Hybrid laser / air coupled pet block detector

Abstract

A method of manufacturing a detector array is provided, the method comprising: preparing a plurality of plates of optical media of an imaging device; forming a plurality of optical boundaries within at least one of the plates of optical media, wherein the plurality of optical boundaries define a 1xN array of non-contiguous independent light redirecting regions within the at least one plate; arranging the plurality of plates into a stack having a reflective layer defined between each adjacent plate; and fixing the positioning of the plurality of plates relative to one another. A detector array formed using the method is also provided.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to U.S. Provisional Application No. 62 / 903,257, filed September 20, 2019, under 35 USC §119(e), the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to a method for manufacturing a detector array for imaging applications such as X-ray imaging, fluorescence fluoroscopy, positron emission tomography (PET), single-photon emission computed tomography (SPECT), computed tomography (CT), gamma cameras, and digital mammography systems. Background Technology

[0004] Imaging is widely used in many medical and non-medical applications. In the field of imaging, it is well known that imaging devices incorporate multiple scintillator arrays to detect radioactivity from a variety of sources. When constructing a scintillator array consisting of discrete scintillator elements, the scintillator elements are typically encapsulated with a reflective medium inserted between the individual elements, thus creating photon boundaries. Conventionally, the reflective medium is used to guide the scintillating light along the scintillator elements into a light guide to accurately pinpoint the location where radiation strikes the detector elements. The reflective medium is further used to increase the light collection efficiency from each scintillator element and to minimize crosstalk or light propagation (light transmission) from one scintillator element to adjacent elements. Reflective media include reflective powders, thin films, coatings, and binders doped with reflective powders, or combinations of materials. Reflective coatings and powders contain one or more pigments, such as MgO, BaSO4, and TiO2. Regardless of the method, the conventional approach to manufacturing radiation detector arrays is a time-consuming and labor-intensive process, where product consistency depends heavily on the skill level of the workforce. These process effects are even more pronounced with the current market trend of higher spatial resolution systems containing an order of magnitude more pixels than current designs.

[0005] Detector arrays are typically integrated with photomultiplier tubes (PMTs) or solid-state photodetectors—such as silicon photomultipliers (SiPMs), avalanche photodiodes (APDs), PIN diodes, and charge-coupled devices (CCDs). Incident high-energy photons absorbed by the scintillating material are converted into lower-energy scintillating photons, which can be guided to the photodetector via one or more of the following methods: the scintillator itself, light guides, and other established light distribution components.

[0006] In arrangements where light guides and / or other constructed components are used, light guides are typically formed by creating slits of varying depths in a suitable substrate. Once encapsulated with a reflective medium, the light guide becomes an effective method for transmitting light and enhancing scintillator positioning information. In arrangements where coatings or reflective strips are used, the coating or reflective strip is applied directly to the scintillator, achieving a similar result. The height and placement of the applied reflective material vary depending on the design.

[0007] Conventionally, the scintillator array has been formed from polished or unpolished crystals in one of the following ways: hand-wrapped in reflective PTFE tape and bundled together; bonded together using a white pigment such as BaSO4 or TiO2 mixed with epoxy resin or RTV; or bonded to a glass light guide with defined spacing and then filled with a reflective material as discussed above.

[0008] Another method utilizes individual reflectors bonded to the sides of certain scintillator elements with the aid of a binder. By arranging the individual elements in space to form an array, the impact of high-energy photons can be precisely decoded. Summary of the Invention

[0009] This document provides a method for manufacturing an optical segmented detector array (such as a scintillator array). The method includes: preparing a plurality of plates of an optical medium for an imaging device; forming a plurality of optical boundaries within at least one of the plates of the optical medium, wherein the plurality of optical boundaries define a 1×N array of non-adjacent independent light redirection regions within the at least one plate; arranging the plurality of plates in a stack, the stack having a reflective layer defined between each adjacent plate; and positioning the plurality of plates relative to each other.

[0010] A detector array is provided, comprising: a plurality of plates of optical medium arranged in a stacked manner, wherein at least one of the plates includes: a 1×N array of non-adjacent independent light redirection regions defined by N-1 optical boundaries, wherein each optical boundary is formed by an array of non-adjacent independent microvoids; a reflective layer defined between two adjacent plates of the detector array for reflecting light from the non-adjacent independent light redirection regions such that no other reflective material exists between the adjacent plates; and a mechanism for maintaining the relative positioning of each plate of the array relative to each other.

