X-ray beam shaper

Patent metadata

Field	Value
Publication number	US-9349494-B2
Application number	US-201314381234-A
Country	US
Kind code	B2
Filing date	Feb 6, 2013
Priority date	Mar 7, 2012
Publication date	May 24, 2016
Grant date	May 24, 2016

Abstract

An imaging system ( 500 ) includes a focal spot ( 508 ) that rotates along a path around an examination region and emits a radiation beam that traverses a field of view of the examination region and a subject or object therein. The system further includes a detector array ( 520 ) that is located opposite the radiation source, across the examination region. The detector array detects radiation traversing the field of view and outputs a signal indicative of the detected radiation. The system further includes a beam shaper that is located between the radiation source and the examination region. The beam shaper rotates with the focal spot and, relative to the focal spot, in an opposite direction of the focal spot with a same angular frequency as the rotating of the focal spot and attenuates the radiation beam which reduces a flux density across the detector array at each rotational angle of the focal spot.

First claim

The invention claimed is:

1. An imaging system, comprising:
a focal spot configured to rotate along a path around an examination region and emit a radiation beam that traverses a field of view of the examination region;
a detector array located opposite the focal point and across the examination region, the detector array configured to detect radiation traversing the field of view and output a signal indicative of the detected radiation; and
a beam shaper located between the focal point and the examination region, the beam shaper configured to rotate with the focal spot and, relative to the focal spot, in an opposite direction of the focal spot with a same angular frequency as the rotating of the focal spot and attenuate the radiation beam which reduces a flux density across the detector array at each rotational angle of the focal spot.

2. The imaging system of claim 1 , further comprising:
a filter located between the focal spot and the beam shaper, wherein the filter attenuates the beam so that an intensity of the beam at each pixel is approximately the same.

3. The imaging system of claim 2 , wherein the beam shaper includes an x-ray attenuating material that attenuates radiation traversing the field of view that does not traverse a subject or object disposed in the examination region.

4. The imaging system of claim 1 , wherein the beam shaper has an elliptical shaped outer perimeter and an elliptical shaped inner perimeter that defines a material free region through the beam shaper and that corresponds to a cross sectional region along the shoulders, abdomen, and/or thorax of a human subject.

5. The imaging system of claim 4 , further comprising:
second and third material free regions corresponding to cross sectional regions of the arms of the human subject.

6. The imaging system of claim 1 , wherein the beam shaper has an elliptical shaped outer perimeter and two circular shaped inner perimeter regions, each defining a material free region through the beam shaper and corresponding to a leg of a human subject.

7. The imaging system of claim 1 , wherein the beam shaper has a first elliptical shaped outer perimeter and second circular shaped inner perimeter region that defines a material free region through the beam shaper and that corresponds to a head of a human subject.

8. The imaging system of claim 1 , wherein the beam shaper is a three dimensional structure with different regions corresponding to different regions of a human subject.

9. The imaging system of claim 1 , further comprising:
a support that supports the beam shaper with respect to the focal spot and rotates along with the focal spot;
a drive system that moves the beam shaper; and
a controller that controls the drive system.

10. The imaging system of claim 9 , wherein the support rotatably supports the beam shaper, and the controller controls the drive system to rotate the beam shaper with respect to the focal spot.

11. The imaging system of claim 9 , wherein the support rotatably supports the beam shaper, and the controller controls the drive system to rotate the beam shaper to a predetermined rotational position and holds the beam shaper at that predetermined rotational position while rotating the rotating gantry.

12. The imaging system of claim 9 , wherein the support supports the beam shaper for radial motion, and the controller controls the drive system to radially move the beam shaper for a scan.

13. The imaging system of claim 9 , wherein the support supports the beam shaper for circumferential motion, and the controller controls the drive system to circumferential move the beam shaper for a scan.

14. A method, comprising:
rotating a focal spot and a beam shaper, together, through a predetermined angular range on a path around an examination region and a subject or object therein at a given angular frequency during a scan of the subject or object in a first direction;
concurrently, rotating the beam shaper in a direction opposite of the first direction, relative to the focal spot, at the same given angular frequency; and
concurrently, detecting radiation emitted by the focal spot that traverses the beam shaper, a field of view, and the subject or object, and strikes a detector located opposite the focal spot, and generating an output signal indicative thereof.

15. The method of claim 14 , wherein the beam traversing the beam shaper and illuminating the detector array has a predetermined flux density profile across the detector array for each angular range for a plurality of different angular ranges.

16. The method of claim 15 , further comprising:
pre-shaping the beam so that an intensity of the beam at each pixel is the same when scanning a subject or object that completely fills the field of view.

17. The method of claim 14 , further comprising:
moving the beam shaper to align the beam shaper with an off center subject or object.

18. The method of claim 14 , further comprising:
radially translating or rotating the beam shaper based on a size of the subject or object.

19. The method of claim 14 , further comprising:
rotating the beam shaper to a predetermined angular position with respect to the focal spot; and
holding the beam shaper at the predetermined angular position while rotating the focal spot and the beam shaper, together, through the predetermined angular range on the path around the examination region.

Assignees

• Koninkl Philips Nv

Inventors

• Roessl Ewald

Classifications

• A61B6/4035

  the source being combined with a filter or grating · CPC title

• A61B6/06

  Diaphragms · CPC title

• A61B6/032

  Transmission computed tomography [CT] · CPC title

• A61B6/4021

  involving movement of the focal spot · CPC title

• G21K1/02 Primary

  using diaphragms, collimators · CPC title