Interposer for semiconductor-based single-photon emission calculation tomography detector

Abstract

To provide a method for testing a semiconductor sensor of a gamma camera.SOLUTION: In order to test or manufacture a semiconductor-based detector in SPECT, an interposer 106, such as an elastomer device with a conductor, is sandwiched between a carrier and a semiconductor detector, the conductor enables temporary, separate connection of a detector electrode to a signal processing circuit, to test the detector operating using the signal processing circuit, and the interposer 106 provides separate electrical connection for testing.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This embodiment relates to a semiconductor detector for single photon emission computed tomography (SPECT) invention. Current detectors are tested before attachment to electronics. The only test is pre-contact attachment, which semiconductor detector manufacturers use as the basis for qualifying detectors for use in multiple applications. A carrier board with a connector is attached to the detector without checking whether the detector has additional problems caused by intermediate steps or interactions with the carrier and electronics. This is not an issue today because the test equipment used to qualify detectors has the connector, and the cost of replacing these detectors, if a problem exists, is insignificant.

[0002] A more serious problem occurs when the package is fully integrated, so that the detector and application specific integrated circuit (ASIC) are assembled into a compact, inseparable unit. The semiconductor detector is not contact-attached and tested when using direct attachment techniques. There is no confirmation that the detector is working as required after attachment. If it does not work properly, the entire assembly, including the ASIC, must be scrapped. Summary of the Invention

[0003] As an introduction, the preferred embodiment described below includes a method and system for testing or manufacturing semiconductor-based detectors in SPECT. An interposer, such as an elastomeric device with conductors, is sandwiched between a carrier and a semiconductor detector. The conductors allow for temporary, separate connection of the detector electrodes to signal processing circuitry, providing for testing of the detector operating with the signal processing circuitry. While the interposer provides separate electrical connections for testing, it may also be used in a final, fully integrated detector for use in a SPECT system.

[0004] In a first embodiment, a SPECT detector system includes a semiconductor SPECT detector having a first conductor exposed on a first detector surface. A carrier has attached signal processing circuitry and a second conductor exposed on the first carrier surface. An interposer is between the first surface of the SPECT detector and the second surface of the carrier. The interposer has a third conductor extending between the first and second interposer surfaces. The third conductor electrically connects the first conductor with the second conductor in separate electrical paths for separate detector cells of the SPECT detector.

[0005] In one embodiment, the SPECT detector is a pixelated detector in which the first conductors are electrically isolated electrodes for the separate detector cells, the carrier is a printed circuit board, and the signal processing circuit is an application specific integrated circuit.

[0006] In another embodiment, the interposer is in loose contact with the SPECT detector without bonding. For example, the carrier is in a test rig with the SPECT detector removably stacked with the interposer on the carrier in a test fixture. In another embodiment, the SPECT detector is bonded to the interposer and the interposer is bonded to the carrier.

[0007] In yet another embodiment, the interposer is an array of third conductors separated by an elastomer.

[0008] In another embodiment, a one-to-one placement of the sensing cells to the pads on the carrier is achieved without separate electrical paths shorting any of the sensing cells. A standard interposer or elastomer device can be used by providing a mask on the first interposer surface. The mask exposes the third conductors for one-to-one placement. For example, the mask is a dielectric of an electrically insulating strip that forms the interposer cells, exposing the third conductors at the pitch of the sensing cells. The electrically insulating strip has a width that accommodates stack-up tolerances.

[0009] In some embodiments, the third conductor is a curved wire within the interposer. In other embodiments, the third conductor is a straight wire within the interposer.

[0010] In one embodiment, the interposer is a plate with the first and second interposer surfaces being the largest parallel surfaces of the plate.

[0011] In a second aspect, a method for testing a semiconductor sensor of a gamma camera is provided. The semiconductor sensor is placed on an elastomeric conductor plate in a test rig. The semiconductor sensor is pressed against the elastomeric conductor plate. The semiconductor sensor is exposed to gamma radiation. Operation of the semiconductor sensor to sense gamma radiation is tested using signals from a detector circuit electrically connected to the semiconductor sensor through the elastomeric conductor plate.

[0012] In one embodiment, pressure creates pixelated electrical paths from detector cell electrodes of the semiconductor sensor to pads on a printed circuit board attached to the detector circuitry. Detection from individual detector cells is tested.

