Semiconductor gamma-ray camera and medical imaging system

• US 6,194,715 B1
• Filed: 04/05/1999
• Issued: 02/27/2001
• Est. Priority Date: 12/23/1994
• Status: Expired due to Term

• Current Assignee: Digirad Corporation
• Original Assignee: Digirad Corporation
• Inventors: Doty, F. Patrick, Lingren, Clinton L., Apotovsky, Boris, Friesenhahn, Stanley J., Augustine, Frank L., Ashburn, William L., Butler, Jack F.
• Primary Examiner(s): Hannaher, Constantine
• Assistant Examiner(s): Israel, Andrew
• Application Number:
  US09/287,552
• Time in Patent Office: 694 Days
• Field of Search: 250/252.1, 250/370.01, 250/370.09
• US Class Current: 250/252.1
• CPC Class Codes: A61B 6/037 Emission tomography
• 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 1/243 Modular detectors, e.g. arrays formed from self contained units constructional or manufacturing details H01L25/00
• CPC Class Codes: G01T 1/247 Detector read-out circuitry for processing gain or off-set correction H04N
• 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: H01L 27/14676 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 high-energy photon imaging system including an imaging head, a signal processor, a data acquisition system and an image processing computer. The imaging head includes a detector including a plurality of closely-packed detection modules. Each detection module includes a plurality of detection elements mounted to a circuit carrier. The detection elements produce electrical pulses having amplitudes indicative of the magnitude of radiation absorbed by the detection elements. The circuit carrier includes channels for conditioning and processing the signals generated by corresponding detection elements and for preparing the processed signals for further processing by a signal processor. Each conditioning and processing channel stores the amplitudes of the detection element electrical pulses exceeding a predetermined threshold. The detection modules employ a fall-through circuit which automatically finds only those detection elements that have a stored pulse amplitude exceeding the threshold. The fall-through circuit searches for the next detection element and associated channel having a valid event. The signal processor performs diagnostics, gain normalization, and response efficiency normalization functions. The data acquisition system controls the acquisition and processing of data received from the conditioning and processing channels, produces image data based upon the data in a format that is compatible with existing imaging cameras, and transmits the data to the image processing computer. The image processing computer formulates images based upon the processed signals and displays the formulated images on a display device.

Claims

1. An imaging system including a plurality of detection modules, each having an exposure surface, a surface opposite the exposure surface, and a plurality of sides, the exposure surface being substantially covered with radiation detecting material, the plurality of detection modules forming at least a 3×

3 array, with each interior detection module of the array being butted on all sides with adjacent detection modules such that the butted detection modules are not positioned generally in a first direction and the interior detection modules have substantially no surrounding dead regions, each detection module including at least one semiconductor detection element for producing electrical pulses indicative of the energy of radiation from high-energy photons impinging on the exposure surface from generally the first direction.

2. The imaging system of claim 1, having a perimeter dead region of less than about 0.5 inches.

3. The imaging system of claim 1, wherein the plurality of detection modules is of a size and shape appropriate to image an entire organ of the human body.

4. The imaging system of claim 3, wherein an active sensing area of the plurality of detection modules is about 64 square inches.

5. The imaging system of claim 1, wherein each of the plurality of detection modules is rectangular and the plurality of detection modules forms a 7×

9 array.

6. The imaging system of claim 1, wherein each detection module has an outside dimension on the order of an inch.

7. The imaging system of claim 1, wherein each semiconductor detection element has dimensions of about a half-inch by a half-inch.

8. The imaging system of claim 1, wherein each semiconductor detection element has a thickness of about 3 mm.

9. The imaging system of claim 1, wherein each semiconductor detection element has a thickness of at least 0.5 mm.

10. The imaging system of claim 1, wherein each semiconductor detection element has a thickness of between about 1 mm and 10 mm.

11. The imaging system of claim 1, wherein each semiconductor detection element has a surface area of between about one to several hundred square millimeters.

12. The imaging system of claim 1, further including at least one shield plate surrounding the plurality of detection modules.

13. The imaging system of claim 12, wherein the shield plate is about 0.5 mm thick.

14. The imaging system of claim 13, wherein the shield plate is made of alumina.

15. The imaging system of claim 12, wherein a total thickness of the combination of the at least one shield plate and the plurality of detection modules is less than about 3 inches.

16. The imaging system of claim 15, wherein a total thickness of the combination of the at least one shield plate and the plurality of detection modules is about 2 inches.

17. The imaging system of claim 1, wherein each of the semiconductor detection elements has dimensions of about 6 mm×

6 mm.

18. The imaging system of claim 1, wherein the plurality of detection modules forms an array having dimensions from 3×

3 to greater than 8×

8.

19. The imaging system of claim 1, wherein the distance between each of the detection modules is on the order of tens of microns.

20. The imaging system of claim 1, wherein the semiconductor detection elements of each detection module forms an array having an outside dimension on the order of an inch.

21. The imaging system of claim 1, further including a collimator positioned with respect to the detection modules to direct high-energy photons to the exposure surfaces of the detection modules.