Methods and apparatus for pixilated detector masking

• US 20060118730A1
• Filed: 12/08/2004
• Published: 06/08/2006
• Est. Priority Date: 12/08/2004
• Status: Active Grant

• Current Assignee: General Medical Systems, Israel, Ltd.
• Original Assignee: General Medical Systems, Israel, Ltd.
• Inventors: Blevis, Ira, Hefetz, Yaron, Pansky, Amir, Liss, Joshua
• Granted Patent: US 7,495,225 B2
• Time in Patent Office: Days
• US Class Current: 250/370.90
• CPC Class Codes: G01T 1/2928 using solid state detectors

Abstract

A method of detecting ionizing radiation is provided. The method includes pixelating a semiconductor substrate such that each pixel comprises a central region and a region of variable response, substantially blocking the ionizing radiation from reaching the region of variable response, and receiving the ionizing radiation with the central region.

Claims

1. A method of detecting ionizing radiation comprising:

pixelating a semiconductor substrate such that each pixel comprises a central region and a region of variable response;

substantially blocking the ionizing radiation from reaching the region of variable response; and

receiving the ionizing radiation at the central region.

2. A method of detecting ionizing radiation in accordance with claim 1 wherein pixelating a semiconductor substrate comprises coupling a plurality of electrodes to a surface of said semiconductor substrate, a size and location of the plurality of electrodes defining a size and location of the pixels.

3. A method of detecting ionizing radiation in accordance with claim 1 wherein substantially blocking the ionizing radiation from reaching the region of variable response comprises masking the semiconductor substrate such that septum of a collimating mask overlay the region of variable response.

4. A method of detecting ionizing radiation in accordance with claim 3 wherein masking the semiconductor substrate comprises sizing a width of the septum to be greater then a width of the region of variable response.

5. A method of detecting ionizing radiation in accordance with claim 1 wherein receiving the ionizing radiation at the central region comprises masking the semiconductor substrate such that mask openings of a collimating mask overlay the central region and the central region remains exposed to the ionizing radiation.

6. A method of detecting ionizing radiation in accordance with claim 1 further comprising collimating the ionizing radiation.

7. A method of detecting ionizing radiation in accordance with claim 6 wherein collimating the ionizing radiation comprises aligning a plurality of apertures of a collimator with a corresponding opening in a collimating mask and the central region.

8. A method of detecting ionizing radiation in accordance with claim 7 further comprising aligning a plurality of apertures of a stacking collimator with a corresponding aperture in the collimator.

9. A method of detecting ionizing radiation in accordance with claim 7 wherein collimating the ionizing radiation comprises sizing a width of a collimator septa to be less than a width of a collimating mask septa.

10. A method of detecting ionizing radiation in accordance with claim 1 further comprising coupling a collimating mask to at least one of an electrode layer, a dielectric layer, and the semiconductor substrate.

11. A method of detecting ionizing radiation in accordance with claim 10 wherein coupling a collimating mask to at least one of an electrode layer, a dielectric layer, and the semiconductor substrate comprises fabricating a pitch of the collimating mask to be substantially equal to a pitch of the semiconductor substrate.

12. A method for aligning a collimator with a detector, said method comprising:

configuring a collimating mask to cover a region of variable response to incident radiation of the detector; and

configuring the collimating mask to expose a region of the detector with a substantially uniform response to the incident radiation.

13. A method in accordance with claim 12 wherein the detector includes pixilated detector elements, said configuring is based on at least one of a size and shape of the pixilated detector elements.

14. A method in accordance with claim 12 further comprising configuring the collimating mask to couple to a detector substrate of the detector.

15. A method in accordance with claim 12 further comprising configuring the collimating mask in a grid arrangement.

16. A method in accordance with claim 15 wherein configuring the collimating mask in a grid arrangement comprises:

configuring the collimating mask with openings that expose a central, uniform response region of a pixel of the detector; and

configuring the collimating mask with openings that overlay a region of variable response of the pixel that substantially surrounds the central region.

17. A method for controlling radiation exposure to a pixilated detector, said method comprising:

substantially blocking radiation exposure to a region of variable response of the detector with a collimating mask; and

exposing a substantially uniformly responsive region of the detector with a collimating mask.

18. A method for controlling radiation exposure in accordance with claim 17 further comprising aligning a collimator with the collimating mask.

19. An imaging system comprising a semiconductor detector that includes:

a pixilated semiconductor substrate that is responsive to ionizing radiation, said substrate including a first surface in a direction of a source of ionizing radiation; and

a collimating mask overlaying said substrate first surface, said collimating mask including a plurality of mask openings exposing a central region of a pixel of said semiconductor detector substrate to the ionizing radiation, said collimating mask including mask septa substantially blocking the incident ionizing radiation from a region of variable response associated with the pixel.