[0013] The operation of the semiconductor sensor, the detection circuit, and the printed circuit board is tested. The printed circuit board is physically connected to the detector circuit, but the semiconductor sensor may be disconnected. For example, testing is performed without the semiconductor sensor being bonded to the elastomeric conductor plate.

[0014] In a third aspect, a SPECT system includes a housing defining a patient region and a gamma camera adjacent to the patient region, the gamma camera including a semiconductor detector, a carrier having attached signal processing circuitry, and an elastomeric device in direct contact between the carrier and the semiconductor detector, the elastomeric device having electrically insulated conductors electrically connecting electrodes of the semiconductor detector to pads of the carrier.

[0015] In one embodiment, the carrier is a printed circuit board, the signal processing circuit is an application specific integrated circuit, and the elastomeric device has a dielectric mask exposing electrically isolated conductors on a surface of the elastomeric device.

[0016] In another embodiment, the semiconductor, carrier, and elastomeric device press together without bonding. In another embodiment, the semiconductor detector is a pixelated detector of sensing cells with separate ones of the electrodes for separate ones of the sensing cells. The pads of the carrier connect with electrically isolated traces that connect to separate inputs of the signal processing circuitry, and the elastomeric device is a plate of isolated conductor and elastomeric material.

[0017] The present invention is defined by the following claims, and nothing in this section should be considered as limiting the scope of those claims. Further aspects and advantages of the present invention are described below in connection with preferred embodiments and may be claimed independently or in any combination. [Brief explanation of the drawings]

[0018] The components and drawings are not necessarily to scale, but rather exaggerated when illustrating the principles of the present invention. Further, with respect to the drawings, like reference characters indicate corresponding parts throughout the different views. [Figure 1] FIG. 1 shows one embodiment of a SPECT detector assembly, such as for testing. [Figure 2] FIG. 2 shows an exemplary test rig using an interposer. [Figure 3] FIG. 3 shows an example of multiple wire shapes in an interposer. [Figure 4] FIG. 4 shows an example of electrical routing connections. [Figure 5] FIG. 5 shows an exemplary mask on the interposer. [Figure 6] FIG. 6 is a cross-sectional view of a SPECT imager or system. [Figure 7] FIG. 7 is a flow chart diagram of an exemplary embodiment of a method for testing a solid-state detector for SPECT use. DETAILED DESCRIPTION OF THE INVENTION

[0019] A multi-module post-contact test fixture is provided for pixelated semiconductor detectors. Ultra-high performance, next-generation SPECT systems are based on semiconductor pixelated detectors using direct attachment technology. The semiconductor detectors are directly attached to the same PCB substrate where the ASIC is located to minimize trace length and parasitic capacitance, thus improving spectral performance beyond what is achievable using vertically stacked connectors and multiple carrier and interposer boards. For testing, direct contact between the carrier with pre-attached ASIC and the sensor is made via an interposer or post-contact attachment. Interposers with pixelated electrical paths can be used as test fixtures to pre-attach different grades of sensors to the carrier and / or to attach sensors to the carrier in manufacturing and commercial settings (i.e., replacing the sensor attachment step).

[0020] 1 illustrates one embodiment of a SPECT detector system 120. The SPECT detector system 120 is used to test the semiconductor detector 102, for example, after initial testing and immediately prior to fabricating a production detector for use as a gamma camera in a SPECT imaging system. Alternatively, the SPECT detector system 120 is used as a production detector assembled into a SPECT imaging system.

[0021] The SPECT detector system 120 includes a SPECT detector 102, an interposer 106, and a carrier 107 having signal processing circuitry 104. This stack of detector 102, interposer 106, and carrier 107 may be disposed within a frame, such as between a base (e.g., a printed circuit board for electronics or signal routing) 108 and a force applicator 114 (e.g., a pressure plate). Other frames may be used. Additional, different, or fewer components may be provided, such as having only a stack of detector 102, interposer 106, and carrier 107.

[0022] The SPECT detector 102 is a semiconductor. The detector 102 is a solid-state detector. Any material can be used, such as SI, CZT, CdTe, and / or other materials. The SPECT detector 102 is fabricated using wafer fabrication at any thickness, such as about 4 mm for CZT. Any size can be used, such as about 5 x 5 cm. FIG. 1 shows the detector 102 as a square. Shapes other than a square, such as a rectangle or a hexagon, can also be used.

