Systems and methods for reducing trace triggering of channels in an X-ray detector

Abstract

The present invention is titled Systems and Methods for Mitigating Trace Triggering in Channels of an X-ray Detector. The present invention provides an X-ray detector; the X-ray detector includes a plurality of detector sub-modules. Each detector sub-module includes a semiconductor layer and a plurality of detector elements. A first detector element of the plurality of detector elements includes a first electrode disposed on a first doped implant, and a second detector element of the plurality of detector elements includes a second electrode disposed on a second doped implant. The first detector element and the second detector element are disposed adjacent to each other on the semiconductor layer and have a gap therebetween. Each detector sub-module further includes a wiring trace extending from one or more of the plurality of detector elements to a readout circuit. The wiring trace is routed within the gap between the first electrode and the second electrode. The first doped implant extends beneath a portion of the wiring trace and is configured to shield the wiring trace from electrical activity occurring beneath due to absorption of X-rays.

Description

BACKGROUND OF THE INVENTION

[0001] The subject matter disclosed herein relates to X-ray detectors, and more particularly, to reducing interference signals originating from interconnect traces in an X-ray detector.

[0002] Non-invasive imaging techniques allow for obtaining images of internal structures or features of a subject (patient, manufactured goods, luggage, packages, or passengers) without physical contact.

[0003] For example, in X-ray based imaging techniques, X-ray radiation penetrates a subject of interest (such as a human patient), and a portion of the radiation affects a detector that collects intensity data. In a digital X-ray system, the detector generates signals representative of the amount or intensity of radiation impinging on discrete pixel regions of the detector surface. The signals can then be processed to generate an image that can be displayed for viewing.

[0004] In one such X-ray based technique, called computed tomography (CT), a scanner can project a fan-shaped or cone-shaped X-ray beam from an X-ray source at multiple angular positions around an object being imaged (such as a patient). The X-ray beam attenuates as it passes through the object and is detected by a set of detector elements that generate signals representative of the intensity or amount of the incident X-rays reaching the detector. The signals are processed to produce data representative of the line integral of the linear attenuation coefficient of the object along the X-ray path. These signals are commonly referred to as "projection data" or simply "projections". By using a reconstruction technique such as filtered backprojection, an image of a cross-sectional slice or three-dimensional volume of the region of interest of the patient or object being imaged can be generated. In a medical context, pathological structures or other structures of interest can then be located or identified from the reconstructed image or rendered volume.

[0005] There is generally a need for improved X-ray detector designs, as well as improved image quality and / or reduced radiation dose. SUMMARY OF THE INVENTION

[0006] An overview of certain embodiments disclosed herein is presented below. It should be understood that these aspects are provided merely to provide a brief overview of these particular embodiments to the reader and are not intended to limit the scope of the present disclosure. Indeed, the present disclosure may cover various aspects that may not be shown below.

[0007] In one embodiment, an X-ray detector is provided. The X-ray detector includes a plurality of detector sub-modules. Each detector sub-module includes a semiconductor layer and a plurality of detector elements. The first detector element among the plurality of detector elements includes a first electrode disposed on a first doped implant, and the second detector element among the plurality of detector elements includes a second electrode disposed on a second doped implant. The first detector element and the second detector element are disposed adjacent to each other on the semiconductor layer and have a gap therebetween. Each detector sub-module further includes a wiring trace extending from one or more of the plurality of detector elements to a readout circuit. The wiring trace is routed within the gap between the first electrode and the second electrode. The first doped implant extends beneath a portion of the wiring trace and is configured to shield the wiring trace from electrical activity occurring beneath due to absorption of X-rays.

[0008] In another embodiment, an X-ray detector is provided. The X-ray detector includes a plurality of detector sub-modules. Each detector sub-module includes a semiconductor layer and a plurality of detector elements disposed on the semiconductor layer. Each detector sub-module further includes a wiring trace extending from the plurality of detector elements to a readout circuit. Each detector element is coupled to a corresponding wiring trace. The wiring trace is routed within a gap between adjacent detector elements among the plurality of detector elements. The X-ray detector further includes a processing circuit configured to perform coincidence detection to determine which of the plurality of detector elements is associated with the location of an X-ray hit when an X-ray coincidence hits one of the detector elements and one or more of the wiring traces coupled to the corresponding detector elements among the plurality of detector elements.

