Solid state gamma camera

• US 6,388,258 B1
• Filed: 10/20/1999
• Issued: 05/14/2002
• Est. Priority Date: 11/24/1996
• Status: Expired due to Fees

• Current Assignee: GE Medical Systems Israel, Ltd
• Original Assignee: GE Medical Systems Israel, Ltd
• Inventors: Hefetz, Yaron, Berlad, Gideon
• Primary Examiner(s): Hannaher, Constantine
• Assistant Examiner(s): Gagliardi, Albert
• Application Number:
  US09/420,904
• Time in Patent Office: 937 Days
• Field of Search: 250/363.02, 250/363.07, 250/369, 250/370.08, 250/371, 250/370.01, 250/360.1, 250/370.09
• US Class Current: 250/363.07
• CPC Class Codes: A61B 6/4258 for detecting non x-ray radiation, e.g. gamma radiation A61B6/037 takes precedence
• CPC Class Codes: G01T 1/1642 using a scintillation crystal and position sensing photodetector arrays, e.g. ANGER cameras
• CPC Class Codes: G01T 1/247 Detector read-out circuitry for processing gain or off-set correction H04N
• CPC Class Codes: G01T 1/2928 using solid state detectors

Abstract

A gamma camera for imaging radiation emitted from or transmitted by an object including a gamma camera head having a front input surface which produces signals, when a photon associated with the radiation is detected by the head, indicative of the position of the position of the detection on the input surface and at a given resolution in the absence of dithering of the head; and a dithering system which differentially translates the detector head or the object in at least one direction parallel to the input surface so that the dithering system translates the detector head or the object by an amount at least equal to the given resolution but less than 50 times the given resolution during acquisition of the signals.

Claims

1. A gamma camera for imaging radiation emitted from or transmitted by an object, comprising:

a gamma camera head having a front, input, surface (18), and which produces signals, when a photon associated with the radiation is detected by the head, indicative of the position of the detection on the input surface, at a given resolution in the absence of dithering of the head; and

a dithering system which differentially translates the detector head or the object in at least one direction parallel to the input surface,

wherein the dithering system translates the detector head or the object by an amount at least equal to the given resolution but less than 50 times the given resolution during acquisition of the signals.

3. A gamma camera according to claim 1 or claim 2 wherein the amount of differential translation is greater than twice the given resolution.

4. A gamma camera according to claim 3 wherein the amount of differential translation is greater than four times the given resolution.

5. A gamma camera according to claim 1 or claim 2 including circuitry which receives the signals and an indication of the position of the head and which distributes the events into an image matrix of pixels having a matrix resolution finer than the given resolution, said image matrix being referenced to the object.

6. A gamma camera according to claim 5 wherein the event is distributed into an image pixel having a reference point closest to a reference point in the head, translated by the position indication.

7. A gamma camera according to claim 5 wherein events acquired at a plurality of head positions having a distance therebetween smaller than the given resolution are distributed to said image matrix.

8. A gamma camera according to claim 5 and comprising an imaging system which provides an image of the distribution of the detected radiation based on the signals, the image having an image resolution which is substantially constant over the surface.

9. A gamma camera according to claim 1 or claim 2 wherein the gamma camera head comprises an array of detector elements which produce said signals in response to the detection of the photons and wherein the spacing of the elements is substantially equal to the given resolution.

2. A gamma camera for imaging radiation emitted from or transmitted by an object, comprising:

a gamma camera head having a front, input, surface, and which produces signals, when a photon associated with the radiation is detected by the head, indicative of the position of the detection on the surface, at a given resolution in the absence of dithering; and

a dithering system which differentially translates the gamma camera head or the object,

wherein the dithering system translates the gamma camera head or the object in two directions parallel to the front surface by an amount greater than the given resolution during acquisition of the signals.

10. A gamma camera for imaging radiation emitted from or transmitted by an object, comprising:

a gamma camera head having a front, input, surface,

a plurality of detectors, each having a physical extent and spacings which define a given physical resolution of the head and which produces signals, when a photon associated with the radiation is detected by the head, indicative of the position of the event on the surface at the physical resolution; and

an imaging system which provides an image of the distribution of the detected radiation, based on the signals, having an image resolution which is substantially constant over the image.

11. A gamma camera according to claim 10 wherein radiation sources whose captured radiation is spaced by a distance greater than the sum of the given resolution and the image pixel, will be separately imaged as sources which have a center spaced by the distance, substantially independent of the position of the capture of the radiation on the surface.

12. A gamma camera according to claim 10 wherein the image of a line source of constant width and having an inclination will have a constant width along its length for any inclination of the line on the surface.

13. A gamma camera according to claim 10 wherein the image of two point sources will have a substantially constant spacing independent of their position on the surface.

14. A gamma camera according to claim 10 wherein the image has a resolution that is substantially equal to the given resolution.

15. A gamma camera according to claim 10 wherein the spacing of the elements is substantially equal to the given resolution.

16. A gamma camera according to claim 10 wherein each detector produces a signal when the head detects a gamma ray, which signal is associated with a cell in an acquisition matrix having the given resolution.

17. A gamma camera according to claim 16, wherein the imaging system comprises:

an image matrix into which said events are individually distributed, said imaging matrix having said image resolution, said image resolution being finer than the given resolution.

18. A gamma camera according to claim 16 and including a dithering system (102) that differentially translates the detector head or the object in at least one direction and wherein the image matrix is referenced to the object and wherein the distribution into the finer image matrix is determined by the amount of the translation.

19. A gamma camera according to claim 16 wherein the imaging system comprises:

an image matrix into which said events are individually distributed, said imaging matrix having said image resolution, said image resolution being poorer than the given resolution by a non-integral value.

20. A gamma camera according to claim 10 wherein the image resolution is at least twice as fine as the given resolution.

21. A gamma camera according to claim 20 wherein the image resolution is at least 4 times as fine as the given resolution.

22. A gamma camera head according to claim 10 wherein the events are subsequently redistributed into a second image matrix having a resolution different from the image matrix or given resolution.

23. A gamma camera head according to claim 22 wherein the second image matrix has a resolution which is poorer than the given resolution by a non-integral value.