps of: generating tomographic image data for the phantom, based on the results of detecting X-rays by the X-ray detector;calculating the angle of gradient of the cylinder axis of the phantom relative to the normal direction of the rotation plane of rotation by the rotational drive unit, based on the generated tomographic image data; andtilting said X-ray generator and said X-ray detector integrally, based on the calculated angle of gradient, to align the normal direction of the rotation plane with the cylinder axis of the phantom.

25. A method of aligning the phantom in an X-ray CT apparatus, equipped with: a phantom retaining unit retaining a phantom with a cylindrical housing on a top plate; an X-ray generator; an X-ray detector for X-rays transmitted through the retained phantom; and a rotational drive unit rotating said X-ray generator and said X-ray detector, comprising the steps of: generating tomographic image data for the phantom, based on the results of detecting X-rays by the X-ray detector;calculating the angle of gradient of the cylinder axis of the phantom relative to the normal direction of the rotation plane of rotation by the rotational drive unit, based on the generated tomographic image data; andtilting the phantom, based on the calculated angle of gradient, to align the cylinder axis of the phantom with the normal direction of the rotation plane.

26. A phantom retaining tool for retaining a phantom on a top plate of a bed apparatus of a X-ray CT apparatus, comprising: a phantom drive unit vertically and/or horizontally moving the phantom while it is retained on the top plate controlled by the control device of the X-ray CT apparatus.

27. A phantom retaining tool for retaining a phantom on a top plate of a bed apparatus of a X-ray CT apparatus, wherein projection data is collected while rotating a X-ray generator and a X-ray detector for the generated X-rays, and tomographic image data is generated based on the collected projection data, comprising: a phantom gradient drive unit changing the vertical and/or horizontal angle of the gradient of the phantom retained on the top plate controlled by the control device of the X-ray CT apparatus.