X-ray detector capable of managing charge sharing

Abstract

An apparatus for detecting X-rays is disclosed. In one example, the apparatus includes: an X-ray absorbing layer (110) comprising a first pixel and a second pixel; and a controller (338). The controller (338) is configured to determine that charge carriers generated by a single X-ray photon are collected by the first pixel and the second pixel. The controller (338) is also configured to determine the energy of the single X-ray photon based on a first voltage detected by the first pixel and a second voltage detected by the second pixel. The first voltage and the second voltage are caused by the single X-ray photon.

Description

[Technical Field]

[0001] This disclosure relates to X-ray detectors, and more particularly to X-ray detectors capable of managing charge sharing. [Background Technology]

[0002] An X-ray detector can be a device used to measure the flux, spatial distribution, spectrum, or other properties of X-rays.

[0003] X-ray detectors have many applications. One important application is imaging. X-ray imaging, a radiographic technique, can be used to reveal the internal structure of inhomogeneous and opaque objects, such as the human body. Another important application is elemental analysis. Elemental analysis is the process of analyzing a sample of a material based on its elemental composition.

[0004] Early X-ray detectors included photographic plates and photographic films. Photographic plates could be glass plates coated with a photosensitive emulsion.

[0005] In the 1980s, light-excited phosphor plates (PSP plates) emerged. A PSP plate can contain fluorescent material with color centers within its crystal lattice. When the PSP plate is exposed to X-rays, the X-ray-excited electrons are trapped in the color centers until these electrons are excited by a laser beam scanning the plate surface. As the laser scans the plate, the trapped excited electrons emit light, which is collected by photomultiplier tubes. The collected light is then converted into a digital image.

[0006] Another type of X-ray detector is the X-ray image intensifier. In an X-ray image intensifier, X-rays first strike an input phosphor (e.g., cesium iodide) and are converted into visible light. The visible light then strikes a photocathode (e.g., a thin metal layer containing a cesium and antimony complex) and induces electron emission. The number of emitted electrons is proportional to the intensity of the incident X-rays. The emitted electrons are projected through electron optics onto an output phosphor, causing the output phosphor to produce a visible light image.

[0007] The operation of a scintillator is somewhat similar to that of an X-ray image intensifier, where the scintillator (e.g., sodium iodide) absorbs X-rays and emits visible light, which can then be detected by an image sensor adapted for visible light.

[0008] Semiconductor X-ray detectors can directly convert X-rays into electrical signals, thus providing better performance than previous generations of X-ray detectors. A semiconductor X-ray detector may include a semiconductor layer that absorbs X-rays at the wavelength of interest. When X-ray photons are absorbed by the semiconductor layer, multiple charged carriers (e.g., electrons and holes) are generated. As used herein, the terms “charged carrier,” “charge,” and “carrier” are used interchangeably. A semiconductor X-ray detector may have multiple pixels, which can independently determine the local intensity of X-rays and the energy of X-ray photons. The charged carriers generated by X-ray photons can be swept across the electric field entering the pixel. If the charged carriers generated by a single X-ray photon are collected by more than one pixel (“charge sharing”), the performance of the semiconductor X-ray detector can be negatively affected. In applications that determine X-ray photon energy (e.g., elemental analysis), charge sharing is particularly problematic for accurate photon energy measurements because the energy of an X-ray photon is determined by the amount of charge it generates. [Summary of the Invention]

[0009] The teachings disclosed herein relate to methods, systems, and apparatuses for X-ray detection. More specifically, these teachings relate to methods, systems, and apparatuses for X-ray detection with charge-sharing management.

[0010] In one example, an apparatus suitable for detecting X-rays is disclosed. The apparatus includes: an X-ray absorbing layer comprising a first pixel and a second pixel; and a controller. The controller is configured to determine that charge carriers generated by a single X-ray photon are collected by the first pixel and the second pixel. The controller is also configured to determine the energy of a single X-ray photon based on a first voltage detected by the first pixel and a second voltage detected by the second pixel, wherein the first voltage and the second voltage are caused by the single X-ray photon.

[0011] According to an embodiment, the controller is further configured to obtain the sum of the absolute values ​​of the first voltage and the second voltage. The controller is further configured to determine the energy of a single X-ray photon based on this sum.

[0012] According to an embodiment, a first pixel is associated with a first capacitor charged by a first voltage; a second pixel is associated with a second capacitor charged by a second voltage; and the sum is obtained by connecting the first and second capacitors in series and measuring the voltage across the series-connected capacitors.

[0013] According to an embodiment, the sum is obtained by adding the absolute values ​​of the first voltage and the absolute values ​​of the second voltage.

[0014] According to an embodiment, the device includes a counter configured to record the number of X-ray photons absorbed by the X-ray absorbing layer, wherein if the sum equals or exceeds a predetermined threshold, a controller is configured to cause the number recorded by the counter to increase by one.

[0015] According to an embodiment, the energy of a single X-ray photon is determined when the rate of change of the first voltage and the rate of change of the second voltage are approximately zero.

[0016] According to an embodiment, if the first voltage and the second voltage begin to change at the same time interval, the controller is configured to determine that the charge carriers generated by a single X-ray photon are collected by the first pixel and the second pixel.

[0017] According to an embodiment, if the absolute values ​​of the first voltage and the second voltage reach a first threshold in the same time period, the controller is configured to determine that the charge carriers generated by a single X-ray photon are collected by the first pixel and the second pixel.

[0018] According to an embodiment, an image is formed by assigning X-ray photons to one of a first pixel and a second pixel based on at least one of the following methods: comparison of a first voltage and a second voltage; and the relative positions of the two pixels.

[0019] According to an embodiment, the device includes a pixel array.

[0020] This article discloses a system comprising the apparatus described above and an X-ray source. The system is configured for X-ray radiography of a human chest or abdomen.

[0021] This article discloses a system comprising the apparatus described above and an X-ray source. The system is configured for X-ray radiography of the human oral cavity.

[0022] This document discloses a cargo scanning or non-invasive inspection (NII) system, which includes the apparatus described above and an X-ray source. The cargo scanning or non-invasive inspection (NII) system is configured to form images based on backscattered X-rays.

[0023] This document discloses a cargo scanning or non-invasive inspection (NII) system, which includes the apparatus described above and an X-ray source. The cargo scanning or non-invasive inspection (NII) system is configured to form an image using X-rays transmitted through the object being inspected.

[0024] This article discloses a whole-body scanner system, which includes the device described above and an X-ray source.

[0025] This article discloses an X-ray computed tomography (X-ray CT) system, which includes the apparatus described above and an X-ray source.

[0026] This article discloses an electron microscope that includes the apparatus, electron source and electron optical system described above.

[0027] This article discloses a system comprising the apparatus described above. The system is configured to measure the dose of an X-ray source.

[0028] This article discloses a system comprising the apparatus described above. The system is an X-ray telescope or X-ray microscope, or a system configured to perform mammography, industrial defect detection, microradiography, casting inspection, weld inspection, or digital subtraction angiography.

[0029] In another example, a method is disclosed. The method includes: determining that charge carriers generated by a single X-ray photon are collected by a first pixel and a second pixel; detecting a first voltage from the first pixel; detecting a second voltage from the second pixel; and determining the energy of the single X-ray photon based on the first and second voltages, wherein the first and second voltages are caused by the single X-ray photon.

[0030] According to an embodiment, the method further includes: obtaining the sum of the absolute values ​​of a first voltage and a second voltage, wherein the first voltage and the second voltage are caused by a single X-ray photon; and determining the energy of the single X-ray photon based on the sum.

[0031] According to an embodiment, a first pixel is associated with a first capacitor charged by a first voltage; a second pixel is associated with a second capacitor charged by a second voltage; and the sum is obtained by connecting the first and second capacitors in series and measuring the voltage across the series-connected capacitors.

[0032] According to an embodiment, the sum is obtained by adding the absolute values ​​of the first voltage and the absolute values ​​of the second voltage.

[0033] According to an embodiment, the method further includes increasing the count of X-ray photons incident on the X-ray absorbing layer comprising the first pixel and the second pixel by one if the sum is equal to or exceeds a predetermined threshold.

[0034] According to an embodiment, the energy of a single X-ray photon is determined when the rate of change of the first voltage and the rate of change of the second voltage are approximately zero.

[0035] According to an embodiment, if the first voltage and the second voltage begin to change at the same time interval, it is determined that the charge carriers generated by a single X-ray photon are collected by the first pixel and the second pixel.

[0036] According to an embodiment, if the absolute values ​​of the first voltage and the second voltage reach a first threshold in the same time period, it is determined that the charge carriers generated by a single X-ray photon are collected by the first pixel and the second pixel.

[0037] According to an embodiment, an image is formed by assigning X-ray photons to one of a first pixel and a second pixel based on at least one of the following methods: comparison of a first voltage and a second voltage; and the relative positions of the two pixels.

[0038] This document discloses a system for phase-contrast X-ray imaging (PCI), comprising: the apparatus described above, a second X-ray detector, and a spacer. The apparatus and the second X-ray detector are separated by the spacer.

[0039] According to an embodiment, the device and the second X-ray detector are configured to simultaneously capture images of the object, respectively.

[0040] According to an embodiment, the second X-ray detector is equivalent to the device.

[0041] This document discloses a system for phase-contrast X-ray imaging (PCI) that includes the apparatus described above. The apparatus is configured to move toward an object (exposed to incident X-rays at varying distances from the object) and capture its image.

[0042] Further advantages and novel features will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following text and the accompanying drawings, or may be learned by producing or operating examples. The advantages of this teaching can be realized and obtained through practice or by using various aspects of the methodologies, tools, and combinations described in the detailed examples discussed below. [Attached Image Description]

[0043] Figure 1A A cross-sectional view of the detector according to an embodiment is schematically shown;

[0044] Figure 1B A detailed cross-sectional view of the detector according to an embodiment is schematically shown;

[0045] Figure 1C A schematic detailed cross-sectional view of an alternative detector according to an embodiment is shown;

[0046] Figure 2A An exemplary top view of a portion of a semiconductor X-ray detector according to an embodiment is shown schematically;

[0047] Figure 2B An exemplary pixel array in a semiconductor X-ray detector according to an embodiment is shown;

[0048] Figure 3AA component diagram of two adjacent electronic systems of a semiconductor X-ray detector according to an embodiment is shown;

[0049] Figure 3B A component diagram of two adjacent electronic systems of a semiconductor X-ray detector in the event of charge sharing, according to an embodiment, is shown, with switch positions marked.

