WO2025116897A1

WO2025116897A1 - Embedded capacitance material usage for single photon emission computed tomography

Info

Publication number: WO2025116897A1
Application number: PCT/US2023/081489
Authority: WO
Inventors: Patanit Sanpitak
Original assignee: Siemens Medical Solutions USA Inc
Current assignee: Siemens Medical Solutions USA Inc
Priority date: 2023-11-29
Filing date: 2023-11-29
Publication date: 2025-06-05
Anticipated expiration: 2026-05-29

Abstract

For single photon emission computed tomography (SPECT) detectors, an embedded capacitance material (ECM) is used in a printed circuit board (PCB) with the semiconductor detector. The high voltage (HV) filtering and/or blocking capacitors are formed from ECM. The ECM interferes less with the radiation or emissions to be detected by the semiconductor detector than a surface mounted capacitor

Description

EMBEDDED CAPACITANCE MATERIAL USAGE FOR SINGLE PHOTON EMISSION COMPUTED TOMOGRAPHY

BACKGROUND

[0001] The present embodiments relate to semiconductor detectors for single photon emission computed tomography (SPECT). For semiconductor (e.g., cadmium zinc telluride - CZT) pixelated detectors in SPECT, a high voltage (HV) bias is applied on the cathode side of the detector. The cathode signal is to be amplified and measured together with the pixel anode signals on the bottom of the detector. The cathode signal needs to have high voltage blocking capacitor between the cathode and the amplifier to protect from the HV bias. This blocking capacitor is positioned above the semiconductor detector to minimize trace inductance and parasitic capacitance. After blocking, the resulting low voltage cathode signal can be safely passed down to the measuring circuit (amplifier). A HV filter capacitor may also be positioned above the semiconductor detector with the blocking capacitor. The HV filter capacitor and HV blocking capacitor on top of the semiconductor detector pose problems with non-uniform attenuation to the sensing radioactivity. The HV capacitors interfere with the SPECT detection due to the nature of the commercial HV capacitor construction (e.g., being made with high Z material such as Nickle (Ni) and Silver-Palladium (AgPd), Titanium Oxide (TiO2), or Barium Titanate (BaTiO3) packed into a small volume.

SUMMARY

[0002] By way of introduction, the preferred embodiments described below include methods and systems for SPECT detectors. An embedded capacitance material (ECM) is used in a printed circuit board (PCB) with the semiconductor detector. The HV filtering and/or blocking capacitors are formed from ECM. The ECM interferes less with the radiation or emissions to be detected by the semiconductor detector.

[0003] In a first aspect, a single photon emission computed tomography (SPECT) detector system is provided. A cathode is on a first surface of a CZT detector. Anode electrodes are on a second surface of the CZT detector. The second surface is opposite the first surface on the CZT detector. A first printed circuit board electrically connects with the cathode. The printed circuit board has an ECM electrically connected to the cathode.

[0004] In a second aspect, a method is provided for receiving signals in a SPECT detector. A voltage bias is applied to a cathode of the SPECT detector through a first printed circuit assembly mounted to the cathode. A cathode signal is received through a first ECM of the first printed circuit assembly. A SPECT image is generated from the cathode signal.

[0005] In a third aspect, a SPECT system includes a housing forming a patient region; and a gamma camera adjacent the patient region. The gamma camera includes a semiconductor detector stacked between first and second printed circuit boards. The first printed circuit board has a first embedded capacitance material connected with a cathode of the semiconductor detector.

[0006] The illustrative embodiments below summarize other aspects or features of the first, second and third aspects above. Aspects or features used for one type of claim (e.g., method or system) may be used in other types.

[0007] The present invention is defined by the following claims, and nothing in this section should be taken as a limitation on those claims. Further aspects and advantages of the invention are discussed below in conjunction with the preferred embodiments and may be later claimed independently or in combination.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The components and the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. Moreover, in the figures, like reference numerals designate corresponding parts throughout the different views.

