Medical imaging detector

Abstract

Systems and methods for a detector for medical imaging are provided. The detector for medical imaging comprises a mesh-shaped detector element (302) formed on a flat face of a first semiconductor layer (502). The mesh detector element (302) includes a metal layer (318) including a plurality of longitudinal strips (305), where each longitudinal strip is positioned over a respective second semiconductor layer (404) having an opposite doping polarity to the first semiconductor layer (502), and embedded in the first semiconductor layer (502). Further, each longitudinal strip is separated from an adjacent longitudinal strip by a respective one of the plurality of openings (307) such that the metal layer (318) does not extend continuously over the width of the mesh detector element (302).

Description

Technical Field

[0001] Embodiments of the subject matter disclosed herein relate to medical imaging, and more particularly, to detectors for medical images. Background Art

[0002] In a computed tomography (CT) imaging system, an electron beam is generated by a cathode and directed toward a target within an x-ray tube. A fan-shaped or cone-shaped x-ray beam generated by the collision of the electrons with the target is directed toward a subject, such as a patient. After being attenuated by the subject, the x-rays strike an array of radiation detectors, thereby generating an image.

[0003] The quality of CT images can be improved by using photon counting CT (PCCT), in which the radiation detector is a photon counting detector and counts photons to provide spectral information. PCCT uses a direct conversion detector and has various advantages over conventional energy integrating detector (EID) CT systems based on indirect conversion detectors. However, one performance limiting factor of PCCT detectors is the electronic noise present during imaging. Electronic noise determines the noise floor of the PCCT detector, which is the minimum energy x-ray that can be aligned by the readout electronics. Summary of the invention

[0004] The present disclosure at least partially solves one or more of the above-identified problems with a detector for medical imaging. The detector for medical imaging includes a mesh detector element formed on a flat face of a first semiconductor layer. The mesh detector element includes a metal layer, the metal layer including a plurality of longitudinal strips, wherein each longitudinal strip is positioned above a corresponding second semiconductor layer having an opposite doping polarity to the first semiconductor layer and embedded in the first semiconductor layer. Further, each longitudinal strip is separated from an adjacent longitudinal strip by a corresponding opening of a plurality of openings, such that the metal layer does not extend continuously across the width of the mesh detector element.

[0005] By using a mesh detector element including openings, the capacitance of the detector element is reduced, which is the largest factor affecting electronic noise in PCCT. Further, by utilizing the openings in the detector element, the contrast-to-noise ratio for soft tissue contrast imaging is increased by 10% to 15%, and the contrast-to-noise ratio for material resolution imaging is maintained or slightly increased.

[0006] The above advantages and other advantages and features of the present specification will be apparent from the following detailed description when considered alone or in conjunction with the accompanying drawings. It should be understood that the above summary is provided to introduce a series of concepts further described in the detailed description in a simplified form. This is not meant to identify key features or essential features of the claimed subject matter, the scope of which is uniquely defined by the claims that follow the detailed description. In addition, the claimed subject matter is not limited to specific implementations that address any shortcomings mentioned above or in any part of this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Various aspects of the present disclosure may be better understood by reading the following detailed description and referring to the accompanying drawings, in which:

[0008] Figure 1 shows a pictorial view of an imaging system according to one or more embodiments of the present disclosure;

[0009] Figure 2 A schematic block diagram of an exemplary imaging system according to one or more embodiments of the present disclosure is shown;

[0010] Figure 3 shows a mesh detector element including longitudinal strips and openings according to one or more embodiments of the present disclosure;

[0011] Figure 4 One or more embodiments of the present disclosure are shown. Figure 3 a portion of a mesh detector element;

[0012] Figure 5 The semiconductor layer is shown positioned on the semiconductor layer according to one or more embodiments of the present disclosure. Figure 3 A cross-sectional view of a mesh detector element;

[0013] Figure 6 One or more embodiments of the present disclosure are shown. Figure 5 an enlarged view of a cross-sectional view of;

[0014] Figure 7 shows a portion of a first example detector array including mesh detector elements according to one or more embodiments of the present disclosure;

[0015] Figure 8 shows a portion of a second example detector array including mesh detector elements according to one or more embodiments of the present disclosure;

[0016] Fig. 9 A third example detector array according to one or more embodiments of the present disclosure is shown; and

[0017] Fig.10 One or more embodiments of the present disclosure are shown. Fig. 9 part of a detector array.

[0018] The accompanying drawings illustrate specific aspects of the described systems and methods. Together with the following description, the accompanying drawings show and explain the structures, methods and principles described herein. In the accompanying drawings, the sizes of components may be enlarged or otherwise modified for clarity. Well-known structures, materials or operations are not shown or described in detail to avoid obscuring various aspects of the described components, systems and methods. DETAILED DESCRIPTION

[0019] Embodiments of the subject matter disclosed herein and the specification relate to methods and systems for reducing the capacitance of a photon counting computed tomography (PCCT) system. Typically, in a computed tomography (CT) imaging system, an x-ray source emits a fan beam or a cone beam toward a subject (such as a patient). Generally speaking, in a CT system, an x-ray source and a detector array rotate around a gantry in an imaging plane and around a patient, and an image is generated from projection data of multiple views at different viewing angles. For example, for one rotation of the x-ray source, a thousand views can be generated by the CT system. The beam impinges on a radiation detector array after being attenuated by the patient. Each x-ray detector or detector array typically includes a collimator for collimating an x-ray beam received at the detector, a scintillator disposed adjacent to the collimator for converting x-rays into light energy, and a photodiode for receiving light energy from an adjacent scintillator and generating an electrical signal therefrom. The intensity of the attenuated beam radiation received at the detector array typically depends on the attenuation of the x-ray beam by the patient. Each detector element of the detector array generates a separate electrical signal indicating the attenuated beam received by each detector element. The electrical signals are sent to a data processing system for analysis. The data processing system processes the electrical signals to facilitate the generation of an image.

[0020] Such conventional CT imaging systems utilize detectors that convert radiographic energy into current signals that are integrated over a period of time, then measured and ultimately digitized. However, a disadvantage of such detectors is that they cannot provide data on the number and / or energy of the detected photons. That is, the light emitted by the scintillator is a function of both the number of x-rays that strike and the energy level of the x-rays. The photodiode may not be able to discern the energy level or photon count from the scintillation. For example, two scintillators may be illuminated with equal intensity and therefore provide equal output to their respective photodiodes. However, despite producing equal light output, the number of x-rays received by each scintillator may be different, and the intensity of the x-rays may be different.

[0021] In contrast, a PCCT detector can provide photon counting and / or energy discrimination feedback with high spatial resolution. The PCCT detector can be operated in an x-ray counting mode, an energy measurement mode for each x-ray event, or both modes. Although a variety of materials can be used in the construction of a hybrid photon counting energy discrimination detector, semiconductors have been shown to be a preferred material. Typical materials for such applications include cadmium zinc telluride (CZT), cadmium telluride (CdTe), and silicon (Si). Other heavy semiconductors such as thallium bromide (TlBr), mercuric iodide (HgI), etc. can also be used.

[0022] The PCCT detector supports both x-ray photon counting and energy measurement or labeling, thereby supporting the acquisition of both anatomical details and tissue characterization information. In this regard, energy identification information or data can be used to reduce the effects of beam hardening, etc. In addition, the PCCT detector supports the acquisition of tissue identification data and thus provides diagnostic information indicative of disease or other pathologies. The PCCT detector can also be used to detect, measure and characterize materials that can be injected into the subject, such as contrast agents and / or other specialized materials, by using optimal energy weighting to enhance the contrast of iodine and calcium (and other high atomic number materials). For example, a contrast agent can include iodine injected into the bloodstream to achieve visualization.

[0023] However, one performance limiting factor of PCCT detectors, particularly for edge-illuminated silicon-based detectors, is the electronic noise present during imaging. Electronic noise determines the noise floor of the PCCT detector, which is the minimum energy x-ray that can be aimed at by the readout electronics. The capacitance of the detector within a PCCT detector is the largest factor affecting electronic noise, so reducing the capacitance of the detector will reduce the noise floor of the detector. In some examples, the detector capacitance can be reduced by creating openings in the interior region of the detector while maintaining a strip-like structure that can continue to produce essentially the same signal from x-rays absorbed in the silicon of the detector. Such detectors can effectively improve the efficiency of silicon PCCT diodes by reducing electronic noise in the readout electronics of the detector and lowering the lowest possible photon count threshold.

[0024] Figure 1 and Figure 2 An example of a PCCT system that can be used to perform contrast scans according to the present technology is provided in. Figure 3An example mesh detector element of a PCCT system is shown, wherein each mesh detector element is used to count photons of x-rays directed by an x-ray source to a subject. Each mesh detector element may include a metal layer positioned above a p-type semiconductor layer and organized into longitudinal strips. The longitudinal strips of each mesh detector element allow charge carriers to be collected and transferred from a detector array to a signal readout trace for image analysis. Each mesh detector element includes openings positioned between the longitudinal strips that are used to reduce the capacitance of the mesh detector element. Figure 4 The longitudinal strips and openings are illustrated in more detail in FIG. Figure 5 and Figure 6 A cross-sectional view of a mesh detector element positioned above a p-type semiconductor layer, an n-type semiconductor layer, and an oxide layer of a detector array is shown. The n-type semiconductor layer collects photons of x-ray radiation and converts them into charge carriers. The charge carriers are then transferred into longitudinal strips of each mesh detector element before being sent as electrical signals to an image processing unit. Figure 7 and Figure 8 A portion of an example detector array is shown, the portion comprising an arrangement of mesh-like detector elements positioned on a planar surface of a semiconductor layer. Further, Fig. 9 and Fig.10 An example detector array including a plurality of detectors is shown. The plurality of detectors may be arranged in a column so that incident x-ray radiation may pass through an edge of the detector array and continue vertically through the column. Each beam of incident x-ray radiation is converted into charge carriers, and one or more of the charge carriers are collected and transferred by the plurality of detectors.

