Universal tile PET detector

Abstract

A scalable medical imaging detector apparatus is provided having interchangeable sensor tiles with fixed external dimensions and fixed or universal mechanical, electrical, and cooling interfaces. Different sensor tile types with different performance levels and production costs are configured with a universal interface for coupling to a medical imaging device, while the rest of the imaging system remains unchanged.

Description

Technical Field

[0001] The following relates generally to nuclear imaging systems and, more particularly, to positron emission tomography (PET) detectors. Background Art

[0002] PET detectors with different requirements for energy, timing, and spatial resolution typically require different PET detectors, including different readout boards, control units, racks, and cooling systems, making it nearly impossible to address different market needs with a single PET detector platform.

[0003] High-end medical imaging systems, such as lutetium yttrium orthosilicate (LYSO)-based time-of-flight (ToF) PET imagers, require silicon photomultiplier (SiPM) sensors on silicon scintillator surfaces with a maximum fill factor to achieve the best coincidence timing resolution for ToF-PET.

[0004] Low-end medical imaging systems are often based on non-ToF scintillators, such as bismuth germanium oxide (BGO) scintillators, where timing resolution is less important and light sharing concepts can be used to reduce the fill factor of the sensor.

[0005] The two concepts often result in different sensor and electronics configurations, which makes any new development very expensive.

[0006] Specific improvements are disclosed below. Summary of the Invention

[0007] In one disclosed aspect, a detector block for an expandable detector in a medical imaging system includes at least one interchangeable sensor tile, the at least one interchangeable sensor tile being one of a plurality of interchangeable sensor tile types, each interchangeable sensor tile type having a common outer dimension. The detector block also includes a universal mechanical interface configured to couple the interchangeable sensor tile to the expandable detector regardless of the type of the interchangeable sensor tile. The at least one interchangeable sensor tile includes an array of sensor dies coupled thereto, each sensor die having a plurality of scintillator crystals coupled thereto.

[0008] In another disclosed aspect, an interchangeable sensor tile for a detector block in a medical imaging system includes an array of sensor dies coupled to the interchangeable sensor tile, each sensor die having a plurality of scintillator crystals coupled thereto. The interchangeable sensor tile is one of a plurality of interchangeable sensor tile types, each interchangeable sensor tile type having outer dimensions configured to mate with a common mechanical interface, and each interchangeable sensor tile type having a different fill factor, the different fill factors being associated with reduced timing resolution and with reduced manufacturing cost.

[0009] In another disclosed aspect, a nuclear imaging system includes a plurality of detector blocks, each detector block including a common mechanical interface, and interchangeable sensor tiles coupled to each respective mechanical interface. Each interchangeable sensor tile includes an array of sensor dies coupled to the interchangeable sensor tile, each sensor die having a plurality of scintillator crystals coupled thereto. The interchangeable sensor tiles are one of a plurality of interchangeable sensor tile types, each having outer dimensions configured to mate with the common mechanical interface. Each interchangeable sensor tile type has a different fill factor, which is associated with reduced timing resolution and reduced manufacturing cost.

[0010] One advantage resides in reduced manufacturing costs.

[0011] Another advantage resides in improved device scalability.

[0012] A given embodiment may provide none of the aforementioned advantages, provide one, two, more, or all of the aforementioned advantages, and / or may provide other advantages, as will become apparent to one of ordinary skill in the art upon reading and understanding this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The invention may take form in various components and arrangements of components, and in various steps and arrangements of steps.The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention.

[0014] Figure 1 The sensor tile arrangement with maximum sensor fill factor for optimal energy, timing, and spatial resolution is illustrated.

[0015] Figure 2 A sensor tile arrangement with a moderate level of sensor fill factor for moderate performance (energy, timing, and spatial resolution) is illustrated.

[0016] Figure 3 The sensor tile arrangement with the lowest level of Value-PET performance at the lowest unit cost among the three illustrated examples is illustrated.

[0017] Figure 4 Illustrated is a scintillator configuration comprising a 12x12 array of scintillator crystals for use in a 6x6 sensor array.

[0018] Figure 5 Illustrated is a scintillator configuration comprising a 10x10 array of scintillator crystals for use in a 5x5 sensor array.

[0019] Figure 6 Illustrated is a scintillator configuration comprising an 8x8 array of scintillator crystals for use in a 4x4 sensor array.

[0020] Figure 7 The diagram shows a configuration using a 5x6 array of sensor dies with a 4.0x4.8mm crystal pitch, so that the outer dimensions of the sensor tile are Figure 1-6 Same as in.

