A large dynamic range radiation detector and method for simultaneously achieving particle counting and energy integration

Abstract

This disclosure relates to a large dynamic range radiation detector and method that simultaneously achieves particle counting and energy integration. The radiation detector includes one or more detection channels, each channel comprising: a sensor, an analog front-end circuit, an analog-to-digital converter, a digital counting module, and a charge integration module. The sensor converts incident radiation into a current signal, the radiation including rays or particles. The analog front-end circuit amplifies the current signal and converts it into a voltage signal. The analog-to-digital converter converts the voltage signal into a digital waveform, the digital waveform including discretized voltage sample values. The digital counting module determines the pulse count information of the radiation based on the digital waveform. The charge integration module determines the charge integration information of the radiation based on the digital waveform. Therefore, both particle counting and energy integration detection methods can be implemented in the digital domain, effectively improving the performance of the radiation detector in terms of noise, energy resolution, and dynamic range.

Description

Technical Field

[0001] This disclosure relates to the field of radiation detection, and more particularly to a large dynamic range radiation detector and method that simultaneously achieves particle counting and energy integration. Background Technology

[0002] In a typical radiation detection and imaging system, such as X-ray computed tomography (CT) or electron microscopy, the detector primarily achieves imaging by detecting the distribution of transmitted or reflected radiation intensity after interacting with the object being detected. Depending on the physical mechanism of the interaction between radiation and the object, the difference in radiation intensity between different regions can reach several orders of magnitude. For example, X-rays attenuate as they pass through an object, and the degree of attenuation is exponentially related to the mass and thickness of the object. Where I0 is the incident X-ray intensity, I is the transmitted X-ray intensity, μ is the linear attenuation coefficient of the object for X-rays, and dx is the path length of the X-rays in the object. A 10-fold difference in mass and thickness results in a more than 20,000-fold difference in transmitted X-ray intensity; while a 20-fold difference in mass and thickness results in an intensity difference of more than 10⁸. In X-ray or electron diffraction imaging systems, due to the very low probability of diffraction, the intensity of the diffracted region and the central beam current can differ by more than six orders of magnitude. This huge intensity contrast places extremely high demands on the performance of radiation detectors; the detectors must possess extremely high dynamic range and sensitivity to ensure accurate capture and differentiation of these weak signals.

[0003] Radiation imaging detectors typically consist of a two-dimensional array of detector units, each including sensor material and corresponding signal processing circuitry. During detection, the sensor material converts radiation (such as X-rays and electrons) into an electrical signal, either directly (e.g., in semiconductor detectors) or indirectly (e.g., in scintillator detectors). The signal processing circuitry then converts the electrical signal into a voltage signal and performs necessary amplification and other processing. When a single X-ray photon or electron interacts with the sensor, it generates a pulsed current signal. The charge of this signal is proportional to the energy deposited by the ray or particle in the detector, allowing the detector to accurately measure the energy of the radiation. Radiation intensity can be measured either by recording the number of X-ray photons or electrons over a period of time (particle counting) or by integrating all the current signals (energy integration or charge integration). Combining these two methods—using counting at low throughput and integration at high throughput—can overcome the limitations of each method, enabling measurements with a wider dynamic range and the acquisition of energy and other information. However, this places high demands on the dynamic range of the input signal to the readout circuitry.

[0004] The current approach combines the two detection methods based on analog circuits, that is, it uses analog signal processing (i.e., in the analog domain) to achieve pulse counting and energy integration. Compared with the separate detection methods, there are certain trade-offs and sacrifices in terms of performance such as noise, energy resolution and dynamic range. Summary of the Invention

[0005] In view of this, this disclosure proposes a large dynamic range radiation detector and method that simultaneously realizes particle counting and energy integration. By realizing the two detection methods of particle counting and energy integration in the digital domain respectively, the performance of the radiation detector in terms of noise, energy resolution and dynamic range is effectively improved.

[0006] According to one aspect of this disclosure, a radiation detector is provided, comprising: one or more detection channels, each detection channel comprising: a sensor, an analog front-end circuit, an analog-to-digital converter, a digital counting module, and a charge integration module; wherein, the sensor is configured to convert incident radiation into a current signal, the radiation including rays or particles; the analog front-end circuit is configured to amplify the current signal and convert it into a voltage signal; the analog-to-digital converter is configured to convert the voltage signal into a digital waveform, the digital waveform including discrete voltage sample values; the digital counting module is configured to determine pulse count information of the radiation based on the digital waveform; and the charge integration module is configured to determine charge integration information of the radiation based on the digital waveform.

[0007] In one possible implementation, the digital counting module includes: a digital filtering circuit and a photon counter; the digital filtering circuit is used to perform digital filtering processing on the digital waveform to obtain a target digital waveform; the digital filtering processing includes: baseline removal, waveform shortening, and stacking reconstruction; the photon counter is used to count the target digital waveform within one or more time windows to obtain the pulse count value of the radiation within one or more time windows; wherein, different voltage thresholds are used when counting in different time windows, and the pulse count information includes the pulse count value of the radiation within one or more time windows.

[0008] In one possible implementation, the digital filtering circuit includes: a first baseline restorer, a digital filter, and a digital shaping filter; the first baseline restorer is used to perform baseline removal on the digital waveform to obtain a digital waveform with a zero baseline; the digital filter is used to shorten the digital waveform with a zero baseline to obtain a shortened digital waveform; the digital shaping filter is used to stack and reconstruct the shortened digital waveform to obtain the target digital waveform.

[0009] In one possible implementation, the charge integration module includes: a second baseline restorer and a digital integrator; the second baseline restorer is used to perform baseline removal on the digital waveform to obtain a digital waveform with a zero baseline; the digital integrator is used to integrate the digital waveform with a zero baseline to obtain the charge integration information of the radiation.

