Signal digitization method and apparatus, computer storage medium, and digital pet system

Abstract

The present application discloses a signal digitization method and apparatus, a computer storage medium, and a digital PET system. The signal digitization method comprises: generating a counting step signal, wherein the waveform of the counting step signal exhibits a stepwise increase in amplitude with the number of excited micro-elements of a photoelectric conversion device; directly sampling the counting step signal to determine a time sequence corresponding to each state change in the counting step signal; and restoring the counting step signal on the basis of the time sequence. In the present application, a counting step signal is generated to replace an outputted analog scintillation pulse signal in the prior art, so that an incident photon sequence can be directly sampled by means of a TDC, and thus a time sequence for excitation of an incident photon is recorded, direct digitization of the incident photon is realized, the incident photon is read out in the form of a digital signal, original information of the incident photon sequence is saved to the greatest extent, and an additional external digitization apparatus is saved, thereby further reducing the costs while improving the system performance.

Description

Signal digitization methods, devices, computer storage media, and digital PET systems

[0001] This application claims priority to Chinese Patent Application No. 202411910892.9, filed on December 24, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This invention relates to the field of medical imaging technology, and in particular to a signal digitization method, apparatus, computer storage medium, and digital PET system. Background Technology

[0003] In positron emission tomography (PET), gamma rays are converted into visible light signals by a scintillation crystal. These visible light signals are further converted into scintillation pulse signals by a photoelectric conversion device. A series of application images can then be obtained by sampling and processing these scintillation pulse signals. In this process, the digitization quality of the scintillation pulses has a significant impact on the final image quality.

[0004] Traditional PET digitization uses a PMT (Photomultiplier tube) to convert the visible light signal from the scintillation crystal into an analog electrical signal. This signal is then filtered, shaped, amplified, integrated, and processed by matched logic circuits. Finally, the coincidence event is sent to a computer in digital form for image reconstruction. In contrast, digital PET technology uses a more efficient SiPM (Silicon photomultiplier tube) for photoelectric conversion and employs a Multi-Voltage Threshold (MVT) method to digitize the signal directly at the source of the pulse sampling. Software algorithms then replace traditional analog circuits to extract information and reconstruct the image. As shown in Figure 1, since the scintillation pulse signal in PET often has a relatively fast rising edge and a relatively slow falling edge, in the MVT sampling method, the time information of the input scintillation pulse waveform crossing the set threshold is usually obtained through TDC (Time to Digital Converter). One TDC in each channel is used to convert the time (T1, T2, T3, T4) when the scintillation pulse crosses the corresponding threshold (V1, V2, V3, V4) at the rising edge, and the other TDC is used to convert the time (T5, T6, T7, T8) when the scintillation pulse is below the threshold at the falling edge. Thus, the waveform information of the scintillation pulse is inverted based on the corresponding voltage-time information (V1, T1), (V2, T2), (V3, T3), (V4, T4), (V4, T5), (V3, T6), (V2, T7), (V1, T8).

[0005] However, in existing digital PET technology, SiPM (Silicon Photodetector) is an integrated circuit-based photodetector consisting of an array of single-photon avalanche diodes (MCs), also known as microcells, and corresponding auxiliary circuitry. Each MC is a photosensitive pixel. SiPM operates the MCs in Geiger mode by applying a bias voltage, with each MC having only a 1 or 0 state, essentially a digital signal. However, in actual operation, the binary signals of hundreds to thousands of MCs are accumulated to form an analog scintillation pulse signal output. The final signal is then digitized externally using the MVT (Multi-Photon Transformer) method. This process cannot recover the incident photon time series from the scintillation signal, making it difficult to overcome the physical limits of system performance. On the other hand, the electronic components used in the digitization circuitry accompanying the MVT method still have room for further optimization, and the overall system processing efficiency still has room for improvement, thereby further reducing system power consumption and cost. Summary of the Invention

[0006] Therefore, it is necessary to provide a signal digitization method, device, computer storage medium, and digital PET system to address at least one technical problem existing in traditional solutions.

[0007] According to a first aspect of this application, a signal digitization method is provided, comprising: generating a counting step signal, wherein the waveform of the counting step signal exhibits an amplitude that increases stepwise with the number of micro-elements of the excited photoelectric conversion device; directly sampling the counting step signal to determine the time sequence corresponding to each state change in the counting step signal; and reconstructing the counting step signal based on the time sequence.

[0008] According to one embodiment of this application, generating the counting step signal includes: outputting a unit step signal when the impulse response signal meets the triggering condition; and generating a counting step signal based on the unit step signal.

[0009] According to one embodiment of this application, the step of outputting a unit step signal when the pulse response signal meets the triggering condition includes: comparing the pulse response signal with a triggering threshold; and outputting a unit step signal in response to the comparison result that the pulse response signal is not less than the triggering threshold.

[0010] According to one embodiment of this application, the unit step signal maintains a 0 output state when the micro-element of the photoelectric conversion device is not excited, and when the micro-element is excited, the amplitude of the unit step signal increases by one unit and maintains the amplitude.

[0011] According to one embodiment of this application, the triggering condition includes: a preset voltage, wherein when the pulse response signal is greater than the preset voltage, the triggering condition is determined to be met, and the unit step signal is output; or a preset waveform feature, wherein when the waveform feature of the pulse response signal conforms to the preset waveform feature, the triggering condition is determined to be met, and the unit step signal is output.

[0012] According to one embodiment of this application, the preset waveform characteristics include: the maximum voltage value of the waveform reaches a preset voltage threshold, the current amplitude of the waveform reaches a preset current threshold, or the cumulative voltage of the waveform reaches a preset amplitude.

[0013] According to one embodiment of this application, generating a counted step signal based on the unit step signal includes: summing the unit step signal to generate the counted step signal.

[0014] According to one embodiment of this application, the summing of the unit step signals includes: summing multiple unit step signals through an in-phase proportional adder circuit and outputting the result to generate the counted step signal; or summing the unit step signals output from different rows and columns through an adder circuit and outputting the result to generate the counted step signal; or setting a corresponding delay for each unit step signal and then summing them to form the counted step signal.

[0015] According to one embodiment of this application, when the micro-element of the photoelectric conversion device is not excited, the amplitude of the counting step signal remains at 0. When one of the micro-elements is excited, the amplitude of the counting step signal increases by one unit and remains at that amplitude. When n of the micro-elements are excited, the amplitude of the counting step signal increases by n units and remains at that amplitude, where n is a positive integer.

[0016] According to one embodiment of this application, directly sampling the counting step signal and determining the time sequence corresponding to each state change in the counting step signal includes: recording the time point when the amplitude of the counting step signal changes and the number of changes; and forming a time sequence based on the number of changes and the time point information of the changes.

[0017] According to one embodiment of this application, the time series includes: time point information corresponding to each jump of the counting step signal, jump count information formed by statistically analyzing all time point information, and source physical address information corresponding to each counting step signal.

[0018] According to one embodiment of this application, the step of restoring the counting step signal based on the time series includes: determining the physical model corresponding to the counting step signal; and restoring the counting step signal based on the physical model and the time series.

[0019] According to one embodiment of this application, after restoring the counting step signal according to the time series, the signal digitization method further includes: outputting a reset signal to clear the pulse response signal.