[0009] In another embodiment, a method for reducing the electrical coupling between a wiring trace and a semiconductor layer beneath an X-ray detector is provided. The method includes subjecting the X-ray detector to a first X-ray exposure before imaging an object using the X-ray detector. Each detector sub-module includes a semiconductor layer and a plurality of detector elements. The first detector element of the plurality of detectors includes a first electrode, and the second detector element of the plurality of detector elements includes a second electrode. The first electrode and the second electrode are disposed adjacent to each other on the semiconductor layer and have a gap therebetween. Each detector sub-module further includes a wiring trace extending from one or more of the plurality of detector elements to a readout circuit. The wiring trace is routed within the gap between the first electrode and the second electrode. The first X-ray exposure generates a cumulative charge near the surface of the semiconductor layer beneath the wiring trace. The method further includes using the X-ray detector during a second X-ray exposure when imaging the object, while the electrical coupling between the wiring trace and a portion of the semiconductor layer beneath the wiring trace is reduced due to the first X-ray exposure, wherein the cumulative charge of the same polarity repels the charge due to the second X-ray exposure beneath the wiring trace, and the electrical coupling is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] These and other features, aspects, and advantages of the subject matter of the present invention will be better understood when the following detailed description is read with reference to the accompanying drawings, in which like reference symbols represent like parts throughout the drawings, wherein:

[0011] Figure 1 is a block diagram representation of a CT system in accordance with aspects of the present disclosure;

[0012] Figure 2 is a schematic diagram of an example of modular X-ray detector sub-modules arranged side by side and stacked in sequence in accordance with aspects of the present disclosure;

[0013] Figure 3 is a cross-sectional view through a portion of an X-ray detector sub-module in accordance with aspects of the present disclosure;

[0014] Figure 4 is a schematic diagram of an example of a portion of an X-ray detector sub-module (having a single p-type implant extension beneath the wiring trace) in accordance with aspects of the present disclosure;

[0015] Figure 5 is a schematic diagram of an example of a portion of an X-ray detector sub-module (having multiple p-type implant extensions beneath the wiring trace) in accordance with aspects of the present disclosure;

[0016] Figure 6Schematic of a portion of an exemplary X-detector sub-module in accordance with aspects of the present disclosure (with a wavy p-type implant extension beneath the wiring trace);

[0017] Figure 7 Cross-sectional view through a portion of an X-ray detector sub-module in accordance with aspects of the present disclosure (e.g., having a thicker electrical insulation layer between electrodes);

[0018] Figure 8 Cross-sectional view through a portion of an x-ray detector sub-module in accordance with aspects of the present disclosure (e.g., having wiring traces routed above the electrodes in the x-direction);

[0019] Figure 9 Cross-sectional view through a portion of an x-ray detector sub-module in accordance with aspects of the present disclosure (e.g., having wiring traces routed above the electrodes in the y-direction);

[0020] Figure 10 Schematic of a portion of an x-ray detector sub-module in accordance with aspects of the present disclosure (e.g., having wiring traces routed above the electrodes in the y-direction);

[0021] Figure 11 Schematic of a portion of an X-ray detector sub-module in accordance with aspects of the present disclosure (e.g., having wiring traces routed above the electrodes);

[0022] Figure 12 Schematic of a portion of an X-ray detector sub-module in accordance with aspects of the present disclosure (e.g., having a change in the position of the edge electrodes);

[0023] Figure 13 Schematic of a portion of an X-ray detector sub-module in accordance with aspects of the present disclosure (e.g., having a change in the size of the edge electrodes);

[0024] Figure 14 Schematic of a portion of an X-ray detector sub-module in accordance with aspects of the present disclosure (e.g., having a change in the shape of the edge electrodes);

[0025] Figure 15 Cross-sectional view through a portion of an X-ray detector sub-module in accordance with aspects of the present disclosure (e.g., having a metal shield for the wiring traces);

[0026] Figure 16 Flowchart of a method for reducing electrical coupling between wiring traces and a semiconductor layer beneath an X-ray detector in accordance with aspects of the present disclosure;

[0027] Figure 17A schematic illustration of a portion of an exemplary X-ray detector sub-module in accordance with aspects of the present disclosure (e.g., having trace extensions); and

[0028] Figure 18 A schematic illustration of a portion of an exemplary X-ray detector sub-module in accordance with aspects of the present disclosure (e.g., utilizing coincidence detection). DETAILED DESCRIPTION

[0029] One or more specific embodiments will be described below. To provide a concise description of these embodiments, not all features of an actual implementation are described in the specification. It should be understood that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developer's specific goals, such as complying with system-related and business-related constraints that may vary from one implementation to another. Additionally, it should be understood that such development efforts may be complex and time-consuming, but would still be a routine task of design, fabrication, and manufacture for those of ordinary skill in the art who would benefit from the present disclosure.

[0030] When introducing elements of various embodiments of the present inventive subject matter, the articles "a," "an," "the," and "said" are intended to mean that there is one or more of the said elements. The terms "comprising," "including," and "having" are intended to be inclusive and mean that additional elements may exist in addition to the listed elements. Further, any numerical examples in the following discussion are intended to be non-limiting, and thus additional numerical values, ranges, and percentages are within the scope of the disclosed embodiments.

[0031] While the following discussion is generally provided in the context of medical imaging, it should be understood that the present technology is not limited to such medical contexts. In fact, providing examples and explanations in such medical contexts is merely for the purpose of facilitating the explanation by providing instances of real-world implementations and applications. However, the current methods may also be used in other contexts, such as non-destructive inspection of manufactured parts or goods (i.e., quality control or quality review applications), and / or non-intrusive inspection of packages, boxes, suitcases, etc. (i.e., security or screening applications). Generally speaking, in any imaging or screening context where a photon counting detector is used, the present methods may be desirable.