[0025] Figures 1 to 10An example configuration with relative positioning of each component is shown. In at least one example, if it is shown as being in direct contact or directly coupled to each other, such elements may be referred to as being in direct contact or directly coupled, respectively. Similarly, in at least one example, the elements shown as being adjacent or adjacent to each other may be adjacent or adjacent to each other, respectively. For example, components placed in coplanar contact with each other may be referred to as being in coplanar contact. For another example, in at least one example, elements positioned to be spaced apart from each other and having only space therebetween without other components may be described and referenced as such. For another example, elements shown as being located above / below / below each other, located on opposite sides or located between the left / right sides of each other may be described and referenced as such relative to each other. In addition, as shown in the figure, in at least one example, the topmost element or the point of the element may be referred to as the "top" of the component, and the bottommost element or the point of the element may be referred to as the "bottom" of the component. As used herein, top / bottom, upper / lower, upper / lower may be relative to the vertical axis of the figure, and may be used to describe the position of the elements relative to each other in the figure. Thus, in one example, the element shown as being located above other elements is positioned vertically above other elements. For another example, the shapes of elements depicted in the figures may be referred to as having those shapes (e.g., such as being rounded, straight, planar, curved, rounded, chamfered, angled, etc.). Furthermore, in at least one example, elements shown as intersecting each other may be referred to as intersecting elements or intersecting each other. Additionally, in one example, elements shown as being within another element or shown as being outside another element may be described and referred to as such.

[0026] Figure 1 An exemplary PCCT system 100 configured for CT imaging using a photon counting detector is illustrated. Specifically, the PCCT system 100 is configured to image a subject 112 (such as a patient, an inanimate object, one or more manufactured parts) and / or a foreign object (such as a dental implant, a stent, and / or a contrast agent present in the body). In some examples, the PCCT system 100 includes a gantry 102, which in turn may also include an x-ray source 104, which is configured to project an x-ray radiation beam 106 (see Figure 2 ) for imaging a subject 112 lying on an examination table 114. Specifically, the x-ray source 104 is configured to project an x-ray radiation beam 106 toward a detector array 108 positioned on an opposite side of the gantry 102. Figure 1A single x-ray source 104 is depicted, but in some examples, multiple x-ray sources and detectors may be employed to project multiple x-ray radiation beams for acquiring projection data at different energy levels corresponding to the patient. In some examples, the x-ray source 104 may implement dual energy gemstone spectroscopy imaging (GSI) by rapid peak kilovolt voltage (kVp) switching. In the examples described herein, the x-ray detector employed is a photon counting detector capable of distinguishing x-ray photons of different energies.

[0027] In some examples, the PCCT system 100 also includes an image processing unit 110 configured to reconstruct an image of a target volume of a subject 112 using an iterative image reconstruction method or an analytical image reconstruction method. For example, the image processing unit 110 may use an analytical image reconstruction method such as filtered back projection (FBP) to reconstruct an image of the patient's target volume. As another example, the image processing unit 110 may use an iterative image reconstruction method such as advanced statistical iterative reconstruction (ASIR), conjugate gradient (CG), maximum likelihood expectation maximization (MLEM), model-based iterative reconstruction (MBIR), etc. to reconstruct an image of the target volume of the subject 112. As further described herein, in some examples, in addition to the iterative image reconstruction method, the image processing unit 110 may also use an analytical image reconstruction method such as FBP.

[0028] In some CT imaging system configurations, an x-ray source projects a cone-shaped x-ray radiation beam that is collimated to lie in the XYZ plane of a Cartesian coordinate system and is often referred to as the "imaging plane". The x-ray radiation beam passes through an object being imaged, such as a patient or subject. The x-ray radiation beam impinges on an array of detector elements after being attenuated by the object. The intensity of the attenuated x-ray radiation beam received at the detector array depends on the attenuation of the x-ray radiation beam by the object. Each detector element of the array produces a separate electrical signal that is a measurement of the attenuation of the x-ray beam at the detector location. The attenuation measurements from all detector elements are collected individually to produce a transmit profile.

[0029] In some CT systems, a gantry is used to rotate the x-ray source and detector array around the object to be imaged in an imaging plane so that the angle at which the x-ray beam intersects the object is constantly changing. A set of x-ray radiation attenuation measurements (e.g., projection data) from the detector array at one gantry angle is called a "view." A "scan" of an object includes a set of views made at different gantry angles or viewing angles during one rotation of the x-ray source and detector.

[0030] Figure 2 An example similar to Figure 11. An exemplary imaging system 200 of the PCCT system 100 of FIG. 1 is shown. According to aspects of the present disclosure, the imaging system 200 is configured to image a subject 204 (eg, Figure 1 In some examples, the imaging system 200 includes Figure 1 The detector array 108 includes a plurality of detector elements 202 that together sense the x-ray radiation beam 106 passing through a subject 204 (e.g., a patient) to acquire corresponding projection data. In some examples, the detector array 108 may be fabricated into a multi-slice configuration including multiple rows of units or detector elements 202, wherein one or more additional rows of detector elements 202 are arranged in a parallel configuration for acquiring projection data.

[0031] In some examples, the imaging system 200 can be configured to traverse different angular positions around the subject 204 to collect the desired projection data. Thus, the gantry 102 and components mounted thereon can be configured to rotate about the rotation center 206 for collecting, for example, projection data at different energy levels. Alternatively, in examples where the projection angle relative to the subject 204 changes over time, the mounted components can be configured to move along a generally curved line rather than along a section of a circle.

[0032] As the x-ray source 104 and the detector array 108 rotate, the detector array 108 collects data of the attenuated x-ray beam. The data collected by the detector array 108 undergoes preprocessing and calibration to adjust the data to represent the line integral of the attenuation coefficient of the scanned subject 204. The processed data is generally referred to as a projection. In some examples, the individual detectors or detector elements 202 in the detector array 108 may include photon counting detectors that register the interaction of individual photons into one or more energy bins.

[0033] The acquired projection data sets may be used for basis material decomposition (BMD). During BMD, the measured projections are converted into a set of material density projections. The material density projections may be reconstructed to form a pair or set of material density maps or images (such as bone maps, soft tissue maps, and / or contrast agent maps) for each corresponding basis material. The density maps or images may then be correlated to form a 3D volumetric image of the basis material (e.g., bone, soft tissue, and / or contrast agent) in the imaging volume.

[0034] Once reconstructed, the base material image produced by the imaging system 200 shows the internal features of the subject 204 represented by the density of the two base materials. The density image can be displayed to show the internal features. In traditional methods of diagnosing medical conditions (such as disease states), and more generally diagnosing medical events, a radiologist or physician will consider a hard copy or display of a density image to discern characteristic features of interest. Such features can include lesions, size and shape of specific anatomical structures or organs, as well as other features that should be discernible in the image based on the skills and knowledge of the individual practitioner.

[0035] In some examples, the imaging system 200 includes a control mechanism 208 to control movement of components, such as rotation of the gantry 102 and operation of the x-ray source 104. In some examples, the control mechanism 208 also includes an x-ray controller 210 configured to provide power and timing signals to the x-ray source 104. In addition, the control mechanism 208 includes a gantry motor controller 212 configured to control the rotational speed and / or position of the gantry 102 based on imaging requirements.

[0036] In some examples, the control mechanism 208 also includes a data acquisition system (DAS) 214 that is configured to sample analog data received from the detector elements 202 and convert the analog data into digital signals for subsequent processing. The DAS 214 may also be configured to selectively aggregate analog data from a subset of the detector elements 202 into a so-called macro detector, as further described herein. The data sampled and digitized by the DAS 214 is sent to a computer or computing device 216. Note that in at least one example, the computing device 216 may be the same as or similar to the image processing unit 110. In some examples, the computing device 216 stores the data in a storage device 218 (e.g., a mass storage device). For example, the storage device 218 may be any type of non-volatile memory and may include a hard drive, a floppy disk drive, a compact disk-read / write (CD-R / W) drive, a digital versatile disk (DVD) drive, a flash drive, and / or a solid-state storage drive.

[0037] In addition, the computing device 216 provides commands and parameters to one or more of the DAS 214, the x-ray controller 210, and the gantry motor controller 212 to control system operations, such as data acquisition and / or processing. In some examples, the computing device 216 controls system operations based on operator input. The computing device 216 receives operator input, which includes, for example, commands and / or scan parameters, via an operator console 220 operatively coupled to the computing device 216. The operator console 220 may include a keyboard (not shown) or a touch screen to allow an operator to specify commands and / or scan parameters.

[0038] Although Figure 2 One operator console 220 is illustrated, but more than one operator console may be coupled to the imaging system 200, e.g., for inputting or outputting system parameters, requesting exams, plotting data, and / or viewing images. Further, in some examples, the imaging system 200 may be coupled to multiple displays, printers, workstations, and / or the like located locally or remotely, e.g., within an institution or hospital or at an entirely different location, via one or more configurable wired and / or wireless networks (such as the Internet and / or a virtual private network, a wireless telephone network, a wireless local area network, a wired local area network, a wireless wide area network, a wired wide area network, etc.).