[0011] A detector assembly including the detector array disclosed herein is also provided. Attached Figure Description

[0012] The features of the embodiments described herein will be more fully disclosed in the following detailed description, which is to be compared with the appended drawings. Figure 1For reference, similar figures refer to similar parts. All figures are schematic and are not intended to represent the actual dimensions of the structures or the relative ratios of their dimensions;

[0013] Figure 1 This is an illustration of a detector array according to an embodiment of the present disclosure;

[0014] Figure 2 It is shown Figure 1 A diagram of a partial exploded view of the detector array;

[0015] Figure 3 This is a diagram illustrating a non-adjacent independent microgap array that forms optical boundaries between scintillator elements in each plate forming the detector array of this disclosure;

[0016] Figures 4A-4B This is an illustration of an example detector assembly according to some embodiments;

[0017] Figure 5 This is a flowchart illustrating a method for manufacturing a detector array according to the present disclosure. Detailed Implementation

[0018] This description of exemplary embodiments is intended to be read in conjunction with the accompanying drawings, which are to be considered part of the entire written description. The drawings are not necessarily drawn to scale, and for clarity and brevity, certain features may be enlarged or shown in some schematic form. In the description, related terms such as “horizontal,” “vertical,” “up,” “down,” “top,” and “bottom,” and their derivatives (e.g., “horizontally,” “downward,” “upward,” etc.) should be interpreted as referring to orientations as described subsequently or as shown in the drawings discussed. These relative terms are for ease of description and are not generally intended to require a specific orientation. Terms including “inward” relative to “outward,” “longitudinal” relative to “lateral,” and such terms should be interpreted as relative to each other or relative to an axis of extension or rotation or a center, as applicable. Terms relating to attachment, coupling, and such as “connected” and “interconnected” refer to a relationship in which structures are directly or indirectly fixed or attached to each other via an intermediate structure, and both movable or rigid attachments or relationships, unless otherwise explicitly described. The term "operable connection" is an attachment, coupling, or connection that allows related structures to operate as intended by virtue of that relationship.

[0019] refer to Figure 1 and Figure 2A detector array 100 according to an embodiment is disclosed. The detector array 100 includes a plurality of plates 110 of optical media arranged in a stacked manner. At least one of the plates 110 includes a 1×N array of non-adjacent independent light redirection regions 115 (i.e., detector elements) within at least one plate 110. Each of the non-adjacent independent light redirection regions 115 is defined by an N-1 number of optical boundaries 120.

[0020] In some embodiments of the detector array 100, each of the plurality of plates 110 includes a 1×N array of non-adjacent independent light redirection regions 115 within each plate 110. The stacking of the plates 110 then forms an M×N array of detector elements 115, where M represents the number of plates 110 of optical medium.

[0021] The plates 110 are assembled into a stack such that a defined reflective layer 130 exists between two adjacent plates 110 in the array. The reflective layer 130 acts as a reflector and reflects light from within the detector element 115 to travel within the detector element 115.

[0022] In some embodiments, the reflective layer 130 may be an inflatable gap between two adjacent plates 110, and the detector array 100 has no other reflective material between the adjacent plates 110. The width of the inflatable gap 130 depends on the surface roughness of the plates 110. In a preferred embodiment, the plates 110 are configured to have a surface roughness such that when the two plates 110 are placed together, the width of the inflatable gap 130 is greater than one to two times the wavelength of the light generated by the optical medium of the detector element 115, thereby suppressing ephemeris waves (suppressed total internal reflection).

[0023] In some embodiments, the reflective layer 130 includes at least one of the following reflective materials: reflective powder, reflective film, reflective coating and adhesive doped with reflective powder, or a combination of reflective materials.

[0024] The stacked plates 110 are held relative to each other in their relative positions within the detector array 100 by means of a mechanism such as a binder or retainer 150.

[0025] In some embodiments, the optical medium is a scintillator crystal, and scintillator plates 110 are stacked to form a detector array 100, which is a scintillator array. The gas gap 130, combined with the surface finish of the scintillator plates 110, defines the light collection efficiency of the scintillator elements 115 and the amount of light sharing occurring between the elements 115. The significant change in the refractive index (IOF) from the detector elements 115 and air increases the total angle of refraction. Based on the IOF (scintillator) / IOF (air) ratio and the surface finish of the scintillator plates 110, the amount of scintillating photons is tuned such that a controlled amount of photons is collimated downwards through the scintillator elements 115, and the controlled amount is transmitted to adjacent scintillator elements 115. An optimal ratio is customized for each scintillator element 115 within the detector array 100, such that each element 115 in the detector array 100 is clearly identified. This ratio can be spatially varied.