[0050] Figure 4A The diagram schematically illustrates the time-varying current (upper curve) and corresponding time-varying electrode voltage (lower curve) of the electrical contacts of the electrodes or resistors of a diode exposed to X-rays when no charge sharing occurs, according to an embodiment. The current is caused by charge carriers generated by X-ray photons incident on the X-ray absorption layer.

[0051] Figure 4B The diagram schematically illustrates the time-varying current (upper curve) flowing through two adjacent electrodes when charge sharing occurs, and the corresponding time-varying electrode voltage (lower curve) according to an embodiment. Each electrode can be an electrical contact of a diode or resistor exposed to X-rays. The current is caused by charge carriers generated by X-ray photons incident on the X-ray absorption layer;

[0052] Figure 5A This schematically illustrates the use of an embodiment. Figure 4A The diagram shows the time variation (upper curve) of the current flowing through the electrodes caused by noise (e.g., dark current) and the corresponding time variation (lower curve) of the electrode voltage in an electronic system operating in the manner shown.

[0053] Figure 5B This schematically illustrates the use of an embodiment. Figure 4B The diagram shows the time variation (upper curve) of the current flowing through two adjacent electrodes caused by noise (e.g., dark current) and the corresponding time variation (lower curve) of the electrode voltage in an electronic system operating in the manner shown.

[0054] Figure 6 The illustration schematically shows the time-varying current (upper curve) flowing through two adjacent electrodes of an X-ray absorbing layer exposed to X-rays when charge sharing occurs and the detected voltage values ​​are added, according to an embodiment. The current is caused by charge carriers generated by X-ray photons incident on the X-ray absorbing layer. In this disclosure, the numerical addition can be the addition of numerical voltage signals (i.e., after the voltages have been converted into digital signals).

[0055] Figure 7 This schematically illustrates the use of an embodiment. Figure 6The diagram shows the time variation of the current flowing through two adjacent electrodes in an electronic system operating in the manner shown (upper curve) and the corresponding time variation of the electrode voltage (lower curve), wherein at least one current is caused by noise (e.g., dark current).

[0056] Figure 8A The illustrations illustrate various examples of how X-ray photons that cause charge sharing at multiple pixels are distributed to one pixel of a pixel to form an image, according to embodiments.

[0057] Figure 8B It shows that it can be achieved Figure 8A An example of a circuit for the strategy.

[0058] Figure 9A The embodiments shown are applicable to system-based (e.g.) Figure 3A and Figure 3B A flowchart of the method for detecting X-rays using the electronic system 121 of pixel 1;

[0059] Figure 9B The embodiments shown are applicable to system-based (e.g.) Figure 3A and Figure 3B A flowchart of the method for detecting X-rays using the electronic system 121 of pixel 2;

[0060] Figure 9C A flowchart illustrating a method for determining the occurrence of charge sharing and combining the voltages generated by shared X-ray photons on adjacent pixels according to an embodiment is shown.

[0061] Figure 10 A system suitable for phase-contrast X-ray imaging (PCI) according to an embodiment is schematically illustrated;

[0062] Figure 11 A system suitable for phase-contrast X-ray imaging (PCI) according to an embodiment is schematically illustrated;

[0063] Figure 12 A system suitable for medical imaging (e.g., chest X-ray radiography, abdominal X-ray radiography, etc.) according to an embodiment is schematically illustrated, which includes the semiconductor X-ray detector described herein;

[0064] Figure 13 A system suitable for dental X-ray radiography according to an embodiment is schematically illustrated, which includes the semiconductor X-ray detector described herein;

[0065] Figure 14 A cargo scanning or non-invasive inspection (NII) system according to an embodiment is illustrated schematically, which includes a semiconductor X-ray detector described herein;

[0066] Figure 15 Another cargo scanning or non-invasive inspection (NII) system according to an embodiment is illustrated schematically, which includes the semiconductor X-ray detector described herein;

[0067] Figure 16 A whole-body scanner system according to an embodiment is schematically illustrated, which includes the semiconductor X-ray detector described herein;

[0068] Figure 17 An X-ray computed tomography (X-ray CT) system according to an embodiment is schematically shown, which includes the semiconductor X-ray detector described herein;

[0069] Figure 18 An electron microscope according to an embodiment is schematically illustrated, which includes the semiconductor X-ray detector described herein; and

[0070] Figure 19 A radiation dosimeter according to an embodiment is schematically shown;

[0071] Figure 20 An elemental analyzer according to an embodiment is schematically shown.

Detailed Implementation Methods

[0072] In the detailed description below, numerous specific details are illustrated with examples to provide a comprehensive understanding of the teachings. However, it will be apparent to those skilled in the art that these teachings can be practiced without such details. In other instances, well-known methods, procedures, components, and / or circuits are described at a relatively high level without detail to avoid unnecessarily obscuring various aspects of these teachings.

[0073] When X-ray photons are absorbed by the semiconductor layer of an X-ray detector with an array of pixels, multiple charged carriers (e.g., electrons and holes) are generated, and these charged carriers can be swept across the circuit in an electric field to measure them. The carriers drift along the direction of the electric field and diffuse in all directions. The envelope of the carrier trajectory can be approximately conical in shape. If the envelope lies on the boundary of two or more pixels of the X-ray detector, charge sharing occurs (as used in this teaching, "charge sharing" means that the carriers generated from a single X-ray photon are collected by two or more pixels). Because the energy of an X-ray photon is determined by the amount of charge it generates, charge sharing leads to inaccurate X-ray photon measurements.

[0074] In this teaching, when it is determined that adjacent pixels share the charge generated by a single photon, for example after the voltages on these pixels have stabilized, the voltages detected at the pixels are added together. In one example, the voltages can be added together using physical capacitors that can be connected in series. In another example, each of the adjacent pixels reads its own voltage and these voltage values ​​are added together. The sum of the voltages can then be used to accurately measure the energy of the photon shared by the adjacent pixels.

[0075] When an X-ray detector is configured to sense an image, photons can be assigned to one of the neighboring pixels to form an image based on the relative positions of neighboring pixels and / or voltage comparisons of neighboring pixels.

[0076] Figure 1A A semiconductor X-ray detector 100 according to an embodiment is schematically illustrated. The semiconductor X-ray detector 100 may include an X-ray absorbing layer 110 and an electron layer 120 (e.g., an ASIC) for processing or analyzing electrical signals generated by incident X-rays in the X-ray absorbing layer 110. In this embodiment, the semiconductor X-ray detector 100 does not include a scintillator. The X-ray absorbing layer 110 may include a semiconductor material, such as silicon, germanium, gallium arsenide, cadmium telluride, cadmium zinc telluride, or combinations thereof. The semiconductor may have a high quality attenuation coefficient for the X-ray energy of interest.

[0077] As in Figure 1B As shown in a detailed cross-sectional view of the detector 100, according to an embodiment, the X-ray absorption layer 110 may include one or more diodes (e.g., pin or pn) formed by one or more discrete regions 114 of a first doped region 111 and a second doped region 113. The second doped region 113 may be separated from the first doped region 111 by an intrinsic region 112 (optionally). The discrete portions 114 are separated from each other by either the first doped region 111 or the intrinsic region 112. The first doped region 111 and the second doped region 113 have opposite types of doping (e.g., region 111 is p-type and region 113 is n-type, or region 111 is n-type and region 113 is p-type). Figure 1B In the example, each discrete region 114 in the second doped region 113 forms a diode together with the first doped region 111 and the intrinsic region 112 (optional). That is, in Figure 1B In the example, the X-ray absorbing layer 110 has multiple diodes, each having a first doped region 111 as a common electrode. The first doped region 111 may also have discrete portions.

[0078] When an X-ray photon strikes the X-ray absorbing layer 110 (which includes a diode), the X-ray photon can be absorbed and generate one or more charged carriers through a number of mechanisms. A single X-ray photon can generate 10 to 100,000 charged carriers. These charged carriers can drift toward one electrode of the diode under an electric field. This field can be an external electric field. Electrical contacts 119B may include discrete portions, each of which is electrically in contact with a discrete region 114. In an embodiment, the charged carriers generated by a single X-ray photon can be shared by two different discrete regions 114.

[0079] As in Figure 1C As shown in the alternative detailed cross-sectional view of detector 100, according to an embodiment, X-ray absorbing layer 110 may include a resistor having a semiconductor material (e.g., silicon, germanium, gallium arsenide, cadmium telluride, cadmium zinc telluride, or combinations thereof), but not a diode. The semiconductor may have a high quality attenuation coefficient for the X-ray energy of interest.

[0080] When an X-ray photon strikes the X-ray absorbing layer 110 (which includes resistors but not diodes), it is absorbed and generates one or more charged carriers through various mechanisms. A single X-ray photon can generate 100,000 to 100,000 charged carriers. These charged carriers can drift toward electrical contacts 119A and 119B under an electric field. This field can be an external electric field. Electrical contact 119B includes discrete portions. In an embodiment, the charged carriers generated by a single X-ray photon can be shared by two different contacts 119B.

[0081] Electronic layer 120 may include electronic system 121 adapted to process or interpret signals generated by X-ray photons incident on X-ray absorbing layer 110. Electronic system 121 may include analog circuitry such as filter networks, amplifiers, integrators, and comparators, or digital circuitry such as a microprocessor and memory. Electronic system 121 may include pixel-shared components or components dedicated to a single pixel. For example, electronic system 121 may include an amplifier dedicated to each pixel and a microprocessor shared across all pixels. Electronic system 121 may be electrically connected to the pixels via vias 131. The space between vias may be filled with a filler material 130, which may increase the mechanical stability of the connection between electronic layer 120 and X-ray absorbing layer 110. Other bonding techniques for connecting electronic system 121 to pixels without using vias are possible.

