Multi-layer reflector for CT detector

• US 7,308,074 B2
• Filed: 12/11/2003
• Issued: 12/11/2007
• Est. Priority Date: 12/11/2003
• Status: Active Grant

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Jiang, Haochuan, Hoffman, David M.
• Primary Examiner(s): SONG, HOON K
• Application Number:
  US10/707,405
• Publication Number:
  US 20050129171A1
• Time in Patent Office: 1,461 Days
• Field of Search: 378/19, 378/4, 378/98.8, 250/370.11, 250/367, 250/368, 250/370.09
• US Class Current: 378/19
• CPC Class Codes: A61B 6/032 Transmission computed tomography [CT]
• CPC Class Codes: A61B 6/4085 Cone-beams
• CPC Class Codes: A61B 6/4411 the apparatus being modular A61B6/4283 takes precedence
• CPC Class Codes: G01T 1/2002 Optical details, e.g. reflecting or diffusing layers

Abstract

A multi-layer reflector for a CT detector is disclosed. The reflector includes an x-ray absorption component that is sandwiched between a pair of highly reflective components. Such a reflector is formed between adjacent scintillators of a CT detector so as to reduce cross-talk between adjacent scintillators as well as maintain a relatively high light output for signal detection. Moreover, the multi-layer reflectors may be disposed one-dimensionally or two-dimensionally across a scintillator array. A method of manufacturing such a reflector and incorporating same into a CT detector is also disclosed.

Claims

1. CT detector comprising:

a scintillator array having a plurality of scintillators;

a reflector interstitially disposed between at least two adjacent scintillators, the reflector including a light absorption element disposed between a pair of reflective elements; and

a reflective layer coated to a top face of the scintillator array, wherein the light absorption element extends in length to an upper surface of the reflective layer.

2. The CT detector of claim 1 wherein the light absorption element is configured to reduce optical cross-talk between the at least two adjacent scintillators.

3. The CT detector of claim 2 wherein the light absorption element is configured to substantially eliminate optical cross-talk between the at least two adjacent scintillators.

4. The CT detector of claim 1 incorporated into a CT imaging system.

5. The CT detector of claim 4 wherein the CT imaging system is configured to acquire radiographic data of a medical patient.

6. The CT detector of claim 1 wherein the reflector interstitially disposed between at least two adjacent scintillators is a composite comprising a high atomic number metal and a low viscosity polymer.

7. The CT detector of claim 6 wherein the low viscosity polymer is one of epoxy and polyurethane.

8. The CT detector of claim 6 wherein the high atomic number metal is one of tungsten and tantalum.

9. The CT detector of claim 6 wherein the high atomic number metal has a density greater than 16 g/cm^3.

10. 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 scintillator array configured to illuminate upon reception of radiographic energy;

a reflective top coat cast on an x-ray receptor surface of the scintillator array;

a reflector assembly disposed between adjacent scintillators of the scintillator array; and

wherein each reflector assembly includes a composite layer sandwiched between at least a pair of reflective layers;

wherein the composite layer extends in length to an upper surface of the reflective top coat; and

wherein the composite layer includes a high-Z metal and a low-viscosity polymer.

11. The CT system of claim 10 wherein the high Z-metal includes one of tungsten and tantalum.

12. The CT system of claim 10 wherein the low-viscosity polymer has a non-translucent color.

13. The CT system of claim 10 wherein the at least a pair of reflective layers includes TiO₂.

14. The CT system of claim 10 wherein each reflective layer has a lateral thickness of approximately 15-90 μ

m and the composite layer has a lateral thickness of approximately 50-100 μ

m.

15. The CT system of claim 10 wherein the reflector assembly is cast between adjacent scintillators.

16. The CT system of claim 10 wherein the composite layer is an optical light absorber.

17. The CT system of claim 10 wherein the composite layer further comprises a low viscosity polymer.

18. The CT system of claim 17 wherein the low viscosity polymer is one of epoxy and polyurethane.

19. The CT system of claim 10 wherein the high-Z metal comprises one of tungsten and tantalum.

20. A method of CT detector manufacturing comprising the steps of:

providing a scintillator array of a plurality of scintillators, wherein the step of providing a scintillator array includes the step of forming a substrate of scintillation material;

disposing a reflective layer between adjacent scintillators;

disposing a reflective layer directly on an x-ray receptor surface of the scintillator array;

disposing a light absorbing composite layer between the reflective layers that are disposed between adjacent scintillators;

pixelating the substrate, wherein the step of pixelating includes at least one of chemically and mechanically forming gaps in the substrate to define the plurality of scintillators;

depositing reflective material into at least the gaps; and

wherein the step of disposing a composite layer in the reflective layer includes the step of creating channels in the reflective material.