[0009] Figure 1 illustrates one embodiment of a SPECT detector circuit;

[0010] Figure 2 illustrates an example semiconductor detector arrangement;

[0011] Figure 3 illustrates one embodiment of a PCB with ECM; [0012] Figure 4 is cross-section view of a SPECT imager or system; and [0013] Figure 5 is a flow chart diagram of an example embodiment of a method for use of a semiconductor detector in SPECT.

DETAILED DESCRIPTION OF THE DRAWINGS AND PRESENTLY PREFERRED EMBODIMENTS

[0014] Various approaches may be used to provide HV capacitance for the cathode on a top (e.g., side facing the patient) of the semiconductor detector in SPECT. The HV bias circuits and capacitors may be positioned on the side next to the detector. This would work well with a system with single detector module or multi detector module with only 2 rows or 2 columns detector modules (2x2, 2xN or Nx2). This would not work well where detector modules are stacked on top of each other and/or in more than 2 rows or columns.

[0015] In another approach, the HV bias circuits and capacitors are placed at the bottom of the detector. The HV conductor then runs along the side of the detector surface, thus creating an additional unwanted electric field. The space under the detector typically already has sensitive low-voltage electronics, making it very difficult to add the HV bias circuitry due to minimum separation requirements. Positioning at the bottom also attenuates the radioactivity going through the module in a Compton camera system.

[0016] In yet another approach, the HV bias circuitry and capacitors are positioned on the top of the semiconductor detector. To reduce attenuation of radiation to be detected, multiple smaller capacitors are used instead of a larger capacitor. The thickness of the single HV capacitor may be reduced with multiple thinner capacitors. Commercially available HV capacitors that can be used in the limited space make this approach difficult.

[0017] The HV bias circuitry is, in part, on a printed circuit assembly (PCA) positioned on top of the semiconductor detector. The PCA is formed with a printed circuit board (PCB). ECM in the PCB provides sufficient capacitance in the space while causing less radiation attenuation. ECM as part of the HV bias PCB replaces the commercially available HV capacitors on top of the HV PCA (PCB assembly). The distribution of the ECM over a larger surface than the commercially available capacitors improves non-uniformity attenuation in the semiconductor detector. The ECM is used for the HV filter capacitor and/or HV blocking capacitor.

[0018] In this arrangement, the HV components are kept away from low voltage sensitive circuitry. The cathode signal pickup path is very short, providing lower noise. No unwanted electrical field is caused next to the detector and low voltage sensitive circuitry. The positioning on top of the semiconductor detector allows for multi-detector module construction and/or arrangements for a Compton camera. The non-uniformity attenuation caused by the HV capacitors is reduced as compared to commercially available, surface mounted HV capacitors.

[0019] Figure 1 illustrates a circuit 100 or plurality of circuits of an example semiconductor detector. HV bias circuits 110 and low voltage signal circuits 160 connect to a cathode of CZT detector 140. CZT is used in this example, but other semiconductor detectors may be used. In Figure 1 , the CZT detector is represented by a model of a current source, resistor, and capacitor in parallel between a cathode and anodes. Other models representing CZT or other semiconductor detectors may be used.

[0020] The HV bias circuit 110 includes a resistor 114 and HV capacitor 116 forming a filter to receive the voltage from the voltage source 112. The voltage source 112 is a source of direct current (DC) HV, such as 500 volts or more. The voltage is high relative to the low voltage of the signal circuit 160, such as high (e.g., by a factor of 100 or more) relative to the low 2, 3, 4, or 5 volt operation of the signal circuit 160. In one arrangement, the HV is 1 ,000, 1 ,500, 2,000, 3,000, 4,000, or 5,000 volts. The filter capacitor 116 may have any of various working voltages (WV) based on the HV provided by the source 112, such as 3000 WV for HV of 2,000 volts. The HV is a bias voltage to apply to the cathode of the CZT detector 140.