[0020] According to a second aspect of this application, a signal digitization method is provided, comprising: generating counting step signals through multiple channels, wherein the waveform of the counting step signals is such that the amplitude increases stepwise with the number of micro-elements of the excited photoelectric conversion device; synchronously and in parallel determining the time series corresponding to the state changes of the counting step signals in each channel; and reconstructing the counting step signals based on the time series.

[0021] According to a third aspect of this application, a signal digitization device is provided, comprising: a counting step signal generation unit configured to generate a counting step signal, the waveform of which exhibits an amplitude that increases stepwise with the number of micro-elements of the excited photoelectric conversion device; a sampling unit configured to directly sample the counting step signal and determine the time sequence corresponding to each state change in the counting step signal; and a reconstruction unit configured to reconstruct the counting step signal based on the time sequence.

[0022] According to one embodiment of this application, the counting step signal generation unit includes: a plurality of detection modules, configured to output a pulse response signal when a photon is detected, and to output a unit step signal when the pulse response signal reaches a trigger condition; and a signal processing module, respectively connected to the plurality of detection modules, configured to generate a counting step signal based on the unit step signal.

[0023] According to one embodiment of this application, the detection module includes: a photon detection submodule, used to output a pulse response signal when a photon is detected; and a threshold comparison submodule, connected to the photon detection submodule, used to output the unit step signal when the pulse response signal reaches a trigger condition.

[0024] According to one embodiment of this application, the triggering condition includes: a preset voltage, whereby the triggering condition is satisfied when the pulse response signal is greater than the preset voltage, and the unit step signal is output; or a preset waveform feature, where the triggering condition is satisfied when the waveform feature of the pulse response signal conforms to the preset waveform feature, and the unit step signal is output.

[0025] According to one embodiment of this application, the preset waveform characteristics include: the maximum voltage value reaches a preset voltage threshold, the current amplitude reaches a preset current threshold, or the cumulative voltage reaches a preset amplitude.

[0026] According to one embodiment of this application, the photon detection submodule includes: a single-photon avalanche diode, the cathode of which is connected to an externally input reverse bias voltage; and a quenching diode, the drain of which is connected to the anode of the single-photon avalanche diode, the source of which is grounded, and the gate of which is connected to an externally input DC voltage.

[0027] According to one embodiment of this application, the signal processing module includes: an in-phase proportional adder circuit, which is connected to a plurality of the detection modules respectively, for adding the unit step signal to generate the counted step signal.

[0028] According to one embodiment of this application, multiple detection modules are respectively connected to the signal input terminal of the non-inverting proportional adder circuit through corresponding input resistors, wherein the resistance value of each input resistor is the same.

[0029] According to one embodiment of this application, the non-inverting proportional adder circuit includes an operational amplifier, a feedback resistor, and a grounding resistor. The output terminal of each of the detection modules is connected to the input resistor and connected to the positive input terminal of the operational amplifier. One end of the feedback resistor is connected to the positive input terminal of the operational amplifier, and the other end of the feedback resistor is connected to the output terminal of the operational amplifier. The negative input terminal of the operational amplifier is grounded through the grounding resistor.

[0030] According to one embodiment of this application, the sampling unit includes: a time-to-digital converter configured to record the time information of each amplitude jump in the counting step signal; and a storage module connected to the time-to-digital converter, configured to package the time information and the address information of the corresponding channel and output them in the form of a time sequence.

[0031] According to one embodiment of this application, the signal digitization device further includes a reset module for outputting a reset signal to clear the pulse response signal.

[0032] According to one embodiment of this application, the signal digitization device further includes a transmission unit connected to the sampling unit and configured to transmit the acquired digitized sampling signal.

[0033] According to one embodiment of this application, the reconstruction unit of the signal digitization device includes: a modeling module for determining the physical model corresponding to the counting step signal; and a data processing module connected to the modeling module and configured to perform signal recovery processing on the time series based on the physical model to restore the counting step signal.

[0034] According to one embodiment of this application, the reconstruction unit further includes: a data conversion module connected to the data processing module, used to convert the counting step signal into unit time counting information.

[0035] According to a fourth aspect of this application, a signal digitization device is provided, comprising: a plurality of counting step signal generation units configured to generate counting step signals, wherein the waveform of the counting step signals exhibits an amplitude that increases stepwise with the number of micro-elements of the excited photoelectric conversion device; a sampling unit connected to each of the counting step signal generation units, the sampling units being configured to directly sample the counting step signals and determine the time sequence corresponding to each state change in the counting step signals; and a reconstruction unit connected to each of the sampling units, the reconstruction units being configured to reconstruct the counting step signals based on the time sequence.

[0036] According to one embodiment of this application, the sampling unit includes multiple TDCs and a storage module. The multiple counting step signal generation units are respectively connected to the same storage module through the TDCs, and the storage module is connected to the reconstruction unit.

[0037] According to a fifth aspect of this application, a signal digitization apparatus is provided, comprising: a plurality of detection modules, each detection module including a plurality of counting step signal generation units configured to generate counting step signals; a plurality of sampling units, each sampling unit connected to the plurality of counting step signal generation units in the same detection module, the sampling units configured to directly sample the counting step signals and determine the time sequence corresponding to each state change in the counting step signals; and a reconstruction unit connected to each sampling unit, the reconstruction unit configured to reconstruct the counting step signals based on the time sequence.

[0038] According to one embodiment of this application, the sampling unit includes multiple TDCs and a storage module. The multiple counting step signal generation units in each of the detection modules are respectively connected to the same storage module through the TDC, and the multiple storage modules are respectively connected to the reconstruction unit.

[0039] According to a sixth aspect of this application, a computer storage medium is provided that stores a computer program thereon, which, when executed by a processor, implements the steps of the signal digitization method as described above.

[0040] According to a seventh aspect of this application, a computer program product is provided, comprising a computer program or instructions that, when executed by a processor, implement the steps of the signal digitization method as described above.

[0041] According to the eighth aspect of this application, a digital PET system is provided, including the signal digitization device as described above.

[0042] The signal digitization method, apparatus, computer storage medium, and digital PET system provided in this application replace the analog output scintillation pulse signal in the prior art with the generation of a counting step signal. This enables direct sampling of the incident photon sequence using a TDC, recording the time series of incident photon excitation, realizing direct digitization of the incident photons and reading them out in the form of digital signals. This preserves the original information of the incident photon sequence to the greatest extent, avoiding the complex process of integrating the signal output by the micro-element into an analog scintillation pulse signal output and then sampling it. It also saves on additional external digitization devices, thereby improving system performance while further reducing costs. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the embodiments of this specification or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this specification. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0044] Figure 1 is a schematic diagram of the digitization of scintillation pulse signals in the prior art;

[0045] Figure 2 is a flowchart illustrating a signal digitization method in one embodiment of this application;

[0046] Figure 3 is a flowchart illustrating the output of the counting step signal in one embodiment of this application;

[0047] Figure 4 is a schematic diagram of a counting step signal in one embodiment of this application;

[0048] Figure 5 is a schematic diagram of the process of collecting and forming time series data in one embodiment of this application;

[0049] Figure 6 is a schematic diagram of the process of restoring the counting step signal in one embodiment of this application;

[0050] Figure 7 is a flowchart illustrating a signal digitization method in another embodiment of this application;

[0051] Figure 8 is a schematic diagram of the signal digitization device in one embodiment of this application;

[0052] Figure 9 is a schematic diagram of the structure of the photoelectric conversion device in the signal digitization device in one embodiment of this application;

[0053] Figure 10 is a schematic diagram of the signal processing module in the signal digitization device according to Figure 9;

[0054] Figure 11 is a schematic diagram of the signal digitization device in one embodiment of this application;

[0055] Figure 12 is a schematic diagram of the signal digitization device in one embodiment of this application;

[0056] Figure 13 is a schematic diagram of the signal digitization device in one embodiment of this application;

[0057] Figure 14 is a schematic diagram of the signal digitization device in one embodiment of this application;

[0058] Figure 15 is a schematic diagram of the signal digitization device in one embodiment of this application;

[0059] Figure 16 is a schematic diagram of a digitization system for implementing a signal digitization method in another embodiment of this application;

[0060] Figure 17 is an internal structural diagram of a computer device in one embodiment of this application. Detailed Implementation

[0061] To make the above-mentioned objectives, features, and advantages of this application more readily understood, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0062] It should be noted that when a component is said to be "fixed to" another component, it can be directly fixed to the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0063] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The terms “and / or” or “and / or” as used herein include any and all combinations of one or more of the associated listed items.