[0010] In one possible implementation, the radiation detector further includes a processing circuit configured to: determine the radiation energy and / or radiation intensity entering the detection channel based on the pulse count information detected by the detection channel when the pulse count value detected by any detection channel within a single time window is less than a specified threshold; the pulse count information includes the pulse count value of the radiation within one or more time windows; or, determine the radiation intensity entering the detection channel based on the charge integral information detected by the detection channel when the pulse count value detected by any detection channel within a single time window is greater than or equal to the specified threshold.

[0011] In one possible implementation, determining the radiation energy entering the detection channel based on the pulse count information detected by the detection channel includes: determining the signal amplitude of the voltage signal generated by the radiation entering the detection channel based on the pulse count values ​​of the radiation entering the detection channel in multiple time windows; wherein the voltage threshold used for counting in different time windows is different; and obtaining the radiation energy entering the detection channel by using a pre-calibrated amplitude-energy mapping relationship corresponding to the detection channel and the signal amplitude of the voltage signal generated by the radiation entering the detection channel.

[0012] In one possible implementation, the calibration process for the amplitude-energy mapping relationship corresponding to different detection channels includes: when each detection channel is exposed to a specified radiation with the same and known energy, obtaining the count rate of each detection channel at different voltage thresholds, wherein the count rate is the pulse count value within a single time window; determining the signal amplitude of the voltage signal generated by each detection channel under the specified radiation based on the count rate of each detection channel at different voltage thresholds; and determining the amplitude-energy mapping relationship corresponding to each detection channel based on the energy of the specified radiation and the signal amplitude of the voltage signal generated by each detection channel under the specified radiation.

[0013] According to another aspect of this disclosure, a radiation detection method is provided for each detection channel in a radiation detector, the method comprising: converting incident radiation into a current signal, the radiation including rays or particles; amplifying the current signal and converting it into a voltage signal; converting the voltage signal into a digital waveform, the digital waveform including discrete voltage sample values; determining pulse count information of the radiation based on the digital waveform; and determining charge integral information of the radiation based on the digital waveform.

[0014] In one possible implementation, determining the pulse count information of the radiation based on the digital waveform includes: performing digital filtering on the digital waveform to obtain a target digital waveform; the digital filtering includes: baseline removal, waveform shortening, and stacking reconstruction; counting the target digital waveform within one or more time windows to obtain the pulse count value of the radiation within one or more time windows; wherein, different voltage thresholds are used when counting in different time windows, and the pulse count information includes the pulse count value of the radiation within one or more time windows.

[0015] In one possible implementation, the digital filtering process of the digital waveform to obtain the target digital waveform includes: baseline removal of the digital waveform to obtain a digital waveform with a zero baseline; waveform shortening of the digital waveform with a zero baseline to obtain a shortened digital waveform; and stacking and reconstructing the shortened digital waveform to obtain the target digital waveform.

[0016] In one possible implementation, determining the charge integral information of the radiation based on the digital waveform includes: performing baseline removal on the digital waveform to obtain a digital waveform with a zero baseline; and integrating the digital waveform with a zero baseline to obtain the charge integral information of the radiation.

[0017] In one possible implementation, the method further includes: if the pulse count value detected by any detection channel within a single time window is less than a specified threshold, determining the radiation energy and / or radiation intensity entering the detection channel based on the pulse count information detected by the detection channel; the pulse count information includes the pulse count value of the radiation in one or more time windows; or, if the pulse count value detected by any detection channel within a single time window is greater than or equal to the specified threshold, determining the radiation intensity entering the detection channel based on the charge integral information detected by the detection channel.

[0018] In one possible implementation, determining the radiation energy entering the detection channel based on the pulse count information detected by the detection channel includes: determining the signal amplitude of the voltage signal generated by the radiation entering the detection channel based on the pulse count values ​​of the radiation entering the detection channel in multiple time windows; wherein the voltage threshold used for counting in different time windows is different; and obtaining the radiation energy entering the detection channel by using a pre-calibrated amplitude-energy mapping relationship corresponding to the detection channel and the signal amplitude of the voltage signal generated by the radiation entering the detection channel.

[0019] In one possible implementation, the calibration process for the amplitude-energy mapping relationship corresponding to different detection channels includes: when each detection channel is exposed to a specified radiation with the same and known energy, obtaining the count rate of each detection channel at different voltage thresholds, wherein the count rate is the pulse count value within a single time window; determining the signal amplitude of the voltage signal generated by each detection channel under the specified radiation based on the count rate of each detection channel at different voltage thresholds; and determining the amplitude-energy mapping relationship corresponding to each detection channel based on the energy of the specified radiation and the signal amplitude of the voltage signal generated by each detection channel under the specified radiation.

[0020] According to various aspects of this disclosure, after amplifying and converting the current signal generated by the sensor using an analog front-end circuit, the waveform of the voltage signal is sampled and digitized using a digital-to-analog converter. Thus, in the digital domain, signal processing and information extraction such as particle counting and energy integration are simultaneously achieved based on the digital waveform using a digital counting module and a charge integration module. Compared with existing detection methods based on analog circuits, digital domain processing is more flexible and reliable, and can overcome the design trade-offs faced by analog circuits, thereby further improving the performance of the entire radiation detector in terms of noise, energy resolution, and dynamic range when simultaneously achieving two detection methods.

[0021] Other features and aspects of this disclosure will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0022] The accompanying drawings, which are included in and form part of this specification, illustrate exemplary embodiments, features, and aspects of this disclosure together with the specification and serve to explain the principles of this disclosure.

[0023] Figure 1 A schematic diagram of the circuit structure of a photon counting detection method in related technologies is shown.

[0024] Figure 2 A schematic diagram of the circuit structure of an energy integration detection method in related technologies is shown.

[0025] Figure 3 A schematic diagram of a counting-integration dual-mode detection circuit structure in the related art is shown.

[0026] Figure 4 A schematic diagram of another counting-integration dual-mode detection circuit structure in the related art is shown.

[0027] Figure 5 A schematic diagram of a radiation detector according to an embodiment of the present disclosure is shown.

