Structured detectors and detector systems for radiation imaging

• US 10,267,927 B2
• Filed: 02/05/2018
• Issued: 04/23/2019
• Est. Priority Date: 09/09/2016
• Status: Active Grant

• Current Assignee: Minnesota Imaging and Engineering LLC
• Original Assignee: Minnesota Imaging and Engineering LLC
• Inventors: Nelson, Robert Sigurd, Nelson, William Bert
• Primary Examiner(s): Porta, David P
• Assistant Examiner(s): Gutierrez, Gisselle M
• Application Number:
  US15/888,637
• Publication Number:
  US 20180172848A1
• Time in Patent Office: 442 Days
• Field of Search: 25036302
• CPC Class Codes: A61B 6/025 Tomosynthesis
• CPC Class Codes: A61B 6/032 Transmission computed tomography [CT]
• CPC Class Codes: A61B 6/035 Mechanical aspects of CT
• CPC Class Codes: A61B 6/037 Emission tomography
• CPC Class Codes: A61B 6/0492 using markers or indicia for aiding patient positioning
• CPC Class Codes: A61B 6/4085 Cone-beams
• CPC Class Codes: A61B 6/4208 characterised by using a particular type of detector
• CPC Class Codes: A61B 6/4258 for detecting non x-ray radiation, e.g. gamma radiation A61B6/037 takes precedence
• CPC Class Codes: A61B 6/4417 related to combined acquisition of different diagnostic modalities
• CPC Class Codes: A61B 6/4435 the source unit and the detector unit being coupled by a rigid structure
• CPC Class Codes: G01N 2223/108 positrons; electron-positron annihilation
• CPC Class Codes: G01N 2223/419 computed tomograph
• CPC Class Codes: G01N 2223/505 scintillation
• CPC Class Codes: G01N 23/046 using tomography, e.g. computed tomography [CT]
• CPC Class Codes: G01N 23/2255 using incident ion beams, e.g. proton beams
• CPC Class Codes: G01T 1/20181 Stacked detectors, e.g. for measuring energy and positional information using a combination of different types of scintillation detectors, e.g. phoswich detectors, G01T1/2008
• 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 1/20184 Detector read-out circuitry, e.g. for clearing of traps, compensating for traps or compensating for direct hits
• CPC Class Codes: G01T 1/20185 Coupling means between the photodiode and the scintillator, e.g. optical couplings using adhesives with wavelength-shifting fibres
• CPC Class Codes: G01T 1/2019 : Shielding against direct hits
• CPC Class Codes: G01T 1/22 : with Cerenkov detectors

Abstract

Detector module designs for radiographic imaging include first and second layers of scintillator rods or pixel arrays oriented in first and second directions. The first and second directions are transversely oriented to define a light sharing region between the first and second layers. Encoding features may be disposed in, on or between the first and second layers, and configured to modulate propagation of optical signals therealong or therebetween.

Claims

1. A detector module comprising:

at least first and second layers comprising a first layer of scintillator rods and a second continuous scintillator layer, layer of scintillator rods or a pixel structured scintillator layer, respectively, configured to generate optical signals in response to ionizing radiation, wherein the scintillator rods extend in a longitudinal direction and the second continuous, scintillator rod or pixel structured scintillator layer extends transversely thereto;

a light sharing region defined between the first and second layers, wherein the optical signals are transmitted between the first layer of scintillator rods and the second continuous, scintillator rod or pixel structured scintillator layer; and

a plurality of photodetector elements configured to convert the optical signals into output characterizing the radiation;

wherein the first and second layers are formed of a unitary scintillator element having a first major surface of the first layer and a second major surface of the second layer, with a thickness of the unitary scintillator element defined between the first and second major surfaces.

2. The detector module of claim 1, wherein:

the first layer comprises a plurality of rod elements defined by a first set of dividers extending into the unitary scintillator element from the first major surface thereof;

the second layer comprises a plurality of rod or pixel structured scintillator elements defined by a second set of dividers extending into the unitary scintillator element from the second major surface thereof; and

each of the first and second sets of dividers has a depth less than the thickness of the unitary scintillator element between the first and second major surfaces.

3. The detector module of claim 2, wherein the dividers are formed by at least one nanocrystal or electroluminescent material disposed between the respective scintillator rod or pixel structured elements.

4. The detector module of claim 2, wherein the depth of the dividers is nonuniform and defines a corresponding nonuniform thickness of the first layer.

5. The detector module of claim 4, wherein the depth of the dividers is selected to define a curved or arcuate boundary between the first and second layers.