[0064] In existing digital PET technology, SiPM (Silicon Photon Microarray) with superior photoelectric conversion performance is typically used as the photoelectric conversion device. SiPM operates each micro-element in Geiger mode by applying a bias voltage. In actual operation, the binary signals generated by hundreds to thousands of micro-elements are summed to form an analog scintillation pulse signal output. Then, devices / instruments other than the SiPM, such as ADC (Analog-to-digital converter) sampling circuits and multiple voltage threshold (MVT) acquisition cards, digitize and reconstruct the SiPM signal to extract the charge and arrival time information of the original SiPM signal, which is used to infer the total number and arrival time of incident photons. However, existing technology essentially treats the already digitized binary signals in the micro-elements (micro-elements only have two states, 0 and 1) as analog signals, sums them, and then digitizes them again. This digital-to-analog-to-digital conversion process leads to the loss of the original information of the incident photon sequence, and the incident photon time series cannot be recovered from the analog SiPM signal. In addition, the binary signals of hundreds to thousands of MCs are accumulated to form an analog signal output, which means that a series of analog signal processing circuits and analog-to-digital conversion circuits are required outside the SiPM to complete the final signal digitization and reconstruction. The increased circuit complexity makes it difficult to further reduce power consumption and size, and also makes it difficult to further improve system performance.

[0065] In view of the technical problems existing in the prior art, this application proposes a signal digitization method, device and supporting application that can further improve system performance.

[0066] In some embodiments, the signal digitization method can be executed by a signal digitization device. For example, the signal digitization method can be stored in a storage device (such as the built-in storage module of the detection device or an external storage device) in the form of a program or instructions, which can implement the signal digitization method when executed. The signal digitization device disclosed in this application for implementing the above-described signal digitization method can be either a device with abundant computing resources (e.g., a computer, server, cloud computing, etc.) or a device with limited computing resources (e.g., FPGA (Field Programmable Gate Array) chip board, ASIC (Application-Specific Integrated Circuit) chip board, etc.).

[0067] The following description, with reference to the accompanying drawings, illustrates some preferred embodiments of the present application. It should be noted that the following description is for illustrative purposes only and is not intended to limit the scope of protection of this application.

[0068] Figure 2 is a flowchart of a signal digitization method in one embodiment of this application. In one embodiment, the signal digitization method 200 may include the following steps 210 to 250.

[0069] Step 210: Generate a counting step signal, wherein the waveform of the counting step signal is such that the amplitude increases stepwise with the number of micro-elements of the excited photoelectric conversion device.

[0070] Typically, the generation of the counting step signal is achieved through a silicon photomultiplier device (SiPM). The SiPM comprises multiple micro-elements, each of which can be excited in response to incident high-energy photons and output a unit step signal. For example, the SiPM may contain an array of single-photon avalanche diodes (APDs) or avalanche diodes (APDs) and corresponding auxiliary circuits. In this case, each single-photon avalanche diode or avalanche diode and its corresponding electronic components constitute a micro-element. How the counting step signal is generated from the unit step signal output by the numerous micro-elements of the SiPM will be further explained below in conjunction with the circuit structure in the device embodiment, and will not be repeated here.

[0071] The waveform of the counting step signal shows that the amplitude increases in a stepwise manner with the number of micro-elements of the excited photoelectric conversion device. For example, when a micro-element is not excited, it always maintains a 0 voltage output state; when a micro-element is excited, the amplitude of the counting step signal increases by one unit and maintains that amplitude, for example, the voltage amplitude increases by one unit, which is 4mV. At this time, the amplitude of the counting step signal is equal to the amplitude of the unit step signal; when n micro-elements are excited, the amplitude of the counting step signal increases by n units and maintains that amplitude. In other words, at a certain time t, the total amplitude of the counting step signal divided by the amplitude of the unit step signal represents the total number of micro-elements excited in SiPM up to time t.

[0072] In this embodiment, the counted step signal contains information about the number of excited micro-elements, or in other words, information about the number of generated unit step signals. Different statistical methods can be used to obtain the counted step signal based on the unit step signal. For example, a counter can be used to count the received counted step signals to obtain the number of unit step signals, or the amplitude of the received counted step signals can be converted to obtain the number of unit step signals.

[0073] Step 230: Directly sample the counting step signal to determine the time sequence corresponding to each state change in the counting step signal.

[0074] Because the counting step signal is formed by multiple unit step signals, its waveform exhibits a step-like shape, where the amplitude of the waveform increases by one unit amplitude for each transition as the number of unit step signals increases. Therefore, unlike existing flicker pulses with relatively fast rise and slow fall edges, the counting step signal has distinct amplitude transition points. The timing information of these amplitude transitions can be directly recorded by a time-to-digital converter (TDC), and then output as a time sequence for each transition point. For example, a counting step signal may contain a total of 9 transitions, each with an amplitude of one unit amplitude, such as 3mV. However, the times corresponding to each transition can be uniformly or non-uniformly distributed. For instance, the 9 transitions might correspond to times of 10ps, 25ps, 35ps, 45ps, 60ps, 80ps, 90ps, 110ps, and 120ps. When sampling this counting step signal, the output time sequence is the time information sequence corresponding to each of these transitions.

[0075] Step 250: Reconstruct the counting step signal information based on the time series.

[0076] In this application, the amplitude of the unit step signal generated by different types of micro-elements in SiPM may be different for different types of high-energy photons, such as gamma photons or neutrons. For example, the amplitude of the unit step signal may be 3mV for gamma photons and 5mV for neutrons. The specific amplitude can be determined by prior experiments. Those skilled in the art should understand that once the corresponding parameters such as the type of high-energy photon, SiPM manufacturing process, material, and micro-element quenching type are determined, the amplitude of the unit step signal generated by a single micro-element after being excited is fixed, which will not be elaborated here.

[0077] Once the amplitude of the unit step signal is determined based on experiments and prior physical models, the counted step signal information can be reconstructed based on the time series information collected in the above steps. That is, the signal waveform can be increased by one unit amplitude and held at each amplitude jump time point using computer software until the next jump time point, and then the signal waveform can be increased by another unit amplitude and held until the last jump time point.

[0078] To further understand the signal digitization method provided in this application, the following explanation will be provided in conjunction with Figures 3-6.

