PRE-PATIENT COLLIMATOR WITH FOCAL SPOT TRACKING CAPABILITY

• US 20170209106A1
• Filed: 01/21/2016
• Published: 07/27/2017
• Est. Priority Date: 01/21/2016
• Status: Active Grant

• Current Assignee: Minfound Medical Systems Company Limited
• Original Assignee: FMI Medical Systems Co., Ltd.
• Inventors: Ikhlef, Abdelaziz
• Granted Patent: US 10,314,553 B2
• Time in Patent Office: Days
• CPC Class Codes: A61B 6/032 Transmission computed tomography [CT]
• CPC Class Codes: A61B 6/06 Diaphragms
• CPC Class Codes: A61B 6/4021 involving movement of the focal spot
• CPC Class Codes: A61B 6/4291 the detector being combined with a grid or grating
• CPC Class Codes: A61B 6/5205 involving processing of raw data to produce diagnostic data
• CPC Class Codes: A61B 6/545 involving automatic set-up of acquisition parameters
• CPC Class Codes: A61B 6/582 Calibration
• CPC Class Codes: A61B 6/583 using calibration phantoms
• CPC Class Codes: G21K 1/02 using diaphragms, collimators

Abstract

A CT scanning system includes a rotatable gantry having an opening for receiving an object to be scanned, an x-ray tube, and a detector comprising an imaging area of pixels and a calibration area of pixels. The system further includes a pre-patient collimator positioned between the x-ray tube and the detector having first and second apertures that pass x-rays respectively to at least a portion of the imaging area of pixels, and to the calibration area of pixels, a motor configured to move the pre-patient collimator, and a computer programmed to determine a focal spot location using energy derived from x-rays that fall upon the calibration area of pixels, and issue commands to a motor to adjust a position of the pre-patient collimator based on the determination.

Claims

1. A CT system comprising:

a rotatable gantry having an opening for receiving an object to be scanned;

an x-ray tube;

a detector comprising an imaging area of pixels and a calibration area of pixels;

a pre-patient collimator positioned between the x-ray tube and the detector having first and second apertures that pass x-rays respectively to at least a portion of the imaging area of pixels, and to the calibration area of pixels;

a motor configured to move the pre-patient collimator; and

a computer programmed to;

determine a focal spot location using energy derived from x-rays that fall upon the calibration area of pixels; and

issue commands to a motor to adjust a position of the pre-patient collimator based on the determination.

2. The CT system of claim 1, wherein the imaging area of pixels and the calibration area of pixels are contiguous with one another.

3. The CT system of claim 1, wherein the imaging area of pixels and the calibration area of pixels have different widths in a Z-direction of the CT scanning system.

4. The CT system of claim 1, wherein the calibration area of pixels includes:

a first area of pixels for providing reference signals; and

a second area of pixels for tracking focal spot motion such that the computer determines the focal spot location.

5. The CT system of claim 4, wherein:

the first area of pixels is one or more rows of central pixels as defined along the Z-direction; and

the second area of pixels are outermost rows of pixels on either side of the first area of pixels as defined along the Z-direction.

6. The CT system of claim 5, wherein the computer is programmed determine a Z-position of the focal spot location using the energy derived from the x-rays that fall upon the second area of pixels.

7. The CT system of claim 1, wherein the computer is programmed to issue commands to the motor to adjust the position of the pre-patient collimator in the Z-direction.

8. The CT system of claim 1, wherein the pre-patient collimator includes a plurality of pre-patient apertures that are not contiguous with one another, one of which is comprised of the first and second apertures, the other apertures of which include both imaging apertures and calibration apertures that are contiguous with one another.

9. The CT system of claim 8, wherein the calibration apertures of the other apertures all have aperture sizes that are approximately the same.

10. The CT system of claim 8, wherein the imaging apertures of the other apertures have widths in the Z-direction that are different from one another such that the x-rays that pass therethrough fall upon different sized portions of the imaging area of pixels.

11. A method of CT imaging, comprising:

passing x-rays through an opening in a pre-patient collimator, through an object, and to at least a portion of a detector, the detector including imaging pixels and calibration pixels;

determining a focal spot location using energy derived from x-rays that fall upon the calibration area of pixels; and

adjusting a position of the pre-patient collimator based on the determination.

12. The method of claim 11, wherein passing the x-rays through the opening includes passing the x-rays to the imaging area of pixels and the calibration area of pixels that are contiguous with one another.

13. The method of claim 11, wherein the imaging area of pixels and the calibration area of pixels have different widths in a Z-direction of the CT scanning system.

14. The method of claim 11, wherein the calibration area of pixels includes:

a first area of pixels for providing reference signals; and

a second area of pixels for tracking focal spot motion such that the computer determines the focal spot location.

15. The method of claim 14, wherein:

the first area of pixels is one or more rows of central pixels as defined along the Z-direction; and

the second area of pixels are outermost rows of pixels on either side of the first area of pixels as defined along the Z-direction.

16. The method of claim 15, further comprising determining a Z-position of the focal spot location using the energy derived from the x-rays that fall upon the second area of pixels.

17. The method of claim 11, wherein adjusting the position of the pre-patient collimator comprises adjusting the position of the pre-patient collimator in the Z-direction.

18. The method of claim 11, wherein the pre-patient collimator includes a plurality of pre-patient apertures that are not contiguous with one another, one of which is comprised of the first and second apertures, the other apertures of which include both imaging apertures and calibration apertures that are contiguous with one another.

19. The method of claim 18, wherein the calibration apertures of the other apertures all have aperture sizes that are approximately the same.

20. The method of claim 18, wherein the imaging apertures of the other apertures have widths in the Z-direction that are different from one another such that the x-rays that pass therethrough fall upon different sized portions of the imaging area of pixels.