[0028] Figure 6 A schematic diagram of a radiation detector according to an embodiment of the present disclosure is shown.

[0029] Figure 7 A schematic diagram of a digital filtering process according to an embodiment of the present disclosure is shown.

[0030] Figure 8 A schematic diagram of a charge integration process according to an embodiment of the present disclosure is shown.

[0031] Figure 9 A schematic diagram is shown of a signal amplitude determination method according to an embodiment of the present disclosure.

[0032] Figure Labels

[0033] exist Figure 4 and Figure 5 In the diagram, 01 is the sensor, 02 is the analog front-end circuit, 03 is the analog-to-digital converter, 04 is the digital counting module, 05 is the charge integration module, 041 is the digital filtering circuit, and 042 is the photon counter. Detailed Implementation

[0034] Various exemplary embodiments, features, and aspects of this disclosure will now be described in detail with reference to the accompanying drawings. The same reference numerals in the drawings denote elements that have the same or similar functions. Although various aspects of the embodiments are shown in the drawings, they are not necessarily drawn to scale unless specifically indicated otherwise.

[0035] As used herein, the terms “comprising,” “including,” “having,” or variations thereof are open-ended and include one or more of the stated features, integrals, elements, steps, components, or functions, but do not exclude the presence or addition of one or more other features, integrals, elements, steps, components, functions, or groups thereof.

[0036] When an element is referred to as “connected,” “coupled,” “responding,” or a variation thereof relative to another element, it may be directly connected, coupled, or responding to another element, or there may be an intermediate element present.

[0037] Although the terms first, second, third, etc., may be used herein to describe various elements / operations, these elements / operations should not be limited by these terms. These terms are only used to distinguish one element / operation from another. Therefore, without departing from the teachings of the inventive concept, a first element / operation in some embodiments may be referred to as a second element / operation in other embodiments.

[0038] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments.

[0039] Furthermore, to better illustrate this disclosure, numerous specific details are set forth in the following detailed description. Those skilled in the art will understand that this disclosure can be practiced without certain specific details. In some instances, methods, means, components, and circuits well known to those skilled in the art have not been described in detail in order to highlight the main points of this disclosure.

[0040] It should be noted that the information (including but not limited to user device information, user personal information, etc.), data (including but not limited to data used for analysis, data stored, data displayed, etc.) and signals involved in this application are all authorized by the user or fully authorized by all parties, and the collection, use and processing of related data must comply with the relevant laws, regulations and standards of the relevant regions.

[0041] It is known that particle counting detection methods (such as those using...) Figure 1 The circuit structure shown illustrates a photon counting detection method for particle counting. This circuit includes a preamplifier (AMP), a shaping amplifier (SHA), a comparator (COMP), and a photon counter. It needs to amplify, shape, and amplitude-discriminate the current signal generated by a single ray or particle, finally outputting the count value. Particle counting can detect the energy of a single ray or particle and is unaffected by electronic noise at low throughput rates; however, at high throughput rates, signal accumulation can occur, leading to count loss and saturation of the output count rate. For energy integration detection methods (such as those using...)... Figure 2 The circuit structure shown represents a particle counting method implemented through energy integration detection. This circuit includes an integrator (INT), a sample-and-hold circuit (Sample), and an analog-to-digital converter (ADC). The current signal generated by all rays or particles in the detector (-HV represents a negative high voltage) is integrated, thus the output is proportional to the total deposited energy. This integration method is unaffected by signal buildup at high throughput rates and can achieve a large dynamic range, but it is limited by electronic noise at low throughput rates and cannot acquire energy information for individual rays or particles.

[0042] As mentioned above, in applications such as radiation detection and imaging, simultaneously achieving particle counting and energy integration can overcome the limitations of each method, enabling measurements with a wider dynamic range and the acquisition of energy information. While there are already implementations that combine the two detection methods—for example, the article "HybridSpectral Micro-CT: System Design, Implementation, and Preliminary Results" by JR Bennett et al. points out the use of two detectors operating separately in particle counting and energy integration modes—this approach introduces significant shot noise during material identification and decomposition because the two detector systems image independently, resulting in uncorrelated particle counting and energy integration data. Furthermore, image registration is required. The challenge in simultaneously achieving particle counting and energy integration with a single detector lies in the fact that the dynamic range or gain of the input signals differs by 4-5 orders of magnitude between the two detection methods, necessitating dedicated readout circuitry. For example, E. Kraft et al., in their paper "Counting and Integrating Readout for Direct Conversion X-ray Imaging: Concept, Realization and First Prototype Measurements," designed a readout chip that duplicates the detector's signal current twice, sending one copy to the subsequent particle counting and energy integration circuits (e.g., ...). Figure 3 The particle counting and energy integration detection method implemented by the counting-integration dual-mode detector circuit structure shown above Figure 1 and Figure 2 The two detection methods shown are combined, and a current buffer is used to replicate the current signal for subsequent particle counting and energy integration. However, the replication circuit (i.e., the current buffer) in this method introduces additional errors and noise, and is susceptible to temperature fluctuations. For example, Figure 4 The detection method implemented by the counting-integration dual-mode detection circuit structure is shown. The range of the integrator circuit is extended by charge injection, and the signal is further amplified by subsequent circuits to meet the counting requirements. These circuits mainly implement the two detection methods simultaneously in the analog domain through analog signal processing. Compared with the individual particle counting or energy integration circuits, there are bound to be some trade-offs and sacrifices in terms of performance such as noise, energy resolution and dynamic range.