[0021] Since the cathode signal is to be picked up from the cathode, the HV circuit 110 includes a blocking arrangement formed from the blocking resistor 118 and the blocking capacitor 120. The blocking arrangement, including the blocking capacitor 120, blocks the DC HV on the cathode and allows only the cathode detection signal, which is relatively lower voltage (e.g., less than 3 volts) to be routed to the cathode signal amplifier 162 of the signal circuit 160. The blocking capacitor 120 may have any of various WV based on the HV provided by the source 112, such as 3000 WV for HV of 2,000 volts.

[0022] The signal circuit 160 includes signal processing components, such as amplifiers 162, 164 operating as pre-amplifiers for receiving the cathode signal and the anode signals. Different amplifiers 162, 164 are provided for each signal, such as each anode signal where multiple anode electrodes are provided on the CZT detector 140 and the cathode signal. Other circuitry may be used, such as filters, transistors, and/or signal processors. The circuity may be formed by an application specific integrated circuit or other semiconductor with transistors.

[0023] Figure 1 represents one circuit arrangement. Other circuits for the HV bias circuit 110 and/or the signal circuit 160 may be used. Additional, different, or fewer components may be used.

[0024] Figure 2 is a block diagram or cross-section view of one embodiment of a SPECT detector system 200. The HV bias circuit 110 and signal circuit 160 are shown as printed circuit assemblies (PCA) 202 and 206, respectively, on PCB 204 and 208, respectively. The semiconductor detector 140 is a block of semiconductor material between a cathode 210 and anodes 220 (e.g., the cathode 210 and anodes 220 are plating deposited or formed on the detector 140 top and bottom surfaces). Flexible circuit material 230 is a jumper between the HV bias PCA 202 and the signal PCA 206. Additional, different, or fewer components may be provided, such as having just one or three or more anodes 220.

[0025] The SPECT detector 140 is a semiconductor. The detector 140 is a solid-state detector. Any material may be used, such as SI, CZT, CdTe, and/or other material. CZT is used in the examples herein. The SPECT detector 140 is created with wafer fabrication at any thickness, such as about 10 mm for CZT. Any size may be used, such as about 5x5 cm. Figure 2 shows a square cross-section shape for the detector 140 viewed from a side. Other shapes than square may be used, such as rectangular or hexagonal. Similarly, viewed from the top or bottom, a square or other shape is provided. [0026] The detector 140 is designed and configured to detect gamma emissions, such as emissions from a patient. For example, the semiconductor is formed as an array of silicon photon multiplier cells.

[0027] The detector 140 is a pixelated detector. The detector 140 forms an array of sensors. For example, the 2.5x2.5 cm or 5x5 cm detector 140 is a 11x11 or 21x21 pixel array of detection cells with a pixel pitch of about 2.2 mm. Each detection cell of the array may separately detect an emission event. Other numbers of pixels, pixel pitch, and/or size of arrays may be used. Other grids than rectangular may be used, such as a hexagonal distribution of pixels or detection cells.

[0028] The anode electrodes 220 and the cathode electrode 210 are provided on opposite surfaces (e.g., cathode on top side and anodes on bottom side) of the detector 140. In the example herein, the lower voltage (e.g., 3 volts or less) anode electrodes 220 are used. The cathode electrode 210 is one electrode but may be separated into separate electrodes. The anode electrodes 220 are conductors exposed on a bottom surface (away form the patient) of the detector 140. The anode electrodes 220 have a same pitch and area as the detection cells and are electrically isolated from each other for separate connections to the detection cells of the detector 140.

[0029] The circuits 110, 160 are formed as PCAs 202, 206 on PCBs 204, 208. The HV PCA 202 connects with the cathode 210. For example, asperity contact maintained by epoxy bonding connects electrode pads of the HV PCA 202 to the cathode 210. As another example, the cathode 210 is formed on the HV PCA 202 and bonded to the detector 140, such as with a conductive paste. Other connections, such as solder or flip-chip bonding, may be used.

