CeBr3 scintillator

• US 7,405,404 B1
• Filed: 09/23/2005
• Issued: 07/29/2008
• Est. Priority Date: 09/23/2004
• Status: Active Grant

• Current Assignee: Radiation Monitoring Devices, Inc. (Dynasil Corp. of America)
• Original Assignee: Radiation Monitoring Devices, Inc. (Dynasil Corp. of America)
• Inventors: Shah, Kanai S.
• Primary Examiner(s): Porta; David P.
• Assistant Examiner(s): Gaworecki; Mark R
• Application Number:
  US11/233,715
• Time in Patent Office: 1,040 Days
• Field of Search: 250/361.R, 252/301.4 H, 252/301.4 R
• US Class Current: 250/361.00R
• CPC Class Codes: C09K 11/7719 Halogenides C09K11/7716 takes precedence
• CPC Class Codes: C30B 11/00 Single-crystal growth by normal freezing or freezing under temperature gradient, e.g. Bridgman-Stockbarger method C30B13/00, C30B15/00, C30B17/00, C30B19/00 take precedence; under a protective fluid C30B27/00
• CPC Class Codes: C30B 29/12 Halides
• CPC Class Codes: G01T 1/20 with scintillation detectors
• CPC Class Codes: G21K 2004/06 with a phosphor layer
• CPC Class Codes: G21K 4/00 Conversion screens for the conversion of the spatial distribution of X-rays or particle radiation into visible images, e.g. fluoroscopic screens photographic processes using X-ray intensifiers G03C5/17; discharge tubes comprising luminescent screens H01J1/62; cathode ray tubes for X-ray conversion with optical output H01J31/50

Abstract

The present invention provides a new scintillator, cerium bromide (CeBr₃), for gamma ray spectroscopy. Crystals of this scintillator have been grown using the Bridgman process. In CeBr₃, Ce³⁺ is an intrinsic constituent as well as a luminescence center for the scintillation process. The crystals have high light output (˜68,000 photons/MeV) and fast decay constant (˜17 ns). Furthermore, it shows excellent energy resolution for γ-ray detection. For example, energy resolution of <4% (FWHM) has been achieved using this scintillator for 662 keV photons (¹³⁷Cs source) at room temperature. High timing resolution (<200 ps-FWHM) has been recorded with CeBr₃-PMT and BaF₂-PMT detectors operating in coincidence using 511 keV positron annihilation γ-ray pairs.

Claims

1. A self-activated scintillator comprising a cerium bromide (CeBr₃) material.

2. An X-ray detector assembly comprising:

a self-activated scintillator comprising a CeBr₃ material;

a photon detection assembly, and

a data analysis system.

3. The X-ray detector of claim 2, wherein the photon detection assembly comprises a photomultiplier tube, a photo diode, or a PIN detector.

4. The X-ray detector if claim 2, wherein the scintillation material is coated with a reflective layer, a moisture resistant layer, or a vapor barrier.

5. A positron emission tomography scanner system comprising:

a patient area;

an assembly of radiation detectors disposed adjacent the patient area, wherein the radiation detectors comprise;

a self-activated scintillator comprising of a cerium bromide (CeBr₃) material;

a scintillation light detector or photomultiplier tube optically coupled to the scintillator; and

a control system coupled to the light detectors or photomultiplier tubes.

6. The positron emission tomography scanner of claim 5, wherein said scintillator is used in coincidence detection positron emission tomography by recording the differential arrival time of two photons so as to localize the annihilation event.

7. The positron emission tomography scanner of claim 6, wherein the localization is to within a distance of less than about 30 cm.

8. The positron emission tomography scanner of claim 5, wherein the radiation detector comprises two or more radiation detectors,

wherein each scintillation light detector comprises a position sensitive detector or array.

9. The positron emission tomography scanner of claim 8, wherein timing signals of individual radiation detectors are equalized by an introduction of individual hardwired delays in signal readout electronics in the control system.

10. The positron emission tomography scanner of claim 5, further comprising a means to correct for different timing offsets of each individual radiation detector.

11. The positron emission tomography scanner of claim 5, wherein timing offsets of individual radiation detectors are stored in a memory in the control system.

12. The positron emission tomography scanner of claim 11, wherein for each radiation detector the timing offsets are subtracted from each gamma-ray time arrival value prior to computation of a localization.

13. An X-ray computed tomography scanner system comprising:

a patient area;

a penetrating X-ray source; and

a detector assembly comprising a self-activated scintillator comprising a cerium bromide (CeBr₃) material.

14. A method of performing time-of-flight positron emission tomography comprising:

administering a patient with a detectable label;

positioning the patient within a field of view of a scintillator to detect emissions from the patient, wherein the scintillator is a self-activated scintillator comprising a cerium bromide (CeBr₃) material; and

detecting a positron annihilation event within a portion of a cross-section of the patient'"'"'s body for generating an image of the patient.

15. A well logging device comprising:

a detector assembly comprising a self-activated scintillator comprising a CeBr₃ material, and a photon detection assembly.

16. The well logging device of claim 15, further comprising a radioactive energy source.

17. The well logging device of claim 16, further comprising a data analysis system.

18. The well logging device of claim 15, wherein the photon detection assembly comprises a photomultiplier tube, a photo diode, a PIN detector, or an avalanche detector.

19. A scintillator comprising a cerium bromide material, wherein Br is the only halide present in the scintillator.

20. The scintillator of claim 19, further comprising a dopant.

21. The scintillator of claim 20, wherein the dopant comprises Lu, La, Eu, Pr, Sr, Tl, Cl, F, or I.

22. The scintillator of claim 21, wherein the dopant is Lu or La, and the Lu dopant is LuBr₃ or the La dopant is LaBr₃.

23. The scintillator of claim 20, wherein the dopant is present in an amount of 10% or less by molar weight.

24. The scintillator of claim 19, wherein the scintillator is a fast scintillator.

25. The scintillator of claim 19, wherein the scintillator comprises a decay time of less than 30 nanoseconds.

26. The scintillator of claim 19, wherein the scintillator comprises a timing resolution of better than 1 nanosecond.

27. The scintillator of claim 19, wherein the scintillator comprises a timing resolution of better than 0.5 nanoseconds.

28. The scintillator of claim 19, wherein the scintillator comprises a timing resolution of better than about 0.2 nanoseconds.

29. The scintillator of claim 19, wherein the scintillator comprises a light output of at least about 68,000 photons/MeV.