[0039] In some examples, the imaging system 200 includes or is coupled to a picture archiving and communication system (PACS) 224. In one exemplary implementation, the PACS 224 is further coupled to a remote system (such as a radiology department information system, a hospital information system) and / or to an internal or external network (not shown) to allow operators at different locations to supply commands and parameters and / or gain access to image data.

[0040] The computing device 216 uses operator-provided and / or system-defined commands and parameters to operate a table motor controller 226, which in turn can control the table 114, which can be a motorized table. Specifically, the table motor controller 226 can move the table 114 to properly position the subject 204 in the gantry 102 to acquire projection data corresponding to a target volume of the subject 204.

[0041] As previously described, the DAS 214 samples and digitizes the projection data acquired by the detector elements 202. Subsequently, the image reconstructor 230 uses the sampled and digitized x-ray data to perform high-speed reconstruction. Figure 2 The image reconstructor 230 is shown as a separate entity, but in some examples, the image reconstructor 230 may form part of the computing device 216. Alternatively, the image reconstructor 230 may not be present in the imaging system 200, and instead the computing device 216 may perform one or more functions of the image reconstructor 230. In addition, the image reconstructor 230 may be located locally or remotely, and may be operably connected to the imaging system 200 using a wired network or a wireless network. In particular, one illustrative example may use computing resources in a "cloud" network cluster for the image reconstructor 230.

[0042] In some examples, image reconstructor 230 stores the reconstructed image in storage device 218. Alternatively, image reconstructor 230 may send the reconstructed image to computing device 216 to generate usable patient information for diagnosis and evaluation. In some examples, computing device 216 may send the reconstructed image and / or the patient information to a display or display device 232 that is communicatively coupled to computing device 216 and / or image reconstructor 230. In some examples, the reconstructed image may be sent from computing device 216 or image reconstructor 230 to storage device 218 for short-term storage or long-term storage.

[0043] Figures 3 to 10 A coordinate system for oriented views is included. In one example, the z-axis can be a vertical axis (e.g., parallel to the rotation axis of the CT gantry), the y-axis can be a longitudinal axis (e.g., in a direction from the detector toward the source), and / or the x-axis can be a transverse axis (e.g., circumferential). However, in other examples, the axes can have other orientations.

[0044] Reference now Fig. 9 , shows a detector array 900. The detector array 900 may be Figure 1 is a non-limiting example of a sensor of the detector array 108. In some examples, Figure 1 The detector array 108 may include more than one hundred sensors (e.g., detector array 900) arranged into cells and / or modules of the detector array 108. Multiple detectors 901 may be arranged in a parallel configuration to form the detector array 900, which may be used to collect projection data, as described above. Further, Fig.10 An enlarged view of a region 1000 of detector array 900 is shown, including a portion of multiple detectors 901. Fig. 9 and Fig.10 .

[0045] The detector array 900 may include a plurality of detectors 901 and a printed circuit board (PCB) 920. Fig. 9 In the example shown, the plurality of detectors 901 and PCB 920 are arranged perpendicularly with respect to the y-axis. Further, in an exemplary embodiment, arrow 922 is oriented parallel to the y-axis and indicates a typical direction of incident x-ray radiation. PCB 920 can be positioned below the plurality of detectors 901 such that the PCB is not between the plurality of detectors 901 and the incident x-ray radiation. Further, positioning PCB 920 below the plurality of detectors 901 (e.g., with respect to the y-axis) can allow for space-efficient packaging of a plurality of detector arrays (such as detector array 900) into a detector array (e.g., Figure 2 in small grids and / or modules of the detector array 108).

[0046] The detector array 900 may include a semiconductor material layer, such as a semiconductor layer 1011. A plurality of detectors 901 may be positioned on a flat surface 1012 of the semiconductor layer 1011. Further, the semiconductor layer 1011 may have a width W6 in the range of 100 μm to 1000 μm, such as 500 μm or 650 μm. Fig.10 As illustrated, the detector array 900 may include a guard ring 1002. The guard ring 1002 may include one or more narrow structures extending along each edge of the planar surface 1012 and surrounding the plurality of detectors 901. In an exemplary embodiment, each such narrow structure includes a p-type semiconductor layer and a metal layer on the planar surface 1012 of the semiconductor layer. In another embodiment, the guard ring includes a plurality of concentric narrow structures that collectively act as a guard ring structure. The guard ring 1002 protects the detector array 900 from electrical (avalanche) breakdown of the semiconductor layer by limiting the maximum electric field.

[0047] The plurality of detectors 901 may be electrically coupled to one or more application specific integrated circuits (ASICs), such as a first ASIC 906 and a second ASIC 908 mounted on a PCB 920. As described in more detail below, the first ASIC 906 and the second ASIC 908 may each count the photons detected by the plurality of detectors 901. The plurality of detectors 901 may be coupled to the first ASIC 906 and the second ASIC 908 via a plurality of wire bonds 926 extending between the plurality of detectors and the PCB 920. Additionally, the plurality of detectors 901 may alternatively be directly coupled to the ASIC 906 and the ASIC 908 via a plurality of wire bonds. Additionally, the PCB 920 may be electrically connected to readout electronics, which may also be used to count the number of photons detected by the plurality of detectors 901. In some examples, the readout electronics may be external to the PCB 920 (e.g., for use during assembly and testing). Further, the readout electronics may form a DAS (e.g., a DAS) of a PCCT system. Figure 2 is part of DAS214).

[0048] The plurality of detectors 901 can be configured to detect photons of x-ray radiation that penetrate an edge 902 of the semiconductor layer 1011 of the detector array 900. The edge 902 can have a width W6 (e.g., 500 μm or 600 μm) along the z-axis. Further, the edge 902 can be oriented orthogonal to the flat surface 1012. Thus, the plurality of detectors 901 can be positioned on a surface of the detector array 900 that is perpendicular to the incident x-ray radiation.

[0049] The plurality of detectors 901 may be arranged in columns, wherein each column extends along the y-axis. For example, the plurality of detectors 901 may include a first column 1008 and a second column 1010. Each column may include one or more detectors, such as a first detector 1014 and a second detector 1016 of the first column 1008. The detector columns (e.g., the first column 1008) and a portion of the semiconductor layer 1011 positioned behind the detector columns (e.g., relative to the z-axis) may be defined as pixels, and thus the detector array 900 may include a plurality of pixels. For example, the pixel 1018 may include the first column 1008 (e.g., the first detector 1014 and the second detector 1016) and a portion of the semiconductor layer 1011 positioned behind the first column relative to the z-axis.

[0050] Each pixel may include a pixel region on the edge 902 of the detector array 900. When an incident x-ray radiation beam penetrates into the pixel region, photons of the x-ray radiation beam may interact with the semiconductor layer 1011, thereby releasing energy. The energy is converted into charge carriers within the corresponding pixel. For example, pixel 1018 may include a pixel region 1006 on the edge 902 of the detector array 900. When incident x-ray radiation penetrates the pixel region 1006, photons of the x-ray radiation are converted into charge carriers within a portion of the semiconductor layer 1011 positioned below the pixel region (e.g., relative to the y-axis), and these charge carriers are detected by the detectors in the first column 1008. Thus, each pixel (e.g., pixel 1018) may receive incident x-ray radiation at a pixel region on the edge 902, convert the x-ray radiation into charge within the semiconductor layer 1011, and collect the charge at the detector within the pixel. The charge collected by the plurality of detectors 901 may then be sent to one or more ASICs of the detector array via a signal readout trace.

[0051] like Fig. 9 As shown, each column of detectors (e.g., Fig.10 The first column 1008 of the detector array 900 can extend along the y-axis from the top of the detector array 900 to the PCB 920. The detectors in each column can be further organized into one or more rows of the detector array 900, such as the first row 910 and the second row 912.

[0052] Each row of multiple detectors 901 includes a single detector in each column. For example, a column 924 of multiple detectors 901 may include a detector in the first row 910 and a detector in the second row 912. Further, the column 924 may include a detector in each of the third row 914, the fourth row 916, and the fifth row 918. In some examples, the detectors in one row may have different lengths from the detectors in different rows. For example, the length of the detector in the first row 910 relative to the y-axis may be shorter than the detector in the second row 912. Thus, the length of the entire first row 910 relative to the y-axis may be shorter than the entire second row 912. In other examples, the detectors in each row may have the same length. For example, the detector in the first row may have the same length as the detector in the second row relative to the y-axis. Thus, the entire first row may have the same length as the entire second row relative to the y-axis.

[0053] Each detector in the plurality of detectors 901 (eg, Fig.10 The first detector 1014 of the detector array 900 can be electrically coupled to the first ASIC 906 and / or the second ASIC 908 mounted on the PCB 920. In some examples, each of the plurality of detectors 901 can be electrically coupled to a sensor bonding pad via a signal readout trace. Further, the sensor bonding pad can be electrically coupled to the first ASIC 906 and / or the second ASIC 908 via a wire bond, which can extend to the PCB 920. Each ASIC can be configured to receive electrical signals from one or more columns and / or rows of the detector array 900.

