Collimator assembly having multi-piece components

• US 20040218713A1
• Filed: 05/02/2003
• Published: 11/04/2004
• Est. Priority Date: 05/02/2003
• Status: Active Grant

• Current Assignee: General Electric Company
• Original Assignee: GE Medical Systems Global Technology Company LLC (GE Healthcare Technologies, Inc.)
• Inventors: Hoffman, David M.
• Granted Patent: US 6,934,354 B2
• Time in Patent Office: Days
• US Class Current: 378/19
• CPC Class Codes: A61B 6/032 Transmission computed tomography [CT]
• CPC Class Codes: A61B 6/06 Diaphragms
• CPC Class Codes: A61B 6/4233 using matrix detectors
• 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: G01T 1/1648 Ancillary equipment for scintillation cameras, e.g. reference markers, devices for removing motion artifacts, calibration devices adapted for flow studies G01T1/1647
• CPC Class Codes: G21K 1/025 using multiple collimators, e.g. Bucky screens; other devices for eliminating undesired or dispersed radiation

Abstract

The present invention is directed to a collimator assembly defined by a series of multi-piece collimator elements or plates that extend along at least one dimension of a scintillator pack. Each collimator element has a collimating component and a shielding component that are structurally independent from one another. The collimating components may be connected to the shielding components or separated by a small air gap. The shielding components are wider than the collimating components but the collimating components have a greater height. With this construction, the collimator assembly optimizes collimation and shielding with lower material requirements and reduced overall size.

Claims

1. A collimator for a CT detector array, the collimator comprising:

a first component configured to collimate high frequency electromagnetic energy rays projected from a projection source toward a subject to be scanned along a projection path; and

a second component configured to shield at least one of a scintillator edge, a reflector, and a photodiode of a CT detector array.

2. The collimator of claim 1 wherein the first component is independent from the second component.

3. The collimator of claim 1 wherein the first component has a width narrower than a width of the second component.

4. The collimator of claim 1 wherein the first component has a thickness greater than a thickness of the second component parallel to the projection path.

5. The collimator of claim 4 wherein the first component has a width less than 200 microns.

6. The collimator of claim 4 wherein the first component and the second component are constructed from materials having high atomic numbers.

7. The collimator of claim 6 wherein the first component is constructed from at least tungsten.

8. The collimator of claim 6 wherein the first component is constructed from material different from the second component.

9. A CT system comprising:

a rotatable gantry having a bore centrally disposed therein and configured to receive a subject to be scanned;

a table movable fore and aft through the bore and configured to position the subject for data acquisition;

a high frequency electromagnetic energy projection source positioned within the rotatable gantry and configured to emit high frequency electromagnetic energy toward the subject along a projection path;

a CT detector array configured to receive high frequency electromagnetic energy impinged by the subject, the CT detector array including;

a scintillator array configured to received high frequency electromagnetic energy and output light relative thereto;

a plurality of collimating elements to filter high frequency electromagnetic energy scatter;

a plurality of shielding elements secured to the scintillator array to at least shield scintillator edges from energy absorption; and

a photodiode array configured to detect light output of the scintillator array and output a series of electrical signals;

a DAS configured to received the electrical signals from the photodiode array; and

an image reconstructor configured to reconstruct an image of the subject from the electrical signals received by the DAS.

10. The CT system of claim 9 wherein each shielding element has a width greater than a width of each collimating element along an x-axis.

11. The CT system of claim 10 wherein each collimating element has a width not exceeding approximately 200 microns.

12. The CT system of claim 11 wherein each collimating element has a width not exceeding approximately 50 microns.

13. The CT system of claim 12 wherein each collimating element has a width of approximately 25 microns.

14. The CT system of claim 9 where the plurality of collimating elements and the plurality of shielding elements are fabricated from at least one material having a high atomic number.

15. The CT system of claim 9 wherein the plurality of shielding elements is fabricated from one of composite materials and cast materials.

16. The CT system of claim 9 incorporated into a medical imaging scanner.

17. A method of manufacturing a CT detector array having individual detector cell optimization, the method comprising the steps of:

forming a scintillator pack defining a plurality of scintillators;

depositing shielding elements on the scintillator pack between adjacent scintillators;

forming an array of collimator elements and aligning the array such that each collimator element generally aligns with a corresponding shielding element; and

coupling a photodiode array to the scintillator pack.

18. The method of claim 17 wherein the shielding elements are independent of the collimating elements.

19. The method of claim 17 wherein the step of depositing the shielding elements includes the step of directly casting shielding material between adjacent scintillators.

20. The method of claim 19 wherein the step of depositing further includes the step of etching a layer of shielding material applied to the scintillator pack.

21. The method of claim 17 wherein each collimator element has a thickness that exceeds a thickness of each shielding element along a y-axis.

22. The method of claim 21 wherein each collimating element has a width not exceeding approximately 50 microns.