[0032] Energy-resolving photon-counting detectors can provide spectral information not available with conventional energy-integrating detectors. One type of energy-discriminating, photon-counting detection technology uses silicon strips as the direct-conversion sensor material. Using silicon as the direct-conversion material can provide a higher count-rate capability than that obtained with other direct-conversion materials such as CZT or CdTe. In some embodiments, by enabling the absorption depth to be selected to any length, the detector can be arranged along the edge to increase the absorption efficiency, and the detector can still be fully depleted without reaching a very high voltage. However, the arrangement of detector elements on the detector sub-module or sensor (especially those along the edge of the detector sub-module or sensor) can cause the wiring traces to be routed along a path away from the detector elements (e.g., pixels). X-rays absorbed in the detector sub-module or sensor under the wiring can induce signals on the traces (hereinafter referred to as trace triggering), resulting in non-local crosstalk effects (i.e., signals attributed to the wrong detector elements).

[0033] The present method addresses these effects by mitigating trace triggering in a channel (e.g., a readout channel), and thus mitigating or eliminating the crosstalk effects. These techniques improve the performance of silicon-based photon-counting detectors, such as computed tomography detectors or other suitable types of radiographic X-ray detectors.

[0034] In view of the foregoing discussion, Figure 1 An embodiment of an imaging system 10 for acquiring and processing image data in accordance with aspects of the trace-triggering mitigation method discussed herein is illustrated. Although the following embodiments are discussed in the context of a computed tomography (CT) imaging system, the embodiments can also be utilized with other imaging systems (e.g., X-ray, PET, CT / PET, SPECT, nuclear CT, etc.). In the illustrated embodiment, system 10 is a computed tomography (CT) system that is designed to acquire X-ray projection data, reconstruct the projection data into tomographic images, and process the image data for display and analysis. The CT imaging system 10 includes one or more X-ray sources 12, such as one or more X-ray tubes or solid-state emission structures that permit generation of X-rays at one or more locations and / or one or more energy spectra during the imaging phase.

[0035] In some specific implementations, the source 12 may be positioned adjacent to the collimator 22, which is used to define the size and shape of one or more X-ray beams 20 that pass through the region where the subject 24 (e.g., a patient) or object of interest is positioned. The subject 24 attenuates at least a portion of the X-rays. The resulting attenuated X-rays 26 impinge on a detector array 28 formed by a plurality of detector elements (e.g., pixels). As discussed herein, the detector 28 may be a photon counting detector, including an energy-discriminating photon counting detector, which outputs transmission information regarding the number and energy of photons impinging on the detector at the measurement location and within a time interval corresponding to a scan or imaging phase. In some such embodiments, the energy-discriminating photon counting detector may be a direct conversion type detector (i.e., without using a scintillator intermediate), such as a silicon strip-based detector. In some embodiments, the detector array 28 may be formed by a plurality of detector sub-modules or sensors (each having a plurality of detector elements). In some embodiments, the detector array 28 and the detector sub-modules may be edge detectors and edge detector sub-modules, which are configured for edge illumination from the X-rays (i.e., the X-rays enter through the edges of the detector sub-modules). Specifically, the detector array 28 may be structured similar to the detector disclosed in U.S. Publication 2019 / 0383955, titled "X-ray Detector System Design," filed on February 19, 2019, which is incorporated herein by reference in its entirety for all purposes.

[0036] Each detector element generates an electrical signal representative of the intensity of the incident X-ray photons (e.g., the energy and number of incident photons) at the position of the detector element when the beam impinges on the detector 28. The electrical signals are acquired and processed to generate one or more scan datasets.

[0037] The system controller 30 commands the operation of the imaging system 10 to perform inspection and / or calibration protocols and to process the acquired data. With respect to the X-ray source 12, the system controller 30 provides power, focal position, control signals, etc. for an X-ray examination sequence. The detector 28 is coupled to the system controller 30, which commands the acquisition of the signals generated by the detector 28. Additionally, via the motor controller 36, the system controller 30 may control the operation of the linear positioning subsystem 32 and / or the rotational subsystem 34 for moving the components of the imaging system 10 and / or the subject 24. The system controller 30 may include signal processing circuitry and associated memory circuitry. In such embodiments, the memory circuitry may store programs, routines, and / or coded algorithms executed by the system controller 30 to operate the imaging system 10 (including the X-ray source 12) and to process the data acquired by the detector 28 in accordance with the steps and processes discussed herein. In one embodiment, the system controller 30 may be implemented as all or part of a processor-based system such as a general or special purpose computer system.

[0038] Source 12 can be controlled by an X-ray controller 38 included within system controller 30. The X-ray controller 38 can be configured to supply power and timing signals to source 12. Additionally, in some embodiments, the X-ray controller 38 can be configured to selectively activate source 12 such that tubes or emitters at different locations within system 10 can be operated either synchronously with one another or independently of one another.