[0082] Figure 2AAn exemplary top view of a portion of a device 100 having a 4×4 array of discrete regions 114 is shown. Charged carriers generated by X-ray photons incident around the footprint of one of these discrete regions 114 are substantially not shared with the other discrete regions 114. A region 210 surrounding the discrete region 114 is called a pixel associated with that discrete region 114, and substantially all (more than 95%, more than 98%, or more than 99%) of the charged carriers generated by X-ray photons incident therein flow towards the discrete region 114. That is, less than 5%, less than 2%, or less than 1% of these charged carriers flow out of the pixel when X-ray photons strike inside it. Pixels can be organized using any suitable array, such as square arrays, triangular arrays, and honeycomb arrays. Pixels can have any suitable shape, such as circular, triangular, square, rectangular, and hexagonal. Pixels can be independently addressable.

[0083] Similarly, when Figure 2A 4×4 array indicator Figure 1B When the discrete portions of the electrical contact 119B are arrayed, the charged carriers generated by X-ray photons incident around the footprint of one of these discrete portions of the electrical contact 119B are substantially not shared with the other discrete portions of the electrical contact 119B. The region surrounding the discrete portions of the electrical contact 119B is called a pixel associated with the discrete portion of the electrical contact 119B, in which substantially all (more than 95%, more than 98%, or more than 99%) of the charged carriers generated by X-ray photons incident therein flow to the discrete portion of the electrical contact 119B. That is, when X-ray photons strike inside the pixel, less than 5%, less than 2%, or less than 1% of these charged carriers flow outside the pixel associated with one discrete portion of the electrical contact 119B. Pixels can be organized in any suitable array, such as square arrays, triangular arrays, and honeycomb arrays. Pixels can have any suitable shape, such as circular, triangular, square, rectangular, and hexagonal. Pixels can be independently addressable.

[0084] As in Figure 2A As shown, two pixels 210 (e.g., 210-1 and 210-2) associated with two adjacent discrete regions 114 can be called two adjacent pixels (as used in this teaching, "adjacent pixel" means a pixel that is close to each other so that the charge carriers generated by a single photon can be shared by these pixels).

[0085] Figure 2B An exemplary pixel array in a semiconductor X-ray detector according to an embodiment is shown. When X-ray photons strike the array, they are absorbed, resulting in the generation of multiple charged carriers. These carriers can move in various directions, such as drifting along the direction of the electric field and diffusing in all directions. Figure 2B In this context, each circle (e.g., 220, 230) represents the footprint of the transport region of charged carriers generated by photons (as used in this teaching, "transport region" means the space into which the charged carriers generated by photons are transported).

[0086] As in Figure 2B As shown, the transmission region may be located inside a pixel (e.g., transmission region 220) or on the boundary of an adjacent pixel (e.g., transmission region 230).

[0087] As discussed above, charge sharing can cause problems in energy measurement when the transmission region sits on the boundary of two or more adjacent pixels. Charge sharing can also cause photon count errors. In this embodiment, the electronics 121 in the X-ray detector can still accurately measure the energy of X-ray photons even if charge sharing occurs in the charge carriers generated by the X-ray photons.

[0088] According to the embodiment, two adjacent pixels do not necessarily share a boundary, but they can be close to each other so that the charge carriers generated by a single photon can be shared by the two pixels. That is, charge sharing can occur in adjacent pixels, even if the adjacent pixels do not share a boundary.

[0089] The size of a pixel can be determined through design, based on the manufacturing process. For example, in... Figure 2B As shown, when corresponding photons collide around the center of a pixel, each pixel is designed to be the same size and large enough to cover the transmission area. If the pixel size is too small, for example, smaller than the transmission area, charge sharing will always occur. On the other hand, if the pixel size is too large, multiple photons are likely to collide with the pixel simultaneously, which can cause difficulties in accurate X-ray detection and image generation.

[0090] Figure 3A A component diagram of two electronic systems 121 in two adjacent pixels of a semiconductor X-ray detector according to an embodiment is shown. In this example, Figure 3A Pixel 1 and Pixel 2 in the image are two adjacent pixels of a semiconductor X-ray detector. For example, in... Figure 3A As shown, the electronic system 121 of pixel 1 is configured to process signals from the electrodes of diode 310 in pixel 1; and the electronic system 121 of pixel 2 is configured to process signals from the electrodes of diode 320 in pixel 2.

[0091] In this example, the electronic system 121 of pixel 1 may include a capacitor module 319, one or more sampling capacitors 316, multiple control switches 318, and a data processing module 330. (As in...) Figure 3AAs shown, capacitor module 319 is electrically connected to the electrode or electrical contact of diode 310. Capacitor module 319 is configured to collect charged carriers from the electrode. Capacitor module 319 may include a capacitor in the feedback circuit of an amplifier. An amplifier configured in this way is called a capacitive transimpedance amplifier (CTIA). CTIA has a high dynamic range by preventing amplifier saturation and improves the signal-to-noise ratio by limiting the bandwidth in the signal path. Charged carriers from the electrode are collected over a period of time (“integration period”) (e.g., as shown in…). Figure 4A As shown, accumulation can occur on the capacitor between t0 and t1 (or between t1 and t2). After the integration period ends, the capacitor voltage is sampled and then reset by reset switch 315. Capacitor module 319 may include capacitors directly connected to the electrodes.

[0092] When there is no charge sharing, multiple control switches 318 are closed to charge each of the one or more sampling capacitors 316 with voltage from the front end (diode and amplifier).

[0093] The electronic system 121 of pixel 2 may include the same structure as the electronic system 121 of pixel 1. For example, in Figure 3A As shown, the electronic system 121 of pixel 2 may include a capacitor module 329, one or more sampling capacitors 326, multiple control switches 328, and a data processing module 330. The capacitor module 329 is electrically connected to the electrodes or contacts of the diode 320. Similar to capacitor module 319, capacitor module 329 is configured to collect charged carriers from the electrodes. Capacitor module 329 may include a capacitor in the feedback circuit of the CTIA. Charged carriers from the electrodes are collected over a period of time (“integration period”) (e.g., as shown in…). Figure 4A As shown, accumulation can occur on the capacitor between t0 and t1 (or between t1 and t2). After the integration period ends, the capacitor voltage is sampled and then reset by reset switch 325. Capacitor module 329 may include capacitors directly connected to the electrodes.

[0094] When no charge sharing occurs, the multiple control switches 328 and one or more sampling capacitors 326 can operate in the same manner as the multiple control switches 318 and one or more sampling capacitors 316. When the multiple control switches 328 are closed, each of the one or more sampling capacitors 316 is charged with a voltage from the front end (diode and amplifier).

[0095] Figure 3A Both electronic systems 121 may include a data processing module 330, which may include downstream circuitry for interpreting and processing signals from upstream of electronic system 121.

[0096] According to an embodiment, the data processing module 330 includes a first voltage comparator 331, a second voltage comparator 332, a counter 338, a voltmeter 334, and a controller 336.

[0097] The first voltage comparator 331 is configured to compare a voltage (e.g., the voltage of an electrode or diode 310 or 320) with a first threshold. The diode may be a diode formed from a discrete region 114 of a first doped region 111, a second doped region 113, and an intrinsic region 112 (optionally). Alternatively, the first voltage comparator 331 is configured to compare the voltage of an electrical contact (e.g., a discrete portion of an electrical contact 119B) with the first threshold. The first voltage comparator 331 may be configured to directly monitor the voltage or to calculate the voltage by integrating the current flowing through the diode or electrical contact over a period of time. The first voltage comparator 331 may be controllably activated or deactivated by a controller 336. The first voltage comparator 331 may be a continuous comparator. That is, the first voltage comparator 331 may be configured to be continuously activated and continuously monitor the voltage. The first voltage comparator 331 configured as a continuous comparator reduces the chance that the system 121 will miss signals generated by incident X-ray photons. The first voltage comparator 331, configured as a continuous comparator, is particularly suitable when the incident X-ray intensity is relatively high. The first voltage comparator 331 can be a clocked comparator, which has the advantage of lower power consumption. The first voltage comparator 331, configured as a clocked comparator, can cause the system 121 to miss signals generated by some incident X-ray photons. When the incident X-ray intensity is low, the chance of missing incident X-ray photons is lower because the time interval between two consecutive photons is relatively long. Therefore, the first voltage comparator 331, configured as a clocked comparator, is particularly suitable when the incident X-ray intensity is relatively low. The first threshold can be 5-10%, 10%-20%, 20-30%, 30-40%, or 40-50% of the maximum voltage that an incident X-ray photon can generate in a diode or resistor. The maximum voltage can depend on the energy of the incident X-ray photon (i.e., the wavelength of the incident X-ray), the material of the X-ray absorbing layer 110, and other factors. For example, the first threshold could be 50mV, 100mV, 150mV, or 200mV.

[0098] The second voltage comparator 332 is configured to compare a voltage (e.g., the voltage of an electrode or diode 310 or 320) with a second threshold. The second voltage comparator 332 may be configured to directly monitor the voltage or calculate the voltage by integrating the current flowing through the diode or electrical contact over a period of time. The second voltage comparator 332 may be a continuous comparator. The second voltage comparator 332 may be controllably started or stopped by a controller 336. When the second voltage comparator 332 is stopped, the power consumption of the second voltage comparator 332 may be less than 1%, less than 5%, less than 10%, or less than 20% of the power consumption when the second voltage comparator 332 is started. The absolute value of the second threshold is greater than the absolute value of the first threshold. As used herein, the term "absolute value" or "modulus" |x| of a real number X is a non-negative value of X regardless of its sign. That is, The second threshold can be 200%-300% of the first threshold. The second threshold can be at least 50% of the maximum voltage that an incident X-ray photon can produce in a diode or resistor. For example, the second threshold can be 100mV, 150mV, 200mV, 250mV, or 300mV. The second voltage comparator 332 and the first voltage comparator 331 can be the same component. That is, the system 121 can have a voltage comparator that can compare the voltage with two different thresholds at different times.

[0099] The first voltage comparator 331 or the second voltage comparator 332 may include one or more operational amplifiers or any other suitable circuitry. The first voltage comparator 331 or the second voltage comparator 332 may have high speed to allow the system 121 to operate at high incident X-ray flux.