[0023] The SPECT detector 102 is designed and constructed to detect gamma emissions, such as emissions from a patient, for example, semiconductor formed as an array of silicon photon multiplying cells.

[0024] The SPECT detector 102 is a pixelated detector. The SPECT detector 102 forms an array of sensors. For example, a 2.5 x 2.5 cm or 5 x 5 cm detector 102 has an 11 x 11 or 21 x 21 pixel array of detector cells with a pixel pitch of approximately 2.2 mm. Each detector cell of the array can separately detect an emission event. Other numbers of pixels, pixel pitches, and / or array sizes can be used. Non-rectangular grids can be used, such as a hexagonal distribution of pixels or detector cells.

[0025] Anode and cathode electrodes are provided on opposing surfaces of the detector 102. In the examples herein, a lower voltage (e.g., 10 volts or less) anode electrode 110 is used. The same or similar configuration can be used for the cathode electrode, such as connecting the cathode electrode to a carrier for high voltage processing circuitry via an interposer. Wire or flex circuits with traces can be used for signal routing from the cathode electrode, with common processing circuitry 104 operating on both the anode and cathode signals.

[0026] The anode electrodes 110 are conductors exposed on the surface of the detector 102. The electrodes 110 have the same pitch as the detection cells and are electrically isolated from each other for separate connection to the detection cells of the detector 102.

[0027] Carrier 107 is a printed circuit board or other material for electrical and physical connection to signal processing circuitry 104. In alternative embodiments, signal processing circuitry 104 is carrier 107 such as a semiconductor chip with exposed pads or electrodes.

[0028] The carrier 107 has signal processing circuitry 104 on one side and exposed conductors 112 on the other side. Traces or wires deposited within the carrier 107 route from the conductors 112 to the signal processing circuitry 104. The conductors 112 are electrodes, pads, or other conductive material for receiving signals from the anode electrodes 110 of the detector 102.

[0029] The signal processing circuitry 104 is analog, digital, or both analog and digital. Wires are routed between devices to filter, amplify, determine timing, determine energy, and / or otherwise process received signals from the detector cells of the detector 102. In one embodiment, the signal processing circuitry 104 is an application specific integrated circuit (ASIC). The ASIC is formatted for processing. There can be multiple ASICs, such as nine ASICs in a 3x3 grid of the detector 102.

[0030] The signal processing circuitry 104 is connected to the carrier 107. The connection can be made by soldering, ball grid array, or bump soldering. Flip chip or other chip-to-carrier 107 connections can be used.

[0031] In one embodiment, the carrier 107 is fixed in or as part of a test rig. The SPECT detector system 120 is a test apparatus such as that shown in FIG. 1 or FIG. 2. The SPECT detector 102 is removably stacked on the carrier 107 along with the interposer 106. The interposer 106 may be fixed to the carrier 107 or may be removable. Fixation involves latches, bolts, clamps, bonding, soldering, or other attachment that prevents movement when aligning the detector 102. The test fixture or rig is provided at a factory or processing facility for testing the SPECT detector 102 before mounting the SPECT detector 102 on the carrier in a manufacturing facility.

[0032] The test rig can test individual SPECT detectors 102 one at a time, as shown in Figure 1. Alternatively, the test rig can accept multiple SPECT detectors 102 for simultaneous but separate testing. In the example of Figure 2, the test rig 202 is closed to press the detector 102 against the interposer 106, forming a protruding and recessing electrical connection of the electrodes 110 with the interposer 106. In the example of Figure 1, a manual or other force presses the plate 114 against the detector 102.

[0033] For testing, the compressed arrangement of detector 102, interposer 106, and carrier 107 is exposed to one or more radiation sources 204. For example, the test rig is within a shielded cabinet. The cabinet is sealed after placing detector 102 within the test rig. Once sealed, the cartridges of the selectable sources 204 are positioned so that radiation from the selected source 204 can pass through an opening to the SPECT detector system 120. The operation of the SPECT detector 102 together with the carrier 107 and signal processing circuitry 104 is tested, such as by measuring signals generated by the signal processing circuitry 104. The operation of the stack is tested. Individual detector cells can be tested.

[0034] In an alternative embodiment, the SPECT detector system 120 is part of a production assembly. For example, the detector 102 is bonded to an interposer 106 that is bonded to a carrier 107. As another example, the force applicator 114 is fixed in place using pressure to hold the stack together. By avoiding bonding when forming a direct attachment, defective components of the stack can be individually removed by removing the force applicator 114. The assembled SPECT detector system 120 is then secured to a SPECT imager for use as part of a gamma camera for scanning a patient.