[0039] System controller 30 can include a data acquisition system (DAS) 40. The DAS 40 receives data collected by the readout electronics of detector 28, such as sampled analog signals from detector 28. The DAS 40 can then convert the data into digital signals for subsequent processing by a processor-based system, such as computer 42. In other embodiments, detector 28 can convert the sampled analog signals into digital signals before transmission to data acquisition system 40. The computer can include processing circuitry 44 (e.g., image processing circuitry). Computer 42 can include or communicate with one or more non-transitory memory devices 46, which can store data processed by computer 42, data to be processed by computer 42, or instructions to be executed by a processor of computer 42 (e.g., processing circuitry 44). For example, the processing circuitry 44 of computer 42 can execute one or more instruction sets stored on memory 46, which can be the memory of computer 42, the memory of the processor, firmware, or a similar instance.

[0040] Computer 42 can also be adapted to control features enabled by system controller 30 (i.e., scan operations and data acquisition), such as in response to commands and scan parameters provided by an operator via operator workstation 48. System 10 can also include a display 50 coupled to operator workstation 48, which allows the operator to view relevant system data, imaging parameters, raw imaging data, reconstructed data, etc. Additionally, system 10 can include a printer 52, which is coupled to operator workstation 48 and is configured to print any desired measurement results. Display 50 and printer 52 can also be connected to computer 42 directly or via operator workstation 48. Additionally, operator workstation 48 can include or be coupled to a picture archiving and communication system (PACS) 54. The PACS 54 can be coupled to a remote system 56, a radiology information system (RIS), a hospital information system (HIS), or coupled to an internal or external network such that other persons at different locations can access the image data.

[0041] Figure 2FIG. is a schematic illustration of an example of modular X-ray detector sub-modules 58 (e.g., detector sensors) arranged side-by-side and stacked in sequence. The detector sub-module 58 can be an edge detector sub-module. As depicted, X-rays enter through the edge 59 of the detector sub-module 58. A guard ring can extend along the edge 59 of the detector sub-module 58 to protect the detector sub-module 58 from electrical breakdown and isolate the detector region from excessive leakage current. In certain embodiments, the detector sub-module 58 can be a planar module. The X-ray detector sub-modules 58 can be stacked in sequence to form a larger detector module, and the larger detector modules can be assembled side-by-side to construct the entire X-ray detector. The detector sub-modules 58 can generally be arranged side-by-side in a direction substantially perpendicular to the z-direction, e.g., in a slightly curved overall configuration. In certain embodiments, the detector sub-modules 58 can be stacked in sequence in the z-direction.

[0042] As shown, each detector sub-module 58 includes a plurality of detector elements 60 (e.g., pixels). The detector elements 60 can be elongated electrodes (e.g., metal electrodes) where the length extensions point towards the focal point of the X-ray system. Depending on the detector topology, the detector elements 60 can correspond to pixels. In certain embodiments, the detector sub-module 58 can be a depth-segmented detector sub-module having a plurality of detector strips 62, where each strip 62 has a plurality of depth segments 65. As depicted, each strip 62 has a first segment 64, a second segment 66, and a third segment 68 associated with different depths (relative to the focal point) along the detection line. As depicted, at least portions of the segments 64, 66, 68 are arranged collinearly. The number of segments 65 can vary (e.g., 1 to 3 or more). For such depth-segmented detector sub-modules 58, each depth segment 65 can be considered a separate detector element (if each depth segment is associated with its own separate charge collection electrode). In certain embodiments, the circuitry can process the depth segments 65 of a single strip 62 logically as a single detector element.

[0043] The shape of detector sub-module 58 can vary. In some embodiments, detector sub-module 58 can have a parallelogram shape, a trapezoidal shape, a triangular shape, or another shape. In some embodiments, one or more edges 59 of detector sub-module 58 can be inclined. The shape of detector element 60 can vary. In some embodiments, detector elements 60 arranged along the inclined side edge 69 of detector sub-module 58 can include tapered edge sections (e.g., trapezoidal or triangular sections and / or truncated trapezoidal or triangular sections with rounded corners). In some embodiments, the section 65 of strip 62 closest to the inclined side edge of detector sub-module 58 can be oriented such that it extends into the area of an adjacent strip 62. In some embodiments, section 65 can also be inclined.

[0044] Figure 3 is a cross-sectional view through a portion of X-ray detector sub-module 70. X-ray detector sub-module 70 includes semiconductor layer 72. Semiconductor layer 72 is made of silicon. In some embodiments, semiconductor layer 72 can be made of gallium arsenide, cadmium zinc telluride, or another semiconductor material. Detector elements or sections 74, 76 (e.g., metal electrodes) are disposed on semiconductor layer 72. The electrodes can be made of aluminum. Specifically, electrodes 74, 76 are disposed on doped implants 78, 80 (e.g., p-type or n-type silicon implants, depending on whether the silicon of the semiconductor layer is n-type or p-type), which are disposed on semiconductor layer 72. Detector elements 74, 76 can be corresponding sections of different section strips disposed adjacent to each other. Detector elements 74, 76 and doped implants 78, 80 are disposed on semiconductor layer 72 with a gap 82 formed therebetween. X-ray detector sub-module 70 includes an insulator layer 84 extending between adjacent electrodes 74, 76. Insulator layer 84 can be silicon dioxide, silicon nitride, polyimide, spin-on glass, or another insulating material. One or more wiring traces 86 (e.g., metal traces) are routed within gap 84 between electrodes 74, 76. As depicted, wiring traces 86 are disposed on insulator layer 84. As depicted, wiring traces 86 are disposed across gap 84 in a uniformly spaced manner. In some embodiments, wiring traces 86 can be routed as close as possible to the edges of electrodes 74, 76. Wiring traces 86 can be coupled to electrodes 74, 76 or different electrodes. Wiring traces 86 are routed along gap 82 (and possibly other gaps) to a readout circuit. As shown, a passivation layer 88 is disposed over these components of X-ray detector sub-module 70. Passivation layer 88 can be made of silicon oxide, silicon nitride, or another insulator.