[0100] Counter 338 is configured to record the number of X-ray photons arriving at the corresponding diode or resistor. Counter 338 can be a software component (e.g., a number stored in computer memory) or a hardware component (e.g., 4017IC and 7490IC).

[0101] Controller 336 may be a hardware component such as a microcontroller or microprocessor. Controller 336 may be configured to initiate a time delay when the first voltage comparator 331 determines that the absolute value of the voltage is equal to or exceeds the absolute value of a first threshold (e.g., the absolute value of the voltage increases from below the absolute threshold to a value equal to or exceeding the absolute value of the first threshold). Absolute values ​​are used here because the voltage can be negative or positive, depending on whether the cathode or anode of a diode is used or which electrical contact is used. Controller 336 may be configured to keep the operation of the second voltage comparator 332, counter 338, and any other circuitry not required for the operation of the first voltage comparator 331 disabled until the time when the first voltage comparator 331 determines that the absolute value of the voltage is equal to or exceeds the absolute value of the first threshold. The time delay may terminate before or after the voltage stabilizes (i.e., the rate of change of the voltage is approximately zero). The phrase "the rate of change of the voltage is approximately zero" means that the voltage change over time is less than 0.1% / ns. The phrase "the rate of change of the voltage is approximately non-zero" means that the voltage change over time is at least 0.1% / ns.

[0102] Controller 336 can be configured to activate the second voltage comparator during a time delay period (including a start and a stop). In an embodiment, controller 336 is configured to activate the second voltage comparator at the start of the time delay. The term "activate" means to cause a component to enter an operating state (e.g., by sending a signal such as a voltage pulse or logic level, by providing power, etc.). The term "deactivate" means to cause a component to enter a non-operating state (e.g., by sending a signal such as a voltage pulse or logic level, by cutting off power, etc.). The operating state may have higher power consumption than the non-operating state (e.g., 10 times higher, 100 times higher, 1000 times higher). Controller 336 itself can be deactivated until the output of the first voltage comparator 331 is equal to or exceeds the absolute value of a first threshold, at which point controller 336 is activated.

[0103] If, during the time delay, the second voltage comparator 332 determines that the absolute value of the voltage is equal to or exceeds the absolute value of the second threshold, the controller 336 may be configured to cause the counter 338 to increment the number recorded by one.

[0104] Controller 336 may be configured to cause voltmeter 334 to measure voltage upon termination of the time delay. Controller 336 may be configured to connect electrodes to electrical ground to reset the voltage and discharge any charge carriers accumulated on the electrodes. In one embodiment, the electrodes are connected to electrical ground after the time delay has ended. In another embodiment, the electrodes are connected to electrical ground for a defined reset period. Controller 336 may connect the electrodes to electrical ground by controlling reset switch 315 or 325. This switch may be a transistor, such as a field-effect transistor (FET).

[0105] In this embodiment, system 121 does not have an analog filter network (e.g., an RC network). In this embodiment, system 121 does not have analog circuitry.

[0106] The voltmeter 334 can feed back the voltage it measures as an analog or digital signal to the controller 336.

[0107] When there is no charge sharing on pixel 1 and pixel 2, the two electronic systems 121 can operate independently and process signals generated from the corresponding electrodes of their diodes (310 or 320). When there is no charge sharing on pixel 1 and pixel 2, multiple control switches 318 close so that the voltage from the front end (diode and amplifier) ​​is reflected on the sampling capacitor and measured by the data processing module 330. The same voltage can also be compared with a threshold by the data processing module 330 (e.g., using a first voltage comparator 331 and / or a second voltage comparator 332).

[0108] Without charge sharing, once the rate of voltage change becomes approximately zero, the voltage is proportional to the number of charge carriers generated by the X-ray photons, which is related to the energy of the X-ray photons. However, when charge sharing occurs on pixel 1 and pixel 2, the voltage... Figure 3A The voltage measured by either of the two electronic systems 121 in pixel 1 is insufficient to estimate the number of charge carriers generated by X-ray photons. Therefore, when charge sharing occurs, a method is needed to estimate the energy of the X-ray photons. In one embodiment, a common switch 340 may exist connecting the two electronic systems 121 of pixel 1 and pixel 2. This common switch 340 can be used to connect the sampling capacitors 316 and 326 from the two pixels in series. Detailed use of the common switch 340 will be discussed later. Figure 3B As described in the text.

[0109] Figure 3B A component diagram of two adjacent electronic systems of a semiconductor X-ray detector according to an embodiment is shown, with switch positions marked. Figure 3A resemblance, Figure 3B Pixel 1 and Pixel 2 in the image are two adjacent pixels of a semiconductor X-ray detector. Figure 3B The electronic systems 121 of pixels 1 and 2 respectively have the same as Figure 3A The electronic systems 121 of pixels 1 and 2 have the same structure. Additionally, Figure 3B The switch positions are marked according to different operating stages of the electronic system 121, which will be described in detail below.

[0110] In this example, a single X-ray photon can strike a common boundary on two adjacent pixels or a region between two adjacent pixels, thereby generating charged carriers and transporting them into both pixels. In this case, each of diodes 310 and 320 may have a voltage increase caused by a portion of the charged carriers.

[0111] In this example, the two electronic systems 121 operate in different phases: phase 1 (Φ1), phase 2 (Φ2), and phase 3 (Φ3). The switch marked with Φ1 is closed only during phase 1. The switch marked with Φ2 is closed only during phase 2. The switch marked with Φ3 is closed only during phase 3. The switches marked with Φ1,2 are closed during both phase 1 and phase 2. The switches marked with Φ1,3 are closed during both phase 1 and phase 3.

[0112] When the two pixels are ready to detect photons, they are in phase 1, where all switches except common switch 340 are closed. The two electronic systems 121 can cooperate either by communicating directly with each other or through a central controller that controls all pixels of the X-ray detector. Based on their cooperation, for example, when they see charge carriers changing the voltages of diodes 310 and 320 simultaneously or at the same time, the two systems 121 can determine that charge sharing has occurred on the two pixels. Because the two pixels are in phase 1 (where all switches except common switch 340 are closed), the voltage from the front end (diodes and amplifiers) is reflected on the sampling capacitor in each of the two electronic systems 121.

[0113] Because the voltage measured by one of these two pixels can only represent a portion of the energy of an X-ray photon, the two voltages can be added together to estimate the photon's energy. Then, the two electronic systems 121 enter stage 2 to add the two voltages together.

[0114] According to the embodiment, in stage 2, the switches marked Φ2 and Φ1,2 are closed, while the other switches are open. (As in...) Figure 3B As shown, the sampling capacitors in pixel 1 and pixel 2 are connected in series in stage 2, such that the voltage across these two series-connected capacitors is equal to the sum of the two voltages of the two diodes excited by the same X-ray photon. The positive terminal of one of the two sampling capacitors is connected to the negative terminal of the other sampling capacitor, thereby adding their respective voltages together. That is, the absolute value of the voltage across the two series-connected capacitors is equal to the sum of the absolute values ​​of the two voltages of the two diodes excited by the same X-ray photon.

[0115] During phase 2, the data processing module 330 in one of the two pixels (e.g., pixel 1) can measure the absolute value of the sum and compare it with a threshold. If the absolute value of the sum is equal to or exceeds the threshold, the number of absorbed photons is determined to increase by one. The energy of the photons can also be measured based on the sum of voltages. In the case of charge sharing on more than two pixels, more than two sampling capacitors (each sampling capacitor from one pixel) can be connected in series to obtain the sum voltage for measuring the energy of X-ray photons.

[0116] According to another embodiment, in stage 2, instead of connecting a sampling capacitor, the two data processing modules 330 can communicate with each other to add the two voltage values ​​of the two diodes excited by the same X-ray photons. Communication between the two pixels can be via a central controller, a bus, or any other suitable communication method. In this case, no sampling capacitor is needed in either pixel; and no common switch 340 is required either.

[0117] After energy measurement, the two pixels can enter phase 3, where the switch marked Φ1,3 is closed and the other switches are open. During phase 3, the capacitor voltage is reset by reset switch 315 or 325. According to an embodiment, the two pixels can reset their voltages simultaneously or at different times. Therefore, the two pixels can enter phase 3 simultaneously or at different times.

[0118] After phase 3, the two pixels can re-enter phase 1, thus preparing them to measure the next incident photon.

[0119] Figure 4A The diagram schematically illustrates the time-varying current (upper curve) flowing through the electrodes or resistor contacts of a diode exposed to X-rays when no charge sharing occurs, and the corresponding time-varying electrode voltage (lower curve) according to an embodiment. The current is caused by charge carriers generated by X-ray photons incident on the X-ray absorption layer. When no charge sharing occurs on two pixels, the electrodes can be as follows: Figure 3A and Figure 3B The diodes 310 or 320 shown are shown in the diagram.

[0120] The voltage of the electrode can be the integral of the current over time. As discussed above, the pixel is in phase 1 when it is ready to detect X-ray photons. During phase 1, at time t0, X-ray photons strike a diode or resistor, charge carriers begin to be generated in the diode or resistor, current begins to flow through the electrodes of the diode or resistor, and the absolute value of the voltage at the electrode or electrical contact begins to increase. At time t1, the first voltage comparator 331 determines that the absolute value of the voltage is equal to or exceeds the absolute value of a first threshold V1, and the controller 336 initiates a time delay TD1, and the controller 336 may deactivate the first voltage comparator 331 at the start of TD1. If the controller 336 was deactivated before t1, the controller 336 is activated at t1. During TD1, the controller 336 activates the second voltage comparator 332. As used herein, the term "during" in the time delay means the start and end (i.e., the end) and any time in between. For example, the controller 336 may activate the second voltage comparator 332 at the end of TD1. If, during TD1, the second voltage comparator 332 determines that the absolute value of the voltage at time t2 is equal to or exceeds the absolute value of the second threshold, the controller 336 causes the counter 338 to increment the recorded number by one. At time te, all charge carriers generated by the X-ray photons drift out of the X-ray absorption layer 110. At time ts, the time delay TD1 terminates. Figure 4A In the example, time ts is after time te; that is, TD1 terminates after all the charge carriers generated by the X-ray photons have drifted out of the X-ray absorption layer 110. Therefore, the rate of change of voltage is approximately zero at time ts. Controller 336 can be configured to deactivate the second voltage comparator 332 at the termination of TD1 or at time t2 or any time in between.