[0054] Further, each detector in the plurality of detectors 901 may collect Fig.10 The semiconductor layer 1011 may generate charge carriers after receiving a plurality of incident photons via one or more x-ray radiation beams. When x-ray radiation strikes the detector array 900 at the edge 902 (e.g., at the pixel area 1006), the photons of the x-ray radiation may pass through the semiconductor layer 1011 of the pixel, where each pixel includes a portion of the semiconductor layer and a column of multiple detectors 901. For example, the photons of the x-ray radiation may strike Fig.10 1006 and may then pass through semiconductor layer 1011 corresponding to first column 1008. As the x-ray radiation passes through semiconductor layer 1011, multiple photons of the x-ray radiation may be converted into charge carriers collected by the detectors of the corresponding column (e.g., first column 1008).

[0055] For example, x-ray radiation may enter the semiconductor layer 1011 of a pixel, and a first number of photons may be converted into charge in a portion of the semiconductor layer positioned behind the first row 910 relative to the z-axis. A detector positioned within the first row 910 of pixels may collect the charge generated from the first number of photons of x-ray radiation. The first number of photons may be less than the total number of photons of x-ray radiation, and a second number of the total number of photons may pass through the portion of the semiconductor layer 1011 positioned behind the first row 910 without being detected. Then, a second number of (undetected) photons of x-ray radiation may enter a portion of the semiconductor layer 1011 positioned behind the second row 912 of the same pixel, and a third number of photons may be converted into charge. A detector within the second row 912 of pixels may collect the charge generated from the third number of photons of x-ray radiation. The third number of photons may be less than the second number of photons, and a fourth number of photons may pass through the portion of the semiconductor layer 1011 positioned behind the second row 912 without being detected, and so on.

[0056] Each electrical signal collected by the plurality of detectors 901 may be sent to the first ASIC 906 or the second ASIC 908 via a signal readout trace. Further, each electrical signal may be an analog electrical signal and may be proportional to the amount of energy of the detected photons. The first ASIC 906 and the second ASIC 908 may convert each analog electrical signal into a digital signal by counting the occurrence of photons. In addition, each ASIC may discern the energy deposited by the photons by comparing the amount of the electrical signal with one or more pre-established thresholds. Specifically, the first ASIC 906 and the second ASIC 908 may each include a plurality of comparators, wherein each of the plurality of comparators outputs a trigger signal that causes the corresponding digital counter to increment when the analog signal exceeds the signal level threshold associated with the comparator. Each of the plurality of comparators may have a different signal level threshold. For example, the first ASIC 906 may include a first comparator having a first signal level threshold and a second comparator having a second signal level threshold, wherein the second signal level threshold may be higher than the first signal level threshold. In addition, the first ASIC 906 may include a third comparator having a third signal level threshold, wherein the third signal level threshold may be higher than the second signal level threshold, and so on, up to the maximum energy level of the photon spectrum. The difference between the threshold pairs defines an energy range or bin. Thus, a number of photons whose energies fall into each bin may be recorded by the ASIC. Thus, the number of photon counts may be sent by the first ASIC 906 or the second ASIC 908 to the PCB 920 for image reconstruction. Alternatively, each ASIC may first perform additional operations on the numerical count information, such as adding together the individual photon counts from bins within a given column to produce a total number of photon counts.

[0057] Reference now Figure 3 , a detector array 301 is shown. The detector array 301 includes a first semiconductor layer, wherein a plurality of mesh detector elements 300 are positioned on top of the first semiconductor layer, thereby forming a plurality of mesh diodes. As described herein, each mesh diode includes a first semiconductor layer, a second semiconductor layer having a doping polarity opposite to that of the first semiconductor layer, an oxide layer, and a metal layer 318. In some examples, as described herein, the first semiconductor layer may be an n-type semiconductor and the second semiconductor layer may be a p-type semiconductor. In other examples, the first semiconductor layer may be a p-type semiconductor and the second semiconductor layer may be an n-type semiconductor.

[0058] The plurality of mesh detector elements 300 may be Figure 2 The detector element 202 or Fig. 9901 of the present invention. Each of the plurality of mesh detector elements 300 can collect charge carriers (e.g., electrical signals) generated from photons radiated from x-rays via a semiconductor. Further, in the illustrated example, the plurality of mesh detector elements 300 can include a first mesh detector element 302 and a second mesh detector element 303. The second mesh detector element 303 is similar to the first mesh detector element 302, and therefore, the description of the second mesh detector element 303 can be omitted for simplicity, and the description of the first mesh detector element 302 provided herein is equally applicable to the second mesh detector element 303 and the additional mesh detector elements of the detector array 301.

[0059] The first mesh detector element 302 may include a metal layer 318. The metal layer 318 may include a first end 312 and a second end 314, and may extend from the first end 312 to the second end 314 along an axis parallel to the y-axis. The first end 312 may be positioned closer to an edge of the detector array (such as Fig. 9 The detector array is configured to receive photons of x-ray radiation. Thus, the first end 312 can be oriented to face the PCCT system (such as Figure 1 The second end 314 can be positioned away from the x-ray radiation source and can include a signal readout trace 316. The signal readout trace 316 can be configured to transmit the electrical signals collected by the first mesh detector element 302 to an image processing system such as a Figure 2 ASIC input to one or more components of the image reconstructor 230).

[0060] In some examples, as described herein, the first mesh detector elements 302 and the second mesh detector elements 303 may each be positioned on a planar surface of an n-type semiconductor layer (e.g., silicon) selectively doped with a p-type implant in a spatially varying pattern (referred to as an implant layer). The planar surface may be oriented orthogonal to an edge of the detector that receives x-ray radiation. The entire implant layer (e.g., p-type silicon) in the implant layer may be positioned below a portion of the metal layer 318 relative to the z-axis. Further, an oxide layer may be positioned between a portion of the metal layer 318 and a portion of each of the n-type semiconductor layer and the implant layer, as described with reference to FIG. Figure 5 and Figure 6 In other examples, the first mesh detector element 302 and the second mesh detector element 303 may each be positioned on a flat surface of a p-type semiconductor layer selectively doped with an n-type implant.

[0061] The first mesh detector element 302 may include a plurality of openings 307, including a first opening 306, thereby forming a plurality of longitudinal strips 305, such as a first longitudinal strip 304, in the metal layer 318 along the semiconductor (e.g., silicon) layer. Each of the plurality of openings 307 may include a gap in the metal layer 318 of the first mesh detector element 302, such that the metal layer does not extend continuously across the width of the first mesh detector element (e.g., relative to the x-axis). Further, the implant layer may include a gap positioned below each opening, such that the implant layer does not extend continuously across the width of the first mesh detector element within the n-type semiconductor layer. For example, the implant layer and the n-type semiconductor layer may each be positioned below a portion of the metal layer 318, while the n-type semiconductor layer (but not the implant layer) is positioned below the openings 307. The longitudinal strips 305 may be configured to collect charge carriers generated from photons collected in the semiconductor layer below the first mesh detector element 302, as described with reference to FIG. Figure 5 The collected charge carriers may result in a photocurrent that is transferred to the signal readout trace 316 and measured by the ASIC. Each of the longitudinal strips 305 may include a metal layer 318 and may be positioned over a portion of the implant layer. Further, each of the longitudinal strips 305 may be positioned over an opening in the oxide layer, as described with reference to Figures 4 to 6 In the illustrated example, the first mesh detector element 302 includes five of the longitudinal strips 305, and each longitudinal strip may extend from the first end 312 of the first mesh detector element to the second end 314. In some examples, the first mesh detector element 302 may include another suitable number of longitudinal strips.

[0062] In the illustrated example, the first mesh detector element 302 is shown with a dashed line 310, which indicates Figure 3 The length of the first mesh detector element is not shown in FIG. The dashed line 310 may allow both the first end 312 and the second end 314 to be Figure 3 307, which may not otherwise be possible due to the length L1 of the first mesh detector element 302 relative to the length of the various features of the first mesh detector element, such as the length L2 of one of the openings 307. In some examples, the first mesh detector element 302 may have a length L1 in the range of 3 mm to 20 mm. Further, in some examples, each of the openings 307 may have a length L2 in the range of 0.25 mm to 5 mm. In other examples, the first mesh detector element 302 and the openings 307 may have other suitable lengths, wherein the length of the openings is less than the length of the first mesh detector element.

[0063] The opening 307 of the first mesh detector element 302 is an area that does not include the metal layer 318, and no portion of the implant layer is positioned below the opening. However, the oxide layer and the n-type semiconductor layer are positioned below the opening 307, as shown in FIG. Figures 4 to 5 The openings 307 can be used to reduce the capacitance of the first mesh detector element 302 by reducing the area of ​​the first mesh detector element that can collect charge carriers and / or carry photocurrent. The reduction in capacitance of the first mesh detector element 302 can reduce the electronic noise of the first mesh detector element and thus can increase detection quality and / or sensitivity.

[0064] The opening 307 does not extend continuously from the first end 312 to the second end 314, but is instead segmented by horizontal bridges 308. Similar to the longitudinal strips 305, the horizontal bridges 308 can be configured to collect and transfer charge carriers generated by incident photons. Each of the horizontal bridges 308 can include a metal layer 318 and can be positioned above the implant layer. Further, as described in reference Figures 4 to 6 As described above, the opening in the oxide layer can be positioned below each of the horizontal bridges 308. The horizontal bridges 308 can be oriented perpendicular to the longitudinal strips 305 and can therefore have a longitudinal axis parallel to the x-axis. Further, the horizontal bridges 308 can span each of the longitudinal strips 305. In this way, each of the openings 307 can be surrounded by two of the longitudinal strips 305 and one or more of the horizontal bridges 308 (e.g., in the xy plane).