[0045] As shown, the doped implant 78 includes a main or base portion 90 and an extension 92 that extends beyond a normal perimeter 94 (indicated by the dashed line). The extension 92 extends beneath both the wiring trace 86 and the electrical insulation layer 84 in a direction from the doped implant 78 to the doped implant 80. In some embodiments, the normal perimeter 94 also represents the outer perimeter of the doped implant 78 at different locations of the doped implant 78. The extension 92 of the doped implant 78 acts as a shield for the wiring trace 86 against charge or electrical activity (e.g., due to X-ray absorption) in the bulk silicon volume (semiconductor layer 72). The extension 92 of the doped implant 78 reduces or minimizes the coupling (e.g., electrical coupling) between the semiconductor layer 72 and the wiring trace 86. In Figure 4 the extension 92 of the doped implant 78 beneath the wiring trace 86 is also depicted. Figure 4 Only a portion of the wiring trace 86 is shown. The doped implant 78 may extend beneath the wiring trace 86 along the entire longitudinal length of the doped implant 78 or only along a portion of the longitudinal length of the doped implant 78.

[0046] In some embodiments, as Figure 5 depicted, both doped implants 78, 80 may include an extension 92 that extends within a gap 82 beneath the wiring trace 86. As Figure 5 depicted, the wiring trace 86 is positioned as close as possible to the edge of the main portion 90 of the doped implants 78, 80 and is thus as close as possible to the electrodes (as opposed to being evenly spaced across the gap 82). Figure 5 Only a portion of the wiring trace 86 is shown.

[0047] In some embodiments, as Figure 6 depicted, the extension 92 of the doped implant 78 that extends beneath the wiring trace 86 has a waveform shape. Specifically, the extension includes a plurality of spaced-apart protrusions 96 that extend across the gap 82 from the doped implant 78 to the doped implant 80. The waveform shape of the extension 92 minimizes the capacitance added to the wiring trace 86 due to the extension 92 being beneath the wiring trace 86. Figure 5 Only a portion of the wiring trace 86 is shown.

[0048] Alternative techniques may be utilized to reduce the coupling (e.g., electrical coupling) between the wiring trace and the underlying semiconductor layer (e.g., bulk silicon). Figure 7 is a cross-sectional view through a portion of the X-ray detector sub-module 98. The X-ray detector sub-module 98 is similar to the X-ray detector sub-module 70 in Figure 3 except that the doped implant 78 does not extend beneath the wiring trace 86. Alternatively, the electrical insulation layer 84 is thicker. The electrical insulation layer 84 (e.g., as Figure 3The one shown) is typically about 200 nanometers (nm) thick. Figure 7 The thickness 100 of the electrical insulating layer 84 in Figure 3 can be about two to three times thicker than the electrical insulating layer 84 in Figure 7 Thus, the thickness 100 of the electrical insulating layer 84 in Figure 7 can be between about 400 and 600 nm. The increased thickness of the electrical insulating layer 84 reduces or minimizes the coupling (e.g., electrical coupling) between the semiconductor layer 72 and the wiring trace 86.

[0049] Another technique for reducing the coupling between the wiring trace and the underlying semiconductor layer can include changing the material used for the electrical insulating layer that is within the gaps between the pixels. Specifically, a material for the electrical insulating layer that minimizes electrical coupling even more than silicon dioxide can be selected. For example, polyimide can be used as the material for the electrical insulating layer.

[0050] As described above, the arrangement of detector elements on the detector sub-module or sensor (especially those along the edges of the detector sub-module or sensor) can cause the wiring traces to be routed along paths that are not adjacent to the detector elements (e.g., pixels). X-rays absorbed in the detector sub-module or sensor below the wiring can induce signals on the traces, resulting in non-local crosstalk effects (i.e., signals attributed to the wrong detector elements). In some embodiments, an additional layer can be utilized to facilitate re-routing of the wiring traces. Figure 8 is a cross-sectional view through a portion of the X-ray detector sub-module 104. In this embodiment, the electrodes 74, 76 are adjacent to each other (in the X direction), but are part of different strips (e.g., segmented strips) that extend from the top portion to the bottom portion of the X-ray detector sub-module 104 (in other words, the electrodes 74, 76 are horizontally adjacent or aligned). The X-ray detector sub-module 104 is similar to Figure 3 the X-ray detector sub-module 70 in