[0035] The interposer 106 is shaped and sized for stacking. The interposer 106 is stacked between the surface of the detector 102 with the exposed anode electrode 110 and the surface of the carrier 107 with the exposed conductors 112. The interposer 106 is a plate with opposing parallel maximum surfaces for contacting the detector 102 and the carrier 107. The interposer 106 is thin, such as 0.10 to 0.20 inches thick. The interposer 106 has the same maximum surface size and shape as the detector 102, such as 2.5x2.5 or 5x5 cm. The maximum surface of the interposer 106 can be smaller, larger, and / or have a different shape than the surface of the detector 102 with the exposed electrode 110.

[0036] The right side of Figure 1 shows a stack of detector 102, interposer 106, and carrier 107 from two perspectives with spaces between the components. The spaces are provided to show the electrodes 110 or 112 of interposer 106 and exposed conductors 302. When stacked, there are no spaces between detector 102, interposer 106, and carrier 107 to form uneven contacts for electrical connection.

[0037] The interposer 106 is formed from an electrically insulating material, with the array of conductors 302 interspersed or held within the insulating material. For example, the interposer 106 is an elastomer, such as silicone, formed around the conductors 302.

[0038] The conductors 302 extend from one opposing surface of the interposer 106 to another opposing surface. The conductors 302 are electrically isolated from one another. The conductors 302 are wires, although traces or other conductive materials could be used.

[0039] The conductors 302 can be straight or curved. Examples are shown in FIG. 3. Straight wires are used for static interconnections, such as in a manufacturing SPECT detector system 120. An interposer 106 with straight wires as conductors 302 replaces bonded or permanent attachments. Curved wires are used for repeated compression, such as in a test rig. Curved wires may be curved at a single radius in a single plane. In other embodiments, the curved wire is spring-shaped (e.g., helical) or has different curvatures in different sections.

[0040] The interposer 106 has exposed conductors 302 on opposing surfaces for mating with the electrodes 110 and conductors 112 of the detector 102 and carrier 107, respectively. The exposed conductors 302 allow for bond-free asperity contact, forming an electrical path from the detector 102 to the carrier 107 and signal processing circuitry 104. Compression fittings without adhesive may also be used. In other embodiments, bonding is used.

[0041] The conductors 302 are arranged to have the same or matching pitch as the electrodes 110 and conductors 112, forming separate electrical paths for separate detection cells to the signal processing circuitry 104. A single conductor 302 or two or more conductors 302 may be provided for each separate electrical path. Figure 4 shows an example in which two conductors 302 (small circles 410, 412) are provided for each electrode 110 (small square) and respective conductor 112 pad (large circle). The bottom row of Figure 4 shows the electrodes 110 or pads 112 with overlapping conductors 302.

[0042] Each path is electrically isolated from the other paths. When stacked, the detector 102, interposer 106, and carrier 107 are aligned to prevent short circuits. The conductors 302 are arranged so that multiple electrodes 110 do not connect to a single conductor 112, and multiple conductors 112 do not connect to a single electrode 110. In other embodiments, cross-connections are provided to one or more conductors 112 and / or electrodes 110.

[0043] The separate paths create a one-to-one arrangement of the sensing cells (e.g., electrodes 110) to the pads (conductors 112) on the carrier 107 without shorting between any of the sensing cells. A microarray of contacts and corresponding conductors 302 (410, 412) are arranged in a one-to-one relationship between the sensor contacts (e.g., electrodes 110) on one side and the ASIC carrier pads (e.g., conductors 112) on the other side. Thus, the interposer 106 replaces the need for a permanent attachment between the detector 102 and the carrier 107. The conductors 302 in this configuration electrically contact the ASIC inputs to the sensor electrodes 110.

[0044] The interposer 106 is custom made in that the size of the conductors 302, as well as the pitch and positioning of the conductors 302, are controlled to establish electrically isolated paths and avoid short circuits between adjacent sensing cells. The conductive / non-conductive combination in the elastomer device allows for one-to-one contact between the ASIC and the sensor.