[0030] Similarly, the signal PCA 206 connects with the anodes 220. For example, asperity contact maintained by epoxy bonding connects electrode pads of the signal PCA 206 to the anodes 220. As another example, the anodes 220 are formed on the signal PCA 206 and bonded to the detector 140, such as with a conductive paste. Other connections, such as solder or flip-chip bonding, may be used.

[0031] The PCBs 204, 208 of the PCAs 202, 206 are laminated structures non-conductive material one which conductive traces, vias, pads, and/or other structures may be deposited or included. The conductors may be one and/or within the non-conductive layers, which are laminated together. Electrical components may be soldered or bonded to the PCBs 204, 208, forming the PCAs 202, 206. For example, pads of an ASIC are soldered or flip-chip bonded to the PCB 208 to form the signal PCA206. The ASIC is formatted for processing. A plurality of ASICs may be provided, such as 9 ASICS in a 3x3 grid of the detector 140.

[0032] Other components, such as resistors, capacitors, inductors, relays, and/or transformers may be connected to form the PCAs 202, 206. The conductors route between the components to form a circuit, such as the HV circuit 110 on the HV PCA202 and the signal circuit 160 on the signal PCA 206. The components provide for analog and/or digital signal processing. Conductors route between devices to filter, amplify, determine timing, determine energy, and/or otherwise process received signals from the detection cells of the detector 140.

[0033] The HV PCB 204 and corresponding HV PCA 202 include one or more ECM 240, 242. The ECM construction is a very thin layer of dielectric material sandwiched in between thin layers of copper sheet (e.g., 0.5 oz weight or 18 pm thick). By using the ECM 240, 242 directly onto or in the HV bias PCA 202 to replace the HV capacitors, the highly attenuate and highly non-uniformity sensitivity of the detector 140 is aided. Since the ECM 240, 242 may be distributed over any area, such as over 30%, 40%, 50%, 60%, 70%, or more of the surface area of the PCB 204 and/or detector 140, the ECM 240, 242 provides a more uniform effect on radiation as compared to a HV capacitor as a mounted component. Non-uniformity created by the HV bias PCA 202 may still exist.

[0034] Figure 3 shows an example of the HV PCB 202. Two ECMs 240, 242 are layered within the PCB 300. Layers of non-conductive material 310 surround the ECMs 240, 242. While two ECMs 240, 242 are shown, one, three, or more ECMs 240, 242 may be included. The structure of the ECMs 240, 242 are embedded within the PCB 300. In the example shown, the ECMs 240, 242 are parallel and extend over most of the area of the PCB 300 when viewed from the top or bottom. Other arrangements may be used, such as having two ECMs 240, 242 on different halves of a same layer of the PCB 300.

[0035] Referring again to Figure 2, one of the ECMs 240 is used as the filtering capacitor 116, so connects with ground and an input from the voltage source 112. The filtering capacitor 116 formed by the ECM 240 is connected in parallel with the voltage source. Another of the ECMs 242 is used as the blocking capacitor 120, so connects from the cathode 210 to the signal PCA 206. The blocking capacitor 120 formed by the ECM 242 is connected in series with the voltage source 112 and the amplifier 162 of the signal PCA 206. This electrical connection allows the cathode signal to be received by the ASIC or other signal processing components of the signal PCA 206. In alternative embodiments, one of the capacitors 116, 120 is formed by a capacitor mounted to the PCB 204.

[0036] A jumper extends from the HV PCA 202 to the signal PCA 206. The jumper may be an insulated wire or non-insulated wire. In one approach, the jumper is formed by a strip of flexible circuit material with a trace. The trace on the flexible circuit material electrically connects the cathode 210 through the ECM 242 to the signal PCA 206. A PCB may be used instead of the flexible circuit material.