[0051] Figure 9is a cross-sectional view through a portion of the X-ray detector sub-module 156. In this embodiment, the electrodes 74, 76 are adjacent to each other (in the y direction) as part of the same strip (e.g., a segmented strip) extending from the top portion to the bottom portion of the X-ray detector sub-module 156 (in other words, the electrodes 74, 76 are vertically adjacent or aligned). The X-ray detector sub-module 156 is similar to Figure 8 the X-ray detector sub-module 104 in Figure 10 A view of the wiring trace 86 routed over the vertically adjacent detector elements or segments 164 (e.g., electrodes) of the strip 166 of a portion of the detector sub-module 168 is provided.

[0052] Figure 11 is a schematic view of a portion of the X-ray detector sub-module 108 (e.g., having the wiring trace 86 routed over the electrodes). As depicted, the detector sub-module 108 has an inclined edge or side 110 that forms an obtuse angle with respect to another edge or side 112 of the detector sub-module 108. In some embodiments, the detector sub-module has an inclined edge or side 110 that forms an acute angle with respect to another edge or side 112. The detector sub-module 108 includes a first strip 114 of segments or electrodes (e.g., detector elements) and a second strip 116 of segments or electrodes. The first strip 114 of segments includes electrodes 118, 120 that form a first detection line (indicated by the dashed line 122), and the second strip of segments includes electrodes 124, 126 that form a second detection line (indicated by the dashed line 128). The electrodes 118, 120 are inclined. The electrodes 120, 126 are located near the guard ring 130 along the edge 110 of the detector sub-module 108. To avoid routing the wiring trace 86 between the gaps of the detector elements, the wiring trace 86 is routed more directly over the electrodes 118, 120, 124, 126 toward and along the edges 110, 112 of the detector sub-module 108 (away from the top portion 131 of the detector sub-module 108) as Figures 8 - 10 depicted in

[0053] In some embodiments, the wiring traces can be routed within the gap between the detector elements disposed along the edge of the detector sub-module and the guard ring along the edge. As Figure 12 depicted, for detector sub-module 132, one or more electrodes 120 disposed along the inclined edge 110 can have a position 134 that is further away from the edge 110 (compared to the position 136 indicated by the dashed outline) to form a gap 138 between the electrode 120 and the guard ring 130 for the wiring trace 86 to be routed along. In some embodiments, as Figure 13 depicted, for detector sub-module 140, the size of the electrode 120 can be changed from a first size 142 (indicated by the dashed outline) to a second size 144 to form a gap 138 for the wiring trace 86 to be routed along. In other embodiments, as Figure 14 depicted, for detector sub-module 146, the shape of the electrode 120 can be changed from a first shape 148 (indicated by the dashed outline) to a second shape 150 to form a gap 138 for the wiring trace 86 to be routed along.

[0054] Figure 15 Alternative ways of shielding the wiring traces are provided. Figure 15 is a cross-sectional view through a portion of the X-ray detector sub-module 152. The X-ray detector sub-module 152 is similar to Figure 3 the X-ray detector sub-module 70 therein, except that the doped implant 78 does not extend into the gap 84. Instead, a metal shielding layer 154 (e.g., made of aluminum or another metal) can be disposed between the insulating layer 84 and the insulating layer 88 in the gap 82 between the doped implants 78 and 80 (equivalent to the detector elements). Then, the wiring trace 86 can be routed within the gap 82 above the metal shielding layer 154 (with the insulating layer 88 below). The insulating layers 88, 106 and the metal shielding layer 154 provide a dedicated layer for the routing of the wiring trace 86.

[0055] As described above, the electrical coupling between the wiring traces and the underlying semiconductor layer (bulk silicon) can be reduced via reconstruction of the detector sub-module. Other techniques can be utilized to reduce the electrical coupling between the wiring traces and the semiconductor layer. Figure 16It is a flowchart of a method 170 for reducing the electrical coupling between the wiring traces of an X-ray detector (e.g., an edge-on detector as described above) and the underlying semiconductor layer. The method 170 includes subjecting the X-ray detector to a first X-ray exposure (block 172) before imaging an object or a subject using the X-ray detector. In other words, during the first exposure, the subject or object is not exposed to X-rays. This first exposure reduces or minimizes the electrical coupling between the wiring traces and the semiconductor layer (e.g., bulk silicon) beneath the wiring traces by creating an accumulation of charges (e.g., positive charges) that move slowly near the surface of the semiconductor layer (e.g., silicon) under the traces. The X-ray-induced charges of the same polarity (e.g., positive charges) are then slightly repelled by the accumulated positive charges and turn away from the traces, thereby reducing the coupling of the charges to the traces. The method 170 further includes using the X-ray detector during a second X-ray exposure when imaging the object or subject, while the electrical coupling between the wiring traces and a portion of the semiconductor layer beneath the wiring traces remains reduced due to the first X-ray exposure (block 174). The second exposure occurs during a time period when the electrical coupling is still reduced or minimized due to the first exposure.