6. The detector module of claim 1, further comprising an encoding pattern configured to modulate light sharing between the first and second layers of the unitary scintillator element.

7. An imaging system comprising a plurality of detector modules configured to interrogate a material sample by detecting ionizing radiation according to claim 1, and further comprising at least one of active or passive encoding implemented with at least one of the detector modules.

8. The imaging system of claim 7, further comprising:

an image processor in communication with the detector modules, the image processor configured to generate images of the material sample based on the ionizing radiation and the encoding;

wherein the material sample includes biological tissue and the image processor is configured for medical imaging thereof, or wherein the material sample includes a non-tissue material and the image processor is configured for non-medical science, industry or inspection imaging thereof.

9. The imaging system of claim 7, wherein the encoding includes non-optical information carriers or modifying at least one electric, magnetic, electromagnetic, acoustic and thermal ionizing radiation properties of the detector modules.

10. The imaging system of claim 9, wherein:

the radiation detector modules include one or more of slab, block, pixelated, array, layered, 3D structured and structured ionizing radiation detector elements; and

the encoding comprises ionizing radiation structured detector elements of the detector modules.

11. The detector module of claim 1, wherein:

the first layer comprises a plurality of scintillator rod elements defined by a first set of dividers extending into the unitary scintillator element from the first major surface thereof;

the second layer comprises a plurality of scintillator rod elements defined by a second set of dividers extending into the unitary scintillator element from the second major surface thereof; and

each of the first and second sets of dividers has a depth less than the thickness of the unitary scintillator element between the first and second major surfaces.

12. The detector module of claim 1, further comprising a third layer comprising scintillator rods configured to generate optical signals in response to ionizing radiation, the third layer adjacent the first or second layer.

13. The detector module of claim 2, wherein the dividers are formed by at least one of a reflective, absorptive, diffusive, refractive, diffractive, or WLS optical feature or material disposed between respective scintillator rod or pixel structured elements.

14. A detector module comprising:

a first layer of elongate scintillator elements, each extending in a longitudinal direction along the first layer;

a second layer of pixel structured scintillator elements extending in first and second transverse directions along the second layer;

at least one intermediate layer disposed between the first and second layers; and

a plurality of photodetectors configured to generate output characterizing optical signals generated by the scintillator elements in response to radiation interacting in one or both of the first and second layers;

wherein one or more of the first and second layers are formed of a unitary scintillator material and further comprising a plurality of dividers formed in the unitary scintillator material, the dividers defining the scintillator elements therein.

15. The detector module of claim 14, wherein the intermediate layer comprises a plurality of elongate scintillator elements disposed at a skew angle with respect to the elements of the first or second layer.

16. The detector module of claim 14, wherein the intermediate layer comprises a plurality of pixel structured scintillator elements.

17. The detector module of claim 14, wherein the intermediate layer comprises a continuous scintillator layer.

18. The detector module of claim 14, wherein the intermediate layer is configured to modulate light sharing between the scintillator elements in the first and second layers.

19. A detector module according to claim 14, further comprising at least one nanocrystal material disposed in, on and or between the scintillator elements and the photodetectors, wherein the nanocrystal material is adapted to shift an emission spectrum of the scintillator elements to match a spectral response of the photodetectors.

20. The detector module of claim 19, wherein the nanocrystal material is adapted to shift the emission spectrum for Cherenkov light emitted by the scintillator elements in response to the radiation to match the spectral response of the photodetectors.

21. The detector module of claim 19, wherein the nanocrystal material is adapted to reduce light trapping of a fluorescence signal generated by the scintillator elements in response to the radiation.

22. The detector module of claim 19, wherein the nanocrystal material is adapted to modulate the optical signals as a function of position along the scintillator elements.

23. The detector module of claim 19, further comprising an optical coating applied between the nanocrystal material and a surface of one or more of the scintillator elements, the optical coating having an index of refraction selected to enhance internal reflection at the surface.

24. A detector module according claim 14, wherein the photodetectors include strip photodetectors with a read out at both ends or continuous area photodetectors with a readout at each of four corners, wherein the photodetectors are disposed to detect the optical signals emitted at opposite sides or ends of one or more of the scintillator elements.

25. A detector module according to claim 14, wherein the photodetectors are disposed to detect optical signals emitted at sides or ends of the scintillator elements and have timing resolution adapted to distinguish signals reflected from opposite sides or ends thereof.

26. A detector module according to claim 14, wherein the layers are curved or generally arcuate to provide a focused geometry of the detector module with respect to a radiation source, wherein the layers define one or more generally cylindrical shell segments oriented along an axial direction transverse to a direction of the radiation source, or wherein the layers define one or more generally spherical shell segments disposed generally transverse to a direction of the radiation source.