[0037] The SPECT detector system 200 may be modular or formed as a module. One or more such detector systems 200 may be tiled, creating a larger SPECT detector or gamma camera. Any number of rows and/or columns may be provided, such as 10x10, 8x16, or 64x64 arrangement. The flexible circuit material 230 is thin enough to allow side by side contact of the detector systems 200 to form an array of such systems 200. In another approach, the SPECT detector systems 200 may be stacked top-to-bottom, such as forming a catcher and scatter detector of a Compton camera. A spacer or empty volume may be provided between any of the adjacent SPECT detector systems 200.

[0038] Figure 4 shows the SPECT detector system 200 used in a SPECT system or imager 400. The SPECT detector system 200 is used as a gamma camera 406 or part of the gamma camera 406 in the SPECT system 400. [0039] The SPECT system 400 is an imaging system for imaging a patient on the bed 404. The gamma camera 406 formed by the SPECT detector system 200 (e.g., detector 140, HV PCA 110 with ECM 240, 242, and/or signal PCA 160) detects emissions from the patient laying on the bed 404. [0040] The SPECT system 400 includes a housing 402. The housing 402 is metal, plastic, fiberglass, carbon (e.g., carbon fiber), and/or other material. In one embodiment, different parts of the housing 402 are of different materials.

[0041] The housing 402 forms a patient region into which the patient is positioned for imaging. The bed 404 may move the patient within the patient region to scan different parts of the patient at different times. Alternatively, or additionally, a gantry holding the gamma camera 406 (e.g., one or more SPECT detector systems 200) moves the gamma camera 406.

[0042] The gamma camera 406 is adjacent the patient region. The gamma camera 406 includes one or more semiconductor detectors 140, such as pixelated detectors with detection cells where separate electrodes are provided for the separate detection cells. The top of the detector 140 is positioned closest to the patient for receiving emissions from the patient. The HV PCA 202 of the SPECT detector system 200 is thus between the patient (source of emissions) and the detector 140. By including ECM 240, 242 instead of surface mounted capacitors, the capacitance used for blocking and/or filtering on the HV bias PCA 202 causes less variance in the sensitivity for detecting across the face of the detector 140.

[0043] Any number of SPECT detection systems 200 may be used to form the gamma camera 406. Figure 4 shows three SPECT detection systems 200 in cross-section tiled to form the gamma camera 406. Any number of SPECT detection systems 200 may be tiled and/or stacked to form the gamma camera 406. The SPECT detection systems 200 may be combined (e.g., stacked along a line extending from the patient and/or tiled in a plane parallel to the patient) to form the gamma camera 406 of any shape and/or size. In another approach, the SPECT detection systems 200 are combined to form catcher and scatter detectors of a Compton camera, such as two parallel plates (e.g., stacked with or without a spacer) of tiled SPECT detector systems 200).

[0044] Figure 5 shows one embodiment of a method for receiving signals in a SPECT detector. By including ECM for capacitance in the HV bias PCA 202, the emissions are exposed to less attenuation and/or variance in attenuation passing from the patient to the detector(s) 140.

[0045] The method is implemented by the system of Figure 1 , Figure 2, Figure 4, and/or another system. The acts are performed in the order shown (i.e., top to bottom or numerically) or another order. For example, acts 502 and 504 are performed while acts 506 and 508 occur. As another example, acts 506 and 508 occur simultaneously. Additional, different, or fewer acts may be provided. For example, act 510 is not performed. As another example, acts for configuring the SPECT system 400 are provided.

[0046] In act 502, a HV signal (direct current) is filtered to be applied as a bias voltage to the cathode 210. The HV source 112 supplies the HV voltage, which is then filtered. Analog filtering is provided, such as with a resistor in series and a capacitance to ground in parallel with the HV source 112. The capacitance is provided by the ECM 240 in the HV PCB 204.

[0047] The filtered HV is provided to the cathode 210 in act 504. The HV passes through the ECM 240, which connects through a resistor 118 to the cathode (see Figure 1).

[0048] In act 506, a cathode signal is received. An emission from the patient interacts with the detector 140, causing generation of an electrical signal at the anode and cathode. While the HV bias is connected to the cathode, the interaction may cause some variation. The cathode signal is received as the HV applied to the cathode with or without variation caused by emission interaction.