20. An imaging system in accordance with claim 19 wherein said pixilated semiconductor substrate is responsive to at least one of emission gamma photons and transmission x-ray photons.

21. An imaging system in accordance with claim 19 wherein said pixilated semiconductor substrate comprises cadmium zinc telluride (CZT).

22. An imaging system in accordance with claim 19 wherein said collimating mask comprises a material having an atomic number greater than seventy-two.

23. An imaging system in accordance with claim 19 wherein said collimating mask comprises at least one of lead, tungsten, alloys thereof, and conglomerates thereof.

24. An imaging system in accordance with claim 19 wherein said collimating mask comprises a thickness of between about one mm and about ten mm.

25. An imaging system in accordance with claim 24 wherein said collimating mask comprises a thickness of between about three mm and about seven mm.

26. An imaging system in accordance with claim 19 wherein said collimating mask comprises a pitch of between about one mm and about six mm.

27. An imaging system in accordance with claim 19 wherein said collimating mask comprises a pitch that is about equal to a pitch of said pixilated semiconductor substrate.

28. An imaging system in accordance with claim 19 wherein a width of said mask septa is greater than a width of said region of variable response.

29. An imaging system in accordance with claim 19 further comprising at least one electrode that defines each pixel.

30. An imaging system in accordance with claim 29 wherein a size and position of each pixel corresponds to a size and position of said electrode.

31. An imaging system in accordance with claim 29 wherein said electrode is coupled to a second surface of said semiconductor substrate.

32. An imaging system in accordance with claim 29 wherein each pixel includes a central region and a region of variable response.

33. An imaging system in accordance with claim 29 wherein each at least one electrode comprises an anode.

34. An imaging system in accordance with claim 19 further comprising an electrode coupled to said semiconductor substrate, said electrode substantially covering said substrate first surface.

35. An imaging system in accordance with claim 34 further comprising a dielectric layer covering said electrode.

36. An imaging system in accordance with claim 19 wherein said mask is in contact with said cathode and said mask is substantially electrically insulated from other detector components.

37. An imaging system in accordance with claim 19 further comprising a collimator removably couplable to said semiconductor substrate.

38. An imaging system in accordance with claim 37 wherein said collimator is configured to receive a second collimator in the direction of the radiation source.

39. An imaging system in accordance with claim 37 wherein said collimator comprises a plurality of apertures separated by septa, each of said plurality of apertures positioned in substantial alignment with one of said plurality of mask openings when said stacking collimator is installed in an assembled position.

40. A collimating mask for a pixilated radiation detector, said collimating mask comprising a mask portion formed generally in a grid arrangement wherein said grid is configured to expose a central region of a pixel defined in a detector substrate of the detector, and to overlay a region surrounding the central region.

41. A detector assembly for an imaging system, said detector assembly comprising:

a radiation detector comprising;

a pixilated semiconductor substrate comprising a pixel electrode coupled to a first surface of said substrate, said pixel electrode defining a pixel region of said substrate;

a cathode covering a second surface of said substrate;

a dielectric layer covering said cathode;

a collimating mask comprising a mask portion comprising openings therethrough surrounded by a mask septa, said mask portion configured to expose a central region of the pixel, and to overlay a region surrounding the central region; and

a collimator removably couplable to said radiation detector, said collimator comprising apertures therethrough, said apertures configured to substantially align with the collimating mask openings, said collimator further configured to receive another collimator such that apertures of each collimator substantially align with respect to each other.

42. A detector assembly in accordance with claim 41 wherein said substrate comprises Cadmium Zinc Telluride (CZT).

43. A detector assembly in accordance with claim 41 wherein said collimating mask comprises a material having an atomic number greater than seventy-two.

44. A detector assembly in accordance with claim 41 further comprising a plurality of adjacent radiation detectors arranged linearly in a one detector by N detector configuration.

45. A detector assembly in accordance with claim 44 wherein said plurality of detectors are oriented in parallel alignment and arranged along an arcuate path.

46. A detector assembly in accordance with claim 41 further comprising a plurality of adjacent radiation detectors arranged planarly in a M detector by N detector configuration.

47. A detector assembly in accordance with claim 46 wherein said plurality of detectors are oriented in parallel alignment and arranged along a concave path.

48. A detector assembly in accordance with claim 41 wherein said mask is in electrical contact with the Cathode and insulated from other components.