[0065] In the illustrated example, the first mesh detector element 302 includes four of the openings 307 positioned between the first end 312 and a first of the horizontal bridges 308. Similarly, the first mesh detector element 302 includes four of the openings 307 positioned between the last of the horizontal bridges 308 and the second end 314 of the first mesh detector element and between each set of consecutive horizontal bridges of the horizontal bridges 308. In some examples, the first mesh detector element 302 may include a different number of openings 307 positioned between the first end 312 and the horizontal bridges, between the second end 314 and the horizontal bridges, and / or between consecutive horizontal bridges of the horizontal bridges 308. Each of the openings 307 may have a width W3 in the range of 20 μm to 50 μm, such as 35 μm. Figure 4 In some examples, the opening 307 may have another suitable width.

[0066] The longitudinal strips 305 may be oriented with their longitudinal axes parallel to the y-axis (eg, parallel to the direction of incident x-ray photons). Further, each of the longitudinal strips 305 may have a width W1 in the range of 10 μm to 50 μm, such as 25 μm. Figure 4 As illustrated. In some examples, the longitudinal strips 305 may have another suitable width. The number and width W1 of the longitudinal strips 305 may be determined based on the width W2 of the first mesh detector element 302 along the x-axis, wherein the width W2 is in the range of 150 μm to 1000 μm, such as 500 μm. It is desirable that the total area of ​​the openings 307 (e.g., adding the area of ​​each opening together) is equal to a certain percentage (e.g., ratio) of the area of ​​the first mesh detector element 302. The ratio between the total area of ​​the openings 307 and the area of ​​the first mesh detector element 302 is at least 10% and no greater than 75%, such as, in some examples, a percentage in the range of 55% to 65%.

[0067] A ratio between the total area of ​​the openings 307 and the area of ​​the first mesh detector element 302 in the range of 55% to 65% can provide an ideal balance between reducing the capacitance (e.g., electronic noise) of the first mesh detector element and maintaining sufficient detection efficiency (e.g., charge collection area). For example, a lower ratio between the total opening area and the area of ​​the first mesh detector element 302 (e.g., such as 10%) can increase the detection efficiency of the first mesh detector by increasing the area used for charge collection, but can reduce the amount of capacitance reduction (e.g., electronic noise reduction) of the first mesh detector. Alternatively, a higher ratio between the total opening area and the area of ​​the first mesh detector (e.g., such as 75%) can reduce the capacitance (e.g., electronic noise) of the first mesh detector element by a greater amount, but may not allow sufficient detection efficiency due to the reduced area used for charge collection. Further, the ratio between the total opening area and the area of ​​the first mesh detector is specifically selected to maintain detection efficiency for an on-edge detector array, where x-ray photons do not directly impinge on the first mesh detector element.

[0068] Figure 4 A portion of a first mesh detector element 302 is shown, including a first end 312, longitudinal strips 305, and openings 307. The first mesh detector element 302 may have a width W2 and each of the longitudinal strips 305 may have a width W1, wherein the width W2 and the width W1 correspond to the width of the metal layer 318 across the entire first mesh detector element and the longitudinal strips, respectively. Further, each of the openings 307 may have a width W3, as shown in reference Figure 3 described.

[0069] The first mesh detector element 302 may be positioned on the semiconductor layer, as shown in FIG. Figure 5As described, the semiconductor layer can be configured to receive photons of x-ray radiation. Further, the metal layer 318 of the first mesh detector element 302 can be positioned above the implant layer 404. The implant layer 404 can be a p-type non-intrinsic semiconductor (e.g., a doped intrinsic semiconductor). As such, the implant layer 404 can have been doped with an electron acceptor element and can have a hole concentration greater than an electron concentration (e.g., electrons are minority carriers). In some examples, the implant layer 404 can include a region of a semiconductor layer doped with boron or gallium. The implant layer 404 can be in contact with an n-type semiconductor (such as Figure 5 Further, the oxide layer 506 ( Figure 6 ) can be positioned above the implant layer 404 and the semiconductor layer and below the metal layer 318 relative to the z-axis. The oxide layer can include oxide openings 406 extending along the metal layer 318 and the implant layer 404. The metal layer 318 can be configured to collect charges generated in the n-type semiconductor layer and passing through the implant layer 404 of the first mesh detector element 302. As such, the metal layer 318 can include aluminum, an alloy of aluminum and silicon, an alloy of aluminum and copper, copper, tungsten, titanium, or any other metal compatible with the device manufacturing line. The metal can also be composed of several layers, such as an initial adhesion layer (such as titanium), a diffusion barrier layer (such as nickel), and a thicker layer of primary conductor material (such as aluminum).

[0070] like Figure 4 As illustrated, the first end region 412 extends from the first end 312 of the metal layer 318 to the beginning of the opening 307. The first end region 412 may be a region of the first mesh detector element 302 that does not include any openings and therefore includes the metal layer 318, the implant layer 404, a portion of the oxide layer, and the oxide opening 406. The first end region 412 may have a length L3 (defined by the length of the metal layer 318) in the range of 20 μm to 100 μm, such as 40 μm. Further, the first end region 412 may include a rounded outer corner 408. The rounded outer corner 408 may help prevent voltage breakdown within the first mesh detector element 302. The rounded outer corner 408 may increase the dielectric strength of the first mesh detector element 302, and therefore may increase the voltage required to cause electrical breakdown across the first mesh detector element, compared to the case where the first mesh detector element 302 has a non-rounded outer corner. The rounded outer corner 408 may have a radius of curvature in the range of 20 μm to 80 μm, such as 45 μm.

[0071] The longitudinal strips 305 may have a longitudinal axis parallel to the y-axis. The longitudinal strips 305 may include a metal layer 318 and may be positioned above the implant layer 404 and the oxide openings 406. The metal layer 318 of each of the longitudinal strips 305 may have the same width W1 as the longitudinal strips (e.g., 35 μm). The implant layer 404 positioned below each of the longitudinal strips 305 may have a width W4 that is smaller than the width W3 by an amount in the range of 5 μm to 25 μm, such as 16 μm. The oxide openings 406 positioned below each of the longitudinal strips 305 may have a width W5 that is smaller than the width W4 by an amount in the range of 2 μm to 20 μm, such as 6 μm. In some examples, the metal layer 318 of the longitudinal strips 305 and the implant layer 404 and the oxide openings 406 positioned below each of the longitudinal strips may have different suitable widths.

[0072] The opening 307 may have a longitudinal axis parallel to the y-axis, and therefore parallel to the longitudinal strip 305. Further, the opening 307 may not include the metal layer 318 and may not have the implant layer 404 or the oxide opening 406 positioned underneath. Instead, the opening 307 may be positioned above the oxide layer and the n-type semiconductor layer, as described with reference to FIG. Figure 5 described.

[0073] Each of the openings 307 may include a curved inner corner 410, wherein each curved inner corner extends along the inner edge of the metal layer 318. For example, the metal layer 318 may have an inner edge 413 that forms a first curved inner corner 411. The inner edge 413 extends straight along the y-axis until the first transition zone 414, wherein the inner edge bends upward (e.g., toward the first end 312) to a point 416, and then downward until the second transition zone 418, wherein the inner edge again extends straight along the y-axis. In some examples, the curved inner corner 410 may have a radius of curvature in the range of 5 μm to 100 μm, such as 25 μm. In other examples, the curved inner corner 410 may have a different suitable radius of curvature. Further, the implant layer 404 and the oxide opening 406 are each curved at the curved inner corner 410, but have different suitable radii of curvature. The curved inner corner 410 can help prevent voltage breakdown within the first mesh detector element 302. The curved inner corners 410 may increase the dielectric strength of the first mesh detector element 302 , and thus may increase the voltage required to cause electrical breakdown across the first mesh detector element, compared to a case where the first mesh detector element 302 has non-curved inner corners.

[0074] Figure 5 Shown along Figure 4 FIG. 4 is a cross-sectional view of the first mesh detector element 302 including the semiconductor layer 502 along the cutting line A1 shown in FIG. Figure 5As shown, the first mesh detector element 302 includes a metal layer 318 positioned on the semiconductor layer 502, an implant layer 404 contained in the semiconductor layer 502, and an oxide layer 506 positioned on the semiconductor layer 502 and below the metal layer 318. The common back electrode 504 can be deposited on the bottom surface of the semiconductor layer 502 relative to the z-axis. In some examples, the common back electrode 504 can have a thickness of about 1 μm along the z-axis. It should be understood that the semiconductor layer 502, the oxide layer 506, and the common back electrode 504 can each extend beyond the first mesh detector element 302 and form a semiconductor layer, an oxide layer, and a common electrode for each mesh detector element of the detector array. Further, the separation region 510 can surround the first mesh detector element 302, so that the separation region is positioned between the first mesh detector element and any other mesh detector element. Similarly, the separation region 510 can extend between each mesh detector element and its adjacent mesh detector element, so that the mesh detector elements are separated by the separation region. The separation region 510 may include a semiconductor layer 502 , an oxide layer 506 , and a common back electrode 504 .

[0075] The semiconductor layer 502 may have a height H1 in the range of 200 μm to 1000 μm, such as 500 μm, where the height H1 extends from a bottom surface of the semiconductor layer to a top surface of the semiconductor layer along the z-axis. In some examples, the first mesh detector elements 302 may have different heights.