27. A method of operating an imaging system comprising a plurality of detector modules according to claim 14, the method comprising:

interrogating a material sample with ionizing radiation;

detecting the ionizing radiation with the plurality of detector modules; and

generating images of the material sample with an image processor in communication with the detector modules, based on the ionizing radiation and the encoding technique;

wherein an active or passive encoding technique is implemented with at least one of the detector modules or the material sample.

28. The method of claim 27, wherein:

the material sample includes biological tissue and the image processor is configured for medical imaging thereof;

or

the material sample includes a non-tissue material and the image processor is configured for imaging thereof.

29. The method of claim 27, wherein the encoding technique comprises:

utilizing non-optical information carriers with or without passive optical encoding;

modifying at least one of electric, magnetic, electromagnetic, acoustic or thermal ionizing radiation properties of the at least one of the detector modules;

or

implementing ionizing radiation structured detector elements of the detector modules.

30. A detector module according to claim 14, further comprising at least one wavelength shifting material disposed in, on or between the scintillator elements and the photodetectors, wherein the wavelength shifting material is adapted to shift an emission spectrum of the scintillator elements to match a spectral response of the photodetectors.

31. The detector module of claim 30, wherein the wavelength shifting material is adapted to at least one of:

shift the emission spectrum for Cherenkov light emitted by the scintillator elements in response to the radiation to match the spectral response of the photodetectors;

reduce light trapping of a fluorescence signal generated by the scintillator elements in response to the radiation; and

modulate the optical signals as a function of position along the scintillator elements.

32. The detector module of claim 14, wherein the intermediate layer is optically coupled with the first layer of elongate scintillator elements and the second layer of pixel structure scintillator elements.

33. A detector module comprising:

at least first and second layers of crossed scintillator rods configured to generate optical signals in response to ionizing radiation, the crossed scintillator rods extending in first and second transverse directions in the first and second layers, respectively;

a light sharing region defined between the first and second layers, wherein the optical signals are transmitted between the respective crossed scintillator rods;

a plurality of photodetector elements configured to convert the optical signals into output characterizing the radiation; and

an encoding pattern applied to one or both of the first and second layers of scintillator rods, or between the scintillator rods, the encoding pattern configured to modulate propagation of the optical signals along one or both layers of scintillator rods, or between the first and second layers of scintillator rods;

wherein the first and second layers of scintillator rods are defined in a unitary scintillator element having the light sharing region defined therein, with a thickness of the unitary scintillator element defined between a first major surface of the first layer and a second major surface of the second layer.

34. The detector module of claim 33, wherein the pattern comprises at least one of a nanocrystal or electroluminescent material or surface adapted to modulate the propagation of optical signals.

35. The detector module of claim 33, further comprising a plurality of dividers extending in the first and second transverse directions in the first and second layers respectively, the dividers defining the scintillator rods in the respective layers.

36. The detector module of claim 35, wherein the dividers comprise at least one of a nanocrystal or electroluminescent optical feature or material disposed between the respective scintillator rods.

37. The detector module of claim 33, wherein the first layer of crossed scintillator rods provides a relatively short optical path length relative to the second layer of crossed scintillator rods.

38. The detector module of claim 34, further comprising an optical coating applied between the nanocrystal material and a surface of one or more of the scintillator elements, the optical coating having an index of refraction selected to enhance internal reflection at the surface.

39. A detector module comprising:

first and second layers of scintillator elements configured to generate optical signals in response to ionizing radiation, wherein the first and second layers are defined in a unitary scintillator element;

a light sharing region defined in the unitary scintillator element between the first and second layers, wherein the optical signals are transmitted between the respective scintillator elements;

a plurality of photodetector elements configured to convert the optical signals into output characterizing the radiation; and

a plurality of dividers extending in one or both of first and second directions in one or both of the first and second layers, respectively, the dividers defining the respective scintillator elements therein.

40. The detector module of claim 39, wherein the scintillator elements comprise one or more of scintillator rods, scintillator pixels, and scintillator blocks.

41. The detector module of claim 39, wherein the dividers comprise nanocrystal or electroluminescent optical features or materials disposed between the respective scintillator elements.

42. The detector module of claim 39, further comprising an encoding pattern applied between the scintillator elements of the first and second layers, or between the layers, the encoding pattern configured to modulate propagation of the optical signals.

43. The detector module of claim 39, detector module of claim 39, further comprising at least one intermediate layer disposed between the first and second layers, the intermediate layer configured to the modulate light sharing between the first and second layers.