[0021] Figure 8 The diagram shows a configuration using a 4x5 array of sensor dies with a 6.0x4.8mm crystal pitch, so that the outer dimensions of the sensor tile are Figure 1-7 Same as in.

[0022] Figure 9 An example of a highly reflective mask is shown in detail.

[0023] Figure 10 The illustrated table relates various scintillator crystal parameters (pitch, readout type, etc.) for different sizes of LYSO scintillators.

[0024] Figure 11 A general tiling concept of LYSO scintillators is illustrated, using a local light guide for each sensor die to read out 9 scintillators with one sensor die.

[0025] Figure 12 The corresponding floodmap is illustrated, showing a clear separation of all scintillators.

[0026] Figure 13 A high-resolution scanner with 9 scintillators (with local light guides as basic building blocks) is shown.

[0027] Figure 14 An array of 9 scintillator die assembled into a scintillator array is shown.

[0028] Figure 15 A flood diagram with 9 scintillators per die is shown, where the scintillator pitch is 1 / 3 the die pitch and the dimensions are 2.6 mm x 2.6 mm x 22 mm.

[0029] Figure 16 An example of a sensor stack with four monolithic LYSO scintillator blocks is illustrated.

[0030] Figure 17 A general tile configuration with maximum fill factor and a single scintillator covering a block of 3x3 sensor dies is illustrated.

[0031] Figure 18 A general tile configuration with maximum fill factor and a single scintillator covering a block of 2x2 sensor dies is illustrated.

[0032] Figure 19 A common tile configuration with a reduced fill factor of 55% is illustrated.

[0033] Figure 20 A common tile configuration with a reduced fill factor of 44% is illustrated.

[0034] Figure 21 An example of a LYSO thick slice detector array is shown.

[0035] Figure 22 A general tile configuration for a thick slice detector array with long thick slices (eg, extending the length of the edge of the detector) is illustrated.

[0036] Figure 23 A general tile configuration for a thick slice detector array with shorter thick slices is illustrated.

[0037] Figure 24 A general tile configuration for a thick layer detector as described above is illustrated, with a reduced 67% sensor fill factor for a low cost design.

[0038] Figure 25 A second general tile configuration is illustrated for a thick layer detector as described above, with a reduced sensor fill factor of 67%. DETAILED DESCRIPTION

[0039] To overcome these issues, the universal tile SiPM detector described in this article can be used to implement the basic construction of a solid-state SiPM-based PET detector, allowing the rest of the PET system infrastructure to be reused without further modification. The basic building block of the sensor is based on an integrated silicon die containing 2x2 or 4x4 SiPMs for separate energy and timing measurements. The universal tile detector can be used for PET, PET computed tomography (CT), PET magnetic resonance imaging (MRI), and other combinations, as well as single-photon emission computed tomography (SPECT) imaging.

[0040] Universal tile sensor tiles are described herein as building blocks for scalable PET detectors, with fixed external dimensions so that the sensor tiles share the same readout platform, electromechanical, and thermal interfaces. Several levels of sensor fill factor are employed, such as 6x6, 5x5, and 4x4 sensor die for the secondary scintillator surface, as well as other combinations, such as 6x5 or 5x4 sensor die for a rectangular scintillator surface on a fixed geometry secondary sensor tile. In one embodiment, the universal tile sensor tile has a secondary dimension, for example, between 48 mm and 54 mm.

[0041] A mechanical interface (which may include a thermal interface such as a cooling plate or heat sink) can be employed for the reader and mounted via weld nuts, snap fits, or other suitable fasteners. The scintillator does not require the use of liquid glue to mount it to the sensor tile, local light guide, or reflector. In one embodiment, a dielectric reflector mask that is insensitive to light is applied over the sensor area. An optically clear adhesive (OCA, a non-liquid glue) can be used to mount the reflector to the scintillator, maintaining an air gap above the non-sensitive portion of the sensor. After the scintillator array is mounted, the gaps between and below the sensors can be filled with underfill material.

[0042] In another embodiment, the sensor PCB sides and the mechanical interface, which may include a heat sink or cold plate, are covered by one or more dielectric reflectors that also cover the scintillator sides around the sensor tiles for increased mechanical stiffness and for increased light collection efficiency. The scintillators need only be mounted on the top and bottom crystal faces. The top surface of the scintillator array can be covered with two or more dielectric reflectors to increase light collection efficiency. Additionally, a dielectric reflector (e.g., Vikuiti [3M's enhanced specular reflector]) can be used to separate the scintillator from the sensor die to form a light-tight gap.