[0079] As shown in Figure 3, the generation of the counting step signal may further include the following steps 211 to 212.

[0080] Step 211: When the pulse response signal meets the triggering condition, output a unit step signal.

[0081] Without photon incidence and disregarding dark counting, the micro-elements in the SiPM's micro-element array are in an unexcited state (equivalent to 0 in binary). When a photon sequence is incident on the SiPM, some of the micro-elements are excited (equivalent to 1 in binary) and generate pulse response signals. In this embodiment, a trigger condition is set to help determine whether a micro-element has received a photon. When the pulse response signal meets the trigger condition, it is determined that the micro-element has received a photon and outputs a unit step signal. By pre-setting the trigger condition, problems such as erroneous readings due to noise interference can be reduced.

[0082] In some specific embodiments, the triggering conditions can be set according to different application scenarios. For example, a preset voltage can be set on the micro-element. After the photon is incident, it interacts with the micro-element to generate a pulse response signal. When the pulse response signal is greater than the preset voltage, it is determined that the triggering condition is met, and a unit step signal is output. Alternatively, the triggering condition can be determined when the waveform of the pulse response signal meets preset characteristics, such as when the maximum voltage reaches a preset voltage threshold, the current amplitude reaches a preset current threshold, or the cumulative voltage reaches a certain amplitude value, and then a unit step signal is output.

[0083] More specifically, when a preset voltage is applied, the micro-element can be connected to a corresponding comparison module. The preset voltage of the comparison module is provided by a digital-to-analog converter integrated on the micro-element chip. When the micro-element detects a photon, it outputs a pulse response signal, which is transmitted to the comparison module. When the amplitude of the pulse response signal reaches the preset voltage, the comparison module outputs a unit step signal. Similarly, when a preset current threshold or a certain amplitude value is applied, this can be achieved using corresponding electronic devices. This is easily implemented by those skilled in the art based on the teachings of this application and will not be elaborated further here.

[0084] The output unit step signal has the following characteristics: when a micro-element is not excited, it always maintains a 0 voltage output state; when a micro-element is excited, the amplitude of the unit step signal increases by one unit and maintains that amplitude, for example, the voltage amplitude increases by one unit to 4mV.

[0085] Specifically, when the pulse response signal meets the triggering condition, the output of the unit step signal may include the following steps 2111 to 2112.

[0086] Step 2111: Compare the impulse response signal with the trigger threshold.

[0087] In this embodiment, a trigger threshold can be set. The magnitude of the trigger threshold and the pulse response signal can be compared to help determine whether the micro-element has received a valid photon. For example, when applied to gamma photon detection, the amplitude of the pulse response signal generated by a single gamma photon is often the same. The trigger threshold can be set slightly lower than this amplitude by a digital-to-analog converter. The pulse response signal output by the micro-element is input into the comparison module and compared with the preset trigger threshold in the comparison module.

[0088] Step 2112: In response to the comparison result that the impulse response signal is not less than the trigger threshold, output a unit step signal.

[0089] When the pulse response signal is greater than or equal to the trigger threshold, it can be determined that the pulse response signal meets the trigger condition. That is, in this embodiment, the comparison result of the pulse response signal being greater than or equal to the trigger threshold can be defined as the trigger condition. In response to the comparison result of the pulse response signal being greater than or equal to the trigger threshold, a unit step signal can be output. Specifically, when any infinitesimal element detects a photon, a pulse response signal is output. In a specific implementation, the trigger threshold can be a trigger voltage V. t The pulse response signal is transmitted to the comparator. When the amplitude of the pulse response signal reaches the trigger voltage V... t At this time, the comparator outputs a unit step signal.

[0090] Step 212: Generate a counting step signal based on the unit step signal.

[0091] Typically, a SiPM contains an m×n (m and n are both non-zero natural numbers) array of micro-elements and corresponding auxiliary circuits. Each micro-element will generate a pulse response signal after detecting a photon. When the pulse response signal meets the triggering condition, it will output a unit step signal. Therefore, the micro-element array can output multiple unit step signals during detection.

[0092] Multiple unit step signals, when output in a certain form, form a counted step signal. For example, the unit step signals output by each micro-element can be summed by an in-phase proportional adder circuit to form a counted step signal; or the unit step signals output by corresponding micro-elements in a certain row or column can be summed by an adder circuit to form a counted step signal; or the unit step signals output by each micro-element can be set with corresponding delays and then directly summed to form a counted step signal. For details on how to output a counted step signal using an adder circuit, please refer to the device embodiment section of this application; further details will not be provided here.

[0093] In one embodiment, the step of generating a counted step signal based on a unit step signal may specifically include summing the unit step signal to obtain a counted step signal. The characteristics of the generated counted step signal will be further described with reference to Figure 4. In Figure 4, when a micro-element is not excited, it always maintains a 0 voltage output state, and at this time, the counted step signal also has no output, which means that the amplitude is always 0 before time t1; when a micro-element is excited, the micro-element outputs a unit step signal, the amplitude of which is, for example, 4mV. At this time, the amplitude of the counted step signal also increases by one unit and maintains that amplitude, which is equal to the amplitude of the unit step signal. That is, at time t1, the amplitude of the counted step signal increases to n1; when two micro-elements are excited, the amplitude of the counted step signal increases by two units and maintains that amplitude. That is, at time t2, the amplitude of the counted step signal increases to n2; similarly, at times t3 and t4, the amplitude of the counted step signal increases to n3 and n4, respectively. It is worth noting that in this application, the moment when a micro-element is excited is by default the moment when the counting step signal jumps. The same micro-element cannot be excited twice at the same time. Since this application is aimed at single-photon application scenarios or basic applications involving the study of photon conversion physical processes or the construction of a priori information databases, the situation where two or more micro-elements are excited at the same time is excluded.

[0094] Furthermore, as shown in Figure 5, directly sampling the counting step signal to determine the time sequence corresponding to each state change in the counting step signal can further include the following steps 231 to 232.

[0095] Step 231: Record the time point when the amplitude of the counting step signal changes and the number of changes.

[0096] In existing technologies, flicker pulse waveforms exhibit relatively fast rise and slow fall edges, resulting in a continuously changing waveform. Unlike existing technologies, counting step signals have distinct amplitude transition points. Visually, this manifests as the waveform amplitude increasing by one unit amplitude with each unit increase in the number of step signals, resulting in an overall stepped waveform. Therefore, the timing information of the signal amplitude transitions can be directly recorded using a time-to-digital converter (TDC). The timing information corresponding to each transition point can then be output sequentially, and the number of recorded transition times represents the number of amplitude transitions in the counting step signal.

[0097] Step 232: Form a time series of transition time information based on the number of transitions.

[0098] Since TDC can record the time information when the signal amplitude changes, the time information recorded after acquiring a complete counting step signal is arranged in chronological order to form the time sequence to be output. This time sequence contains at least three aspects of information: the time point information corresponding to each jump of the counting step signal, the jump count information formed by the statistics of all time point information, and the physical address information corresponding to each SiPM.

[0099] Further, as shown in Figure 6, the reconstruction of the counting step signal based on the time series may further include the following steps 251 to 252.

[0100] Step 251: Determine the physical model corresponding to the counting step signal.

