Imaging apparatus and method with event sensitive photon detection

• US 7,078,699 B2
• Filed: 05/14/2003
• Issued: 07/18/2006
• Est. Priority Date: 10/04/2002
• Status: Expired due to Fees

• Current Assignee: Varian Medical Systems Incorporated (Siemens AG)
• Original Assignee: Varian Medical Systems Incorporated (Siemens AG)
• Inventors: Seppi, Edward J.
• Primary Examiner(s): Gabor, Otilia
• Application Number:
  US10/438,684
• Publication Number:
  US 20040066878A1
• Time in Patent Office: 1,161 Days
• Field of Search: 250/358.1, 250/363.01, 250/363.03, 250/366, 250/367, 250/368, 250/369, 378/50, 378/53, 378/54, 378/56, 378/57
• US Class Current: 250/358.1
• 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 1/2985 In depth localisation, e.g. using positron emitters; Tomographic imaging (longitudinal and transverse section imaging; apparatus for radiation diagnosis sequentially in different planes, steroscopic radiation diagnosis); using external radiation sources A61B6/02
• CPC Class Codes: G01V 5/226 using tomography
• CPC Class Codes: G01V 5/234 Measuring induced radiation, e.g. thermal neutron activation analysis

Abstract

An imaging apparatus (10) includes a photon detector (20) and an accessing circuit (44) coupled thereto. The photon detector (20) detects photons and generates signals in response thereto. The accessing circuit (44) reads out the signals from the photon detector (20) at a sufficiently high rate so that it operates in an event sensitive mode. The apparatus (10) also includes a signal processing module (15) for processing the signals and generating data regarding the images of the object. In accordance with various embodiments of the present invention, the signal processing module (15) may include a spatial resolution circuit (56), a photon energy resolution circuit (57), a temporal resolution circuit (58), or any combination thereof.

Claims

1. A method for examining an object, comprising:

directing an externally generated radiation beam towards an object to generate a positron-electron annihilation process to produce photons in the object;

detecting the photons;

generating a signal in response to the detected photons; and

determining a characteristic of the object based at least on the signal.

2. The method of claim 1, wherein the object comprises at least a portion of an animal body.

3. The method of claim 1, wherein the object comprises a non-animal object.

4. The method of claim 1, wherein the object comprises a passenger, a luggage or a cargo, and the determining a characteristic of the object comprises determining whether the object contains contraband or explosive.

5. The method of claim 1, wherein the object comprises a mineral rock, and the determining a characteristic of the object comprises determining whether the object contains a diamond.

6. The method of claim 1, wherein the determining comprises generating data regarding the object.

7. The method of claim 6, wherein the data comprises image data.

8. The method of claim 6, wherein the data comprises PET or SPECT data.

9. The method of claim 1, wherein the characteristic of the object comprises a composition, an electron density, an atomic number density, a mass density, a morphology, an appearance, or a functionality.

10. The method of claim 1, wherein the directing the externally generated beam comprises directing a pencil-beam, a fan beam, or a cone beam towards the object.

11. The method of claim 1, further comprising accessing the signal as the signal is generated and before the signal integrates with another signal.

12. The method of claim 1, wherein the determining comprises identifying one or a combination of a spatial coordinate, a time of generation, and an energy of the detected photons.

13. The method of claim 1, wherein the detecting the photons comprises using a first detector to sense a first photon generated in a positron-electron annihilation process, and using a second detector to sense a second photon generated in the positron-electron annihilation process.

14. The method of claim 13, wherein the determining a characteristic of the object comprises determining whether the first photon and the second photon both originated from the same positron-electron annihilation process based at least on a time when the first photon is detected in the first detector and a time when the second photon is detected in the second detector.

15. The method of claim 13, wherein the determining a characteristic of the object comprises determining an energy level associated with the first photon and an energy level associated with the second photon.

16. The method of claim 15, wherein the determining an energy level further comprises considering only signals associated with an energy level that is approximately 0.5 MeV or higher.

17. The method of claim 13, wherein the determining a characteristic of the object further comprises determining an origin of the first and second photons where the positron-electron electron annihilation process occurred.

18. The method of claim 1, wherein:

the step of directing an externally generated radiation beam comprises using a radiation source;

the step of detecting the photons comprises using a first detector and a second detector; and

the radiation source is not located between the first and the second detectors.

19. A system for examining an object, comprising:

means for externally generating a radiation beam and directing the radiation beam towards an object to generate a positron-electron annihilation process to produce photons in the object;

means for detecting the photons;

means for generating a signal in response to the detected photons; and

means for determining a characteristic of the object based at least on the signal.

20. The system of claim 19, wherein the means for externally generating the radiation beam comprises means for generating a pencil-beam, a fan beam, or a cone beam.

21. The system of claim 19, further comprising means for accessing the signal as the signal is generated and before the signal integrates with another signal.

22. The system of claim 19, wherein the means for determining a characteristic of the object comprises means for generating data regarding the object.