[0043] The light sharing concept of a one-to-one coupling of a 2x2 scintillator on a sensor die can be used with a 2x2 SiPM sensor and a sensor die with more pixels (e.g., 2x3, 3x3, or 4x4, etc.). Scintillators with 2 / 3, 4 / 3, or 3 / 2 the sensor pitch can also be used.

[0044] Local glass light guides can be used with scintillator arrays in high-resolution designs where one sensor die can read nine scintillators, where the die pitch is given by the maximum achievable sensor packaging fraction (e.g., 8 mm die pitch, etc.). Local glass light guides can also be used when one sensor die reads nine scintillators at a relaxed packaging fraction (e.g., 12 mm die pitch).

[0045] In another embodiment, multiple monolithic scintillators can be read out at a maximum sensor fill factor (e.g., 2x2 or 3x3 blocks) or a reduced sensor fill factor (e.g., 2x2 or 3x3 blocks), with sensors located at the corners of the scintillator (e.g., 4 or 5 per monolithic block). Additionally or alternatively, scintillator slabs that match 1 / 2, 1 / 3, or 1 / 4 of the sensor pixel pitch or sensor die pitch can be read out to achieve a pitch of 4 mm, 2.6 mm, or 2.0 mm. The scintillator slab can be used over the entire vertical or horizontal extension of the sensor tile or over 1 / 2 of the sensor tile. In another embodiment, a mixed vertical and horizontal slab is used within one sensor tile, wherein the width of the slab is 1 / 2 the width of the sensor tile. A reduced sensor fill factor can also be used for readout of scintillator slabs, wherein the sensor dies are positioned at the ends of the scintillator slab.

[0046] The described universal tile concept allows for sensor tile designs with variable PET performance and cost structures while keeping the external dimensions, as well as the electromechanical and thermal interfaces, constant. The universal tile concept is based on sensor units ("tiles") with a variable number of silicon dies, enabling different performance levels: maximum sensor fill fraction for ultimate ToF performance; medium fill fraction for intermediate ToF performance; low sensor fill fraction for low-end or non-ToF applications; and so on. Also disclosed are pixelated readout with one-to-one coupling and light sharing concepts with local light guides for each sensor die.

[0047] In the following examples, it is assumed that each sensor die can read four equally sized scintillator pixels through direct one-to-one coupling. However, as will be appreciated by those skilled in the art, the examples described herein are not limited by this assumption.

[0048] Figure 1-3 An example of a general tile concept with three performance levels is shown. Figure 1 In the example, the sensor tile arrangement 10 with the largest sensor fill factor is used for the best energy, timing and spatial resolution. Figure 2 A sensor tile arrangement 12 is shown with a medium level of sensor fill factor for medium performance (energy, timing and spatial resolution). Figure 3 A sensor tile arrangement 14 is shown that has a lower level of value-PET performance and has the lowest bill of materials (BOM) or unit cost among the three illustrated examples. The tile geometry is indicated by sensor dies 15, each of which includes an array of scintillator crystals on a sensor tile 16. The visible area of the sensor tile 16 is free of silicon. For a light-tight package, this area is covered by a dielectric reflective film (not shown). Figure 1-3Each of the diagrams shows several scintillator matrix configurations: for example, a one-to-one coupled crystal array configuration 20 shown in the upper left corner, a configuration 22 with 2x3 rectangular scintillators per sensor die pitch in the upper right corner, and a high resolution configuration 24 with 3x3 scintillators in the lower right corner. It will be understood that although the diagrams are shown for exemplary purposes, the diagrams in the upper right corner show a one-to-one coupled crystal array configuration 20, a configuration 22 with 2x3 rectangular scintillators per sensor die pitch in the upper right corner, and a high resolution configuration 24 with 3x3 scintillators in the lower right corner. Figure 1-3 A multiple scintillator crystal array configuration is shown in each sensor tile in , but according to one embodiment, a single crystal array configuration common to each sensor die in the sensor tile may be employed. A scintillator crystal 26 is also shown.

[0049] Figure 4-6 A side view of the general tile concept proposed above is shown with three performance level examples showing the scintillator crystals 26, sensor dies 15 and sensor tiles 16 in an array. Figure 4-6 The reflector is not shown, and in this example encapsulates four scintillators. Figure 4 A scintillator configuration 40 is shown comprising a 12x12 array of scintillator crystals 26 for use in a 6x6 sensor array. The pitch of each sensor die is 4.0 mm while maintaining the outer dimensions.