[0101] For different types of high-energy photons, such as gamma photons or neutrons, the amplitude of the unit step signal generated by different types of micro-elements in SiPM may be different. For example, for gamma photons, the amplitude of the unit step signal may be 3mV, and for neutrons, the amplitude of the unit step signal may be 5mV. The specific amplitude can be determined based on prior experiments. Those skilled in the art need to understand that once the corresponding parameters such as the type of high-energy photon, SiPM manufacturing process, material, and micro-element quenching type are determined, the amplitude of the unit step signal generated after a single micro-element is excited is fixed.

[0102] Therefore, the physical model satisfied by the counted step signal can be determined based on the type of high-energy photons (e.g., gamma photons, neutrons), the SiPM manufacturing process (e.g., PN junction design, packaging), the micro-element material (e.g., avalanche diodes, single-photon avalanche diodes), the matched quenching method (e.g., resistor quenching or transistor-controlled quenching), and the corresponding parameters of the unit step signal output circuit. Once the relevant parameters are determined, the amplitude of each jump in the counted step signal can be determined based on this physical model. This physical model can be determined through extensive experiments, prior knowledge, or simulations.

[0103] Step 252: Reconstruct the counting step signal based on the physical model and time series.

[0104] Once the amplitude of the unit step signal is determined, the counting step signal information can be reconstructed based on the time series information collected in the above steps. For example, computer software can be used to increase the signal waveform by one unit amplitude at each amplitude transition time point and hold it until the next transition time point, then increase the signal waveform by another unit amplitude and hold it until the last transition time point.

[0105] Since the counted step signal contains information about the number of received unit step signals, the incident photon sequence of SiPM can be directly digitized using digitization processing methods.

[0106] The signal digitization method provided in this application can directly digitize and output counted step signal information, eliminating the need to set multiple thresholds to collect simulated flicker pulse signals, thus saving additional external digitization devices and preserving the original information of the incident photon sequence to the greatest extent. An external computer can combine the prior information of the incident photon sequence with the digitized sampled signal and accurately reconstruct the time series of the incident photons through algorithms.

[0107] In a further embodiment of this application, after digitizing the counting step signal and outputting the digitized sampling signal, the signal digitization method may further include: outputting a reset signal to clear the pulse response signal. That is, after the current SiPM detection process is completed, the output reset signal clears all the micro-element counts to zero, waiting for the next detection.

[0108] The signal digitization method provided in this application replaces the analog output scintillation pulse signal in the prior art with a counting step signal, thereby enabling direct sampling of the incident photon sequence, recording the time series of incident photon excitation, realizing direct digitization of the incident photons and reading them out in the form of digital signals. This preserves the original information of the incident photon sequence to the greatest extent, avoids the complex process of integrating the signal output by the micro-element into an analog scintillation pulse signal output and then sampling it, saves additional external digitization devices, and improves system performance while further reducing costs.

[0109] Figure 7 is a flowchart of a signal digitization method in another embodiment of this application, which may include the following steps 710-740.

[0110] Step 710: Multiple channels generate counting step signals respectively. The waveform of the counting step signal shows that the amplitude increases stepwise with the number of micro-elements of the excited photoelectric conversion device.

[0111] For PET equipment, whether it is ring PET, flat PET or other variable-shaped PET, it often has multiple detectors. Each detector may include multiple SiPM arrays. Each SiPM array has multiple SiPM channels. Each channel's SiPM includes multiple micro-element arrays. The method for generating a counting step signal in a single channel's SiPM can be referred to the above embodiments, and will not be repeated here.

[0112] Step 720: Synchronously and in parallel determine the time series corresponding to the state changes of the counting step signal in each channel.

[0113] For each channel, the signals in each channel can be digitized synchronously in parallel. The generation and digitization of the counting step signal in each channel are independent of each other and do not affect each other. At the same time, each channel is assigned an address by the system, such as an IP address. The time series information collected by each channel is packaged together with the address information and sent to the processor for processing.

[0114] Step 740: Reconstruct the counting step signal information based on the time series.

[0115] After the time series information in each channel is sent to the processor, the processor can create tasks to restore the counting step signal of each channel according to the methods described in the above embodiments.

[0116] Furthermore, once the counting step signals in each channel are restored, they can be used for single-event coincidence in PET or for photon scattering matching. The output digitized time series can be used to preserve the original information of the incident photon sequence to the greatest extent, eliminating the complex analog-to-digital conversion process and directly realizing the digitization of photon signals. This avoids the signal information loss caused by complex conversion and can restore the time series information of photons, thereby further improving the system performance.

[0117] Based on the description of the above-described signal digitization method embodiments, this application also provides a fast, accurate, and stable signal digitization device. The device may include apparatus (including distributed systems), software (applications), modules, components, servers, clients, etc., using the methods described in the embodiments of this specification, combined with necessary hardware implementation. Based on the same innovative concept, the apparatuses in one or more embodiments provided in this application are as described in the following embodiments. Since the implementation schemes and methods for solving the problem are similar, the implementation of specific apparatuses in the embodiments of this specification can refer to the implementation of the foregoing methods, and repeated details will not be repeated. As used below, the terms "module" or "module group" can refer to a combination of software and / or hardware that implements a predetermined function. Although the apparatuses described in the following embodiments are preferably implemented in software, hardware implementations, or a combination of software and hardware, are also possible.

[0118] Figure 8 is a schematic diagram of the signal digitization device in one embodiment of this application. In one embodiment, the signal digitization device may include a counting step signal generation unit 80, a sampling unit 90, and a reconstruction unit 100. The counting step signal generation unit 80 is configured to generate a counting step signal, the waveform of which shows that the amplitude increases stepwise with the number of micro-elements of the excited photoelectric conversion device. The sampling unit 90 is configured to directly sample the counting step signal and determine the time sequence corresponding to each state change in the counting step signal. The reconstruction unit 100 is configured to reconstruct the counting step signal based on the time sequence.

[0119] More specifically, the counting step signal generation unit 80 may include multiple detection modules 810 and a signal processing module 820. The multiple detection modules 810 can output a pulse response signal when a photon is detected, and can also output a unit step signal when the pulse response signal reaches a trigger condition. In practical applications, the multiple detection modules 810 in the signal digitization device can be arranged in an m×n array (m and n are both positive integers).

[0120] In the absence of photon incident, and disregarding dark counting, the detection module 810 is in an unexcited state (equivalent to an output of 0 in binary). When a photon sequence is incident on the signal digitization device, the detection module 810, which receives photons, is excited (equivalent to an output of 1 in binary) and generates a pulse response signal. In this embodiment, by setting trigger conditions, it can be assisted in determining whether the detection module 810 has received photons. When the pulse response signal meets the trigger conditions, it is determined that the detection module 810 has received photons and outputs a unit step signal. By pre-setting trigger conditions, problems such as false readings caused by noise interference can be reduced.

[0121] In some specific embodiments, the triggering conditions can be set according to different application scenarios. For example, a preset voltage can be set on the micro-element in the detection module 810. After the photon is incident, it interacts with the micro-element to generate a pulse response signal. When the pulse response signal is greater than the preset voltage, it is determined that the triggering condition is met, and the detection module outputs a unit step signal. Alternatively, the triggering condition can be determined when the waveform of the pulse response signal meets preset characteristics, such as the maximum voltage reaching a preset threshold, the current amplitude reaching a preset threshold, or the cumulative voltage reaching a certain amplitude. These are things that those skilled in the art can easily conceive of based on the teachings of this application, and will not be listed here one by one.