[0076] In some examples, the semiconductor layer can be silicon. Further, the semiconductor layer 502 can be an n-type non-intrinsic semiconductor (e.g., a doped intrinsic semiconductor). As such, the semiconductor layer 502 can have been doped with an electron donor element and can have an electron concentration greater than a hole concentration (e.g., electrons are majority carriers). In some examples, the semiconductor layer 502 can include silicon doped with phosphorus, arsenic, antimony, or bismuth. The semiconductor layer 502 can be combined with a p-type semiconductor (such as an implant layer 404). As shown, the semiconductor layer 502 can be positioned below the implant layer 404 (e.g., relative to the z-axis) and adjacent to the implant layer (e.g., relative to the x-axis). Further, the implant layer 404 can be positioned below a portion of the metal layer 318 of each longitudinal strip 305 of the first mesh detector element 302.

[0077] The semiconductor layer 502 may be configured to have a first end portion (eg, Fig. 9The x-ray photons may be absorbed into the semiconductor layer 502 and converted into charge carriers capable of transferring an electrical signal. The charge carriers may travel at least partially along the z-axis through the semiconductor layer 502, through the implant layer 404, and to the metal layer 318 of the longitudinal strip 305, where the charge carriers may travel to the second end of the first mesh detector element 302 (e.g., Figure 3 Further, the charge carriers can be transmitted as electrical signals from the first mesh detector element 302 via a second end 314 of the first mesh detector element 302. Figure 3 The signal readout trace 316 transfers the signal readout trace to the ASIC.

[0078] The common back electrode 504 can be positioned below the semiconductor layer 502 relative to the z-axis. An electrical bias potential (e.g., a voltage) can be applied to the common back electrode 504 relative to the potential of the mesh detector to generate an electric field across the semiconductor layer. In this way, the common back electrode 504 can influence charge carriers of one charge polarity generated within the semiconductor layer 502 to travel toward the metal layer 318 of the first mesh detector element 302 (e.g., away from the common back electrode 504 relative to the z-axis), while charge carriers of the opposite polarity move toward the common back electrode 504.

[0079] The metal layer 318 can be positioned above the semiconductor layer 502 relative to the z-axis. Similarly, a portion of the metal layer 318 can be positioned above the implant layer 404. The oxide opening 406 can be positioned intermediate the metal layer 318 and the implant layer 404 relative to the z-axis. A portion of the metal layer 318 can be in coplanar contact with a portion of the implant layer 404 through the oxide opening 406. In this way, charge carriers generated in the semiconductor layer 502 can travel to the metal layer 318 via the implant layer 404 and through the oxide opening 406. The oxide layer 506 can separate the metal layer 318 from the implant layer 404 except at the location of the oxide opening 406. Further, the oxide layer 506 is positioned intermediate a portion of the metal layer 318 and a portion of the semiconductor layer 502 such that no portion of the metal layer is in coplanar contact with the semiconductor layer. Reference Figure 6 The oxide layer 506 is further described.

[0080] The openings 307 of the first mesh detector element 302 may be positioned between the longitudinal bars 305 relative to the x-axis. The openings 307 may not include the metal layer 318, and therefore, relative to the z-axis, the oxide layer 506 may be the topmost layer of the diode opening. In this way, the openings 307 are used to reduce the capacitance of the first mesh detector element 302 by reducing the area of ​​the metal layer 318.

[0081] Figure 6 Shows Figure 5 , including one of the longitudinal strips 305 and a portion of two of the openings 307 of the first mesh detector element 302. The semiconductor layer 502, metal layer 318, implant layer 404, oxide layer 506, and oxide openings 406 are each illustrated.

[0082] When compared to the semiconductor layer 502, the oxide layer 506 can be relatively thin and can have a height in the range of 0.2 μm to 10 μm. The oxide layer 506 can be positioned above the semiconductor layer 502 relative to the z-axis, and a portion of the oxide layer can be in coplanar contact with the semiconductor layer. The oxide layer 506 and the semiconductor layer 502 can be in coplanar contact except at the location of the implant layer 404. At the location of the implant layer 404, a portion of the oxide layer 506 can be in coplanar contact with the implant layer, and the implant layer can be embedded in the semiconductor layer 502. Further, the oxide layer 506 can have a termination edge positioned so that the oxide opening 406 is positioned above the center of the implant layer 404 (e.g., relative to the x-axis). The oxide opening 406 can allow a portion of the metal layer 318 to be in coplanar contact with the implant layer 404.

[0083] Metal layer 318 terminates at first edge 602 and second edge 604, and thus, opening 307 may begin at the first edge and second edge and extend outward from the metal layer relative to the x-axis. First edge 602 and second edge 604 may be positioned above semiconductor layer 502 and oxide layer 506 relative to the z-axis, wherein the oxide layer is positioned above the semiconductor layer. Thus, oxide layer 506 may be exposed to the surrounding environment through opening 307. Further, a portion of oxide layer 506 and a portion of semiconductor layer 502 are in coplanar contact.

[0084] The first mesh detector element 302 may be Fig.10 A non-limiting example of the first detector 1014. Thus, Fig. 9 The detector array 900 may include a plurality of mesh detector elements similar to the first mesh detector element 302. Further, when arranged in a detector array (e.g., the detector array 900), the plurality of mesh detector elements (e.g., the first mesh detector element 302) may be formed on a planar surface of a semiconductor layer and organized into rows and / or columns. The mesh detector elements may be spaced apart in a manner that reduces the amount of dead / inactive area of ​​the detector array while reducing manufacturing complexity.

[0085] Figure 7A portion of an example detector array 700 is shown. The portion of the illustrated detector array 700 includes a corner 701 of the detector array. In some examples, the corner 701 may be rounded. In other examples, the corner 701 may not be rounded, but instead include two straight edges meeting at an angle, such as 90 degrees. The detector array 700 may include a plurality of detector elements, such as a first mesh detector element 706, a second mesh detector element 708, and a third mesh detector element 710. Further, the detector array 700 may include a semiconductor region 714, an outer edge 702, and a guard ring 704. The detector array 700 may include a back common electrode (not shown), such as Figure 5 A common back electrode 504 is provided.

[0086] The semiconductor region 714 may include a portion of the detector array 700 where no mesh detector elements (e.g., the first mesh detector element 706) are located. As such, the semiconductor region 714 may include a semiconductor layer and an oxide layer, wherein the oxide layer is located above the semiconductor layer (e.g., with respect to the z-axis) and in coplanar contact with the semiconductor layer. As such, the semiconductor region 714 may be similar to Figure 5 The separation area 510.

[0087] The outer edge 702 can serve as the outer edge of the detector array 700. As such, the outer edge 702 can extend completely around the detector array 700, with no component of the detector array extending beyond the outer edge. The outer edge 702 can include one or more straight edges and one or more corners, such as a straight edge 703 and a corner 701. In some examples, the straight edge 703 may not be aligned with the y-axis, and therefore, may not be parallel to the edge of the first mesh detector element 706 or the second mesh detector element 708. For example, relative to the y-axis, the bottom of the straight edge 703 may be farther along the x-axis than the top of the straight edge (e.g., the bottom of the straight edge 703 may be angled inward). In this way, the detector array 700 can be assembled into a cell and / or module of a PCCT detector including non-orthogonal sides. In other examples, the straight edge 703 may be aligned with the x-axis and / or may be orthogonal to an adjacent straight edge of the outer edge 702. The guard ring 704 can be positioned between the outer edge 702 and the mesh detector element (such as the third mesh detector element 710) so that the mesh detector element is separated from the outer edge. Further, the guard ring 704 can define the outer boundary of the semiconductor region 714 in which x-ray generated charge carriers can be measured (e.g., the active region of the semiconductor). Charge carriers generated between the guard ring 704 and the outer edge 702 are collected on the guard ring 704. Such collected charge can be measured by the system electronics, but does not form part of the imaging data.

[0088] The first mesh detector element 706 may include longitudinal strips, openings, and horizontal bridges, the longitudinal strips, the openings, and the horizontal bridges may be similar to Figure 3 The second mesh detector element 708 may include longitudinal bars 305, openings 307 and horizontal bridges 308. The second mesh detector element 708 may include longitudinal bars and openings, which may be similar to the longitudinal bars 305 and the openings 307, respectively. The second mesh detector element 708 may not include any horizontal bridges. In some examples, the second mesh detector element 708 may be short enough so that no horizontal bridges are required to collect and / or transfer charge carriers, and thus the horizontal bridges may be omitted from the second mesh detector element. For example, the first mesh detector element 706 may be longer than the second mesh detector element 708, so the first mesh detector element may include horizontal bridges to increase the size of the metal layer of the first mesh detector element, while the second mesh detector element may not include horizontal bridges. Further, the longitudinal bars and openings of the second mesh detector element 708 may have a longer length than the longitudinal bars and openings of the first mesh detector element 706.

[0089] The third mesh detector element 710 may include longitudinal strips, openings, and a horizontal bridge, and the longitudinal strips, the openings, and the horizontal bridge may be similar to Figure 3 305, openings 307 and horizontal bridges 308 of the third mesh detector element 710. Further, the third mesh detector element 710 may include a charge carrying region 716. The charge carrying region 716 may be similar in composition to the longitudinal strips (e.g., may include a metal layer positioned above the implant layer and the oxide openings) and may therefore be used to collect and transfer charge carriers. Due to the proximity of the third mesh detector element to the guard ring 704 and the inward inclination of the straight edge 703 relative to the x-axis, the third mesh detector element 710 may include a charge carrying region 716. In order to position the third mesh detector element 710 close to the guard ring 704, the first edge 720 of the third mesh detector element may be inclined relative to the y-axis. Further, the first edge 720 may be inclined relative to the second edge 722 of the third mesh detector element 710, which may further reduce the surface area of ​​the third mesh detector element along the x-axis. As such, the inclination of the first edge 720 may cause the charge carrying region 716 to not have a sufficient shape and / or surface area to position one or more openings within the charge carrying region 716.