[0049] To protect electronics used in measuring the cathode signal, a blocking capacitor 120 is used. The blocking capacitor 120 blocks the DC HV voltage.

[0050] The blocking capacitor 120 is the ECM 242 of the HV PCB 204.

The cathode signal is received through the ECM 242 of the HV PCA 202. The cathode signal is routed to electronics (e.g., amplifier 162) for measurement, such as electronics at least in part on the signal PCA 206. Where the signal PCA 206 is mounted on an opposite side of the SPECT detector 140 as the HV PCA 202, the cathode signal is routed on a jumper between the PCBs 204, 208. In one approach, the cathode signal is routed on a trace on a strip of flexible circuit material 230.

[0051] In act 508, the anodes 220 receive anode signals caused by interaction of the emissions with the detector 140. The anode signals from the anodes 220 are received by electronics of the signal PCA 206. For example, a preamplifier 164 receives the anode signal from one of the anodes 220.

[0052] In act 510, a processor generates a SPECT image from the cathode signal and anode signals. The anode signals are used to measure the location, time, and/or energy of each detected emission. A count of emissions by location over time is binned. The cathode signal is used as a reference (with anode signals) to determine the depth of interaction to improve energy resolution. Measuring the depth of interaction in thick CZT detectors allows improved imaging and spectroscopy for hard X- ray imaging above 100 keV. Interaction depth information is used to correct events to the detector "focal plane" for correct imaging and can be used to improve the energy resolution of the detector at high energies by allowing event-based corrections for incomplete charge collection. Background rejection is also improved by allowing low energy events from the rear and sides of the detector to be rejected. The depth sensing is performed by making simultaneous measurements of cathode and anode signals, where the interaction depth at a given energy is proportional to the ratio of cathode/anode. The energy of the anode signal relative to the cathode signal may be thresholded to distinguish emissions from the radiopharmaceutical in the patient from background radiation or noise, so that the counts are more likely from emission events in the patient.

[0053] The counts from one or more SPECT detector systems 200 and their relative locations are used to generate the image. Using an optimization or a machine-learned model, an image representing spatial distribution of emission events in the patient is generated from the counts of different locations of the gamma camera 406. Each of the modules or SPECT detector systems 200 apply the voltage bias in act 504 and receive signals in acts 506, 508 to measure the counts. These counts are used to generate a SPECT image.

[0054] Since ECM 240, 242 are used in the HV bias PCA 202, less interference or variation in interference is provided as compared to using surface mounted capacitors. The resulting image from the received signals may have less artifact or noise caused by attenuation of the capacitance.

[0055] The following is a list of non-limiting illustrative embodiments disclosed herein:

[0056] Illustrative Embodiment 1 . A single photon emission computed tomography (SPECT) detector system comprising: a cadmium zinc telluride (CZT) detector; a cathode on a first surface of the CZT detector; anode electrodes on a second surface of the CZT detector, the second surface opposite the first surface on the CZT detector; and a first printed circuit board electrically connected with the cathode, the printed circuit board comprising an embedded capacitance material electrically connected to the cathode.

[0057] Illustrative Embodiment 2. The SPECT detector system of illustrative embodiment 1 wherein the embedded capacitance material is electrically connected to the cathode as a blocking capacitor.

[0058] Illustrative Embodiment 3. The SPECT detector system of any of illustrative embodiments 1 or 2 further comprising a second printed circuit board electrically connected to the anode electrodes, wherein the first printed circuit board is configured as a high voltage bias assembly and the second printed circuit board is configured as a signal processing assembly operating at a lower voltage than the high voltage bias board.

[0059] Illustrative Embodiment 4. The SPECT detector system of illustrative embodiment 3 wherein flexible circuit material electrically connects the cathode signal through the embedded capacitance material to the signal processing assembly.