[0122] The generated unit step signal has the following characteristics: when a micro-element is not excited, it always maintains a 0 voltage output state; when a micro-element is excited, the amplitude of the unit step signal increases by one unit and maintains that amplitude, for example, the voltage amplitude increases by one unit to 4mV.

[0123] The signal processing module 820 is connected to multiple detection modules 810 respectively. The signal processing module 820 can be used to generate a counting step signal based on the unit step signal.

[0124] When multiple detection modules 810 detect photons, they output multiple unit step signals respectively. In this embodiment, the signal processing module 820 can generate a counted step signal based on the unit step signal, and use the counted step signal to facilitate the counting of the number of received unit step signals.

[0125] Typically, a SiPM (SiPhase Integrated Photon Array) comprises an m×n (m and n are positive integers) array of micro-elements and corresponding auxiliary circuits. Each micro-element generates a pulse response signal upon detecting a photon. When the pulse response signal meets the triggering condition, it outputs a unit step signal. Therefore, the detector module array can output multiple unit step signals during detection. Multiple unit step signals, when output in a specific manner, form a counted step signal. For example, after each detector module 810 outputs a unit step signal, the signal processing module 820 sums the unit step signals using a non-inverting proportional adder circuit and outputs a counted step signal. Alternatively, after the detector modules 810 in a certain row or column output unit step signals, the signal processing module 820 sums the unit step signals using an adder circuit and outputs a counted step signal. Another approach is to first set a corresponding delay for the unit step signals output by each detector module, and then directly sum them using the signal processing module 820 to form a counted step signal.

[0126] The sampling unit 90 is connected to the signal processing module 820. The sampling unit 90 can be used to directly digitize the counted step signal and output a digitized sampled signal. Since the counted step signal contains information about the number of received unit step signals, the sampling unit 90 can use digitization methods to directly digitize the SiPM incident photon sequence. The digitization processing method described above can be any of the digitization processing methods described in the method embodiments section of this application, and will not be repeated here.

[0127] Figure 9 is a schematic diagram of the structure of the detection module 810 in one embodiment of this application. In one embodiment, the detection module 810 may include a photon detection submodule 8110 and a threshold comparison submodule 8120.

[0128] The photon detection submodule 8110 can be used to output a pulse response signal when a photon is detected. Referring to Figure 9, the photon detection submodule 8110 may include a single-photon avalanche diode D1 and a quencher diode Q1. The cathode of the single-photon avalanche diode D1 is connected to an externally input reverse-biased voltage. The anode of the single-photon avalanche diode D1 is connected to ground via the quencher diode Q1. The drain of the quencher diode Q1 is connected to the anode of the single-photon avalanche diode D1. The source of the quencher diode Q1 is grounded, and the gate of the quencher diode Q1 is connected to an externally input DC voltage V. q DC voltage V q It can be used with the pulse width for controlling the quenching tube.

[0129] The threshold comparison submodule 8120 can be connected to the photon detection submodule 8110. The threshold comparison submodule 8120 can be used to output a unit step signal when the pulse response signal reaches the trigger condition. Referring to Figure 9, the threshold comparison submodule 8120 may include a comparator U1. The output terminal of the photon detection submodule 8110 can be connected to the positive input terminal of the comparator U1, and the negative input terminal of the comparator U1 is connected to an externally input trigger voltage V. t .

[0130] When the single-photon avalanche diode D1 detects a photon, it outputs a pulse response signal. This pulse response signal is transmitted to the positive input of comparator U1, which then compares the pulse response signal with the trigger voltage V. t Comparison is performed. When the amplitude of the pulse response signal reaches the trigger voltage V... t At that time, comparator U1 outputs a unit step signal V. ij Where i and j represent the number of rows and columns in the microarray, respectively, j = 1, 2, 3, ..., N. The trigger voltage V of the multiple detection modules 810... t The trigger voltage V of multiple detection modules 810 can be the same. t All of these can be provided by a single on-chip digital-to-analog converter (DAC).

[0131] Figure 10 is a schematic diagram of the structure of the signal processing module 820 in one embodiment of this application. In one embodiment, the signal processing module 820 may include an in-phase proportional adder circuit 8210.

[0132] The in-phase proportional adder circuit 8210 can be connected to N detection modules 810 respectively. The in-phase proportional adder circuit 8210 can be used to sum the unit step signals output by any detection module 810 to generate a count step signal.

[0133] In one embodiment, the outputs of multiple detection modules 810 can be connected to the signal inputs of a non-inverting proportional adder circuit 8210 via multiple input resistors 8220. Referring to Figure 10, the non-inverting proportional adder circuit 8210 may include an operational amplifier U2 and a feedback resistor R. f and grounding resistance Rs. The unit step signal output by N detection modules 810 can be V respectively. i1 V i2 ... V iN The outputs of the N detection modules 810 are connected one-to-one through the input resistors 8220 (R1, R2, ..., R in the diagram). N Connect the positive input terminal of operational amplifier U2, and the feedback resistor R f One end is connected to the positive input terminal of operational amplifier U2, and the feedback resistor R f The other end is connected to the output of operational amplifier U2, and the negative input of operational amplifier U2 is grounded through grounding resistor Rs.

[0134] Operational amplifier U2 can sum multiple unit step signals and output a counted step signal Vo. Specifically, the counted step signal Vo = R f ×(V i1 / R1+V i2 / R2+V i3 / R3+...V iN / R N This is equivalent to multiplying the unit step signal output by each detection module 810 by a proportional summation. Since all N input resistors 8220 have the same resistance value, the multiplication ratio of the unit step signal output by each detection module 810 is the same, ensuring that the voltage input to the in-phase proportional summator circuit 8210 is identical for each detection module 810. Due to the different arrival times of photons, each detection module 810 outputs a unit step signal with a time difference. Therefore, a counting step signal with an amplitude varying over time is generated at the output of the in-phase proportional summator circuit 8210. For example, if the two detection modules 810 are triggered at 1ns and 2ns respectively, the in-phase proportional adder circuit 8210 outputs a counting step signal with a unit amplitude of A0 at 1ns and holds it. At 2ns, the unit step signal output by the second triggered detection module 810 is added, so the amplitude of the counting step signal output by the in-phase proportional adder circuit 8210 at 2ns becomes 2A0, thus forming a stepped counting step signal.

[0135] In one specific embodiment, the signal digitization device includes 32×32 square arrangement of detection modules 810 (as shown in Figure 9, n=32), resulting in a total of 32×32=1024 detection modules 810. Each detection module 810 converts a pulse response signal into a unit step signal at a digital logic high level. The 1024 detection modules 810 are then connected to a non-inverting proportional adder circuit 8210, which converts the unit step signal into a counting step signal. If the power supply of the non-inverting proportional adder circuit 8210 is 4.1V, then the output voltage range of the non-inverting proportional adder circuit 8210 is 0-4.1V. When the number of triggered detection modules 810 ranges from 0 to 1024, then A0 = 4.1V ÷ 1024 ≈ 4mV.

[0136] Figure 11 is a schematic diagram of the structure of the sampling unit 90 in one embodiment of this application. In one embodiment, the sampling unit 90 may include a TDC and a storage module.