[0090] The second mesh detector element 708 and the third mesh detector element 710 may include a signal readout trace 712. The signal readout trace 712 may be positioned at an end of the mesh detector element opposite to the direction of the incident x-ray photons. For example, the end 724 of the detector array 700 may be configured to receive x-ray radiation (e.g., x-ray photons) within the semiconductor layer. Further, the signal readout trace 712 may be configured to send electrical signals from the second mesh detector element 708 and the third mesh detector element 710 to the image processing unit. Although in Figure 7 Not illustrated in FIG. 7 , the first mesh detector element 706 may also include a signal readout trace.

[0091] It should be understood that the detector array 700 may include more than three mesh detector elements positioned within the semiconductor region 714 of the detector array. The mesh detector element positioned near the middle of the detector array 700 may be similar to the first mesh detector element 706. The mesh detector element positioned near the additional corner of the detector array 700 may be similar to the third mesh detector element 710. Further, the mesh detector element positioned near the guard ring 704 may include one or more inclined edges, which may cause one or more portions of the mesh detector element to lack sufficient area for including openings. In portions where the available area of ​​the mesh detector element is insufficient, openings may be omitted, and therefore, one or more rows of openings may include more or fewer openings than other rows. The mesh detector elements may be organized into rows and / or columns so as to maximize the surface area of ​​the semiconductor layer covered by the mesh detector elements. In this way, the number of dead / inactive areas of the detector array 700 may be reduced by the orientation and organization of the mesh detector elements within the detector array.

[0092] Figure 8 8. A portion of a second example of a detector array 800 is shown. The detector array 800 may include an outer edge 802 and a guard ring 804, which functions are similar to Figure 7 The outer edge 702 and the guard ring 704 of the detector array 800 are shown. The guard ring 804 can be positioned between the outer edge 802 and the mesh detector elements of the detector array 800. In this way, the guard ring 804 can collect leakage current originating from the outer edge 802, thereby preventing it from excessively affecting the detector array 800.

[0093] The detector array 800 may include a mesh detector element 806. The mesh detector element 806 may be triangular and may include rounded outer corners, such as corner 808. The rounded outer corners may reduce the chance of voltage breakdown across the mesh detector element 806. Further, the triangular shape of the mesh detector element 806 may allow the mesh detector element to be positioned close to the guard ring 804. Further, in some examples, the mesh detector element 806 may include non-rounded outer corners (e.g., two straight lines meet at an angle).

[0094] The detector array 800 can be configured to receive x-rays at a first end 810 and transmit electrical signals from a second end 812. In some examples, the mesh detector elements 806 can be connected via signal readout traces such as Figure 3 The signal readout trace 316) sends an electrical signal.

[0095] The mesh detector element 806 may include longitudinal strips, openings, and horizontal bridges, which may be similar to Figure 3 The longitudinal bars 305, openings 307 and horizontal bridges 308 of the mesh detector element 806 may have the same longitudinal bars, openings and horizontal bridges as previously described mesh detector elements (e.g., Figure 3 The first mesh detector element 302 or Figure 7 For example, each horizontal bridge of the mesh detector element 806 may have a size greater than Figure 7 The horizontal bridges of the first mesh detector element 706 may be shorter in length and / or the ratio of the total area of ​​the openings to the area of ​​the mesh detector element may be greater than Figure 3 The ratio of the total area of ​​the openings of the first mesh detector element 302 to the area of ​​the mesh detector element.

[0096] The mesh detector element 806 may include regions without openings, such as the charge carrying region 814, which may be functionally similar to Figure 7charge carrying regions 716. As such, the charge carrying regions 814 may be similar in composition to the longitudinal strips (e.g., may include a metal layer positioned above an implant layer and oxide openings) and may therefore be used to collect and / or transfer charge carriers. The charge carrying regions 814 may be a result of the triangular shape of the mesh detector element 806 and the proximity of the mesh detector element to the guard ring 804. The first edge 816 of the mesh detector element 806 may be tilted relative to a second edge 818 of the mesh detector element. The tilt of the first edge 816 may cause the mesh detector element 806 to not have sufficient surface area for one or more openings along the first edge. As such, the charge carrying regions 814 may not be of sufficient shape and / or not have sufficient surface area to position one or more additional openings. Similar to Figure 7 As shown in the third mesh detector element 710 , due to the inclination of the first edge 816 , the mesh detector element 806 may include more openings in some rows than in other rows.

[0097] It should be understood that the detector array 800 may include more than one mesh detector element positioned within the guard ring 804 of the detector array. The mesh detector elements positioned near the guard ring 804 may include one or more angled edges and, therefore, may not include a constant number of diode openings and / or longitudinal strips along the length of the mesh detector element. The mesh detector elements positioned near the middle of the detector array 800 may not include angled edges and, therefore, may be similar to Figure 3 The first mesh detector element 302. The mesh detector elements can be organized into rows and / or columns to maximize the surface area of ​​the semiconductor layer covered by the mesh diodes. In this way, the number of dead / inactive areas of the detector array 800 can be reduced by the orientation and organization of the mesh detector elements within the detector array.

[0098] The technical effect of a PCCT detector including a mesh detector element composed of longitudinal strips, openings, and horizontal bridges is that an image can be reconstructed with greater resolution and less noise. By including openings in the mesh detector element, the capacitance of the mesh detector element is reduced, and the electronic noise of the PCCT detector is reduced. In this way, the contrast-to-noise ratio (CNR) of soft tissue contrast imaging can be increased, and the CNR of material resolution imaging can be maintained or increased.

[0099] The present disclosure also provides support for a detector for medical imaging, the detector comprising: a mesh detector element formed on a planar surface of a first semiconductor layer, the mesh detector element comprising a metal layer, the metal layer comprising a plurality of longitudinal strips, each longitudinal strip being positioned above a corresponding second semiconductor layer having an opposite doping polarity to the first semiconductor layer, and being embedded in the first semiconductor layer and separated from adjacent longitudinal strips by corresponding openings in a plurality of openings, such that the metal layer does not extend continuously over the width of the mesh detector element. In a first example of the detector, the detector further comprises: an oxide layer on the planar surface of the first semiconductor layer, wherein the oxide layer comprises a plurality of oxide openings, each oxide opening being aligned with a corresponding longitudinal strip. In a second example of the detector, optionally including the first example, each longitudinal strip is in coplanar contact with the corresponding second semiconductor layer via a corresponding oxide opening. In a third example of the detector, optionally including one or both of the first and second examples, the mesh detector element has a total area defined by the width of the metal layer and the length of the metal layer, wherein each of the plurality of openings has an opening area, and wherein the total opening area defined by adding each opening area comprises at least 10% of the total area. In a fourth example of the detector, optionally including one or more or each of the first to third examples, the plurality of longitudinal strips comprises a first longitudinal strip and a second longitudinal strip, wherein the plurality of openings comprises a first opening separating the first longitudinal strip from the second longitudinal strip, wherein the first longitudinal strip has a first inner edge extending parallel to the second inner edge of the second longitudinal strip, and wherein the first inner edge is connected to the second inner edge via a bent edge of the metal layer. In a fifth example of the detector, optionally including one or more or each of the first to fourth examples, the plurality of longitudinal strips comprises five longitudinal strips and wherein the plurality of openings comprises four openings. In a sixth example of the detector, one or more or each of the first to fifth examples may be optionally included, the plurality of openings may include a first row of openings and a second row of openings separated by a horizontal bridge, and wherein each of the plurality of longitudinal strips extends continuously along the length of the metal layer from a first end region of the mesh detector element to a second end region of the mesh detector element. In a seventh example of the detector, one or more or each of the first to sixth examples may be optionally included, the mesh detector element may include a signal readout trace at the second end region. In an eighth example of the detector, one or more or each of the first to seventh examples may be optionally included, the mesh detector element may be a first mesh detector element among a plurality of mesh detector elements formed on the flat surface of the first semiconductor layer.In a ninth example of the detector, optionally including one or more or each of the first to eighth examples, the flat surface of the first semiconductor layer is the first flat surface of the first semiconductor layer, and the detector further includes a common back electrode positioned on the second flat surface of the first semiconductor layer. In a tenth example of the detector, optionally including one or more or each of the first to ninth examples, the first semiconductor layer, the common back electrode and the plurality of mesh detector elements form a first sensor, and wherein the detector includes the first sensor and a plurality of additional sensors, the sensors being arranged so that an edge of the first semiconductor layer of the first sensor orthogonal to the first flat surface and the second flat surface is configured to receive photons of x-ray radiation. In an eleventh example of the detector, optionally including one or more or each of the first to tenth examples, the first semiconductor layer is an n-type semiconductor and the second semiconductor layer is a p-type semiconductor.