[0060] Illustrative Embodiment 5. The SPECT detector system of illustrative embodiment 4 wherein the signal processing assembly comprises an application specific integrated circuit with a second amplifier connected to receive a second signal from the cathode and first amplifiers connected to receive signals from the anode electrodes.

[0061] Illustrative Embodiment 6. The SPECT detector system of any of illustrative embodiments 1-5 wherein the embedded capacitance material forms two capacitors, a first of the two capacitors comprising a blocking capacitor and a second of the two capacitors comprising a filter capacitor, the second capacitor connected in parallel with a voltage source and the first capacitor connected in series with the voltage source.

[0062] Illustrative Embodiment 7. The SPECT detector system of any of illustrative embodiments 1-6 wherein the first printed circuit board directly connects to the cathode with asperity contact.

[0063] Illustrative Embodiment 8. The SPECT detector system of any of illustrative embodiments 1-7 wherein the CZT detector, cathode, anode electrodes, and first printed circuit board comprise a first module tiled with additional modules.

[0064] Illustrative Embodiment 9. A method for receiving signals in a single photon emission computed tomography (SPECT) detector, the method comprising: applying a voltage bias to a cathode of the SPECT detector through a first printed circuit assembly mounted to the cathode; receiving a cathode signal through a first embedded capacitance material of the first printed circuit assembly; and generating a SPECT image from the cathode signal.

[0065] Illustrative Embodiment 10. The method of illustrative embodiment

9 wherein receiving the cathode signal comprises routing the cathode signal through the first embedded capacitance material of the first printed circuit assembly to a second printed circuit assembly mounted on an opposite side of the SPECT detector as the first printed circuit assembly; and further comprising: receiving anode signals as the second printed circuit assembly; wherein generating the SPECT image comprises generating from the cathode signal and the anode signals.

[0066] Illustrative Embodiment 11. The method of illustrative embodiment

10 wherein routing comprises routing on a trace on flexible circuit material. [0067] Illustrative Embodiment 12. The method of any of illustrative embodiments 9-11 further comprising filtering the voltage bias, the filtering using a second embedded capacitance on the first printed circuit assembly. [0068] Illustrative Embodiment 13. The method of any of illustrative embodiments 9-12 wherein generating the SPECT image comprises generating with counts received from a plurality of modules, each of the modules applying the voltage bias and receiving respective ones of the cathode signal.

[0069] Illustrative Embodiment 14. A single photon emission computed tomography (SPECT) system comprising: a housing forming a patient region; and a gamma camera adjacent the patient region, the gamma camera comprising a semiconductor detector stacked between first and second printed circuit boards, the first printed circuit board comprising a first embedded capacitance material connected with a cathode of the semiconductor detector.

[0070] Illustrative Embodiment 15. The SPECT system of illustrative embodiment 14 wherein the first and second printed circuit boards connect to the semiconductor detector with asperity contact.

[0071] Illustrative Embodiment 16. The SPECT system of any of illustrative embodiments 14 or 15 wherein the semiconductor detector comprises a cadmium zinc telluride detector.

[0072] Illustrative Embodiment 17. The SPECT system of any of illustrative embodiments 14-16 wherein the first embedded capacitance material is configured as a blocking capacitor electrically connected to the cathode.

[0073] Illustrative Embodiment 18. The SPECT system of illustrative embodiment 17 wherein the blocking capacitor electrically connects through a jumper to the second printed circuit board.

[0074] Illustrative Embodiment 19. The SPECT system of any of illustrative embodiments 14-18 wherein the first printed circuit board comprises a second embedded capacitance material configured to filter a cathode bias voltage.

[0075] Illustrative Embodiment 20. The SPECT system of any of illustrative embodiments 14-19 wherein the gamma camera comprises a plurality of the semiconductor detectors. [0076] Independent of the grammatical term usage, individuals with male, female or other gender identities are included within the term. While the invention has been described above by reference to various embodiments, many changes and modifications can be made without departing from the scope of the invention. It is therefore intended that the foregoing detailed description be regarded as illustrative rather than limiting, and that it be understood that it is the following claims, including all equivalents, that are intended to define the spirit and scope of this invention.