[0050] Figure 5 A scintillator configuration 50 is illustrated comprising a 10x10 array of scintillator crystals 26 for use in a 5x5 sensor array. The pitch of each sensor die is 4.8 mm, providing a sensor array while maintaining the outer dimensions.

[0051] Figure 6 A scintillator configuration 60 is illustrated that includes an 8x8 array of scintillator crystals 26 for use in a 4x4 sensor array. The pitch of each sensor die is 6.0 mm, providing a sensor array while maintaining the outer dimensions.

[0052] In one embodiment, the packing fraction of the scintillator is maximized in all cases. An advantage of the BOM is that different scintillators (e.g., LYSO, LuGAGG, Lutetium Orthosilicate (LSO), Gadolinium Orthosilicate (GSO), and BGO, any of which may be used according to the various embodiments described herein) and scintillator pitches (e.g., 4.0 mm, 4.8 mm, and 6.0 mm) can be used without changing the sensor tiles or the readout infrastructure. According to one example, the silicon fill factor is 100% for Type 1, 70% for Type 2, and 44% for Type 3, which is the main cost factor. This reduction is even more than proportional to the silicon fill factor due to the fixed costs of each sensor tile associated with (e.g.) PCB mounting, testing, and for yield considerations.

[0053] The dead area of the sensor tile is covered with a highly reflective dielectric mirror to create a light-tight package for the scintillator. This effectively reduces light losses in the setup. In general, the universal tile concept also allows designs to use different numbers of dies in the x and y directions, as in Figure 7 and 8 As shown in .

[0054] Figure 7 and 8 An example of a generic tile concept is shown, with different pitches in the x and y directions to allow pixelated readout of rectangular pixels. This concept allows for cost-effective designs where the resolution of the axial field of view is different from the resolution of the xy plane of the PET scanner. Figure 7 A configuration 70 is shown using a 5×6 array of sensor die 15 having a crystal pitch of 4.0×4.8 mm, resulting in a dimension on a side of the sensor tile 16 of approximately 48 mm. Figure 8 A configuration 80 is shown using a 4×5 sensor die array 15 having a crystal pitch of 6.0×4.8 mm while maintaining the outer dimensions. The sensor dies 15 are arranged on a sensor tile 16 .

[0055] Regarding BGO scintillators, one aspect of the claimed innovation involves using a matched reflector mask for lower silicon fill factors to reduce degradation in energy resolution. The dead areas of the sensor tiles are covered with highly reflective dielectric mirrors, effectively reducing the silicon fill factor and thus minimizing light loss.

[0056] Figure 9 An example of a highly reflective mask 94 used to study light loss for smaller silicon fill factors is shown in detail.

[0057] LYSO scintillators can also be used in combination with the concepts described in this article. The reduced silicon fill factor has a significant impact on the achievable time-of-flight (ToF) accuracy. Measurements and simulations show that for equal scintillator lengths, the timing degrades as 1 / sqrt(fill_factor). The generic tile concept allows different designs to find the best compromise between cost and timing performance. For larger scintillators, the net image resolution degrades. To overcome this degradation, a non-pixelated readout can be used to maintain a high spatial resolution.

[0058] Figure 10 A table 110 is shown that correlates various scintillator crystal parameters (pitch, readout type, etc.) for different sizes of LYSO scintillators. Intrinsic building blocks are packaged in a dielectric reflector grid to form a scintillator array.

[0059] The concept of common tile light sharing for LYSO and BGO scintillators is as follows Figure 11 and 12 shown. Figure 11 A general tiling concept of LYSO scintillators 120 is shown using a local light guide (not shown) for each sensor die to read out nine scintillators with one sensor die. Figure 12 A corresponding flood map 130 is shown showing a clear separation of all scintillators. The same concept applies to BGO scintillators where the resolution of the flood map is reduced (due to lower light output).

[0060] In one embodiment, a scintillator with a polished top surface is used. This approach can improve light yield by 35%-40% for LYSO crystals and by approximately 60%-70% for BGO crystals. This approach also allows for the LYSO light-sharing concept, with an effective energy resolution better than 10.5% while using less than 50% of the sensor area.