[0026] refer to Figure 3 Each optical boundary 120 in the scintillator plate 110 is formed by an array of non-adjacent, independent microvoids 12 formed in the optical medium. Multiple microvoids 12 are defined collectively for conveying scintillating light through the optical segmentation portion 115 of the scintillator. The microvoids 12 are positioned in the spatial plane 14 of the optical medium to define the optical boundaries 120 of the optical segmentation portion 115 of the detector array 100. The microvoids 12 can be deployed in a specific uniform pattern with varying sizes, or randomly placed. The microvoids can be deployed in a single layer or multiple layers, or randomly dispersed within a given volume. The microvoids can be deployed in a planar, curved, or other geometrically arranged configuration on the spatial plane 14. To this extent, the optical segmentation portion of the scintillator can define various cross-sectional configurations other than squares. For example, the optical segmentation portion can define triangular, trapezoidal, or hexagonal geometries. Alternatively, the optical segmentation portion can define combinations of configurations, such as octagons and squares.

[0027] A laser source 30 is used to form microvoids. The laser source 30 generates a laser beam 32 and sequentially focuses it onto the optical medium at each selected location (x, y, z). The laser source 30 generates a laser beam 32 of sufficient power to ablate the target optical medium at the focal point, thereby causing damage to the crystal structure of the optical medium at that location, which will be referred to herein as microvoid 12. The microvoid causes photons encountering it to scatter. In industry, microvoids are sometimes referred to as microcracks.

[0028] As mentioned herein, the optical medium used for detector array 100 may be a scintillator, a light-transmitting block, or a light guide. The optical medium is made of a material that does not absorb laser wavelengths. The strong energy focused at the focal point of the laser beam creates microvoids within the target optical medium, which extend outward from the origin in all directions. Further details of the laser process used to form the microvoids can be found in U.S. Patent No. 8,470,214, the contents of which are incorporated herein by reference.

[0029] Figure 4A The illustration shows an example of a detector assembly 100A according to some embodiments. The detector assembly 100A includes a detector array 100 and at least one photodetector 18. The detector array 100 is coupled to the at least one photodetector 18, and a scintillator element array 115 is optically coupled to the at least one photodetector 18. The at least one photodetector 18 may be selected from, but is not limited to, PMTs, position-sensitive PMTs, SiPMs, APDs, PIN diodes, CCDs, and other solid-state detectors.

[0030] In this arrangement, a scintillator element 115 deployed within the detector array 100 is used to detect incident gamma rays and subsequently generate an optical signal corresponding to the amount of energy deposited by the initial interaction between the gamma rays and the scintillator element 115. The detector array 100 is used to reflect the light and deliver it downwards along the scintillator element 115 to a photodetector 18. The signal generated by the photodetector 18 is then post-processed and utilized, depending on the purpose of the imaging device.

[0031] In some embodiments, the light guide 20 may be selectively placed between the detector array 100 and the receiving photodetector 18, if necessary. The light guide 20 defines a selected configuration, such as segmented or continuous. When employing the light guide 20, its optimization depends on the selection of the scintillator element 115 and the photodetector 18.

[0032] In embodiments utilizing the light guide 20, the detector array 100 is used to reflect light generated within the scintillator element and deliver it downwards along the scintillator element 115 to the coupled light guide 20 and photodetector 18. The signal generated by the photodetector 18 is then post-processed and utilized, depending on the purpose of the imaging device.

[0033] In the detector array 100 of this disclosure, the relative positioning of each detector element 115 is maintained by using a holding mechanism 16 to maintain the relative positioning of the scintillator plates 110 within the detector array 100. In some embodiments, the holding mechanism 16 may be a retainer surrounding the outer periphery of the detector array 100. Figure 4AThe detector assembly 100A is illustrated as having such a retainer 16. Such a retainer 16 can be made of conventional materials—such as shrink wrap, rubber bands, tape, or combinations thereof—and can be used to tightly and uniformly enclose or hold the plates 115 together. Although in Figure 4A The diagram shows the entire height of detector array 100, but in some applications, retainer 16 may include one or more retainers that only span a portion of the height of detector array 100.

[0034] In other embodiments, the retaining mechanism 16 may be a binder applied between the detector array 100 and the continuous light guide 20.

[0035] Figure 4B The illustration shows another example of a detector assembly 100B deployed above a continuous light guide 20. In this example, the relative positioning of the individual scintillator elements 115 is maintained by a mechanism 16, which is a bonding agent applied between the detector array 100 and the continuous light guide 20. The continuous light guide 20 is deployed above an array of photodetectors 18, such as in a panel detector.

