CT detector array having non-pixelated scintillator array

• US 7,224,766 B2
• Filed: 01/04/2005
• Issued: 05/29/2007
• Est. Priority Date: 04/30/2003
• Status: Active Grant

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Vartuli, James S., Jiang, Haochuan, Hoffman, David M.
• Primary Examiner(s): Ho; Allen C.
• Application Number:
  US11/029,612
• Publication Number:
  US 20050133725A1
• Time in Patent Office: 875 Days
• Field of Search: 378/19, 378/98.8, 250/367, 250/368, 250/370.09, 250/370.11, 117 81- 83, 252/301.4 R
• US Class Current: 378/19
• CPC Class Codes: A61B 6/032 Transmission computed tomography [CT]
• CPC Class Codes: A61B 6/4233 using matrix detectors
• CPC Class Codes: G01N 2223/419 computed tomograph
• CPC Class Codes: G01N 23/046 using tomography, e.g. computed tomography [CT]
• CPC Class Codes: G01T 1/1644 using an array of optically separate scintillation elements permitting direct location of scintillations G01T1/1645 takes precedence
• CPC Class Codes: G01T 1/201 using scintillating fibres
• 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
• CPC Class Codes: G21K 1/02 using diaphragms, collimators

Abstract

The present invention is a directed to a non-pixelated scintillator array for a CT detector as well as an apparatus and method of manufacturing same. The scintillator array is comprised of a number of ceramic fibers or single crystal fibers that are aligned in parallel with respect to one another. As a result, the pack has very high dose efficiency. Furthermore, each fiber is designed to direct light out to a photodiode with very low scattering loss. The fiber size (cross-sectional diameter) may be controlled such that smaller fibers may be fabricated for higher resolution applications. Moreover, because the fiber size can be controlled to be consistent throughout the scintillator array and the fibers are aligned in parallel with one another, the scintillator array, as a whole, also is uniform. Therefore, precise alignment with the photodiode array or the collimator assembly is not necessary.

Claims

1. A method of manufacturing a CT detector array having a non-pixelated scintillator array, the method comprising the steps of:

developing a material base from which scintillators may be grown;

pulling a rod of scintillator material from the material base;

cutting the rod to form a plurality of scintillator fibers;

aligning the plurality of scintillator fibers into a scintillator bundle;

slicing the scintillator bundle into a number of scintillator packs; and

applying a reflector coating to the number of scintillator packs.

2. The method of claim 1 wherein the step of developing a material base includes the steps of:

dissolving a number of chemicals to form a precursor solution; and

heating the precursor solution to form a transparent gel.

3. The method of claim 2 further comprising the steps of:

heating the pulled rod of scintillator material;

calcining the rod;

sintering the rod; and

annealing the sintered rod.

4. The method of claim 3 further comprising the step of converting the rod into a ceramic phase having a garnet structure prior to the sintering step.

5. The method of claim 3 wherein the step of developing a material base includes the steps of:

mixing a number of powder oxides with a ball mill and a dissolving solution;

drying the dissolved solution;

melting the dissolved solution; and

homogenizing the dissolved solution.

6. The method of claim 5 wherein the number of powder oxides includes Tb₄O₇, Lu₂O₃, Al₂O₃, and Ce₂O₃ and the dissolving solution includes alcohol.

7. The method of claim 5 wherein the step of pulling includes the steps of:

growing a seed fiber in the homogenized solution; and

pulling the seed fiber downward to develop the rod of scintillator material.

8. The method of claim 5 further comprising the step of optically coupling the scintillator packs to a photodiode array configured to detect illumination from the scintillator pack and output electrical signals responsive thereto, the photodiode array having a plurality of photodiodes.

9. The method of claim 8 wherein the coupling further comprises aligning each photodiode with a single respective scintillator pack to detect light from the scintillator fibers therein.

10. The method of claim 2 wherein the number of chemicals includes lutetium acetate hydrate, terbium acetate hydrate, cerium nitrate, and aluminum formate hydrate.

11. The method of claim 2 wherein the number of chemicals includes Y₂O₃, Gd₂ O₃, Eu₂ O₃, and Pr(NO₃)₃×

H₂O.

12. A method for constructing a non-pixelated scintillator array comprising the steps of:

developing a plurality of single crystal fibers of scintillation material;

casting the plurality of single crystal fibers with an adhesive material;

curing the plurality of single crystal fibers and adhesive material to form a cured pack of a first dimension;

cutting the cured pack to a specified dimension that is different from the first dimension; and

wherein the plurality of crystal fibers has a uniform cross-sectional diameter.

13. The method of claim 12 wherein the step of developing further includes the step of growing the plurality of single crystal fibers from a mixture of Tb₄O₇, Lu₂O₃, Al₂O₃ and CeO₂.

14. The method of claim 13 wherein the step of growing further comprises:

incorporating one of distilled water and alcohol into the mixture;

allowing the mixture to dry; and

melting and homogenizing the dried mixture.

15. The method of claim 14 further comprising the step of pulling crystal fibers from the homogenized mixture.

16. The method of claim 12 further comprising the step of coating a layer of reflective material to one end surface of the cured pack.

17. The method of claim 12 further comprising the step of sputter coating reflective metal on one end surface of the cured pack.

18. The method of claim 12 further comprising the step of depositing adhesive material in any voids existing between adjacent crystal fibers.

19. A method of manufacturing a CT detector array comprising the steps of:

preparing a material base from which scintillators may be grown;

pulling a rod of scintillator material from the material base;

cutting the rod to form a plurality of scintillator fibers;

aligning the plurality of scintillator fibers into a scintillator bundle;

slicing the scintillator bundle into a number of scintillator packs;

applying a reflector coating to the number of scintillator packs;

optically coupling one of the scintillator packs to a single light detection element configured to detect illumination of the scintillator pack and output electrical signals generally indicative of high frequency electromagnetic energy received by the scintillator pack.

20. The method of claim 19 further comprising the steps of:

heating the pulled rod of scintillator material;

calcining the rod;

sintering the rod; and

annealing the sintered rod.