[0056] To ensure the counting of X-rays, trace extensions can be added to certain spaces on the detector sub-module. Figure 17A schematic diagram of a portion of an exemplary X-ray detector sub-module 176 (e.g., having trace extensions) is shown. As described above, each depth segment can be considered a separate detector element (if each depth segment is associated with its own separate charge collection electrode). In some embodiments, the circuitry can treat the depth segments of a single strip logically as a single detector element. As depicted, the detector sub-module 176 (e.g., an edge detector sub-module) includes a depth-segmented detector sub-module having a plurality of detector strips 178 (e.g., detector strips 180, 182, 184), where each strip 178 has a plurality of depth segments 186. As depicted, each strip 178 has a first segment 188, a second segment 190, and a third segment 192 associated with different depths (relative to the focal point) along a detection line. As depicted, at least a portion of the segments 188, 190, 192 are arranged collinearly. The number of segments 186 can vary (e.g., 1 to 3 or more). Each segment 186 has a corresponding wiring trace 194 that is routed towards a readout circuit (e.g., and associated with a readout channel). As depicted, the wiring trace 194 extends from a bottom portion 195 of the segment 186. To ensure that X-rays hitting within the space or gap 196 between segments 188 (e.g., the top segments) are counted (i.e., to increase the sensitivity within these gaps 196), corresponding trace extensions 198 (e.g., metal trace extensions) are coupled to the corresponding wiring traces 194 of each segment 188. The trace extension 198 extends within the gap 196 in a direction from the bottom portion 195 of the segment 186 towards the top portion 200 of the segment 186.

[0057] Figure 18FIG. 0 is a schematic diagram of a portion of an X-ray detector sub-module 202 that illustrates the use of coincidence detection to ensure accurate counting of X-rays and determination of X-ray hit locations. As depicted, detector sub-module 202 (e.g., an edge detector sub-module) includes a depth-segmented detector sub-module having a plurality of detector strips 204 (e.g., detector strips 206, 208), where each strip 204 has a plurality of depth segments 210. As described above, each depth segment can be considered a separate detector element (if each depth segment is associated with its own separate charge collection electrode). In some embodiments, the circuit can logically treat the depth segments of a single strip as a single detector element. As depicted, each strip 204 has a first segment 212, a second segment 214, and a third segment 216 associated with different depths (relative to the focal point) along the detection line. As depicted, at least a portion of segments 212, 214, 216 are arranged collinearly. The number of segments 210 can vary (e.g., 1 to 3 or more). Each segment 210 has a corresponding wiring trace 218 that is routed towards the readout circuit (and is associated with a readout channel).

[0058] A processing circuit, as part of an X-ray detector or X-ray system, uses coincidence detection to determine which segment 210 (or segments) within the same strip 204 are triggered by an X-ray hit. As Figure 18 depicted, the electron cloud (depicted by an X within a circle) resulting from an X-ray hit 220 represents the X-ray hit 220. Two separate X-ray hits 220 (X-ray hits 222, 224) are shown. Assuming that the trace trigger (by X-ray hit 220) coincides with a charge sharing trigger on an associated pixel (i.e., the X-ray hit 220 hits and simultaneously triggers both a segment 210 and its corresponding wiring trace 218), the processing circuit can use coincidence detection to determine the location of the X-ray hits and with what pixels they should be associated. Additionally, the processing circuit can determine the depth of the X-ray impact 220 along the strip 204 of segments 210. Further, the processing circuit can associate a single segment 210 with an X-ray hit 220 to avoid double counting (i.e., incorrectly providing an X-ray hit 220 to a segment 210 due to its corresponding wiring trace 218 hitting at a location remote from the segment 210). In particular, the coincidence detection performed by the processing circuit is a logical deduction where a particular combination of coincidence hit channels is consistent with a hit that has occurred near a particular electrode (e.g., a segment or detector element).

[0059] For example, if an X-ray hit 222 triggers both segments 212 and 214 simultaneously (e.g., due to triggering of the wiring trace 218 for segment 212 at a location remote from segment 212), the processing circuit determines that the event (X-ray hit 222) belongs to segment 214. If an X-ray hit 224 triggers segments 212, 214, 216 (where segments 212 and 214 are triggered due to triggering of the respective wiring traces 218 for segments 212, 214 at a location remote from both segments 212 and 214), the processing circuit determines that the event (X-ray hit 224) belongs to segment 216. In other words, the processing circuit is configured to assign the X-ray hit 220 to the segment 210 during coincidence detection (when assuming that trace triggering (by the X-ray hit) conforms to charge sharing triggering on the relevant pixels), where the segment 210 is adjacent to the most easily triggered trace of those segments 210 within the strip 204 triggered by the X-ray hit 220. In some embodiments, the processing circuit is configured to estimate the energy of the X-ray hit 220 (i.e., the total amplitude of the peak) based on a linear combination (e.g., sum) of the pulse heights of each readout channel associated with the segment 210 and the wiring trace 218 triggered by the X-ray hit 220. For example, the estimated energy of the X-ray hit 222 can be a linear combination of the pulse heights of the readout channels associated with both segment 214 and the wiring trace 218 for segment 210. It should be noted that the X-ray hit 220 can hit multiple segments 210 simultaneously.