[0043] In view of this, the embodiments of this disclosure aim to provide a radiation detector and detection method based on particle counting and energy integration using digital signal processing. The core lies in simultaneously acquiring pulse counting information and charge integration information from the radiation detector in the digital domain, thereby achieving both particle counting and energy integration detection methods. Specifically, in the radiation detector, rays or particles are first converted into current signals by a sensor. The current signals generated by the sensor are amplified, and the waveforms are sampled and digitized. Signal processing and information extraction for particle counting and energy integration are then performed in the digital domain, respectively. Compared with existing implementations based on analog circuits, the implementation based on digital signal processing is more flexible and reliable, overcoming the design trade-offs faced by analog circuits, thereby further improving the performance of both detection methods in terms of noise, energy resolution, and dynamic range.

[0044] It should be noted that the radiation detector and method disclosed in this embodiment can simultaneously achieve particle counting and energy integration, and are applicable to radiation detection and imaging and related application fields. This detector and method are not limited to any specific type of radiation detection and imaging equipment, and are applicable to a range of applications, including but not limited to medical diagnosis, security inspection, industrial non-destructive testing, environmental monitoring, and scientific research experiments. It can process radiation signals with a wide range of intensity (flux rate) and acquire information such as particle energy and intensity.

[0045] Figure 5 A schematic diagram of a radiation detector according to an embodiment of the present disclosure is shown. Figure 5 As shown, the radiation detector includes: one or more detection channels (also called detector units) 00, each detection channel including: sensor 01, analog front-end circuit 02, analog-to-digital converter 03, digital counting module 04 and charge integration module 05;

[0046] Among them, sensor 01 is used to convert incoming radiation into an electric current signal, and the radiation includes rays or particles;

[0047] Analog front-end circuit 02 is used to amplify the current signal and convert it into a voltage signal;

[0048] Analog-to-digital converter 03 is used to convert voltage signals into digital waveforms, which include discrete voltage sample values;

[0049] Digital counting module 04 is used to determine the pulse count information of radiation based on digital waveforms;

[0050] Charge integration module 05 is used to determine the charge integration information of radiation based on the digital waveform.

[0051] In some embodiments, the sensor is typically made of a material capable of absorbing radiant energy and generating charge pairs. For example, the sensor may be a direct-conversion semiconductor detector, including but not limited to silicon (Si), cadmium telluride (CdTe), cadmium zinc telluride (CZT), gallium arsenide (GaAs), and novel perovskite materials; or it may be an indirect-conversion scintillator detector, including but not limited to cesium iodide (CsI), gadolinium silicate oxylutetium (GOS), gadolinium aluminum garnet (GAGG), and lutetium oxynitride (LYSO), which first convert radiation (rays or particles) into scintillating light, and then convert it into an electrical signal through an optoelectronic device.

[0052] In practical applications, the output of sensor 01 can be directly connected to the analog front-end circuit (AFE) 02. The analog front-end circuit 02 amplifies the current signal and converts it into a voltage signal. Then, it is converted into a digital waveform by an analog-to-digital converter (ADC) 03. The ADC 03 can obtain discrete voltage sample values ​​by sampling the continuous voltage signal. These discrete voltage sample values ​​can be plotted on a coordinate axis to obtain the digital waveform of the voltage signal, which can be understood as a digitized analog signal. Furthermore, the digitized waveform (i.e., the digital waveform) is divided into two paths: one path is input to the digital counting module 04 to obtain pulse counting information, and the other path is input to the charge integration module 05 to obtain charge integration information. Thus, in the digital domain, both particle counting and energy integration detection methods are simultaneously achieved through digital signal processing. By amplifying and converting the current signal generated by the sensor, sampling and digitizing the waveform of the voltage signal, and then performing signal processing and information extraction for particle counting and energy integration in the digital domain, the digital signal processing method is more flexible and reliable than the existing analog circuit-based implementation method. It can overcome the design trade-offs faced by analog circuits, thereby further improving the performance of the two detection methods in terms of noise, energy resolution and dynamic range.

[0053] Considering that if the duration of each pulse of the voltage signal (i.e., the digital waveform) is too long, the next pulse will arrive before the previous pulse has finished (i.e., in the case of a high count rate), and the two will accumulate. This accumulation will cause the pulse count information output by the digital counting module 04 to be inaccurate, thus affecting the results of subsequent processing (such as energy calculation); therefore, in order to accurately achieve digital pulse counting at a high count rate, in some embodiments, such as Figure 6 As shown, the digital counting module 04 may include: a digital filter circuit 041 and a photon counter 042;

[0054] Digital filter circuit 041 is used to perform digital filtering on digital waveforms to obtain the target digital waveform; such as Figure 7 As shown, digital filtering processes include: baseline removal (i.e., baseline restoration), waveform shortening, and stacking reconstruction;

[0055] Photon counter 042 is used to count the target digital waveform within one or more time windows to obtain the pulse count value of radiation within one or more time windows; wherein, the voltage threshold used when counting in different time windows is different, and the pulse count information includes the pulse count value of radiation within one or more time windows.

[0056] As is known, in radiation detection, the signal waveform typically contains a fast rising edge and a relatively slow falling edge (exponential decay). If the falling edge of the original signal lasts for 10 μs, and the arrival time interval between two particles is only 1 μs, then the second pulse will fall on the "tail" of the first pulse. This is pulse stacking. Pulse stacking affects subsequent digital signal processing (such as determining signal amplitude), making it impossible to accurately reconstruct the energy of the second particle. Simultaneously, pulse stacking also causes baseline elevation of the voltage signal (baseline drift), which affects the accuracy of voltage signal amplitude measurement, thus impacting the accuracy of energy measurement. Therefore, to ensure the accuracy of subsequent measurements, baseline culling can be performed on the digital waveform to correct or suppress baseline drift. Furthermore, by shortening the waveform to compress its width (e.g., transforming a long-tailed waveform lasting 10 μs into an isosceles trapezoidal or triangular pulse with a width of only 1 μs), the narrower signal width prevents stacking with the preceding pulse even if a particle arrives 2 μs later. This allows for accurate measurement of the amplitude of each pulse while maintaining the count rate. In some cases, even after waveform shortening, the pulses in the digital waveform may still be stacked together. Therefore, it is possible to restore two or more pulses that are too close in time and overlap together to their original independent pulses through stacking reconstruction, thereby restoring the energy and arrival time information of each incident particle. In other words, the overlapping and blurred pulses are restored to their original clear independent pulses.

