Semiconductor radiation detector with downconversion element

• US 6,194,726 B1
• Filed: 09/22/1998
• Issued: 02/27/2001
• Est. Priority Date: 12/23/1994
• Status: Expired due to Term

• Current Assignee: Digirad Corporation
• Original Assignee: Digirad Corporation
• Inventors: Pi, Bo, Conwell, Richard L., Collins, Timothy C.
• Primary Examiner(s): Hannaher, Constantine
• Assistant Examiner(s): Gabor, Otilia
• Application Number:
  US09/158,639
• Time in Patent Office: 889 Days
• Field of Search: 250/363.1, 250/370.11, 250/363.02, 250/363.06
• US Class Current: 250/363.1
• CPC Class Codes: A61B 6/4258 for detecting non x-ray radiation, e.g. gamma radiation A61B6/037 takes precedence
• CPC Class Codes: G01T 1/161 Applications in the field of nuclear medicine, e.g. in vivo counting apparatus for radiation diagnosis A61B6/00
• CPC Class Codes: G01T 1/1642 using a scintillation crystal and position sensing photodetector arrays, e.g. ANGER cameras
• 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 1/20182 Modular detectors, e.g. tiled scintillators or tiled photodiodes stacked detectors G01T1/20181
• 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 1/20188 Auxiliary details, e.g. casings or cooling
• CPC Class Codes: G01T 1/2019 Shielding against direct hits
• CPC Class Codes: H01L 27/146 Imager structures
• CPC Class Codes: H01L 27/14658 X-ray, gamma-ray or corpuscular radiation imagers measuring X-, gamma- or corpuscular radiation G01T1/00
• CPC Class Codes: H04N 5/32 Transforming X-rays cameras or camera modules for generating image signals from X-rays H04N23/30; circuitry of SSIS for transforming X-rays into image signals H04N25/30

Abstract

A radiation detection device for gamma radiation is disclosed having an array of crystals optically positioned adjacent an optional collimator, the crystals emitting visible light upon illumination by the incident gamma radiation. An array of photodetectors is optically positioned adjacent the crystal array on the side of the crystal array opposite that of the collimator. A select photodetector in the photodetector array provides an output signal when the select photodetector is illuminated by the visible light. An integrated circuit having an input from the output signals of said array of photodetectors is used to process and output signals indicative of the intensity and position of the gamma radiation.

Claims

1. A modular radiation detection device for incident gamma radiation having a first frequency range, comprising:

a plurality of modules, each module including;

a down-conversion material, the down-conversion material emitting photons in a frequency range less than that of the first frequency range upon illumination by the incident gamma radiation;

an array of semiconductor photodetector elements positioned in line with the downconversion material, each photodetector element having a photodetector active area configured so as to receive a substantial portion of the photons of the second frequency range, providing an output signal when illuminated by the emitted light; and

an integrated circuit having an input from the output signals of said array of photodetectors; and

wherein the modules are all-side buttable.

2. The detection device of claim 1, further comprising a collimator to receive and collimate the incident gamma radiation having a first frequency range.

3. The detection device of claim 2, wherein said collimator includes a parallel array of holes having a predetermined shape.

4. The detection device of claim 3, wherein said hole shape is hexagonal.

5. The detection device of claim 3, wherein said hole shape is square.

6. The detection device of claim 3, wherein the downconversion material is formed of an array of crystals for each of the plurality of modules.

7. The detection device of claim 6, wherein the crystals in the array are each separated by a layer of a substantially reflective material.

8. The detection device of claim 7, wherein the collimator holes are separated by septal walls, and wherein at least a portion of the septal walls of the collimator are substantially aligned with the substantially reflective material.

9. The detection device of claim 7, wherein at least a portion of the array of semiconductor photodetector elements are aligned with the substantially reflective material.

10. The detection device of claim 1, wherein said down-conversion material includes CsI.

11. The detection device of claim 10, wherein the CsI is activated with thallium.

12. The detection device of claim 10, wherein the CsI has a thickness in the range of a few millimeters to several centimeters.

13. The detection device of claim 12, wherein the CsI has a thickness of about 5 mm.

14. The detection device of claim 1, wherein the integrated circuit includes a separate input for each photodetector element.

15. The detection device of claim 1, wherein the downconversion material is formed of one crystal for each of the plurality modules.

16. The detection device of claim 1, wherein the semiconductor photodetector elements include CZT elements.

17. The detection device of claim 16, wherein the semiconductor photodetector elements further comprise electrodes for providing an electric field across the CZT elements, at least one of the electrodes being transparent to photons having frequencies in the second frequency range.

18. The detection device of claim 1, wherein the semiconductor photodetector elements include silicon PIN diodes and wherein the semiconductor photodetector elements further comprise electrodes for providing an electric field across the PIN diodes, at least one of the electrodes being transparent to photons having frequencies in the second frequency range.

19. The detection device of claim 1, wherein the semiconductor photodetector elements include mercuric iodide elements and wherein the semiconductor photodetector elements further comprise electrodes for providing an electric field across the mercuric iodide elements, at least one of the electrodes being transparent to photons having frequencies in the second frequency range.

20. The detection device of claim 1, wherein the semiconductor photodetector elements include gallium arsenide elements and wherein the semiconductor photodetector elements further comprise electrodes for providing an electric field across the gallium arsenide elements, at least one of the electrodes being transparent to photons having frequencies in the second frequency range.

21. The detection device of claim 1, wherein the plurality of modules is of a size and shape appropriate to image an organ of the human body.

22. The detection device of claim 1, wherein each module is square and the plurality of modules forms an N×

M array.

23. The detection device of claim 1, wherein a total thickness of the device is less than about 3 inches.

24. The detection device of claim 23, wherein a total thickness of the device is about 2 inches.

25. The detection device of claim 1, further comprising a video monitor.

26. The detection device of claim 1, further comprising a housing surrounding the plurality of modules, wherein said housing includes a cooling system to control a temperature within the detection device.

27. The detection device of claim 26, wherein said housing seals the modules from the environment.