[0121] Controller 336 can be configured to cause voltmeter 334 to measure voltage at the end of time delay TD1. In an embodiment, controller 336 causes voltmeter 334 to measure voltage after the rate of change of voltage has become approximately zero after the end of time delay TD1. When no charge sharing occurs, the voltage at this moment is proportional to the number of charge carriers generated by the X-ray photons, which is related to the energy of the X-ray photons. Controller 336 can be configured to determine the energy of the X-ray photons based on the voltage measured by voltmeter 334. One way to determine the energy is by loading the voltage into a chamber. Counter 338 may have a sub-counter for each chamber. When controller 336 determines that the energy of the X-ray photons falls into a chamber, controller 336 may cause the number recorded in the sub-counter of that chamber to increment by one. Thus, system 121 is able to detect X-ray images and is able to distinguish the X-ray photon energy of each X-ray photon.

[0122] After TD1 terminates, controller 336 connects the electrode to electrical ground during the reset period RST to allow the accumulated charge carriers on the electrode to flow to ground and reset the voltage. After TD1 terminates and before the reset period RST, the pixel can end phase 1 and enter phase 3. Since there is no charge sharing in this example, the pixel does not need phase 2, which involves adding voltages.

[0123] After RST, system 121 re-enters phase 1 and prepares to detect another incident X-ray photon. Implicitly, in Figure 4A In the example, system 121 can handle incident X-ray photons at a rate limited to 1 / (TD1+RST). If the first voltage comparator 331 is disabled, controller 336 can activate it at any time before RST terminates. If controller 336 is disabled, it can be activated before RST terminates.

[0124] Figure 4B The diagram schematically illustrates the time-varying current (upper curve) flowing through two adjacent electrodes when charge sharing occurs, and the corresponding time-varying electrode voltage (lower curve) according to an embodiment. Each electrode can be an electrical contact of a diode or resistor exposed to X-rays. The current is caused by charge carriers generated by X-ray photons incident on the X-ray absorption layer. When charge sharing occurs on two pixels, the two electrodes can be as shown in... Figure 3A and Figure 3B Diodes 310 and 320 are shown in the figure.

[0125] The voltage at each electrode can be the integral of the corresponding current over time. As discussed above, two pixels (pixel 1 and pixel 2) are in phase 1 when they are ready to detect X-ray photons. During phase 1, at time t0, an X-ray photon strikes the region near or between the boundaries of two adjacent pixels (which include two diodes 310 and 320 or two resistors). Charge carriers begin to be generated in the diodes or resistors, current begins to flow through the electrodes of the diodes or resistors, and the absolute value of the voltage at each electrode or electrical contact begins to increase. The two pixels then determine that charge sharing occurs at both pixels.

[0126] According to an embodiment, if the time points at which the absolute values ​​of the two voltages begin to increase differ by a specified amount (e.g., 10 μs, 1 μs, 100 ns, or 10 ns), it is considered that charge sharing has occurred between the two pixels.

[0127] As in Figure 4BAs shown, since the number of charge carriers transmitted into the two pixels may differ, the two pixels may have different voltage and / or current increase rates. Therefore, during phase 1, the two voltages may reach a first threshold V1 at different times. In one embodiment, one of the two voltages does not reach the first threshold V1 during phase 1. In one embodiment, at least one of the two voltages reaches a second threshold V2 during phase 1.

[0128] In another embodiment, the two pixels independently determine whether a photon strikes them. If the voltage on one pixel reaches V1, it is determined whether the voltage on that pixel exceeds V2 within a certain delay. If the voltages on both pixels exceed V2 approximately simultaneously (i.e., within a specified time difference), charge sharing is considered to have occurred between the two pixels.

[0129] In another embodiment, the two pixels independently determine whether a photon strikes them. If the voltages of the pixels reach V1 approximately simultaneously (i.e., within a specified time difference), and the voltage of at least one pixel reaches V2 within a certain delay, charge sharing is considered to have occurred between the two pixels.

[0130] In an embodiment, V2 can be set to a value corresponding to 1 / 2 to 1 / 4 of the energy of the incident X-ray photon.

[0131] In an embodiment, when the voltage of a pixel begins to rise or reaches V1 or V2, depending on the specific circumstances, the pixel may set an indicator to indicate this fact. The logic circuitry may determine the time difference between the indicators of adjacent pixels based on this time difference, and determine whether charge sharing occurs and between which pixels charge sharing occurs.

[0132] In an embodiment, when the voltage of a pixel exceeds V2 and the voltage of any adjacent pixel has reached V1 by that time, it can be considered that charge sharing has occurred.

[0133] As discussed above, when charge sharing occurs at two pixels, the voltage measured at one of the two pixels cannot represent the energy of the X-ray photon. Therefore, if charge sharing is determined to occur at two pixels, the sum of the voltages measured at these pixels after voltage stabilization can be used to estimate the energy of the X-ray photon. The voltage at a pixel stabilizes when the rate of change of voltage is approximately zero for a certain period of time (e.g., less than 1% / ns). For two pixels sharing the charge generated by a single photon, their voltages can stabilize approximately simultaneously.

[0134] Phase 1 can end when or after the voltage at both pixels has stabilized. Figure 4BIn the example, at time te, all the charge carriers generated by the X-ray photons drift out of the X-ray absorption layer 110. Thus, the rate of change of voltage at each pixel can be approximately zero after te. Here, at time ts after te, phase 1 ends and two pixels enter phase 2.

[0135] During phase 2, the voltage detected at pixel 2 is added to the voltage detected at pixel 1 either by connecting capacitors in series or by numerical summation. If, during phase 2, the second voltage comparator 332 of pixel 1 determines that the absolute value of the added voltage is equal to or exceeds the absolute value of a second threshold, the controller 336 of pixel 1 causes the counter 338 of pixel 1 to increment the number recorded by one.

[0136] The controller 336 of pixel 1 can be configured to cause the voltmeter 334 of pixel 1 to measure the summed voltage during phase 2. In an embodiment, the controller 336 of pixel 1 causes the voltmeter 334 of pixel 1 to measure the summed voltage after the rate of change of voltage during phase 2 has become approximately zero. When charge sharing caused by X-ray photons occurs at pixels 1 and 2, the summed voltage at that moment is proportional to the number of charge carriers generated by the X-ray photons, which is related to the energy of the X-ray photons. The controller 336 of pixel 1 can be configured to determine the energy of the X-ray photons based on the voltage measured by the voltmeter 334 of pixel 1. One way to determine the energy is by loading the voltage into a chamber. The counter 338 of pixel 1 may have a sub-counter for each chamber. When the controller 336 of pixel 1 determines that the energy of the X-ray photons falls into a chamber, the controller 336 of pixel 1 may cause the number recorded in the sub-counter of that chamber to increment by one. Therefore, even when charge sharing occurs, the system 121 is able to detect the X-ray image and is able to distinguish the energy of each X-ray photon.

[0137] After obtaining the summed voltage, the two pixels can end phase 2 and enter phase 3. During phase 3, each controller 336 connects the electrode to electrical ground during the reset period RST to allow the charge carriers accumulated on the electrode to flow to ground and reset the voltage.

[0138] After RST, each system 121 re-enters Phase 1 and prepares to detect another incident X-ray photon.

[0139] Figure 5A This schematically illustrates the use of an embodiment. Figure 4A The diagram illustrates the time-varying current (upper curve) and corresponding time-varying electrode voltage (lower curve) caused by noise (e.g., dark current) in an electronic system operating in the manner shown. The electrodes can be as follows: Figure 3A and Figure 3BDiodes 310 or 320 are shown. During phase 1, noise begins at time t0. If the noise is not large enough to cause the absolute value of the voltage to exceed the absolute value of V1, controller 336 does not activate the second voltage comparator 332. If the noise is large enough at time t1 to cause the absolute value of the voltage to exceed the absolute value of V1 as determined by the first voltage comparator 331, controller 336 activates time delay TD1 and controller 336 may deactivate the first voltage comparator 331 at the start of TD1. During TD1 (e.g., at the end of TD1), controller 336 activates the second voltage comparator 332. During TD1, the noise is unlikely to be large enough to cause the absolute value of the voltage to exceed the absolute value of V2. Therefore, controller 336 does not cause the number recorded by counter 338 to increase. At time te, the noise ends. At time ts, time delay TD1 terminates. Controller 336 can be configured to deactivate the second voltage comparator 332 at the end of TD1. If the absolute value of the voltage does not exceed the absolute value of V2 during TD1, the controller 336 may not be configured to cause the voltmeter 334 to measure the voltage.

[0140] After TD1 terminates, the pixel ends phase 1 and enters phase 3 because it has not determined that charge sharing has occurred. During phase 3, the controller 336 connects the electrode to electrical ground during the reset period RST to allow carriers accumulated on the electrode due to noise to flow to ground and reset the voltage. Therefore, system 121 is very effective in noise suppression.

[0141] Figure 5B This schematically illustrates the use of an embodiment. Figure 4B The diagram illustrates the time-varying current (upper curve) and corresponding time-varying electrode voltage (lower curve) of two adjacent electrodes caused by noise (e.g., dark current) in an electronic system operating in the manner shown. In this example, during phase 1, the noise begins at the same time t0 or within the same time period at two adjacent pixels (pixel 1 and pixel 2). Thus, the two pixels, as in... Figure 4B That kind of cooperation during the process.

[0142] As discussed above, stage 1 can end when the rate of change of voltage at the two pixels is approximately zero. Figure 5B In the example, the noise ends at time te. Thus, the rate of voltage change at each pixel can be approximately zero after te. Here, at time ts after te, phase 1 ends and two pixels enter phase 2.