[0057] In practical applications, baseline removal can be achieved using existing hardware circuits (such as baseline restorers) or digital processing algorithms (such as first finding the intervals in the digital waveform without pulses, calculating the average value of the data points in these intervals to obtain the baseline value, and subtracting this baseline value from the original digital waveform to obtain the baseline-removed digital waveform). This disclosure does not limit the scope of these methods. Furthermore, waveform shortening can be achieved using existing digital signal processing algorithms (such as trapezoidal shaping or peak shaping algorithms) or digital filters (such as filters based on digital deconvolution or delay subtraction). Additionally, existing digital shaping filters (such as digital trapezoidal filters, digital CR (differential)-RC (integral) digital pulse shaping filters, etc.) or digital stacking reconstruction algorithms (such as detecting the rising edge, inflection point, or slope change of the digital waveform to determine whether the digital waveform is composed of a single pulse or multiple pulses superimposed; if it is composed of multiple pulses superimposed, mathematical methods (such as least squares) can be used to call a pre-stored "standard single pulse shape" for fitting, taking into account the arrival time and amplitude of each independent pulse). It should be understood that the digital filter circuit 041 described above can be implemented using hardware circuits, software algorithms, or a combination of hardware and software methods, and this embodiment of the present disclosure does not limit this.

[0058] In some embodiments, the digital filtering circuit 041 includes: a first baseline restorer, a digital filter, and a digital shaping filter; wherein, the first baseline restorer is used to perform baseline removal on the digital waveform to obtain a digital waveform with a zero baseline. Exemplarily, the first baseline restorer can use an existing sample-and-hold baseline restorer (such as a moving average baseline restorer) or a digital differential baseline restorer to remove the DC component in the digital waveform (i.e., the digitized analog waveform) to obtain a digital waveform with a zero baseline. This disclosure does not limit the type of the first baseline restorer; wherein, the digital filter is used to shorten the digital waveform with a zero baseline to obtain a shortened digital waveform. For example, a digital filter based on digital deconvolution or delay subtraction can be used to obtain a narrower (i.e., shortened) digital waveform to achieve pulse signal differentiation at high count rates and obtain a higher output count rate; wherein, the digital shaping filter is used to perform stacking reconstruction on the shortened digital waveform to obtain a target digital waveform. For example, a digital shaping filter based on known shapes such as digital trapezoidal or digital CR-RC can be used to achieve stacking reconstruction, which is beneficial for obtaining more accurate energy spectrum at high count rates.

[0059] In practical applications, the charge integration module 05 can directly integrate digital waveforms in the digital domain (e.g., by integrating the digital waveform using a digital integrator) to obtain charge integration information. In other words, the charge integration value (i.e., charge integration information, or energy integration information) can be obtained by integrating the digital waveform output by the analog-to-digital converter 03. It is known that digital waveform signals are not limited by power supply voltage, and larger signals can be achieved by increasing the bit width of the digital waveform signal. Therefore, charge integration information can be obtained by directly integrating the digitized waveform.

[0060] Considering that baseline offset caused by pulse stacking in the voltage signal may affect the integral value, therefore, in some embodiments, such as Figure 8 As shown, the charge integration module 05 can first perform baseline recovery (i.e., baseline removal) on the digital waveform and then perform digital integration on the baseline-removed digital waveform to obtain charge integration information. Specifically, a digital baseline restorer that does not affect the integration result can be introduced at high count rates to suppress the influence of baseline offset on charge integration. Thus, the charge integration module 05 can include: a second baseline restorer and a digital integrator; wherein, the second baseline restorer is used to perform baseline removal on the digital waveform to obtain a digital waveform with a zero baseline. The second baseline restorer can also be an existing sample-and-hold baseline restorer (such as a moving average baseline restorer) or a digital differential baseline restorer to remove the DC component in the digital waveform (i.e., the digitized analog waveform) to obtain a digital waveform with a zero baseline; the digital integrator is used to integrate the digital waveform with a zero baseline to obtain the radiated charge integration information. It should be understood that the digital integrator can be any integrator known in the art, as long as it can integrate the digital waveform, and this embodiment of the present disclosure does not limit this.

[0061] As we know, the photon counter 042 first compares the digital waveform with a preset voltage threshold using a discriminator to distinguish valid radiation events from other possible interference. When a pulse in the digital waveform exceeds the voltage threshold, a logic signal is output, indicating that a valid radiation event has been detected. This logic signal then drives a counter to count the pulses. Each time a logic signal is received (representing the detection of a pulse exceeding the voltage threshold, or a valid radiation event), the counter increments by one, thus recording the number of detected pulses. The cumulative value of the counter within a fixed time window (e.g., 1 second), i.e., the pulse counter, is the count rate. Therefore, the number of radiation events detected within any time window can be determined by the counter reading, which is important data for assessing radiation energy and intensity.

[0062] As described above, the pulse counting information includes the pulse count value of radiation within one or more time windows. Each detection channel 00 can output pulse counting information and charge integration information. By utilizing the pulse counting information and charge integration information, radiation intensity and accurate energy can be detected under different count rate conditions. Thus, the advantages of both pulse counting and charge integration methods can be utilized, and the count rate range and energy range can be expanded after processing the signals from both methods.

[0063] Therefore, in some embodiments, the radiation detector may further include a processing circuit 11, to which pulse count information and charge integration information output by each detection channel 00 can be input. The processing circuit 11 is used to: determine the energy of a single radiation entering the detection channel and / or the radiation intensity entering the detection channel based on the pulse count information detected by the detection channel when the pulse count value detected by any detection channel within a single time window is less than a specified threshold; or, determine the radiation intensity entering the detection channel based on the charge integration information detected by the detection channel when the pulse count value detected by any detection channel within a single time window is greater than or equal to a specified threshold.