[0045] FIG. 5 illustrates an embodiment of an interposer 106 that allows for the use of off-the-shelf, standardized, or non-custom conductor 302 arrangements. A mask 502 is disposed on or formed on one or both of the largest opposing surfaces of the interposer 106. The mask 502 is not conductive (i.e., insulating). The mask 502 causes electrical isolation of the paths, creating a one-to-one arrangement. The conductors 302 are exposed through gaps or holes 504 in the mask 502, or the mask 502 includes conductive portions between insulating strips, creating separate electrical paths. The inter-pixel street mask 502 matches one-to-one with the electrodes 110 and conductors 112 without shorting signals.

[0046] In one embodiment, the mask 502 is formed from a crosshatch pattern of strips or as a grid. Other configurations, such as a sheet with circular or other shaped holes for exposing the conductors 302, may be used. The exposed portions have the same size and / or pitch as the electrodes 110 and / or conductors 112. The width of the strips or insulating portions accommodates tolerance stackup. The width of the strips of the inter-pixel street mask 502 is selected to accommodate tolerance stackup, such as two or more of mask alignment, mask tolerance, pixel / street tolerance, and / or another tolerance. The width is selected to avoid short circuits.

[0047] The mask 502 is thin to allow uneven contact under the application of pressure or force. In one embodiment, the thin anode interpixel street mask 502 is a dielectric of electrically insulating strips that form interposer cells 504, exposing the third conductors 302 at the pitch of the detector cells. Any thickness can be used, such as thin dielectric epoxy glass resins with thicknesses of 75 μm, 120 μm, and 190 μm.

[0048] In one embodiment, a mask 502 is screened onto the interposer 106 in two steps (H / V) and cured. The mask 502 can be spun onto the interposer 106, imaged, and selectively removed (photolithography). The mask can be molded into the interposer using a die that forms recessed channels in the interposer (embedded mask). The mask can be applied directly onto the solid-state detector (street passivation) using imaged resist and an evaporated thin film of aluminum oxide.

[0049] The interposer 106 provides a short conductive path while allowing for easy disassembly. Direct mounting, with an additional interposer 106, allows for minimal trace length and limits parasitic capacitance. The same test rig can be used to test multiple SPECT detectors 102 sequentially. After removing the detectors 102, the interposer 106 can be placed between the detector circuit ASIC board 107 and the test head / board to simultaneously test the detector circuit / ASIC inputs. Testing using signal processing by the signal processing circuit 104 can be more comprehensive and test individual detector cells. Testing can be performed as part of an assembly or immediately prior to assembly. The interposer 106 can be placed between the solid-state sensor 102 and any test head / fixture / device other than the ASIC board 107 to test the solid-state sensor 102. Other test configurations may also be used.

[0050] 6 shows a SPECT detector system 120 used in a SPECT system or imager 600. The SPECT detector system 120 is used as a gamma camera 606 or as part of a gamma camera 606 in the SPECT system 600.

[0051] SPECT system 600 is an imaging system for imaging a patient on a bed 604. A gamma camera 606 formed by SPECT detector system 120 (e.g., detector 102 with signal processing circuitry 104, interposer 106, and carrier 107) detects emissions from the patient.

[0052] SPECT system 600 includes a housing 602. Housing 602 may be metal, plastic, fiberglass, carbon (e.g., carbon fiber), and / or other materials. In one embodiment, multiple components of housing 602 are multiple materials.

[0053] The housing 602 defines a patient area where a patient is positioned for imaging. A bed 604 allows the patient to be moved within the patient area to scan different portions of the patient at different times. Alternatively, or additionally, a gantry holding the SPECT detector system 120 moves the detector 102.

[0054] A gamma camera 606 is adjacent to the patient area. The gamma camera 606 includes one or more semiconductor detectors 102, such as pixelated detectors, with detector cells, each with a separate electrode provided for each detector cell. A carrier 107, such as a printed circuit board, may be the same as or different from that used for testing. The carrier 107 includes electrically isolated traces and pads that electrically connect to separate inputs of the attached signal processing circuitry 104. An elastomeric device (i.e., an interposer 106) provides direct contact between the carrier 107 and the semiconductor detectors 102. The elastomeric device is an electrically isolated conductor 302 and a plate of elastomeric material. The conductor 302 electrically connects the electrodes 110 of the semiconductor detector 102 to the pads 112 of the carrier 107. In some embodiments, a dielectric mask 502 is used to expose the electrically isolated conductors 302 on the surface of the elastomeric device.