[0061] Regarding the mounting and fabrication of the scintillator building blocks, in one embodiment, an optically clear adhesive can be used to mount the scintillator on a glass plate without spilling any glue to maintain air pockets on all sides of the scintillator. A Vikuiti dielectric mirror film can be used between the molds.

[0062] When using high-resolution LYSO scintillators, local light sharing can also be employed to read out the scintillator, with a pitch smaller than the sensor pixels. Figure 11 The example in shows 9 scintillators per die, with a scintillator size of 2.6 mm and a local light guide with an 8 mm pitch per die. The 9 scintillator package is separated to the next die by a dielectric reflector.

[0063] Figure 13 A high-resolution scanner is shown having nine scintillators 140 (eg, 2.6 mm x 2.6 mm x 22 mm, or some other suitable size) with a local light guide 142 as the basic building block. Figure 14 An array 150 of nine scintillator dies 152 is shown after assembly into a scintillator array.

[0064] Figure 15 A flood map 160 is shown with 9 scintillators per quill, where the scintillator pitch is 1 / 3 the wafer pitch and the dimensions are 2.6 mm x 2.6 mm x 22 mm.

[0065] Figure 16 An example of a sensor stack 210 having four monolithic LYSO scintillator blocks 212 is shown.

[0066] Figure 17 and Figure 18 A common tile configuration with maximum fill factor (ie, little or no pitch between dies 15 to read two different single scintillator sizes) is shown: 3x3 blocks 220 ( Figure 17 ) or 2x2 blocks 230( Figure 18 ). A smaller block 230 of 16mm x 16mm x 19mm LYSO shows good energy and timing performance at a comparable scintillator price.

[0067] The example to the right shows good time-of-flight performance with 10.0% energy resolution on a 230xps LYSO block on a 16x16x19mm LYSO cube on Trix 1. In addition to the high-performance detector designs described above, a universal tile concept can be leveraged to create a low-cost version by exploiting the freedom of sensor die placement. For single-tile readout, edges and corners are used for good event localization, but other areas can be ignored. This allows for sensor designs with 55% or 44% sensor fill factors while maintaining good spatial resolution below 2-3mm.

[0068] Figure 19 A general tile configuration 260 is shown with a reduced fill factor of 55%. The die 15 are shown in a checkerboard arrangement so that each monolithic scintillator 262 has a sensor die below its center and at each corner. The space between the sensor dies is unoccupied.

[0069] Figure 20 A general tile configuration 270 is shown, with a reduced fill factor of 44%. The die 15 is shown in a corner-only arrangement, so that each monolithic scintillator 272 has a sensor die under each corner. The space between the sensor dies is unoccupied. These (and other) general tile configurations with reduced fill factors can be used for monolithic scintillator readouts, for example, low-cost BGO detectors for high-resolution non-ToF applications.

[0070] The generic tile configuration can also be optimized for thick scintillator layers. In other words, the sensor concept allows stacks with thick detector layers to be used for PET imaging. Figure 21 An example of a LYSO thick-slice detector array 280 is shown, where each thick-slice detector array 280 has a dielectric mirror 282 between each thick slice 284, which is polished or top-ground to increase light yield. This feature provides a compromise between pixelation and single-slice scintillator readout. Calibration procedures can be simplified and implemented at the system level because simultaneous events are automatically collimated across vertical and horizontal thick slices. Measurements on the thick slices show a Trig1 timing resolution of 230 ps and an energy resolution of 11.5% (on a 32 mm long slice).

[0071] Figure 22 A general tile configuration 290 is shown for a thick layer detector array having a long thick layer 292 (eg, extending the length of the edge of the detector). The die 15 is also shown. Figure 23 A general tile configuration for a thick slice detector array is shown with shorter thick slices 302 (e.g., spanning less than the width of the detector). In one embodiment, the thick slices have a width that matches the sensor pixel pitch (e.g., 4 mm or other width). In another embodiment, the thick slices can be 1 / 3 the sensor die pitch (e.g., 2.6 mm) or 1 / 4 the sensor die pitch (e.g., 2 mm). The combination of vertical and horizontal thick slices can simplify system-level auto-calibration routines because if the thick slices detect simultaneous events in the vertical direction, the events are always collimated in one dimension.

[0072] Figure 22 and 23 The examples in Figure 1 show two different general tile designs for optimal performance. Depending on the scintillator manufacturing process, thick-slice detectors can be less expensive than pixelated or monolithic approaches to achieve the same sensitivity while improving PET performance. Spatial resolution is determined by the width of the thick slice in one direction (e.g., 2.0 mm, 2.6 mm, 4.0 mm, etc.).