[0143] During phase 2, the voltage detected at pixel 2 is added to the voltage detected at pixel 1 by either connecting capacitors in series or by numerical summation. In this example, the controller 336 of pixel 1 activates the second voltage comparator 332 after pixel 1 determines that charge sharing has occurred, after the voltages of the two pixels have stabilized, or after the start of phase 2. The noise is unlikely to be large enough to cause the absolute value of the summed voltage to exceed the absolute value of V2, where the probability of having two noises simultaneously at two adjacent pixels is already very low. Therefore, the controller 336 of pixel 1 does not cause the counter 338 of pixel 1 to increase the number recorded. Each controller 336 can be configured to deactivate the second voltage comparator 332 at the end of phase 2. If the absolute value of the voltage (or the summed voltage) does not exceed the absolute value of V2 during phase 2, each controller 336 can be configured not to cause the voltmeter 334 to measure the voltage.

[0144] After obtaining the summed voltage, the two pixels can end phase 2 and enter phase 3. During phase 3, each controller 336 connects the electrode to electrical ground during the reset period RST to allow carriers accumulated on the electrode due to noise to flow to ground and reset the voltage. Therefore, system 121 is very effective in suppressing noise, even when voltage summing is initiated for potential charge sharing management.

[0145] According to another embodiment, whether charge sharing occurs at two pixels can be determined using the time it takes for the absolute value of a voltage to equal or exceed the absolute value of a first threshold V1. If the absolute values ​​of the two voltages reach the first threshold within the same time period (e.g., 10 μs, 1 μs, 100 ns, or 10 ns), charge sharing is considered to occur at the two pixels. This decision strategy can help suppress concurrent noise at adjacent pixels when photons collide within a specified pixel.

[0146] Figure 6 The diagram schematically illustrates the time-varying current (upper curve) flowing through two adjacent electrodes of an X-ray absorbing layer exposed to X-rays when charge sharing occurs and the detected voltage values ​​are summed, according to an embodiment. The current is caused by charge carriers generated by incident X-ray photons on the X-ray absorbing layer. When charge sharing occurs on two pixels, the two diodes can be... Figure 3A and Figure 3B Diodes 310 and 320 are shown in the figure.

[0147] The voltage at each electrode can be the integral of the corresponding current with respect to time. As described above, when two pixels (pixel 1 and pixel 2) are ready to detect X-ray photons, they are in phase 1. During phase 1, at time t0, an X-ray photon strikes the region near or between the boundaries of two adjacent pixels (which include two diodes 310 and 320 or two resistors), charge carriers begin to be generated in the diodes or resistors, current begins to flow through the electrodes of the diodes or resistors, and the absolute value of each of the two voltages at the electrodes or electrical contacts begins to increase. The two pixels then determine that charge sharing occurs at both pixels.

[0148] According to an embodiment, the absolute values ​​of the two voltages begin to increase at two different times (e.g., t01 and t02 within the same time period). For example, the same time period could be 10 μs, 1 μs, 100 ns, or 10 ns. If so, it is determined that charge sharing occurs at both pixels.

[0149] like Figure 6 As shown, since the number of charge carriers transmitted into the two pixels may be different, the two pixels may have different voltage and / or current increase rates. Therefore, during stage 1, the two voltages may reach the first threshold V1 at different times.

[0150] As described above, if charge sharing occurs at two pixels, the sum of the voltages measured at these pixels after voltage stabilization can be used to obtain the energy of the X-ray photon.

[0151] Phase 1 can end when or after the voltage at both pixels has stabilized. Figure 6 In the example, at time te, all the charge carriers generated by the X-ray photons drift out of the X-ray absorption layer 110. Thus, the rate of change of voltage at each pixel can be approximately zero after te. Here, at time th after te, phase 1 ends.

[0152] In this example, the voltage detected at pixel 2 is added to the voltage detected at pixel 1, for example, via a central controller or bus. The central controller or bus can operate independently of switches 318, 328, and 340. Thus, phase 2 can be a very short period of time or a period that overlaps with phase 3 and / or phase 1 after the voltage has stabilized. If, during phase 2, the second voltage comparator 332 of pixel 1 determines that the absolute value of the added voltage is equal to or exceeds the absolute value of a second threshold, the controller 336 of pixel 1 causes the counter 338 of pixel 1 to increment the number recorded by one.

[0153] After obtaining the summed voltage, the two pixels can end phase 2 and enter phase 3. In an embodiment, the two pixels can directly enter phase 3 after phase 1, wherein phase 2 includes the numerical voltage summation performed therein and overlaps with phase 3 and / or phase 1 after the voltage stabilizes.

[0154] During phase 3, each controller 336 connects its electrode to electrical ground during the reset period RST to allow the charge carriers accumulated on the electrode to flow to ground and reset the voltage.

[0155] After the RST, each system 121 re-enters Phase 1 and prepares to detect another incident X-ray photon. If the first voltage comparator 331 is deactivated, the controller 336 can activate it at any time before the RST terminates. If the controller 336 is deactivated, it can be activated before the RST terminates.

[0156] Figure 7 This schematically illustrates the use of an embodiment. Figure 6 The diagram shows the time variation (upper curve) of the current flowing through two adjacent electrodes caused by noise (e.g., dark current) and the corresponding time variation (lower curve) of the electrode voltage in an electronic system operating in the manner illustrated.

[0157] In this example, during phase 1, noise begins at the same time t0 or within the same time period at two adjacent pixels (pixel 1 and pixel 2). Thus, the noise at the two pixels... Figure 6 That kind of cooperation during the process.

[0158] As described above, stage 1 can end when or after the voltage at both pixels has stabilized. Figure 7 In the example, the noise ends at time te. Thus, the rate of change of voltage at each pixel can be approximately zero after te. Here, at time th after te, phase 1 ends.

[0159] In this example, the voltage detected at pixel 2 is added to the voltage detected at pixel 1, for example, via a central controller or bus. The central controller or bus can operate independently of switches 318, 328, and 340. Thus, phase 2 can be a very short period of time or a period that overlaps with phase 3 and / or phase 1 after the voltage has stabilized. The noise is unlikely to be large enough to cause the absolute value of the added voltage to exceed the absolute value of V2, and the probability of having two noises simultaneously at two adjacent pixels is already very low. Therefore, the controller 336 of pixel 1 does not cause the counter 338 of pixel 1 to increase the number recorded. If the absolute value of the voltage (or the added voltage) does not exceed the absolute value of V2 during phase 2, each controller 336 can be configured not to cause the voltmeter 334 to measure the voltage.

[0160] After obtaining the summed voltage, the two pixels can end phase 2 and enter phase 3. In an embodiment, the two pixels can directly enter phase 3 after phase 1, wherein phase 2 includes the numerical voltage summation performed therein and overlaps with phase 3 and / or phase 1 after the voltage stabilizes.

[0161] During phase 3, each controller 336 connects its electrode to electrical ground during the reset period RST to allow charge carriers accumulated on the electrode due to noise to flow to ground and reset the voltage. Thus, the electronic system 121 is very effective in suppressing noise, even when voltage summation is initiated for potential charge sharing management and the summation is numerically represented.

[0162] Figure 8A The illustrations depict various examples of assigning X-ray photons that cause charge sharing at multiple pixels to one of the pixels to form an image or to measure the energy of the X-ray photons, according to embodiments. As described above, when charge sharing due to X-ray photons occurs at two or more adjacent pixels, voltage summation can be performed at a selected pixel among the adjacent pixels, and X-ray photons can be assigned to the selected pixel or the energy of the X-ray photons can be measured by the selected pixel. In one embodiment, X-ray photons can be assigned to pixels based on a strategy different from the strategy used to select pixels for voltage summation. For non-imaging applications, it is irrelevant which pixel the photons are assigned to.

[0163] Figure 8A The illustration shows a strategy for selecting one pixel from adjacent pixels for voltage summation or for distributing X-ray photons. (Example) Figure 8A As shown, when the transmission area 810 is located across four adjacent pixels, the top left pixel 815 is selected. When the transmission area 820 is located on the boundary of two vertically adjacent pixels, the top pixel 825 is selected. When the transmission area 830 is located on the boundary of two horizontally adjacent pixels, the left pixel 835 is selected. When the transmission area 840 is located across three pixels (bottom left, bottom right, and top right) (as shown...), the top left pixel 815 is selected. Figure 8A As shown), select the bottom left pixel 845. Thus, Figure 8A The strategies shown favor left pixels over right pixels, top pixels over bottom pixels, and bottom-left pixels over top-right pixels. According to an embodiment, different strategies for selecting one pixel from adjacent pixels can be based on different preferences for the relative positions of adjacent pixels. According to an embodiment, different strategies for selecting one pixel from adjacent pixels can be based on a comparison of the absolute values ​​of the voltages detected at those pixels after the voltages on the adjacent pixels have stabilized. For example, the pixel with the highest absolute value of the detected electrode voltage can be selected.

[0164] Figure 8B This shows that it can be achieved Figure 8A An example of a circuit for the strategy.

[0165] Figure 9A The embodiments shown are applicable to system-based (e.g.) Figure 3A and Figure 3B The flowchart illustrates the method for detecting X-rays using the electronic system 121 (of pixel 1). At 902, the time t0 at which the electrode voltage begins to increase is determined. The electrode can be an electrical contact of a diode or resistor exposed to X-rays. At 904, this time t0 is compared with the time t0 of the adjacent pixel. At 905, it is determined whether charge sharing occurs, for example, by determining whether the time t0 of pixel 1 and the time t0 of the adjacent pixel are within the same time period (e.g., 10 μs, 1 μs, 100 ns, or 10 ns). If charge sharing occurs, the process proceeds to 910. Otherwise, if no charge sharing occurs, the process proceeds to 906.

[0166] At 906, for example, a first voltage comparator 331 is used to compare the absolute value of the voltage at the electrode of the diode or the electrical contact of the resistor exposed to X-rays with a first threshold V1. At 907, if the absolute value of the voltage is not equal to or does not exceed the absolute value of the first threshold, the process returns to step 906. If at 907 the absolute value of the voltage is equal to or exceeds the absolute value of the first threshold, for example after a certain time delay or after the voltage stabilizes, the process continues to step 908. At 908, for example, a second voltage comparator 332 is used to compare the absolute value of the voltage with a second threshold. Then, the process moves to 913.