[0055] The semiconductor detector 102, carrier 107, and elastomeric device press together without bonding. This press fit for direct electrical attachment provides the SPECT detector system 120 for use in imaging a patient. The force fit may be released to gain access to a broken component. Alternatively, the SPECT detector system 120 is a bonded unit in which the various components are bonded together.

[0056] 7 illustrates one embodiment of a method for testing a semiconductor sensor of a gamma camera. An elastomeric conductor plate is positioned between the semiconductor sensor and the carrier. The elastomeric conductor plate allows the semiconductor sensor to be tested for operation using signal processing, which also allows individual detector cells to be tested and / or imaged.

[0057] This method may be implemented by the system shown in FIG. 1, FIG. 2, or another system. A test rig or fixture is used for testing. An emission source emits a beam of light onto a semiconductor sensor press-fit within the test rig. Signal processing circuitry is used for testing, such as testing operation (i.e., detecting radiation from the source) or testing data output by the signal processing circuitry. Other systems, semiconductor sensors, elastomeric conductive plates, and / or carriers may also be used.

[0058] The actions may be performed in the order shown (i.e., top to bottom or numerically) or in other orders. Additional, different, or fewer actions may be provided. For example, actions may be provided for placing an elastomeric conductive plate in a test fixture. As another example, actions may be provided for sealing a cabinet, selecting a source, and / or positioning a source.

[0059] In operation 702, the semiconductor sensor is placed on an elastomer conductive plate in a test rig. The elastomer conductive plate may be fixed in the test rig or may be removable, such as placed on a carrier. The elastomer conductive plate and / or the semiconductor sensor are placed in the test rig. The placement may be aligned with the elastomer conductive plate and / or the carrier using alignment pins. A stack is formed.

[0060] In operation 704, the semiconductor sensor is pressed against the elastomeric conductive plate. After the semiconductor sensor is laminated with the elastomeric conductive plate and carrier, the laminate is pressed together. The plate or press may be lowered or rotated to contact the stack. Pressure is then applied and maintained. The pressure may be manual, hydraulic, or pneumatic. The pressure may be regulated to avoid overpressure.

[0061] Pressure creates a concave-convex contact between the semiconductor sensor, the elastomeric conductive plate, and the conductors of the carrier. Pixelated electrical paths are formed from the detector cell electrodes of the semiconductor sensor to pads on a printed circuit board attached to the detector circuit. The electrical paths extend through the elastomeric conductive plate and are electrically isolated from each other, allowing for individual sensor cell testing.

[0062] In operation 706, the semiconductor sensor is exposed to gamma radiation. When pressed together, the test fixture containing the semiconductor sensor is positioned for detection. A gamma radiation source may be positioned to emit gamma rays at the semiconductor sensor. An opening may be opened, or the radiation source may be positioned with an opening so that light rays can pass from the radiation source to the semiconductor sensor.

[0063] In operation 708, the operation of the solid-state sensor is tested. The operation of sensing gamma rays or radiation from the source is tested. The solid-state sensor generates an electrical signal in response to detecting the emitted radiation. The sensing can be done cell by cell, such that one cell detects a given radiation and another cell does not.

[0064] The signal from the semiconductor sensor passes through the elastomeric conductive plate to the carrier, which routes the signal to the detector circuit (e.g., ASIC). Separate electrical paths to the detector circuit allow testing of individual detector cells of the semiconductor sensor.

[0065] Using the signal processed by the detector circuit, the test is the operation of the semiconductor sensor, the detector circuit, and the printed circuit board, which is physically connected to the detector circuit, which outputs information based on the signal from the semiconductor sensor in response to emissions from the source.

[0066] The stack is tested, but the semiconductor sensor is not bonded to the elastomeric conductive plate, which allows the stack to be tested while still allowing removal of the semiconductor sensor.

[0067] Multiple semiconductor sensors are tested. Based on their performance, including their individual cells, the semiconductor sensors are graded and assigned to specific SPECT imaging systems. Once assigned, the semiconductor sensors are stacked with a carrier, with or without an intervening elastomeric conductive plate, to form a gamma camera. The gamma camera can then be used to image a patient.

[0068] Although the present invention has been described above with reference to various embodiments, many changes and modifications can be made without departing from the scope of the present invention. It is therefore to be understood that the above detailed description is to be interpreted as illustrative rather than limiting, and that it is the following claims, including all equivalents, which define the spirit and scope of the present invention.