[0100] The present disclosure also provides support for a detector for medical imaging, the detector comprising: an n-type semiconductor layer, an oxide layer positioned on a first planar surface of the n-type semiconductor layer, a common back electrode positioned on a second planar surface of the n-type semiconductor layer, and a plurality of mesh detector elements formed on the first planar surface of the n-type semiconductor layer, each mesh detector element comprising a metal layer, the metal layer comprising a plurality of longitudinal strips, each longitudinal strip being positioned above a corresponding p-type semiconductor layer, embedded in the n-type semiconductor layer and separated from adjacent longitudinal strips by a corresponding opening in a plurality of openings of the mesh detector element. In a first example of the detector, each longitudinal strip is in coplanar contact with the corresponding p-type semiconductor layer via a corresponding oxide opening. In a second example of the detector, optionally including the first example, each mesh detector element has a total area defined by a width of the metal layer and a length of the metal layer, wherein each of the plurality of openings has an opening area, and wherein the total opening area defined by adding each opening area comprises 10% of the total area. In a third example of the detector, optionally including one or both of the first and second examples, the plurality of longitudinal strips include a first longitudinal strip and a second longitudinal strip and wherein the plurality of openings include a first opening separating the first longitudinal strip from the second longitudinal strip. In a fourth example of the detector, optionally including one or more or each of the first to third examples, the plurality of longitudinal strips include five longitudinal strips and wherein the plurality of openings include four openings. In a fifth example of the detector, optionally including one or more or each of the first to fourth examples, the plurality of openings include a first row of openings and a second row of openings separated by a horizontal bridge, and wherein each of the plurality of longitudinal strips extends continuously along the length of the metal layer.

[0101] The present disclosure also provides support for a detector for medical imaging, the detector comprising: an n-type semiconductor layer having a perimeter defined by a top edge, a first side edge, a second side edge, and a bottom edge, the top edge being configured to receive photons of x-ray radiation, the first side edge meeting the top edge at a first corner of the n-type semiconductor layer; and a plurality of mesh detector elements formed on a first flat surface of the n-type semiconductor layer, the plurality of mesh detector elements comprising: a first mesh detector element positioned at the first corner, the first mesh detector element comprising a first metal A metal layer, the first metal layer includes a first plurality of longitudinal strips, each first longitudinal strip is separated from an adjacent first longitudinal strip by a corresponding first opening in a plurality of first openings of the first mesh detector element; and a second mesh detector element, the second mesh detector element is positioned closer to the second side edge than the first mesh detector element, the second mesh detector element includes a second metal layer, the second metal layer includes a second plurality of longitudinal strips, each second longitudinal strip is separated from an adjacent second longitudinal strip by a corresponding second opening in a plurality of second openings of the second mesh detector element, wherein the plurality of first openings includes a different number of openings than the plurality of second openings. In a first example of the detector, the plurality of first openings includes a first row of openings and a second row of openings separated by a first horizontal bridge, and wherein the plurality of second openings includes a third row of openings and a fourth row of openings separated by a second horizontal bridge.

[0102] In another representation, an on-edge detector array for a diagnostic imaging system is provided, the on-edge detector array comprising an n-type semiconductor layer and a plurality of mesh detector elements positioned on a planar face of the n-type semiconductor layer. Each mesh detector element comprises a plurality of detector strips extending along the length of the mesh detector element. Further, each detector strip comprises a metal layer at least partially positioned above the p-type semiconductor layer and separated from adjacent detector strips by openings. As such, the p-type semiconductor layer and the metal layer do not extend continuously along the width of the mesh detector element.

[0103] When introducing the elements of various embodiments of the present disclosure, the articles "one", "a kind of" and "the" are intended to mean one or more elements present in the element. The terms "first", "second", etc. do not represent any order, amount or importance, but are used to distinguish one element from another element. The terms "include", "comprise", and "have" are intended to be inclusive, and mean that additional elements may also exist in addition to the listed elements. As used herein, the terms "connected to", "coupled to", etc., an object (e.g., material, element, structure, member, etc.) may be connected to or coupled to another object, regardless of whether the one object is directly connected or coupled to another object, or whether there are one or more intervening objects between the one object and another object. In addition, it should be understood that the reference to "an embodiment" or "embodiment" of the present disclosure is not intended to be interpreted as excluding the existence of additional embodiments that are also combined with the cited features.

[0104] In addition to any previously indicated modifications, those skilled in the art may devise numerous other variations and alternative arrangements without departing from the spirit and scope of the present specification, and the appended claims are intended to cover such modifications and arrangements. Therefore, although the above has been described in detail and in detail in conjunction with what are currently considered to be the most practical and preferred aspects, it will be apparent to those of ordinary skill in the art that many modifications, including but not limited to form, function, mode of operation, and use, may be made without departing from the principles and concepts set forth herein. Likewise, as used herein, the examples and embodiments are intended to be illustrative in all respects only and should not be construed as limiting in any way.

Claims

1. A detector for medical imaging, the detector comprising: A mesh detector element (302) is formed on a flat surface of a first semiconductor layer (502), the mesh detector element (302) comprising a metal layer (318), the metal layer comprising a plurality of longitudinal strips (305), each longitudinal strip being positioned above a corresponding second semiconductor layer (404) having an opposite doping polarity to the first semiconductor layer (502), and being embedded in the first semiconductor layer (502) and separated from adjacent longitudinal strips by corresponding openings in a plurality of openings (307), so that the metal layer (318) does not extend continuously across the width of the mesh detector element (302).

2. The detector according to claim 1, further comprising an oxide layer (506) located on the flat surface of the first semiconductor layer (502), wherein the oxide layer (506) comprises a plurality of oxide openings (406), each oxide opening (406) being aligned with a corresponding longitudinal strip (305).

3. The detector according to claim 2, wherein each longitudinal strip (305) is in coplanar contact with the respective second semiconductor layer (404) via a respective oxide opening (406).

4. A detector according to claim 1, wherein the mesh detector element (302) has a total area defined by a width of the metal layer (318) and a length of the metal layer (318), wherein each of the plurality of openings (307) has an opening area, and wherein the total opening area defined by adding each opening area comprises at least 10% of the total area.

5. A detector according to claim 1, wherein the plurality of longitudinal strips (305) include a first longitudinal strip and a second longitudinal strip, wherein the plurality of openings (307) include a first opening separating the first longitudinal strip from the second longitudinal strip, wherein the first longitudinal strip has a first inner edge (413) extending parallel to a second inner edge of the second longitudinal strip, and wherein the first inner edge (413) is connected to the second inner edge via a bent edge (411) of the metal layer.

6. The detector of claim 1, wherein the plurality of longitudinal strips (305) comprises five longitudinal strips, and wherein the plurality of openings (307) comprises four openings.

7. A detector according to claim 1, wherein the plurality of openings (307) include a first row of openings and a second row of openings separated by a horizontal bridge (308), and wherein each of the plurality of longitudinal strips (305) extends continuously along the length of the metal layer (318) from a first end region (412) of the mesh detector element (302) to a second end region (314) of the mesh detector element (302).

8. The detector of claim 7, wherein the mesh detector element (302) comprises a signal readout trace (316) located at the second end region (314).

9. The detector according to claim 1, wherein the mesh detector element (302) is a first mesh detector element among a plurality of mesh detector elements (300) formed on the flat surface of the first semiconductor layer (502).

10. The detector of claim 9, wherein the planar surface of the first semiconductor layer (502) is a first planar surface of the first semiconductor layer (502), and the detector further comprises a common back electrode (504) positioned on a second planar surface of the first semiconductor layer (502).

11. The detector of claim 10, wherein the first semiconductor layer (502), the common back electrode (504) and the plurality of mesh detector elements (300) form a first sensor, and wherein the detector comprises the first sensor and a plurality of additional sensors, the sensors being arranged such that an edge of the first semiconductor layer (502) of the first sensor orthogonal to the first flat surface and the second flat surface is configured to receive photons of x-ray radiation.

12. The detector of claim 1, wherein the first semiconductor layer (502) is an n-type semiconductor and the second semiconductor layer (404) is a p-type semiconductor.

13. A detector for medical imaging, the detector comprising: An n-type semiconductor layer (714) having a perimeter defined by a top edge, a first side edge (703), a second side edge, and a bottom edge, the top edge being configured to receive photons of x-ray radiation, the first side edge (703) being disposed between the second side edge and the bottom edge. The first corner (701) of the n-type semiconductor layer (714) intersects with the top edge; and A plurality of mesh detector elements (706, 708, 710), wherein the plurality of mesh detector elements are formed on a first planar surface of the n-type semiconductor layer (714), and the plurality of mesh detector elements (706, 708, 710) include: a first mesh detector element (710), the first mesh detector element being positioned at the first corner (701), the first mesh detector element (710) comprising a first metal layer, the first metal layer comprising a first plurality of longitudinal strips, each first longitudinal strip being separated from an adjacent first longitudinal strip by a corresponding first opening of a plurality of first openings of the first mesh detector element (710); and A second mesh detector element (708), the second mesh detector element being positioned closer to the second side edge than the first mesh detector element (710), the second mesh detector element (708) comprising a second metal layer, the second metal layer comprising a second plurality of longitudinal strips, each second longitudinal strip being separated from an adjacent second longitudinal strip by a corresponding second opening among a plurality of second openings of the second mesh detector element (708), wherein the plurality of first openings comprises a different number of openings than the plurality of second openings.

14. The detector of claim 13, wherein the plurality of first openings comprises a first row of openings and a second row of openings separated by a first horizontal bridge, and wherein the plurality of second openings comprises a third row of openings and a fourth row of openings separated by a second horizontal bridge.

Images