[0064] As mentioned above, the pulse count value detected within a single time window is the count rate. If the pulse count value detected by any detection channel within a single time window is less than a specified threshold, that is, the count rate of the detection channel is less than the specified threshold (this specified threshold can be customized based on empirical data). A count rate less than the specified threshold can be understood as a low count rate condition. It is known that radiation intensity usually refers to particle flux, that is, the number of particles passing through a unit area per unit time. The unit time can be the time of one or more time windows, and the unit area is the area of ​​the sensor. The number of particles is the pulse count value. Under this low count rate condition, for example, the pulse count value detected by the detection channel within one or more time windows can be determined as the radiation intensity entering the detection channel.

[0065] Correspondingly, a pulse count value detected by any detection channel within a single time window that is greater than or equal to a specified threshold can be understood as a count rate greater than or equal to the specified threshold. A count rate greater than or equal to the specified threshold can be understood as a high count rate condition. It is understood that even if the particle counting module 04 suppresses the influence of pulse stacking by setting the digital filter circuit 041, under a high count rate condition, it may still be impossible to completely distinguish pulses stacked together. Therefore, when the radiation intensity is very high (i.e., a high count rate condition), the radiation intensity entering the detection channel can be determined based on the charge integral information detected by the detection channel. It is known that when the radiation intensity is very high, individual pulses will overlap and cannot be distinguished for counting. However, the total current is proportional to the radiation intensity, and the charge integral information can be understood as the total current within a certain time window. Therefore, based on the known mapping relationship between the total current and the radiation intensity, the corresponding radiation intensity can be determined based on the charge integral information. This disclosure embodiment does not limit this.

[0066] It should be understood that the above-described method of determining radiation intensity using pulse counting information under low count rate conditions and using charge integration information under high count rate conditions is one possible implementation provided by the embodiments of this disclosure. In fact, radiation intensity can also be determined using charge integration information under low count rate conditions, or the count rate conditions can be disregarded, and both pulse counting information and charge integration information can be used to determine radiation intensity (for example, using the radiation intensity determined by one type of information to supplement the radiation intensity determined by another type of information). The embodiments of this disclosure do not limit this.

[0067] In practical applications, the processing circuit 11 described above can be any known circuit with digital signal processing capabilities in the art, such as, but not limited to, application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSP devices, DSPDs), programmable logic devices (PLDs), field-programmable gate arrays (FPGAs), general-purpose processors, controllers, microcontrollers, microprocessors, etc. The embodiments disclosed herein do not impose any limitations on this.

[0068] It is known that when the material of sensor 01 is fixed, the amount of charge Q generated by a single radiation on sensor 01 is directly proportional to its radiation energy; the higher the radiation energy, the more charge is generated. Since the charge Q (i.e., the current signal) output by sensor 01 is very weak, it needs to be amplified and converted into a voltage signal by analog front-end circuit 02. Given a fixed structure for analog front-end circuit 02, the voltage signal amplitude is also directly proportional to the amount of charge Q detected by sensor 01. The voltage signal amplitude V is directly proportional to the radiation energy E of the incident particle. Therefore, the particle energy can be determined by measuring the voltage signal amplitude. In some embodiments, determining the radiation energy entering the detection channel based on the pulse count information detected by the detection channel may include:

[0069] The signal amplitude of the voltage signal generated by the radiation entering the detection channel is determined based on the pulse count values ​​of the radiation entering the detection channel in multiple time windows; wherein, the voltage threshold used when counting in different time windows is different.

[0070] The radiation energy entering the detection channel is obtained by using the pre-calibrated amplitude-energy mapping relationship corresponding to the detection channel and the signal amplitude of the voltage signal generated by the radiation entering the detection channel.

[0071] In practical applications, the voltage threshold can be varied from small to large or from large to small. The voltage threshold remains consistent within the same time window (e.g., 1 second). It should be understood that as the voltage threshold changes, the cumulative pulse value counted by the photon counter differs across different time windows. For example, as shown... Figure 9 As shown, by threshold scanning (i.e., varying the voltage threshold), the count rate (i.e., the pulse count value of a single time window) corresponding to different voltage thresholds can be obtained, resulting in a curve showing the count rate changing with the voltage threshold. This curve exhibits a process of first increasing, then decreasing, plateauing, and then decreasing again. The peak value of this curve can be considered the baseline voltage of the voltage signal, and the middle of the falling edge after a plateau period can be considered the peak voltage of the voltage signal. The difference between the baseline voltage and the peak voltage is the signal amplitude of the voltage signal. Therefore, the signal amplitude of the voltage signal generated by the radiation entering the detection channel can be determined based on the pulse count values ​​(i.e., the count rate at different voltage thresholds) of the radiation entering the detection channel over multiple time windows.

[0072] As mentioned above, the voltage signal amplitude V is proportional to the radiation energy E of the incident particle. However, due to manufacturing errors in the analog front-end circuit 02 and analog-to-digital converter 03 in each detection channel of the detector, the signal gain and noise introduced by each detection channel are different, resulting in different voltage signal amplitudes output for the same charge input. Therefore, the amplitude-energy mapping relationship corresponding to each detection channel can be pre-calibrated, that is, the mapping relationship between voltage signal amplitude and radiation energy can be pre-established. Then, the signal amplitude of the voltage signal generated by the radiation entering the detection channel can be substituted into the mapping relationship to obtain the radiation energy entering the detection channel (that is, the energy of a single ray or particle).