[0036] In some embodiments of detector assemblies 100A and 100B, the at least one photodetector 18 may be a PMT, a position-sensitive PMT, a SiPM, an APD, a PIN diode, a CCD, or other types of solid-state detectors.

[0037] In embodiments of detector assemblies 100A, 100B that include a light guide 20 deployed between detector array 100 and at least one photodetector 18, scintillator element 115 is optically coupled to at least one photodetector 18 via light guide 20.

[0038] In some embodiments of detector assemblies 100A and 100B, the light guide 20 is configured to be continuous over a plurality of scintillator element arrays 115 and a plurality of at least one photodetector 18.

[0039] refer to Figure 5Flowchart 200 in the present document discloses a method for manufacturing the detector array 100 of the present disclosure. The method includes preparing a plurality of plates 110 of an optical medium for an imaging device (step 210); forming a plurality of optical boundaries 120 within at least one of the plates 110 of the optical medium, wherein the plurality of optical boundaries 120 define a 1×N array of non-adjacent independent light redirection regions (i.e., detector elements) within at least one plate, where N represents the number of individual detector elements 115 (step 220); arranging the plurality of plates into a stack having a reflective layer 130 defined between two adjacent plates 110 (step 230); and positioning the plurality of plates relative to each other (step 240).

[0040] In some embodiments of the method, the reflective layer 130 may be an air-filled gap between each adjacent plate 110. In some embodiments, the reflective layer includes at least one of the following reflective materials: reflective powder, reflective film, reflective coating and adhesive doped with reflective powder, or a combination of reflective materials.

[0041] In some embodiments of the method, a plurality of optical boundaries 120 are formed within each plate 110 of the optical medium, thereby the stacking of the plurality of plates 110 in the detector array forms an M×N array of non-adjacent independent optical redirection regions, where M represents the number of plates 110.

[0042] In some embodiments of the method, fixing the positioning of the plurality of plates 110 includes attaching each of the plates 110 to at least one photodetector 18 using an adhesive 16. In some embodiments, detector assemblies 100A, 100B include light guides 20, and the method includes fixing the positioning of the plurality of plates 110, which includes attaching each of the plates 110 to the light guide 20 using an adhesive 16, and then attaching the light guide 20 to at least one photodetector 18.

[0043] In some embodiments of the method, forming multiple optical boundaries 120 includes forming multiple non-adjacent independent light redirection regions 12 in each of the spatial surfaces 14 of the plate 110 by focusing a laser beam 32 of a selected wavelength at a focal point at different selected locations on the spatial surface 14, thereby altering the optical properties of the optical medium at the focal point.

[0044] In some embodiments of the detector array 100, the optical medium is a scintillator, and wherein the optical boundary 120 defines the boundary between the individual optical segment resolution elements 115 of the scintillator.

[0045] In some embodiments of the detector array 100, the optical medium is a light-transmitting object, and wherein the optical boundary 120 defines a portion of a light guide within the light-transmitting object.

[0046] In some embodiments of the detector array 100, multiple optical segmented resolution elements are linear in shape.

[0047] In some embodiments of the detector array 100, the space surface 14 is curved.

[0048] It should be understood that the foregoing description is an exemplary embodiment of the present invention, and the present invention is not limited to the specific forms shown. Modifications to the design and arrangement of the elements may be made without departing from the scope of the present invention.

Claims

1. A method of manufacturing a detector array, comprising: preparing a plurality of plates of optical media of an imaging device; forming a plurality of optical boundaries within at least one of the plates of optical media, wherein the plurality of optical boundaries define a 1 x N array of non-contiguous individual light redirecting regions within the at least one plate, wherein the optical boundaries are formed from an array of non-contiguous individual micro voids formed using a laser source; arranging the plurality of plates into a stack having a reflective layer defined between each adjacent plate; and fixing the positioning of the plurality of plates relative to one another, wherein the reflective layer is a gas-filled gap between each adjacent plate.

2. The method of claim 1, wherein the reflective layer comprises at least one of the following reflective materials: reflective powder, reflective film, reflective paint, and an adhesive doped with reflective powder, or a combination of reflective materials.

3. The method of claim 1, wherein the plurality of optical boundaries are formed within each plate of optical media, whereby the stack of the plurality of plates forms an M x N array of non-contiguous individual light redirecting regions in the detector array, where M represents the number of plates.

4. The method of claim 1, wherein fixing the positioning of the plurality of plates comprises attaching each of the plates to at least one photodetector using a bonding agent.

5. The method of claim 1, wherein fixing the positioning of the plurality of plates comprises attaching each of the plates to a light guide using a bonding agent, and then attaching the light guide to at least one photodetector.