[0167] At 910, it is determined that the voltage at pixel 1 and its neighboring pixels is stable, for example, by determining that the rate of change of voltage at each pixel is approximately zero over a period of time (e.g., 1 ms or 0.1 ms). At 912, the sum of the absolute values ​​of the voltages at pixel 1 and its neighboring pixels is obtained. At 914, the absolute value of the summed voltages is compared with a second threshold, for example, using a second voltage comparator 332. Then, the process moves to 915.

[0168] At step 915, if the absolute value of the voltage or the sum of the voltages is not equal to or does not exceed the absolute value of the second threshold, the process proceeds to step 920. If the absolute value of the voltage or the sum of the voltages is equal to or exceeds the absolute value of the second threshold, the process continues to step 916. At step 916, for example, controller 336 is used to cause the number recorded in counter 338 to increment by one. At step 918, for example, controller 336 is used to determine the X-ray photon energy based on the voltage or the sum of the voltages. There may be one counter in each energy chamber. After measuring the X-ray photon energy, the counter of the chamber to which the photon energy belongs may be incremented by one. The method proceeds to step 920 after step 918. At step 920, the voltage is reset to ground, for example, by connecting the electrodes of a diode or the electrical contacts of a resistor to ground. After step 920, the process may return to step 902.

[0169] Figure 9B This illustrates a system-based approach suitable for various applications, according to embodiments (e.g.,...). Figure 3A and Figure 3B The flowchart illustrates a method for detecting X-rays using the electronic system 121 (pixel 2). At 1002, for example, a first voltage comparator 331 is used to compare the absolute value of the voltage at the electrode of the diode or the electrical contact of the resistor exposed to the X-rays with a first threshold V1. At 1003, if the absolute value of the voltage is not equal to or does not exceed the absolute value of the first threshold, the process returns to step 1002. If the absolute value of the voltage at 1003 is equal to or exceeds the absolute value of the first threshold, the process continues to step 1004.

[0170] At 1004, the time t1 at which the electrode voltage reaches the first threshold V1 is determined. At 1006, this time t1 is compared with the time t1 of the adjacent pixel. At 1007, it is determined whether charge sharing occurs, for example, by determining whether the time t1 of pixel 2 and the time t1 of the adjacent pixel are within the same time period (e.g., 10 μs, 1 μs, 100 ns, or 10 ns). If charge sharing occurs, the process moves to 1020. At 1020, it is determined that the voltage at pixel 1 and the adjacent pixel is stable, for example, by determining that the rate of change of voltage at each pixel is approximately zero for a period of time (e.g., 1 ms or 0.1 ms). At 1022, the absolute value of the voltage of pixel 2 is sent to the adjacent pixel for voltage summation by connecting capacitors in series or by numerical addition. After 1022, the process returns to 1002.

[0171] Otherwise, if no charge sharing occurs at 1007, for example after a certain time delay or after the voltage stabilizes, the process moves to 1008. At 1008, for example, a second voltage comparator 332 is used to compare the absolute value of the voltage with a second threshold. At 1009, if the absolute value of the voltage is not equal to or does not exceed the absolute value of the second threshold, the process proceeds to step 1014. If the absolute value of the voltage at 1009 is equal to or exceeds the absolute value of the second threshold, the process continues to step 1010. At 1010, for example, a controller 336 is used to cause the number recorded in counter 338 to increment by one. At 1012, for example, the controller 336 is used to determine the X-ray photon energy based on the voltage. Each energy chamber may have a counter. After measuring the X-ray photon energy, the counter of the chamber to which the photon energy belongs may be incremented by one. The method proceeds to step 1014 after step 1012. At 1014, for example, the voltage is reset to ground by connecting the electrodes of a diode or the electrical contacts of a resistor to ground. After 1014, the process can return to 1002.

[0172] Figure 9CA flowchart illustrating a method for determining the occurrence of charge sharing and combining the voltages generated on adjacent pixels by shared X-ray photons according to an embodiment is provided. In this flowchart, several signals are transmitted between adjacent pixels. The signal "RESET" informs the receiving pixel to reset its voltage and any stored signals. The signal "NV1" sent by a pixel to an adjacent pixel informs the adjacent pixel that the voltage on that pixel is V1 or higher. The signal "COMBINE" sent by a pixel to an adjacent pixel informs the adjacent pixel to combine its voltage with the voltage of that pixel.

[0173] The semiconductor X-ray detector 100 can be used for phase-contrast X-ray imaging (PCI) (also known as phase-sensitive X-ray imaging). PCI includes techniques that utilize at least part of the phase shift of the X-ray beam caused by an object (including the spatial distribution of the phase shift) to form an image of the object. One way to obtain the phase shift is to transform the phase into an intensity change.

[0174] PCI can be combined with tomography to obtain the 3D distribution of the real part of an object's refractive index. Compared to conventional intensity-based X-ray imaging (e.g., radiography), PCI is more sensitive to density variations within an object. PCI is particularly useful for imaging soft tissues.

[0175] According to an embodiment, Figure 10 A PCI-compatible system 1900 according to an embodiment is schematically illustrated. System 1900 may include at least two X-ray detectors 1910 and 1920. One or both of the two X-ray detectors 1910 are semiconductor X-ray detectors 100 described herein. X-ray detectors 1910 and 1920 may be separated by a spacer 1930. The spacer 1930 may absorb very few X-rays. For example, the spacer 1930 may have a very small quality attenuation coefficient (e.g., <10 cm⁻¹). 2 g -1 <1cm 2 g -1 <0.1cm 2 g -1 or <0.01cm 2 g -1 The quality attenuation coefficient of spacer 1930 may be uniform (e.g., the variation between any two points in spacer 1930 is less than 5%, less than 1%, or less than 0.1%). Spacer 1930 may cause the phase of X-rays passing through spacer 1930 to change by the same amount. For example, spacer 1930 may be a gas (e.g., air), a vacuum chamber, and may include aluminum, beryllium, silicon, or combinations thereof.

[0176] System 1900 can be used to acquire the phase shift of incident X-rays 1950 caused by the imaged object 1960. X-ray detectors 1910 and 1920 can simultaneously capture two images (e.g., intensity distributions). Because X-ray detectors 1910 and 1920 are separated by spacer 1930, the two images are at different distances from the object 1960. The phase can be determined from the two images, for example, using a linearized algorithm based on Fresnel diffraction integrals.

[0177] According to an embodiment, Figure 11 A system 1800 suitable for PCI is schematically illustrated. This system 1800 includes a semiconductor X-ray detector 100 as described herein. The semiconductor X-ray detector 100 is configured to move toward an object 1860 (which is exposed to incident X-rays 1850 at different distances from the object 1860) and capture its images. These images are not necessarily captured simultaneously. The phase can be determined from the images, for example, using an algorithm based on linearization of Fresnel diffraction integrals.

[0178] Figure 12 A system including the semiconductor X-ray detector 100 described herein is schematically illustrated. This system can be used for medical imaging, such as chest X-ray radiography, abdominal X-ray radiography, etc. The system includes an X-ray source 1201. X-rays emitted from the X-ray source 1201 pass through an object 1202 (e.g., a human body part such as the chest, limb, abdomen, etc.), are attenuated to varying degrees due to the internal structure of the object 1202 (e.g., bones, muscles, fat, and organs, etc.), and are projected onto the semiconductor X-ray detector 100. The semiconductor X-ray detector 100 forms an image by detecting the intensity distribution of the X-rays.

[0179] Figure 13 A system including the semiconductor X-ray detector 100 described herein is schematically illustrated. This system can be used for medical imaging, such as dental X-ray radiography. The system includes an X-ray source 1301. X-rays emitted from the X-ray source 1301 pass through an object 1302 (which is a part of the oral cavity of a mammal, such as a human). The object 1302 may include the maxilla, jawbone, teeth, mandible, or tongue. The X-rays are attenuated to varying degrees due to the different structures of the object 1302 and are projected onto the semiconductor X-ray detector 100. The semiconductor X-ray detector 100 forms an image by detecting the intensity distribution of the X-rays. Teeth absorb more X-rays than cavities, infections, and periodontal ligaments. The dose of X-ray radiation received by dental patients is typically small (approximately 0.150 mSv for a full-mouth series).

[0180] Figure 14This illustration depicts a cargo scanning or non-invasive inspection (NII) system, including a semiconductor X-ray detector 100 described herein. The system can be used to inspect and identify items in transport systems such as shipping containers, vehicles, ships, and baggage. The system includes an X-ray source 1401. X-rays emitted from the X-ray source 1401 can be backscattered from an object 1402 (e.g., a shipping container, vehicle, ship, etc.) and projected onto the semiconductor X-ray detector 100. Different internal structures of the object 1402 can backscatter X-rays differently. The semiconductor X-ray detector 100 forms an image by detecting the intensity distribution of the backscattered X-rays and / or the energy of the backscattered X-ray photons.

[0181] Figure 15 Another cargo scanning or non-invasive inspection (NII) system is schematically illustrated, comprising a semiconductor X-ray detector 100 described herein. The system can be used for baggage screening at bus stops and airports. The system includes an X-ray source 1501. X-rays emitted from the X-ray source 1501 pass through baggage 1502, are differentially attenuated due to the baggage's contents, and are projected onto the semiconductor X-ray detector 100. The semiconductor X-ray detector 100 forms an image by detecting the intensity distribution of the transmitted X-rays. The system can reveal the contents of the baggage and identify items prohibited on public transport, such as firearms, drugs, sharp weapons, and flammable materials.

[0182] Figure 16 A whole-body scanner system is schematically illustrated, including a semiconductor X-ray detector 100 described herein. This whole-body scanner system can detect objects on a human body for security screening purposes without physical undressing or physical contact. The whole-body scanner system may be able to detect non-metallic objects. The whole-body scanner system includes an X-ray source 1601. X-rays emitted from the X-ray source 1601 can be backscattered from the person being screened 1602 and objects on it, and projected onto the semiconductor X-ray detector 100. Objects and the human body can backscatter X-rays differentially. The semiconductor X-ray detector 100 forms an image by detecting the intensity distribution of the backscattered X-rays. The semiconductor X-ray detector 100 and the X-ray source 1601 can be configured to scan the person in a linear or rotational direction.