[0073] In some embodiments, considering the inconsistency in signal gain introduced by noise and analog circuits in different channels, the correspondence between the count rate and voltage threshold can be obtained by scanning the count rate of different detection channels at different voltage thresholds when the same charge signal (i.e., radiation of the same energy) is injected. This calibrates the inconsistency of signal gain and thresholds in different channels, i.e., obtains the amplitude-energy mapping relationship corresponding to different detection channels. Specifically, the calibration process of the amplitude-energy mapping relationship corresponding to different detection channels may include:

[0074] When a specified radiation with the same and known energy is injected into each detection channel, the count rate of each detection channel at different voltage thresholds is obtained (that is, the pulse count value of each detection channel in multiple time windows, with different voltage thresholds used in different time windows), and the count rate is the pulse count value within a single time window;

[0075] Based on the count rate of each detection channel at different voltage thresholds, determine the signal amplitude of the voltage signal generated by each detection channel under a specified radiation (this process can be referred to above). Figure 9 The relevant descriptions shown are used to obtain the corresponding signal amplitude, which will not be repeated here.

[0076] Based on the energy of the specified radiation and the signal amplitude of the voltage signal generated by each detection channel under the specified radiation, the amplitude-energy mapping relationship corresponding to each detection channel is determined.

[0077] For example, using a specified radiation of known energy (such as...) 137 The detector channels were irradiated with 662 keV gamma rays emitted by Cs. The voltage signal amplitude measured in one of the detection channels under the specified radiation was... Because the voltage signal amplitude is directly proportional to the radiated energy, the signal amplitude measured by this detection channel under arbitrary radiation is... Its corresponding energy is This means obtaining the amplitude-energy mapping relationship corresponding to the detection channel. It should be understood that... Given the signal amplitude, then the measured signal amplitude will be... Substituting this mapping relationship, the corresponding radiation energy can be obtained; and since different detection channels measure different signal amplitudes under the same specified radiation, their respective amplitude-energy mapping relationships can be established for different detection channels.

[0078] Based on the radiation detectors eliminated in the above embodiments of this disclosure, this disclosure also provides a radiation detection method, applied to each detection channel in a radiation detector, the method comprising:

[0079] Step 101: Convert the incoming radiation into an electrical signal, wherein the radiation includes rays or particles;

[0080] Step 102: Amplify the current signal and convert it into a voltage signal;

[0081] Step 103: Convert the voltage signal into a digital waveform, the digital waveform including discrete voltage sample values;

[0082] Step 104: Determine the pulse count information of the radiation based on the digital waveform; and determine the charge integral information of the radiation based on the digital waveform.

[0083] In some embodiments, determining the pulse count information of the radiation based on the digital waveform includes: performing digital filtering on the digital waveform to obtain a target digital waveform; the digital filtering includes: baseline removal, waveform shortening, and stacking reconstruction; counting the target digital waveform within one or more time windows to obtain the pulse count value of the radiation within one or more time windows; wherein, different voltage thresholds are used when counting in different time windows, and the pulse count information includes the pulse count value of the radiation within one or more time windows.

[0084] In some embodiments, performing digital filtering on the digital waveform to obtain the target digital waveform includes: removing the baseline of the digital waveform to obtain a digital waveform with a zero baseline; shortening the digital waveform with a zero baseline to obtain a shortened digital waveform; and stacking and reconstructing the shortened digital waveform to obtain the target digital waveform.

[0085] In some embodiments, determining the charge integral information of the radiation based on the digital waveform includes: performing baseline removal on the digital waveform to obtain a digital waveform with a zero baseline; and integrating the digital waveform with a zero baseline to obtain the charge integral information of the radiation.

[0086] In some embodiments, the method further includes: if the pulse count value detected by any detection channel within a single time window is less than a specified threshold, determining the radiation energy and / or radiation intensity entering the detection channel based on the pulse count information detected by the detection channel; the pulse count information includes the pulse count value of the radiation in one or more time windows; or, if the pulse count value detected by any detection channel within a single time window is greater than or equal to the specified threshold, determining the radiation intensity entering the detection channel based on the charge integral information detected by the detection channel.

[0087] In some embodiments, determining the radiation energy entering the detection channel based on the pulse count information detected by the detection channel includes: determining the signal amplitude of the voltage signal generated by the radiation entering the detection channel based on the pulse count values ​​of the radiation entering the detection channel in multiple time windows; wherein the voltage threshold used for counting in different time windows is different; and obtaining the radiation energy entering the detection channel by using a pre-calibrated amplitude-energy mapping relationship corresponding to the detection channel and the signal amplitude of the voltage signal generated by the radiation entering the detection channel.

[0088] In some embodiments, the calibration process for the amplitude-energy mapping relationship corresponding to different detection channels includes: when each detection channel is exposed to a specified radiation with the same and known energy, obtaining the count rate of each detection channel at different voltage thresholds, wherein the count rate is the pulse count value within a single time window; determining the signal amplitude of the voltage signal generated by each detection channel under the specified radiation based on the count rate of each detection channel at different voltage thresholds; and determining the amplitude-energy mapping relationship corresponding to each detection channel based on the energy of the specified radiation and the signal amplitude of the voltage signal generated by each detection channel under the specified radiation.

[0089] The radiation detector and detection method according to embodiments of this disclosure can simultaneously achieve both particle counting and energy integration detection methods. Under low count rate conditions, energy information of a single ray or particle is obtained through particle counting, while under high count rate conditions, reliable radiation intensity (flux) information is obtained through energy integration, thus expanding the dynamic range of the system detection. Furthermore, based on full waveform sampling and digital signal processing of the radiation signal, it avoids the design trade-offs that analog circuits would have to make to achieve both detection methods, thereby improving the performance of each detection method in terms of noise, energy resolution, and dynamic range. It integrates more intelligent digital circuit functions, such as implementing inconsistency correction in energy detection and suppressing baseline drift caused by temperature and high count rates.

[0090] The various embodiments of this disclosure have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A radiation detector, characterized in that, include: One or more detection channels, each detection channel including: a sensor, analog front-end circuitry, an analog-to-digital converter, a digital counting module, and a charge integration module; The sensor is used to convert incoming radiation into an electrical signal, wherein the radiation includes rays or particles; The analog front-end circuit is used to amplify the current signal and convert it into a voltage signal; The analog-to-digital converter is used to convert the voltage signal into a digital waveform, the digital waveform including discrete voltage sample values; The digital counting module is used to determine the pulse count information of the radiation based on the digital waveform; The charge integration module is used to determine the charge integration information of the radiation based on the digital waveform.

