X-RAY CT APPARATUS

• US 20070003005A1
• Filed: 06/29/2006
• Published: 01/04/2007
• Est. Priority Date: 06/30/2005
• Status: Active Grant

• Current Assignee: Toshiba Medical Systems Corporation (Canon Inc.), Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Toshiba Medical Systems Corporation (Canon Inc.), Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: MATSUDA, Keiji
• Granted Patent: US 7,535,987 B2
• Time in Patent Office: Days
• US Class Current: 378/16
• CPC Class Codes: A61B 6/583 using calibration phantoms
• CPC Class Codes: G01N 2223/419 computed tomograph
• CPC Class Codes: G01N 2223/612 biological material
• CPC Class Codes: G01N 23/046 using tomography, e.g. computed tomography [CT]
• CPC Class Codes: H05G 1/70 Circuit arrangements for X-ray tubes with more than one anode; Circuit arrangements for apparatus comprising more than one X ray tube or more than one cathode H05G1/58 takes precedence

Abstract

An X-ray CT apparatus includes a plurality of X-ray tubes, a plurality of X-ray detectors corresponding to the plurality of X-ray tubes, respectively, a support mechanism which supports the X-ray tubes and the X-ray detectors to allow the X-ray tubes and the X-ray detectors to rotate about a single rotation axis, a reconstruction unit which reconstructs image data on the basis of outputs from the X-ray detectors, and a plurality of filters which are respectively provided for the plurality of X-ray tubes and each have a characteristic in which an X-ray path length changes along a curve approximate to an inverted Gaussian curve from the rotation center to the two ends of an X-ray beam.

Claims

1. An X-ray CT apparatus comprising:

a plurality of X-ray tubes;

a plurality of X-ray detectors corresponding to said plurality of X-ray tubes, respectively;

a support mechanism which supports the X-ray tubes and the X-ray detectors to allow the X-ray tubes and the X-ray detectors to rotate about a single rotation axis;

a reconstruction unit which reconstructs image data on the basis of outputs from the X-ray detectors; and

a plurality of filters which are respectively provided for said plurality of X-ray tubes and each have a characteristic in which an X-ray path length changes along a curve approximate to an inverted Gaussian curve from the rotation center to two ends of an X-ray beam.

2. An apparatus according to claim 1, further comprising a mechanism which attaches/detaches the filters.

3. An apparatus according to claim 1, which further comprises a plurality of slits which are respectively provided for said plurality of X-ray tubes and limit X-ray thicknesses, and in which

the filter is placed between the X-ray tube and the slit.

4. An apparatus according to claim 1, wherein said each filter further has a characteristic in which an intensity of X-rays transmitted through said each filter changes along a curve approximate to a Gaussian curve from the rotation center to two ends of an X-ray beam.

5. An apparatus according to claim 1, wherein said each filter further has a characteristic in which an intensity of X-rays transmitted through said each filter and a cylindrical homogeneous phantom changes curvilinearly from the rotation center to two ends of an X-ray beam.

6. An apparatus according to claim 1, wherein said each filter has a characteristic in which an intensity of X-rays transmitted through the filter exceeds 90% of a maximum intensity at the rotation center at a middle portion less than 10 cm away from the rotation center, and an intensity at a peripheral portion more than 20 cm away from the rotation center is less than 50% of the maximum intensity at the rotation center.

7. An apparatus according to claim 1, wherein said each filter has a curved surface shape with a thickness of a central portion being small, and a thickness gradually increasing toward peripheral portions.

8. An X-ray CT apparatus comprising:

a plurality of X-ray tubes;

a plurality of X-ray detectors corresponding to said plurality of X-ray tubes, respectively;

a support mechanism which supports the X-ray tubes and the X-ray detectors to allow the X-ray tubes and the X-ray detectors to rotate about a single rotation axis;

a reconstruction unit which reconstructs image data on the basis of outputs from the X-ray detectors; and

a plurality of filters which are respectively provided for said plurality of X-ray tubes and each have a characteristic in which an intensity of X-rays transmitted through said each filter changes along a curve approximate to a Gaussian curve from the rotation center to two ends.

9. An X-ray CT apparatus comprising:

a plurality of X-ray tubes;

a plurality of X-ray detectors corresponding to said plurality of X-ray tubes, respectively;

a support mechanism which supports the X-ray tubes and the X-ray detectors to allow the X-ray tubes and the X-ray detectors to rotate about a single rotation axis;

a reconstruction unit which reconstructs image data on the basis of outputs from the X-ray detectors; and

a plurality of filters which are respectively provided for said plurality of X-ray tubes and each have a characteristic in which an intensity of X-rays transmitted through the filter and a cylindrical homogeneous phantom decreases curvilinearly from the rotation center to two ends.

10. An X-ray CT apparatus comprising:

a plurality of X-ray tubes;

a plurality of X-ray detectors corresponding to said plurality of X-ray tubes, respectively;

a support mechanism which supports the X-ray tubes and the X-ray detectors to allow the X-ray tubes and the X-ray detectors to rotate about a single rotation axis;

a reconstruction unit which reconstructs image data on the basis of outputs from the X-ray detectors; and

a plurality of filters which are respectively provided for said plurality of X-ray tubes and each have a characteristic in which an intensity of X-rays transmitted through the filter exceeds 90% of a maximum intensity at the rotation center at a middle portion less than 10 cm away from the rotation center, and an intensity at a peripheral portion more than 20 cm away from the rotation center is less than 50% of the maximum intensity at the rotation center.

11. A filter provided for an X-ray tube of an X-ray CT apparatus, which has a characteristic in which an X-ray path length changes along a curve approximate to an inverted Gaussian curve from a center to two ends.

12. A filter provided for an X-ray tube of an X-ray CT apparatus, which has a characteristic in which an intensity of X-rays transmitted through the filter changes along a curve approximate to a Gaussian curve from a center to two ends.

13. A filter provided for an X-ray tube of an X-ray CT apparatus, which has a characteristic in which an intensity of X-rays transmitted through the filter and a cylindrical homogeneous phantom changes curvilinearly from a center to two ends.

14. A filter provided for an X-ray tube of an X-ray CT apparatus, which has a characteristic in which an intensity of X-rays transmitted through the filter exceeds 90% of a maximum intensity at a center at a middle portion less than 10 cm away from the center, and an intensity at a peripheral portion more than 20 cm away from the center is less than 50% of the maximum intensity at the center.