21. The method of claim 20 wherein mechanically forming gaps includes dicing the substrate.

22. The method of claim 20 wherein the step of depositing includes the step of casting.

23. The method of claim 20 wherein the step of creating includes at least one of laser cutting, wire cutting, and etching.

24. The method of claim 20 further comprising the step of depositing composite material into the channels.

25. The method of claim 24 wherein the composite material includes a metal and a polymer.

26. The method of claim 24 wherein the step of depositing composite material into the channels includes casting.

27. A CT detector comprising:

a scintillator array having a plurality of scintillators;

a reflective top coat cast on an x-ray receptor surface of each of the plurality of scintillators; and

a reflector interstitially disposed between at least two adjacent scintillators, the reflector including a light absorption composite element disposed between a pair of reflective elements, wherein the light absorption composite element extends in length to an upper surface of the reflective top coat, and wherein the light absorption composite element is configured to absorb x-rays.

28. The CT detector of claim 27 wherein the light absorption composite element is further configured to absorb approximately 50% of the x-ray photons across a gap between the at least two adjacent scintillators.

29. A CT detector comprising:

a scintillator array having a plurality of scintillators;

a reflective top coat cast on an x-ray receptor surface of each of the plurality of scintillators; and

a reflector interstitially disposed between at least two adjacent scintillators, the reflector including a light absorption element disposed between a pair of reflective elements wherein the light absorption element extends in length to an upper surface of the reflective top coat, and wherein the light absorption element is configured to reduce x-ray punch through.

30. A CT detector comprising:

a scintillator array having a plurality of scintillators;

a reflective top coat cast on an x-ray receptor surface of each of the plurality of scintillators; and

a reflector interstitially disposed between at least two adjacent scintillators, the reflector including a light absorption element disposed between a pair of reflective elements wherein the light absorption element extends in length to an upper surface of the reflective top coat, and wherein the light absorption element includes a high atomic number metal composite.

31. The CT detector of claim 30 wherein the metal composite includes a cured metal powder and low viscosity polymer combination.

32. The CT detector of claim 31 wherein the polymer includes polyurethane.

33. The CT detector of claim 30 wherein the metal composite includes at least one of tungsten, tantalum, and a metal powder with density greater than 16 g/cm³.

34. A CT detector comprising:

a scintillator array having a plurality of scintillators;

a reflective top coat cast on an x-ray receptor surface of each of the plurality of scintillators; and

a reflector interstitially disposed between at least two adjacent scintillators, the reflector including a light absorption element disposed between a pair of reflective elements wherein the light absorption element extends in length to an upper surface of the reflective top coat, and wherein the pair of reflective elements include TiO₂.

35. 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 scintillator array configured to illuminate upon reception of radiographic energy;

a reflective top coat cast on an x-ray receptor surface of the scintillator array;

a reflector assembly disposed between adjacent scintillators of the scintillator array; and

wherein each reflector assembly includes a first light absorptive layer sandwiched between at least a pair of reflective layers wherein the first light absorptive layer extends in length to an upper surface of the reflective top coat; and

wherein the at least a pair of reflective layers includes TiO₂.

36. 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 scintillator array configured to illuminate upon reception of radiographic energy;

a reflective top coat cast on an x-ray receptor surface of the scintillator array;

a reflector assembly disposed between adjacent scintillators of the scintillator array; and

wherein each reflector assembly includes a first layer comprising a high atomic number metal and a low viscosity polymer, the first layer sandwiched between at least a pair of reflective layers, and wherein the first layer extends in length to an upper surface of the reflective top coat; and

wherein each reflective layer has a lateral thickness of approximately 15-90 μ

m and the composite layer has a lateral thickness of approximately 50-100 μ

m.

37. 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 scintillator array configured to illuminate upon reception of radiographic energy;

a reflective top coat cast on an x-ray receptor surface of the scintillator array;

a reflector assembly disposed between adjacent scintillators of the scintillator array; and

wherein each reflector assembly includes a first layer sandwiched between at least a pair of reflective layers, the first layer including a low viscosity polymer comprising one of epoxy and polyurethane, and wherein the first layer extends in length to an upper surface of the reflective top coat; and

wherein the reflector assembly is cast between adjacent scintillators.