2. The radiation detector according to claim 1, characterized in that, The digital counting module includes: a digital filtering circuit and a photon counter; The digital filtering circuit is used to perform digital filtering processing on the digital waveform to obtain the target digital waveform; the digital filtering processing includes: baseline removal, waveform shortening, and stacking reconstruction. The photon counter is used to count the target digital waveform within one or more time windows to obtain the pulse count value of the radiation within one or more time windows; wherein, the voltage threshold used when counting in different time windows is different, and the pulse count information includes the pulse count value of the radiation within one or more time windows.

3. The radiation detector according to claim 2, characterized in that, The digital filtering circuit includes: a first baseline restorer, a digital filter, and a digital shaping filter; The first baseline restorer is used to perform baseline removal on the digital waveform to obtain a digital waveform with a baseline of zero; The digital filter is used to shorten the digital waveform with zero baseline to obtain a shortened digital waveform. The digital shaping filter is used to stack and reconstruct the shortened digital waveform to obtain the target digital waveform.

4. The radiation detector according to claim 1, characterized in that, The charge integration module includes: a second baseline restorer and a digital integrator; The second baseline restorer is used to perform baseline removal on the digital waveform to obtain a digital waveform with a baseline of zero; The digital integrator is used to integrate the digital waveform with a baseline of zero to obtain the charge integration information of the radiation.

5. The radiation detector according to any one of claims 1 to 4, characterized in that, The radiation detector also includes: The processing circuit is configured to: determine the radiation energy and / or radiation intensity entering the detection channel based on the pulse count information detected by the detection channel when the pulse count value detected by any detection channel within a single time window is less than a specified threshold; the pulse count information includes the pulse count value of the radiation within one or more time windows; or, If the pulse count value detected by any detection channel within a single time window is greater than or equal to the specified threshold, the radiation intensity entering the detection channel is determined based on the charge integral information detected by that detection channel.

6. The radiation detector according to claim 5, characterized in that, The step of determining the radiation energy entering the detection channel based on the pulse count information detected by the detection channel includes: The signal amplitude of the voltage signal generated by the radiation entering the detection channel is determined based on the pulse count values ​​of the radiation entering the detection channel in multiple time windows; wherein, the voltage threshold used when counting in different time windows is different. The radiation energy entering the detection channel is obtained by using the pre-calibrated amplitude-energy mapping relationship corresponding to the detection channel and the signal amplitude of the voltage signal generated by the radiation entering the detection channel.

7. The radiation detector according to claim 6, characterized in that, The calibration process for the amplitude-energy mapping relationship corresponding to different detection channels includes: When a specified radiation with the same and known energy is injected into each detection channel, the count rate of each detection channel at different voltage thresholds is obtained, wherein the count rate is the pulse count value within a single time window; The signal amplitude of the voltage signal generated by each detection channel under the specified radiation is determined based on the count rate of each detection channel at different voltage thresholds. Based on the energy of the specified radiation and the signal amplitude of the voltage signal generated by each detection channel under the specified radiation, the amplitude-energy mapping relationship corresponding to each detection channel is determined.

8. A radiation detection method, characterized in that, The method, applied to each detection channel in a radiation detector, includes: The incoming radiation is converted into an electrical signal, the radiation including rays or particles; The current signal is amplified and converted into a voltage signal; The voltage signal is converted into a digital waveform, the digital waveform including discrete voltage sample values; Based on the digital waveform, pulse count information of the radiation is determined; and, based on the digital waveform, charge integral information of the radiation is determined.

9. The method according to claim 8, characterized in that, Determining the pulse count information of the radiation based on the digital waveform includes: The digital waveform is subjected to digital filtering to obtain the target digital waveform; the digital filtering process includes: baseline removal, waveform shortening, and stacking reconstruction. The target digital waveform is counted within one or more time windows to obtain the pulse count value of the radiation within one or more time windows; wherein, the voltage threshold used when counting in different time windows is different, and the pulse count information includes the pulse count value of the radiation within one or more time windows.

10. The method according to claim 8, characterized in that, The method further includes: If the pulse count value detected by any detection channel within a single time window is less than a specified threshold, the radiation energy and / or radiation intensity entering the detection channel are determined based on the pulse count information detected by that detection channel; the pulse count information includes the pulse count values ​​of the radiation within one or more time windows; or, If the pulse count value detected by any detection channel within a single time window is greater than or equal to the specified threshold, the radiation intensity entering the detection channel is determined based on the charge integral information detected by that detection channel.

11. The method according to claim 10, characterized in that, The step of determining the radiation energy entering the detection channel based on the pulse count information detected by the detection channel includes: The signal amplitude of the voltage signal generated by the radiation entering the detection channel is determined based on the pulse count values ​​of the radiation entering the detection channel in multiple time windows; wherein, the voltage threshold used when counting in different time windows is different. The radiation energy entering the detection channel is obtained by using the pre-calibrated amplitude-energy mapping relationship corresponding to the detection channel and the signal amplitude of the voltage signal generated by the radiation entering the detection channel.

12. The method according to claim 11, characterized in that, The calibration process for the amplitude-energy mapping relationship corresponding to different detection channels includes: When a specified radiation with the same and known energy is injected into each detection channel, the count rate of each detection channel at different voltage thresholds is obtained, wherein the count rate is the pulse count value within a single time window; The signal amplitude of the voltage signal generated by each detection channel under the specified radiation is determined based on the count rate of each detection channel at different voltage thresholds. Based on the energy of the specified radiation and the signal amplitude of the voltage signal generated by each detection channel under the specified radiation, the amplitude-energy mapping relationship corresponding to each detection channel is determined.

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