Claims

I (WE) CLAIM:

1 . A single photon emission computed tomography (SPECT) detector system comprising: a cadmium zinc telluride (CZT) detector; a cathode on a first surface of the CZT detector; anode electrodes on a second surface of the CZT detector, the second surface opposite the first surface on the CZT detector; and a first printed circuit board electrically connected with the cathode, the first printed circuit board comprising an embedded capacitance material electrically connected to the cathode.

2. The SPECT detector system of claim 1 wherein the embedded capacitance material is electrically connected to the cathode as a blocking capacitor.

3. The SPECT detector system of claim 1 further comprising a second printed circuit board electrically connected to the anode electrodes, wherein the first printed circuit board is configured as a high voltage bias assembly and the second printed circuit board is configured as a signal processing assembly operating at a lower voltage than the high voltage bias board.

4. The SPECT detector system of claim 3 wherein flexible circuit material electrically connects the cathode signal through the embedded capacitance material to the signal processing assembly.

5. The SPECT detector system of claim 4 wherein the signal processing assembly comprises an application specific integrated circuit with a second amplifier connected to receive a second signal from the cathode and first amplifiers connected to receive signals from the anode electrodes.

6. The SPECT detector system of claim 1 wherein the embedded capacitance material forms two capacitors, a first of the two capacitors comprising a blocking capacitor and a second of the two capacitors comprising a filter capacitor, the second capacitor connected in parallel with a voltage source and the first capacitor connected in series with the voltage source.

7. The SPECT detector system of claim 1 wherein the first printed circuit board directly connects to the cathode with asperity contact.

8. The SPECT detector system of claim 1 wherein the CZT detector, cathode, anode electrodes, and first printed circuit board comprise a first module tiled with additional modules.

9. A method for receiving signals in a single photon emission computed tomography (SPECT) detector, the method comprising: applying a voltage bias to a cathode of the SPECT detector through a first printed circuit assembly mounted to the cathode; receiving a cathode signal through a first embedded capacitance material of the first printed circuit assembly; and generating a SPECT image from the cathode signal.

10. The method of claim 9 wherein receiving the cathode signal comprises routing the cathode signal through the first embedded capacitance material of the first printed circuit assembly to a second printed circuit assembly mounted on an opposite side of the SPECT detector as the first printed circuit assembly; and further comprising: receiving anode signals as the second printed circuit assembly; wherein generating the SPECT image comprises generating from the cathode signal and the anode signals.

11 . The method of claim 10 wherein routing comprises routing on a trace on flexible circuit material.

12. The method of claim 9 further comprising filtering the voltage bias, the filtering using a second embedded capacitance on the first printed circuit assembly.

13. The method of claim 9 wherein generating the SPECT image comprises generating with counts received from a plurality of modules, each of the modules applying the voltage bias and receiving respective ones of the cathode signal.

14. A single photon emission computed tomography (SPECT) system comprising: a housing forming a patient region; and a gamma camera adjacent the patient region, the gamma camera comprising a semiconductor detector stacked between first and second printed circuit boards, the first printed circuit board comprising a first embedded capacitance material connected with a cathode of the semiconductor detector.

15. The SPECT system of claim 14 wherein the first and second printed circuit boards connect to the semiconductor detector with asperity contact.

16. The SPECT system of claim 14 wherein the semiconductor detector comprises a cadmium zinc telluride detector.

17. The SPECT system of claim 14 wherein the first embedded capacitance material is configured as a blocking capacitor electrically connected to the cathode.

18. The SPECT system of claim 17 wherein the blocking capacitor electrically connects through a jumper to the second printed circuit board.

19. The SPECT system of claim 14 wherein the first printed circuit board comprises a second embedded capacitance material configured to filter a cathode bias voltage.

20. The SPECT system of claim 14 wherein the gamma camera comprises a plurality of the semiconductor detectors.