23. The system of claim 19, wherein the means for detecting the photons comprises a first detector and a second detector, and the means for externally generating the radiation beam is not located between the first and the second detectors.

24. A method for examining an object, comprising:

generating a particle in an object;

detecting the particle;

generating a signal using a detector in response to the detected particle;

accessing the generated signal using an accessing circuit that has an accessing rate equal to or greater than a signal generating rate associated with the detector; and

analyzing the signal to generate data regarding the object.

25. The method of claim 24, wherein the generating a particle comprises directing a beam towards the object.

26. The method of claim 25, wherein the directing a beam comprises directing a pencil-beam, a fan beam, or a cone beam towards the object.

27. The method of claim 24, wherein the generating a particle comprises introducing a radioactive isotope into the object.

28. The method of claim 24, wherein the particle comprises a photon generated in a positron-electron annihilation process.

29. The method of claim 24, wherein the particle comprises a proton, a positron, a neutron, or an electron.

30. The method of claim 24, wherein the analyzing comprises identifying one or a combination of a spatial coordinate, a time of generation, and an energy of the detected particle.

31. The method of claim 24, wherein the object comprises at least a portion of a body of a patient undergoing a positron emission tomography (PET) scanning or a single-photon emission computed tomography (SPECT) scanning.

32. The method of claim 24, wherein the object comprises a passenger, a luggage or a cargo, and the process further comprising determining whether the object contains contraband or explosive based at least on the generated data.

33. The method of claim 24, wherein the object comprises a mineral rock, and the process further comprising determining whether the object contains a diamond.

34. The method of claim 24, wherein the signal generating rate is associated with a rate at which particles are detected.

35. A system for examining an object, comprising:

means for generating a particle in an object;

means for detecting the particle;

means for generating a signal in response to the detected particle;

an accessing circuit for accessing the generated signal the accessing circuit having an accessing rate ectual to or greater than a signal generating rate associated with the means for generating; and

means for analyzing the signal to generate data regarding the object.

36. The system of claim 35, wherein the means for generating a particle comprises means for directing a beam towards the object.

37. The system of claim 35, wherein the means for generating a particle comprises means for introducing a radioactive isotope into the object.

38. The system of claim 35, wherein the particle comprises a photon generated in a positron-electron annihilation process.

39. The system of claim 35, wherein the particle comprises a proton, a positron, a neutron, or an electron.

40. The system of claim 35, wherein the means for analyzing comprises means for identifying one or a combination of a spatial coordinate, a time of generation, and an energy of the detected particle.

41. The system of claim 35, wherein the signal generating rate is associated with a rate at which particles are detected by the means for detecting.

42. An imaging apparatus, comprising:

a conversion panel configured to generate a light photon in response to a radiation;

a photo detector array aligned with the conversion panel and configured to generate a signal in response to the light photon received from the conversion panel;

an access circuit coupled to the photo detector array, the accessing circuit having accessing rate equal to or greater than a signal generating rate associated with the photo detector; and

a signal processing circuit coupled to the access circuit and configured to generate image data in response to the signal received by the access circuit.

43. The apparatus of claim 42, wherein the photo detector array having a plurality of amorphous silicon photo detectors arranged in a two dimensional array.

44. The apparatus of claim 42, wherein the access circuit being configured to read signals generated in the photo detector array at a rate between approximately 10⁴ and 10 ⁸ times per second.

45. The apparatus of claim 42, wherein the access circuit being further configured to reset the photo detector array after reading one or more signals therefrom.

46. The apparatus of claim 42, further comprising

an additional conversion panel positioned adjacent to the conversion panel, the additional conversion panel configured to generate a light photon in response to a radiation;

and

an additional photo detector array aligned with the additional conversion panel, the additional photo detector array coupled to the access circuit and is configured to generate a signal in response to the light photon received from the additional conversion panel.

47. The apparatus of claim 46, wherein the signal processing circuit being further configured to determine whether a radiation detected at the conversion panel is associated with a radiation detected at the additional conversion panel based at least on a position of a radiation source relative to the conversional panel and the additional conversional panel.

48. The apparatus of claim 46, wherein the signal processing circuit being configured to determine whether a radiation detected at the conversion panel is associated with a radiation detected at the additional conversion panel based at least on an energy level of a radiation detected at the conversion panel and an energy level of a radiation detected at the additional conversion panel.

49. The apparatus of claim 46, wherein the signal processing circuit being configured to determine whether a radiation detected at the conversion panel is associated with a radiation detected at the additional conversion panel based at least on a position of a first particle detected at the conversion panel and a position of a second particle detected at the additional conversion panel.

50. The apparatus of claim 42, further comprising an accelerator configured to direct a radiation beam onto an object to generate the radiation.

51. The apparatus of claim 42, further comprising a platform for supporting an object.

52. The apparatus of claim 42, wherein the signal generating rate is associated with a rate at which photons are received by the conversion panel. for supporting an object.