Claims

1. 1. A single photon emission computed tomography (SPECT) detector system, comprising: a SPECT detector comprising a semiconductor having a first conductor exposed on a first detector surface; a carrier having signal processing circuitry attached thereto, the carrier having second conductors exposed on a first carrier surface; and an interposer between a first surface of the SPECT detector and a second surface of the carrier, the interposer having third conductors extending between the first interposer surface and the second interposer surface, the third conductors electrically connecting the first conductors with the second conductors in separate electrical paths for separate detector cells of the SPECT detector; A SPECT detector system comprising:

2. the SPECT detector, wherein the first conductor is an electrically isolated electrode for the separate detection cell; the carrier comprises a printed circuit board; the signal processing circuitry comprises a pixelated detector including an application specific integrated circuit; The SPECT detector system of claim 1 .

3. The SPECT detector system of claim 1 , wherein the interposer is in bond-free asymmetric contact with the SPECT detector.

4. 4. The SPECT detector system of claim 3, wherein the carrier is in a test rig in which the SPECT detector is removably stacked with the interposer on the carrier in a test fixture.

5. The SPECT detector system of claim 1 , wherein the interposer comprises an array of the third conductors separated by an elastomer.

6. 2. The SPECT detector system of claim 1, wherein the separate electrical paths include one-to-one placement of the detector cells to pads on the carrier without shorting between any of the detector cells.

7. the interposer comprising a mask on the first interposer surface; the mask exposes the third conductor for the one-to-one placement; The SPECT detector system of claim 6.

8. the mask comprises a dielectric of an electrically insulating strip forming an interposer cell exposing the third conductor at the pitch of the detector cell; the electrical insulating strip has a width that accommodates a tolerance stackup; The SPECT detector system of claim 7.

9. The SPECT detector system of claim 1 , wherein the third conductor comprises a bent wire within the interposer.

10. The SPECT detector system of claim 1 , wherein the third conductor comprises a straight wire within the interposer.

11. The SPECT detector system of claim 1 , wherein the interposer comprises a plate, the first and second interposer surfaces being the largest parallel surfaces of the plate.

12. the SPECT detector is bonded to the interposer; the interposer is bonded to the carrier; The SPECT detector system of claim 1 .

13. 1. A method for testing a semiconductor sensor of a gamma camera, comprising: placing the semiconductor sensor on an elastomeric conductor plate within a test rig; pressing the semiconductor sensor against an elastic conductor plate; exposing the semiconductor sensor to gamma radiation; testing the operation of the semiconductor sensor to sense the gamma rays using signals from a detector circuit electrically connected to the semiconductor sensor through the elastomeric conductor plate; A method comprising:

14. the pressing step includes forming a pixelated electrical path from an electrode of a detector cell of the semiconductor sensor to a pad of a printed circuit board attached to the detector circuit; the testing step includes testing detection from individual detector cells. The method of claim 13.

15. the testing step includes testing the operation of the semiconductor sensor, the detector circuit, and a printed circuit board together; the printed circuit board is physically connected to the detector circuit; The method of claim 13.

16. 16. The method of claim 15, wherein the testing step includes testing the semiconductor sensor without bonding it to the elastomeric conductor plate.

17. 16. The method of claim 15, including removing the semiconductor sensor and testing the operation of the detector circuit using a test board on which the elastomeric conductor plate and the detector circuit are stacked.

18. 1. A single photon emission computed tomography (SPECT) system, comprising: a housing defining a patient area; a gamma camera adjacent to the patient area, the gamma camera comprising: a carrier having a semiconductor detector and attached signal processing circuitry; and an elastomeric device in direct contact between the carrier and the semiconductor detector, the elastomeric device having electrically insulated conductors electrically connecting electrodes of the semiconductor detector to pads on the carrier; A SPECT system comprising:

19. the carrier comprises a printed circuit board; the signal processing circuitry comprises an application specific integrated circuit, and the elastomeric device has a dielectric mask on a surface of the elastomeric device that exposes the electrically isolated conductors.

19. The SPECT system of claim 18.

20. 20. The SPECT system of claim 18, wherein the semiconductor, the carrier, and the elastomeric device press together without adhesion.

21. the semiconductor detector comprises a pixelated detector having separate electrodes of the detector cell; the pads of the carrier connect with electrically isolated traces to separate inputs of the signal processing circuitry; 20. The SPECT system of claim 18, wherein the elastomeric device comprises a plate of the insulated conductor and an elastomeric material.

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