6. The method of claim 1, wherein forming the plurality of optical boundaries comprises forming a plurality of non-contiguous individual light redirecting regions in a spatial surface within at least one of the plates by focusing a laser beam of a selected wavelength at focal points at different selected locations on the spatial surface, thereby changing an optical property of the optical media at the focal points.

7. The method of claim 1, wherein the optical media is a scintillator, and wherein the optical boundaries define boundaries between individual optically segmented resolution elements of the scintillator.

8. The method of claim 1, wherein the optical media is a light transmissive object, and wherein the optical boundaries define a portion of a light guide within the light transmissive object.

9. The method of claim 7, wherein the plurality of individual optically segmented resolution elements are rectilinear.

10. The method of claim 6, wherein the spatial surface is curvilinear.

11. A detector array, comprising: a plurality of plates of optical media arranged in a stack, wherein at least one of the plates comprises: a 1 x N array of non-contiguous individual light redirecting regions defined by N-1 optical boundaries, wherein each optical boundary is formed from an array of non-contiguous individual micro voids formed using a laser source; a reflective layer defined between two adjacent plates of the detector array, the reflective layer for reflecting light from the non-contiguous individual light redirecting regions such that there is no other reflective material between the adjacent plates, wherein the reflective layer is a gas-filled gap between each adjacent plate; and a mechanism for maintaining the relative positioning of each of the plates of the array relative to one another.

12. The detector array of claim 11, wherein each of the plates comprises a 1 x N array of non-contiguous individual light redirecting regions defined by N-1 optical boundaries, wherein each optical boundary is formed by an array of non-contiguous individual micro voids; wherein the stack of plates forms an M x N array of non-contiguous individual light redirecting regions, where M represents the number of plates.

13. The detector array of claim 11, wherein the reflective layer comprises at least one of the following reflective materials: reflective powder, reflective film, reflective paint, and adhesive doped with reflective powder, or a combination of reflective materials.

14. The detector array of claim 11, wherein the optical medium is a scintillator, the non-contiguous individual light redirecting regions are scintillator elements, and the detector array is a scintillator array.

15. The detector array of claim 11, wherein the non-contiguous individual light redirecting regions are linear in shape.

16. A detector assembly comprising: a detector array comprising: a plurality of scintillator plates arranged in a stack, wherein at least one scintillator plate comprises: a 1 x N array of scintillator elements defined by N-1 optical boundaries, wherein each optical boundary is formed by an array of non-contiguous individual micro voids formed using a laser source; a reflective layer defined between each adjacent scintillator plate of the array, the reflective layer for reflecting light from the scintillator elements such that there is no other reflective material between adjacent scintillator plates, wherein the reflective layer is a gapped gap between each adjacent scintillator plate; and a mechanism for maintaining the relative positioning of each scintillator plate of the array relative to one another.

17. The detector assembly of claim 16, wherein each scintillator plate comprises a 1 x N array of non-contiguous individual light redirecting regions defined by N-1 optical boundaries, wherein each optical boundary is formed by an array of non-contiguous individual micro voids; wherein the stack of scintillator plates forms an M x N array of non-contiguous individual light redirecting regions, where M represents the number of plates.

18. The detector assembly of claim 16, wherein the reflective layer comprises at least one of the following reflective materials: reflective powder, reflective film, reflective paint, and adhesive doped with reflective powder, or a combination of reflective materials.

19. The detector assembly of claim 16, further comprising at least one photodetector, and the array of scintillator elements is coupled to the at least one photodetector.

20. The detector assembly of claim 16, wherein the mechanism for maintaining the relative positioning of each scintillator plate relative to one another comprises a retainer that circumscribes an outer perimeter of the detector array.

21. The detector assembly of claim 19, wherein the mechanism for maintaining the relative positioning of each scintillator plate relative to one another comprises a binding agent for binding the detector array to the at least one photodetector.

22. The detector assembly of claim 19, wherein the at least one photodetector is a photomultiplier tube, a position sensitive photomultiplier tube, a silicon photomultiplier tube, an avalanche photodiode, a pin diode, a CCD, or a solid state detector.

23. The detector assembly of claim 19, further comprising a light guide disposed between the array of scintillator elements and the at least one photodetector, wherein the scintillator elements are optically coupled to the at least one photodetector via the light guide.

24. The detector assembly of claim 22, wherein the mechanism for maintaining the relative positioning of each scintillator plate relative to one another comprises a binding agent for binding the stack of scintillator plates to the at least one photodetector.

25. The detector assembly of claim 23, wherein the light guide is configured to be continuous over a plurality of the array of scintillator elements and a plurality of the at least one photodetector.

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