[0183] Figure 17An X-ray computed tomography (X-ray CT) system is schematically illustrated, including a semiconductor X-ray detector 100 as described herein. The X-ray CT system uses computer-processed X-rays to produce tomographic images (virtual “slices”) of specific areas of a scanned object. These tomographic images can be used for diagnostic and therapeutic purposes in various medical disciplines, or for defect detection, failure analysis, metrology, component analysis, and reverse engineering. The X-ray CT system includes the semiconductor X-ray detector 100 and the X-ray source 1701 described herein. The semiconductor X-ray detector 100 and the X-ray source 1701 can be configured to rotate synchronously along one or more circular or helical paths.

[0184] Figure 18 An electron microscope is schematically illustrated, including a semiconductor X-ray detector 100 as described herein. The electron microscope includes an electron source 1801 (also called an electron gun) configured to emit electrons. The electron source 1801 may have various emission mechanisms, such as thermionic, photocathode, cold emission, or plasma sources. The emitted electrons pass through an electron optical system 1803 configured to shape, accelerate, or focus the electrons. The electrons then reach a sample 1802 from which an image detector can form an image. The electron microscope may include the semiconductor X-ray detector 100 described herein for energy-dispersive X-ray spectroscopy (EDS). EDS is an analytical technique used for elemental analysis or chemical characterization of samples. When electrons are incident on a sample, they cause characteristic X-rays to be emitted from the sample. The incident electrons excite electrons in the inner shells of atoms in the sample, ejecting electrons from the shells and creating electron holes where the electrons were located. Electrons from outer higher-energy shells then fill these holes, and the energy difference between the higher and lower energy shells can be released in the form of X-rays. The quantity and energy of X-rays emitted from the sample can be measured by a semiconductor X-ray detector 100.

[0185] Figure 19 A radiation dosimeter is schematically illustrated, comprising a semiconductor X-ray detector 100 as described herein. This radiation dosimeter is capable of measuring the average dose rate of radiation (e.g., X-rays) from a radiation source 1901. The radiation source 1901 could be a volcano 1910 or an atomic bomb explosion. The radiation dosimeter may include a cavity 1902 comprising air or other gas. X-rays passing through the gas will ionize the gas, producing positive ions and free electrons. Incoming photons will create a number of such ion pairs proportional to their energy. The X-ray detector associated with the radiation dosimeter can measure the average dose rate within a gas volume or a number of interacting photons. Although X-ray detectors are typically single-pixel detectors in non-imaging applications, an X-ray detector 100 with multiple pixels as described herein, capable of managing charge sharing that may occur on adjacent pixels, can also be used.

[0186] Figure 20 An elemental analyzer, including the semiconductor X-ray detector 100 described herein, is schematically illustrated. This elemental analyzer measures the presence of one or more elements of interest on an object (e.g., a toy). A high-energy beam of charged particles (e.g., electrons or photons) or an X-ray beam is directed onto the object. The atoms of the object are excited and emit X-rays at specific wavelengths characteristic of the element. The X-ray detector 100 receives the emitted X-rays and determines the presence of an element based on the energy of the emitted X-rays. For example, the X-ray detector 100 may be configured to detect X-rays at wavelengths that Pb would emit. If the X-ray detector 100 actually receives X-rays of these wavelengths from the object, it can indicate the presence of Pb. The semiconductor X-ray detector 100 described herein may have other applications, such as in X-ray telescopes, X-ray mammography, industrial X-ray defect detection, X-ray microscopy or microradiography, X-ray casting inspection, X-ray nondestructive testing, X-ray weld inspection, X-ray digital subtraction angiography, etc. The semiconductor X-ray detector 100 can be used in place of photographic film, photographic sheet, PSP board, X-ray image intensifier, scintillator or another semiconductor X-ray detector.

[0187] As various aspects and embodiments have been disclosed herein, other aspects and embodiments will become apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for illustrative purposes and are not intended to be limiting; their true scope and spirit are indicated by the following claims.

Claims

1. An apparatus suitable for detecting X-rays, comprising: An X-ray absorbing layer, the X-ray absorbing layer including a first pixel and a second pixel; as well as The controller is configured to: Determine whether the charge carriers generated by a single X-ray photon are collected by the first pixel and the second pixel. After determining that the charge carriers generated by a single X-ray photon are collected by the first pixel and the second pixel, determine the energy of the single X-ray photon based on a first voltage detected from the first pixel and a second voltage detected from the second pixel, wherein the first voltage and the second voltage are caused by the single X-ray photon. If the first voltage and the second voltage begin to change at the same time interval, or if the absolute values ​​of the first voltage and the second voltage reach a first threshold at the same time interval, the controller is further configured to determine that charge carriers generated by a single X-ray photon are collected by the first pixel and the second pixel.

2. The apparatus of claim 1, wherein the controller is further configured to: Obtain the sum of the absolute values ​​of the first voltage and the second voltage; and The energy of the individual X-ray photon is determined based on the sum.

3. The apparatus according to claim 2, wherein: The first pixel is associated with a first capacitor charged by the first voltage; The second pixel is associated with a second capacitor charged by the second voltage; and The sum is obtained by connecting the first capacitor and the second capacitor in series and measuring the voltage across the series-connected first capacitor and second capacitor.

4. The apparatus of claim 2, wherein the sum is obtained by adding the absolute values ​​of the first voltage and the absolute values ​​of the second voltage.

5. The apparatus of claim 2, further comprising a counter configured to record the number of X-ray photons absorbed by the X-ray absorbing layer, wherein if the sum is equal to or exceeds a predetermined threshold, the controller is configured to cause the number recorded by the counter to increase by one.

6. The apparatus of claim 1, wherein the energy of the single X-ray photon is determined when the time variation of the first voltage and the time variation of the second voltage are less than 0.1% / ns.

7. The apparatus of claim 1, wherein the X-ray photons are distributed to one of the first pixel and the second pixel to form an image based on at least one of the following methods: A comparison of the first voltage and the second voltage; and The relative positions of the first pixel and the second pixel.

8. The apparatus of claim 1, wherein the apparatus comprises a pixel array.

9. A system comprising the apparatus of claim 1 and an X-ray source, wherein the system is configured for X-ray radiography of a human chest or abdomen.

10. A system comprising the apparatus of claim 1 and an X-ray source, wherein the system is configured for X-ray radiography of a human oral cavity.

11. A cargo scanning or non-invasive inspection (NII) system comprising the apparatus of claim 1 and an X-ray source, wherein the cargo scanning or non-invasive inspection (NII) system is configured to form an image based on backscattered X-rays.

12. A cargo scanning or non-invasive inspection (NII) system comprising the apparatus of claim 1 and an X-ray source, wherein the cargo scanning or non-invasive inspection (NII) system is configured to form an image using X-rays transmitted through the object being inspected.

13. A whole-body scanner system comprising the apparatus as described in claim 1 and an X-ray source.

14. An X-ray computed tomography (X-ray CT) system comprising the apparatus and X-ray source as described in claim 1.

15. An electron microscope comprising the apparatus, electron source, and electron optical system as described in claim 1.

16. A system comprising the apparatus of claim 1, wherein the system is configured to measure the dose of an X-ray source.

17. A system comprising the apparatus of claim 1, wherein the system is an X-ray telescope or an X-ray microscope, or wherein the system is configured for performing mammography, industrial defect detection, microradiography, casting inspection, weld inspection, or digital subtraction angiography.

18. A method comprising: It is determined that the charge carriers generated by a single X-ray photon are collected by the first pixel and the second pixel; Detect the first voltage from the first pixel; Detect the second voltage from the second pixel; as well as The energy of the single X-ray photon is determined based on the first voltage and the second voltage, wherein the first voltage and the second voltage are caused by the single X-ray photon; Specifically, if the first voltage and the second voltage begin to change during the same time period, or if the absolute values ​​of the first voltage and the second voltage reach a first threshold during the same time period, it is determined that the charge carriers generated by a single X-ray photon are collected by the first pixel and the second pixel.

19. The method of claim 18, further comprising: Obtain the sum of the absolute values ​​of the first voltage and the second voltage; as well as The energy of the individual X-ray photon is determined based on the sum.

20. The method of claim 19, wherein: The first pixel is associated with a first capacitor charged by the first voltage; The second pixel is associated with a second capacitor charged by the second voltage; and The sum is obtained by connecting the first capacitor and the second capacitor in series and measuring the voltage across the series-connected first capacitor and second capacitor.

21. The method of claim 19, wherein the sum is obtained by adding the absolute values ​​of the first voltage and the absolute values ​​of the second voltage.

22. The method of claim 19, further comprising increasing the count of X-ray photons incident on the X-ray absorbing layer comprising the first pixel and the second pixel by one if the sum is equal to or exceeds a predetermined threshold.

23. The method of claim 18, wherein the energy of the single X-ray photon is determined when the time variation of the first voltage and the time variation of the second voltage are less than 0.1% / ns.

24. The method of claim 18, wherein if the first voltage and the second voltage begin to change at the same time interval, it is determined that the charge carriers generated by the single X-ray photon are collected by the first pixel and the second pixel.

25. The method of claim 18, wherein the X-ray photons are assigned to one of the first pixel and the second pixel to form an image based on at least one of the following: A comparison of the first voltage and the second voltage; and The relative positions of the first pixel and the second pixel.

26. A system suitable for phase-contrast X-ray imaging (PCI), comprising: The apparatus as described in claim 1; Second X-ray detector; as well as A spacer, wherein the device and the second X-ray detector are separated by the spacer.

27. The system of claim 26, wherein the device and the second X-ray detector are configured to simultaneously capture images of the object, respectively.

28. The system of claim 26, wherein the second X-ray detector is equivalent to the device.

29. A system suitable for phase-contrast X-ray imaging (PCI), the system comprising the apparatus of claim 1, wherein the apparatus is configured to move toward an object and capture an image of the object, the object being exposed to incident X-rays at different distances from the object.

Images