[0073] Figure 24 A general tile configuration 310 for a thick layer detector as described above is shown with a reduced sensor fill factor of 67% for a low cost design. The die 15 is also shown.

[0074] Figure 25 A general tile configuration 320 for a thick layer detector as described above is shown with a reduced sensor fill factor of 67% for a low cost design and with the same Figure 24 Different sensor die orientations are shown. Die 15 is also shown.

[0075] The above-described sparse universal tile sensor configuration facilitates providing a low-cost PET system by sacrificing ToF resolution and focusing on high spatial resolution.

[0076] The present invention has been described with reference to the preferred embodiments. By reading and understanding the aforementioned detailed description, those skilled in the art may make various modifications and variations. It is intended that this disclosure be understood to include all such modifications and variations, as long as they fall within the scope of the appended claims or their equivalents.

Claims

1. A plurality of interchangeable sensor tiles for use in a detector block in a medical imaging system, each interchangeable sensor tile comprising: an array of sensor dies coupled to the interchangeable sensor tiles, each sensor die having a plurality of scintillator crystals coupled thereto; wherein each interchangeable sensor tile is one of a plurality of interchangeable sensor tile types and the plurality of interchangeable sensor tiles comprises a plurality of sensor tile types, each interchangeable sensor tile type has the same outer dimensions and the interchangeable sensor tiles are configured to couple to an expandable detector in the medical imaging system via a common mechanical interface; and Each interchangeable sensor tile type has a different fill factor of the sensor die (15) on the sensor tile (10; 12; 14), wherein a lower fill factor is associated with lower timing resolution and lower manufacturing cost.

2. The plurality of interchangeable sensor tiles of claim 1, wherein: The array of sensor dies includes one of a 4x4 array, a 4x5 array, a 5x5 array, a 5x6 array, and a 6x6 array.

3. The plurality of interchangeable sensor tiles of claim 1 , wherein: Each plurality of scintillator crystals is arranged in one of a 2×2 array and a 3×3 array.

4. The plurality of interchangeable sensor tiles of claim 1 , further comprising a dielectric reflector mask located on the sensor side of each interchangeable sensor tile, wherein The dielectric reflector mask covers the areas of the sensor tiles that are not populated with scintillator crystals.

5. The plurality of interchangeable sensor tiles of claim 1 , wherein: At least one interchangeable sensor tile has a fill factor such that less than all of the interchangeable sensor tiles are populated with sensor dies.

6. The plurality of interchangeable sensor tiles of claim 5, wherein: The plurality of scintillator crystals includes a plurality of monolithic crystals, each monolithic crystal being positioned on at least four respective sensor dies.

7. The plurality of interchangeable sensor tiles of claim 5, wherein: The plurality of scintillator crystals includes a plurality of thick layer scintillator crystals, each thick layer crystal spanning more than one sensor die.

8. The plurality of interchangeable sensor tiles of claim 7, wherein: The width of the thick layer of scintillator crystal is less than a pitch of the sensor dies on the interchangeable sensor tile.

9. The plurality of interchangeable sensor tiles of claim 1 , wherein: The plurality of scintillator crystals are one of bismuth germanium oxide (BGO), lutetium yttrium orthosilicate (LYSO) crystals, lutetium orthosilicate (LSO), and gadolinium orthosilicate (GSO).

10. The plurality of interchangeable sensor tiles of claim 1 , wherein: The medical imaging system is one of a positron emission tomography (PET) imaging system, a PET computed tomography (CT) imaging system, a PET magnetic resonance (MR) imaging system, and a single photon emission computed tomography (SPECT) imaging system.

11. The plurality of interchangeable sensor tiles of claim 1 , wherein: The universal mechanical interface includes a cooling plate or heat sink coupled to the sensor tile via one or more mechanical fasteners.

12. The plurality of interchangeable sensor tiles of claim 11, wherein: The one or more mechanical fasteners are at least one of a weld nut and a snap fit.

13. A detector block for an expandable detector in a medical imaging system, comprising: at least one interchangeable sensor tile comprising one of the plurality of interchangeable sensor tiles according to any one of the preceding claims; as well as The universal mechanical interface is configured to couple the interchangeable sensor tiles to the expandable probe regardless of the type of the interchangeable sensor tiles.

14. A nuclear imaging system comprising: A plurality of detector blocks, each detector block as recited in claim 13, each detector block comprising said common mechanical interface.

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