[0060] It should be noted that one or more embodiments for mitigating trace triggering in the channels disclosed above can be combined.

[0061] The technical effects of the disclosed subject matter include providing systems and methods for mitigating trace triggering in channels (e.g., readout channels) and thus mitigating or eliminating crosstalk effects. In some embodiments, the electrical coupling between the wiring trace and the underlying semiconductor volume (e.g., bulk silicon) can be reduced. In some embodiments, the wiring trace can be re-routed. In additional embodiments, a dedicated layer can be provided for re-routing the wiring trace. In even additional embodiments, coincidence detection can be used to correctly attribute X-ray hits to the appropriate pixels. Overall, these embodiments can reduce false trigger events. These techniques improve the performance of silicon-based photon counting detectors, such as computed tomography detectors or other suitable types of radiographic X-ray detectors.

[0062] Refer to the technology proposed in this document and protected by the claims, and apply it to physical objects and specific examples with practical natures, where the practical natures clearly improve the current technical field and thus are not abstract, intangible, or purely theoretical. Additionally, if any claim appended to the end of this specification contains one or more elements designated as "means for [performing]... function" or "steps for [performing]... function", such elements are intended to be interpreted in accordance with 35 U.S.C. § 112(f). However, for any claim containing elements designated in any other way, such elements are not intended to be interpreted in accordance with 35 U.S.C. § 112(f).

[0063] This written description uses examples to disclose the subject matter, including the best mode, and also enables those skilled in the art to practice the subject matter, including manufacturing and using any device or system and performing any included method. The patent scope of the subject matter is defined by the claims, and may include other examples that occur to those skilled in the art. If such other examples have structural elements that are not different from the literal language of the claims, or if they include equivalent structural elements with minor differences from the literal language of the claims, such other examples are intended to fall within the scope of the claims.

Claims

1. An X-ray detector, the X-ray detector comprising: A plurality of detector sub-modules, wherein each detector sub-module comprises: A semiconductor layer; A plurality of detector elements, wherein a first detector element among the plurality of detector elements comprises a first electrode disposed on a first doped implant, and a second detector element among the plurality of detector elements comprises a second electrode disposed on a second doped implant, the first detector element and the second detector element are disposed adjacent to each other on the semiconductor layer and have a gap therebetween; and A wiring trace, the wiring trace extending from one or more of the plurality of detector elements to a readout circuit, wherein the wiring trace is routed within the gap between the first electrode and the second electrode; Wherein the first doped implant extends beneath a portion of the wiring trace and is configured to shield the wiring trace from electrical activity occurring beneath due to absorption of X-rays.

2. The X-ray detector according to claim 1, wherein the X-ray detector comprises a photon-counting X-ray detector.

3. The X-ray detector according to claim 1, wherein each detector sub-module comprises an edge detector sub-module.

4. The X-ray detector according to claim 1, wherein a subset of the detector elements among the plurality of detector elements is located at a side edge of a corresponding edge of the detector sub-module.

5. The X-ray detector according to claim 1, wherein each detector sub-module comprises an electrically insulating layer, the electrically insulating layer is disposed on the semiconductor layer and extends between the first electrode and the second electrode, and the wiring trace is disposed on the electrically insulating layer.

6. The X-ray detector according to claim 1, wherein a portion of the first doped implant extending beneath the portion of the wiring trace comprises a series of spaced protrusions extending from the first doped implant towards the second doped implant.

7. An X-ray detector, the X-ray detector comprising: A plurality of detector sub-modules, wherein each detector sub-module comprises: A semiconductor layer; A plurality of detector elements, the plurality of detector elements being disposed on the semiconductor layer; and A wiring trace, the wiring trace extending from the plurality of detector elements to a readout circuit, wherein each detector element is coupled to a corresponding wiring trace, and the wiring trace is routed within a gap between adjacent detector elements among the plurality of detector elements; and A processing circuit, the processing circuit being configured to perform coincidence detection to determine which of the plurality of detector elements is associated with the location of an X-ray hit when the X-ray coincidence hits one of the plurality of detector elements and one or more of the wiring traces coupled to the corresponding detector element among the plurality of detector elements.

8. The X-ray detector according to claim 7, wherein the processing circuit is configured to determine the position of the X-ray hit by deriving that a specific combination of coincidence hit trace lines is consistent with the X-ray hit that has occurred near a specific detector element among the plurality of detector elements.

9. The X-ray detector according to claim 7, wherein each detector element includes a plurality of segments, and the processing circuit is configured to associate a single segment of a corresponding detector element with the X-ray hit.

10. The X-ray detector according to claim 7, wherein the plurality of detector elements includes a first detector element and a second detector element that are arranged adjacent to each other and have a corresponding gap therebetween, wherein the gap does not contain any trace lines, and the corresponding trace lines coupled to the first detector element are coupled to trace extensions that extend into the corresponding gap.

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