[0137] Because the counting step signal has obvious amplitude jump points, its waveform shows that as the number of unit step signals increases, the amplitude of the waveform increases by one unit for each jump, resulting in an overall stepped waveform. Therefore, in this embodiment, the counting step signal generated by the counting step signal generation unit 80 can be directly input into the time-to-digital converter (TDC). The TDC records the time information of each amplitude jump in the counting step signal, and then sends and stores the time information corresponding to each jump point in the storage module. The storage module matches the above time series with channel number / address information and outputs it in a packaged form.

[0138] Since TDC can record the time information when the signal amplitude changes, the time information recorded after acquiring a complete counting step signal is arranged in chronological order to form the time sequence to be output. This time sequence contains at least three aspects of information: the time point information corresponding to each jump of the counting step signal, the jump count information formed by the statistics of all time point information, and the physical address information corresponding to each SiPM.

[0139] The storage module can be a FIFO (First Input First Output) memory. The FIFO memory is connected to the TDC (Time Control Controller) and can be used to collect and store the transition time information recorded by the TDC, based on the time series output by the TDC and the output P-group count threshold-time pairs. The FIFO memory is a first-in, first-out dual-port buffer; the first data to enter is the first to be removed, thus buffering continuous data streams and preventing data loss during input and storage operations.

[0140] When the counting step signal is input to the sampling unit, the TDC records the transition time of the counting step signal in sequence. The FIFO memory stores the data centrally, and the external computer can then reconstruct the entire counting pulse signal using prior information.

[0141] In one embodiment, the signal digitization device may further include a reset module, which can be used to output a reset signal to clear the pulse response signal. After the TDC and storage module have completed their work and output time series frames (each channel outputs approximately 30 bits of Gray code), the reset module can output a reset signal to clear all the counts of the detection module 810, in preparation for the next detection operation.

[0142] Figure 12 is a schematic diagram of the signal digitization device in another embodiment of this application. This signal digitization device can be applied to PET systems, SPECT systems, etc. In this case, the device includes multiple counting step signal generation units. Each counting step signal generation unit can generate a counting step signal as described in the above embodiments. For example, in the embodiment of Figure 12, the device includes three counting step signal generation units. Each counting step signal generation unit can generate a corresponding counting step signal after receiving photons. Each counting step signal is output to the corresponding connected TDC. Multiple TDCs can be connected to the same storage module at the same time. After the TDC of each channel records the time series information collected by the channel, the storage module marks the time series information of each channel received with the corresponding channel address information, and then packages and outputs the data according to the order of receipt. The data reconstruction unit reconstructs the counting step signal information based on the data.

[0143] Figure 13 is a schematic diagram of the signal digitization device in another embodiment of this application. This signal digitization device is similar to that in the embodiment of Figure 12 and can be applied to systems with multiple detection modules, such as PET systems and SPECT systems. Each detection module contains multiple counting step signal generation units. Each counting step signal generation unit can generate a counting step signal as described in the above embodiments. The difference is that in the embodiment of Figure 13, the detection modules can be divided into multiple groups. Each group of detection modules can, for example, include two counting step signal generation units. The two counting step signal generation units are respectively connected to the same storage module through a TDC. Each counting step signal generation unit can generate a corresponding count after receiving a photon. Each counting step signal is output to the corresponding connected TDC. Two or more TDCs can be connected to the same storage module simultaneously. After the TDC of each channel records the time series information collected by that channel, the storage module marks the time series information of each channel with the corresponding channel address information, and then packages and outputs the data according to the order of receipt. Multiple storage modules are connected to the reconstruction unit respectively. The reconstruction unit reconstructs the counting step signal information based on the data received from each storage module. It can even further perform further work such as event filtering and matching based on the reconstructed counting step signal information. This is something that those skilled in the art can easily think of based on the above scheme, and will not be elaborated here.

[0144] The signal digitization device provided in this application generates a counting step signal to replace the analog output scintillation pulse signal in the prior art, thereby enabling direct sampling of the incident photon sequence with TDC, recording the time series of incident photon excitation, realizing direct digitization of the incident photons and reading them out in the form of digital signals. This preserves the original information of the incident photon sequence to the greatest extent, avoids the complex process of integrating the signal output by the micro-element into an analog scintillation pulse signal output and then sampling it, saves additional external digitization devices, and improves system performance while further reducing costs.

[0145] Figure 14 is a schematic diagram of the structure of a signal digitization device in one embodiment of the present application. In one embodiment, the signal digitization device may include a transmission unit 910 and a reconstruction unit 100.

[0146] The transmission unit 910 can be used to transmit the acquired digital sampling signal. The reconstruction unit 100 can be connected to the transmission unit 910. The reconstruction unit 100 can be used to reconstruct the digital sampling signal based on prior information to restore the counting step signal; the reconstruction unit 100 can also be used to convert the counting step signal into counting information per unit time.

[0147] The digital sampling signal can refer to the digital sampling signal acquired by the sampling unit in the above embodiments. In this embodiment, the signal digitization device can read the digital sampling signal from the sampling unit through the transmission unit 910. After acquiring the digital sampling signal, the reconstruction unit 100 can analyze the signal characteristics of the counting step signal through prior information, such as a prior physical model, and then reconstruct the digital signal based on the prior information to restore the counting step signal. For example, the digital sampling signal can be reconstructed based on the function or shape model conforming to the counting step signal to restore the counting step signal. Furthermore, the counting step signal is converted to obtain the counting information per unit time.

[0148] The aforementioned signal digitization device reconstructs the digitized sampled signal based on prior information, preserving the original information of the incident photon sequence to the greatest extent possible, accurately recovering the incident photon time series, and realizing the digital reconstruction of the counting step signal without sacrificing photon detection efficiency.

[0149] Figure 15 is a schematic diagram of the signal digitization device in another embodiment of this application. In one embodiment, the reconstruction unit 100 may include a modeling module 1510 and a data processing module 1520.

[0150] The modeling module 1510 can be used to determine the physical model corresponding to the counting step signal. The data processing module 1520 can be connected to the modeling module 1510, and the data processing module 1520 can be used to perform signal recovery processing on the digitized sampled signal based on the physical model to restore the counting step signal.

[0151] As can be seen from the above embodiment of the signal digitization device, the counting step signal follows a physical model. The voltage amplitude of the counting step signal is the count number × A0. The modeling module 1510 can set a corresponding physical model according to the characteristics of the counting step signal, for example, it can use a step-like exponential model or an approximate linear function model to represent the counting step signal. Furthermore, the data processing module 1520 can use signal processing methods such as fitting algorithms and neural network algorithms to perform signal recovery processing on the digitized sampled signal based on the physical model determined by the modeling module 1510, and recover the counting step signal from the time series of the digitized sampled signal.

[0152] In one embodiment, the reconstruction unit 100 may further include a data conversion module 1530. The data conversion module 1530 may be connected to the data processing module 1520, and the data conversion module 1530 may be used to convert the counting step signal into counting information per unit time.

[0153] It should be understood that the devices and modules shown in Figures 8-15 can be implemented in various ways. For example, in some embodiments, the devices and modules can be implemented by hardware, software, or a combination of software and hardware. The hardware portion can be implemented using dedicated logic; the software portion can be stored in memory and executed by an appropriate instruction execution device, such as a microprocessor or dedicated hardware. Those skilled in the art will understand that the methods and devices described above can be implemented using computer-executable instructions and / or included in processor control code, for example, such code provided on a carrier medium such as a disk, CD, or DVD-ROM, a programmable memory such as read-only memory (firmware), or a data carrier such as an optical or electronic signal carrier. The devices and modules described in this application can be implemented not only by hardware circuits such as very large-scale integrated circuits or gate arrays, semiconductors such as logic chips, transistors, or programmable hardware devices such as field-programmable gate arrays, programmable logic devices, etc., but also by software executed by various types of processors, or by a combination of the aforementioned hardware circuits and software (e.g., firmware).

