CT detector having a segmented optical coupler and method of manufacturing same

• US 7,084,404 B2
• Filed: 11/04/2005
• Issued: 08/01/2006
• Est. Priority Date: 03/12/2003
• Status: Expired due to Term

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Hoffman, David M., Hoge, Michael F.
• Primary Examiner(s): GAGLIARDI, ALBERT J
• Application Number:
  US11/163,973
• Publication Number:
  US 20060043305A1
• Time in Patent Office: 270 Days
• Field of Search: 250/363.02, 250/368, 250/370.11
• US Class Current: 250/363.02
• CPC Class Codes: A61B 6/032 Transmission computed tomography [CT]
• CPC Class Codes: A61B 6/4291 the detector being combined with a grid or grating
• 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 1/2002 Optical details, e.g. reflecting or diffusing layers
• CPC Class Codes: G01T 1/20183 Arrangements for preventing or correcting crosstalk, e.g. optical or electrical arrangements for correcting crosstalk
• CPC Class Codes: G01T 1/20185 Coupling means between the photodiode and the scintillator, e.g. optical couplings using adhesives with wavelength-shifting fibres
• CPC Class Codes: G01T 1/202 the detector being a crystal
• CPC Class Codes: G01T 1/2985 In depth localisation, e.g. using positron emitters; Tomographic imaging (longitudinal and transverse section imaging; apparatus for radiation diagnosis sequentially in different planes, steroscopic radiation diagnosis); using external radiation sources A61B6/02

Abstract

The present invention is a directed to a CT detector for a CT imaging system that incorporates a segmented optical coupler between a photodiode array and a scintillator array. The segmented optical coupler also operates as a light collimator which improves the light collection efficiency of the photodiode array. The segmented optical coupler is defined by a series of reflector elements that collectively form a plurality of open cells. The open cells form light transmission cavities and facilitate the collimation of light from a scintillator to a photodiode. The cavities may be filled with optical epoxy for sealing to the photodiode array.

Claims

1. A CT system comprising:

a rotatable gantry having a bore centrally disposed therein;

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

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

a detector array disposed within the rotatable gantry and configured to detect high frequency electromagnetic energy projected by the projection source and impinged by the subject, the detector array including;

a plurality of scintillators arranged in a scintillator array;

a plurality of photodiodes arranged in a photodiode array; and

a light collimator having a plurality of collimator plates that collectively define a plurality of light transmission cavities disposed between the plurality of scintillators and the plurality of photodiodes, the plurality of collimator plates formed of light reflective material and arranged such that each light transmission cavity is disposed entirely between a light reception surface of a photodiode and a light emission surface of a scintillator, wherein the plurality of light transmission cavities are air-filled.

2. The CT system of claim 1 wherein the detector array includes a thin film optical coupler coupling the light collimator to the plurality of photodiodes.

3. The CT system of claim 1 wherein each light transmission cavity is defined by a number of reflector elements.

4. The CT system of claim 3 wherein each light transmission cavity collimates light between a single scintillator and a single photodiode.

5. The CT system of claim 1 wherein the plurality of collimator plates are bonded to at least one of the plurality of scintillators and the plurality of photodiodes.

6. The CT system of claim 1 configured to acquire CT data from a medical patient.

7. A CT scanner having a detector array designed to convert received x-rays to electrical signals that can be processed to reconstruct a CT image, the detector array comprising:

a scintillator array;

a photodiode array; and

a light collimator array formed between the scintillator array and the photodiode array, the light collimator array arranged to sit atop a light reception surface of the photodiode array and define a single air-filled optical transmission window between an aligned scintillator and an aligned photodiode, wherein the light collimator array is defined by a 2D grid of collimator plates, each collimator plate including light reflective material.

8. The CT scanner of claim 7 wherein the light collimator array is bonded to at least one of the scintillator array and the photodiode array.

9. The CT scanner of claim 7 wherein each collimator plate further includes x-ray absorbent material.

10. The CT scanner of claim 7 wherein voids defined between adjacent collimator plates are epoxy-filled.

11. The CT scanner of claim 7 configured to acquire CT imaging data from a medical patient.

12. A CT imaging system comprising:

a rotatable gantry having a bore centrally disposed therein;

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

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

a detector array disposed within the rotatable gantry and configured to detect high frequency electromagnetic energy projected by the projection source and impinged by the subject, the detector array including;

a scintillator array;

a photodiode array; and

an optical window array secured between the scintillator array and a top surface of the photodiode array, the optical window array including a plurality of disjointed optically coupling cells, each cell sandwiched between a scintillator and a corresponding photodiode, wherein the plurality of disjointed optically coupling cells are air-filled.

13. The system of claim 12 wherein adjacent optically coupling cells are separated by a light reflective wall.

14. The system of claim 12 wherein the optical window array is bonded to at least one of the scintillator array and the photodiode array.

15. The system of claim 12 configured for medical imaging.