[0154] It should be noted that the above description of the modules is for convenience only and should not be construed as limiting this specification to the embodiments described. It is understood that those skilled in the art, after understanding the principle of the device, may arbitrarily combine the modules or construct subsystems connected to other modules without departing from this principle. For example, the modules may share a single storage module, or each module may have its own separate storage module. Such modifications are all within the scope of this specification.

[0155] Figure 16 is a schematic diagram of a signal digitization system for implementing a signal digitization method in one embodiment of this application. Referring to Figure 16, the signal digitization system S00 may include a processing component S20, which further includes one or more processors, and memory resources represented by a memory S22 for storing instructions, such as application programs, that can be executed by the processor of the processing component S20. The application programs stored in the memory S22 may include one or more instructions, with each module corresponding to a set of instructions. Furthermore, the processing component S20 is configured to execute instructions to perform the aforementioned signal digitization method.

[0156] The operations and / or methods described in the embodiments of this specification, implemented by a single processor, may also be implemented jointly or independently by multiple processors. For example, if, in this application specification, the processor of the processing device executes steps 1 and 2, it should be understood that steps 1 and 2 may also be executed jointly or independently by two different processors of the processing device (e.g., the first processor executes step 1, the second processor executes step 2, or the first and second processors jointly execute steps 1 and 2).

[0157] The signal digitization system S00 may further include: a power supply component S24 configured to perform power management of the signal digitization system S00; a wired or wireless network interface S26 configured to connect the signal digitization system S00 to a network; and an input / output (I / O) interface S28. The signal digitization system S00 can operate on an operating system stored in memory S22, such as Windows Server, Mac OS X, Unix, Linux, FreeBSD, or similar.

[0158] In an exemplary embodiment, a computer-readable storage medium including instructions is also provided, such as a memory S22 including instructions, which can be executed by a processor of the signal digitization system S00 to perform the above method. The storage medium may be a computer-readable storage medium, such as a ROM, random access memory (RAM), CD-ROM, magnetic tape, floppy disk, and optical data storage device.

[0159] In an exemplary embodiment, a computer program product is also provided, the computer program product including instructions that can be executed by a processor of a signal digitization system S00 to perform the above method.

[0160] In one embodiment, a computer device, which may be a server, is provided. Its internal structure is shown in Figure 17, which is an internal structure diagram of a computer device according to one embodiment of this application. The computer device includes a processor, memory, and a network interface connected via a system bus. The processor provides computing and control capabilities. The memory includes a non-volatile storage medium and internal memory. The non-volatile storage medium stores an operating system, computer programs, and a database. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage medium. The database stores user- and task-related data used in the aforementioned signal digitization method. The network interface communicates with external terminals via a network connection. When the computer program is executed by the processor, it implements a signal digitization method.

[0161] Those skilled in the art will understand that the structure shown in Figure 17 is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0162] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to these.

[0163] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on its differences from other embodiments. In particular, hardware + program embodiments are basically similar to method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments.

[0164] It should be noted that the devices, electronic devices, servers, etc., described above according to the method embodiments may also include other implementation methods, and specific implementation methods can be referred to the description of the relevant method embodiments. Furthermore, new embodiments formed by the combination of features between various methods, devices, and server embodiments still fall within the scope of this application, and will not be elaborated upon here.

[0165] In the description of this specification, the references to "one embodiment," "an embodiment," and / or "some embodiments," "some embodiments," "other embodiments," "ideal embodiments," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative descriptions of the above terms do not necessarily refer to the same embodiment or example, and certain features, structures, or characteristics in one or more embodiments of this specification may be appropriately combined.

[0166] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0167] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

[0168] The basic concepts have been described herein. It is obvious that the detailed disclosure above is merely illustrative and does not constitute a limitation of this specification. Although not explicitly stated herein, various modifications, improvements, and corrections may be made to this specification by those skilled in the art. Such modifications, improvements, and corrections are suggested in this specification and therefore remain within the spirit and scope of the exemplary embodiments described herein.

[0169] Furthermore, those skilled in the art will understand that various aspects of this specification can be described and illustrated in several patentable ways, including any new and useful combinations of processes, machines, products, or substances, or any new and useful improvements thereof. Accordingly, various aspects of this specification can be implemented entirely by hardware, entirely by software (including firmware, resident software, microcode, etc.), or by a combination of hardware and software. All of the above hardware or software may be referred to as a “data block,” “module,” “engine,” “module,” “component,” or “system.” Furthermore, various aspects of this specification may be represented as a computer product located on one or more computer-readable media, including computer-readable program code.

[0170] Computer storage media may contain a propagated data signal containing computer program code, for example, on baseband or as part of a carrier wave. This propagated signal may take various forms, including electromagnetic, optical, and suitable combinations thereof. Computer storage media can be any computer-readable medium other than a computer-readable storage medium, which can be connected to an instruction execution system, apparatus, or device to enable communication, propagation, or transmission of a program for use. The program code located on the computer storage medium can be propagated through any suitable medium, including radio, cable, fiber optic cable, RF, or similar media, or any combination of the above media.

[0171] The computer program code required for the operation of each part of this manual can be written in any one or more programming languages, including object-oriented programming languages ​​such as Java, Scala, Smalltalk, Eiffel, JADE, Emerald, C++, C#, VB.NET, Python, etc.; conventional procedural programming languages ​​such as C, Visual Basic, Fortran 3003, Perl, COBOL 3002, PHP, ABAP; dynamic programming languages ​​such as Python, Ruby, and Groovy; or other programming languages. This program code can run entirely on the user's computer, or as a standalone software package on the user's computer, or partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the latter case, the remote computer can be connected to the user's computer through any network, such as a local area network (LAN) or wide area network (WAN), or connected to an external computer (e.g., via the Internet), or in a cloud computing environment, or used as a service such as Software as a Service (SaaS).

[0172] Furthermore, unless expressly stated in the claims, the order of processing elements and sequences, the use of numbers and letters, or other names described in this specification are not intended to limit the order of the processes and methods described herein. Although various examples have been discussed in the foregoing disclosure of some embodiments of the invention that are currently considered useful, it should be understood that such details are for illustrative purposes only, and the appended claims are not limited to the disclosed embodiments; rather, the claims are intended to cover all modifications and equivalent combinations that conform to the spirit and scope of the embodiments described herein. For example, while the system components described above can be implemented using hardware devices, they can also be implemented solely using software solutions, such as installing the described system on existing servers or mobile devices.

[0173] Similarly, it should be noted that, in order to simplify the description disclosed herein and thus aid in the understanding of one or more embodiments of the invention, the foregoing description of embodiments in this specification may sometimes combine multiple features into a single embodiment, drawing, or description thereof. However, this method of disclosure does not imply that the subject matter of this specification requires more features than those mentioned in the claims. In fact, the embodiments contain fewer features than all the features of a single embodiment disclosed above.

[0174] In some embodiments, numbers describing the quantity of components and attributes are used. It should be understood that such numbers used in the description of embodiments are modified in some examples with the terms "approximately," "approximately," or "generally." Unless otherwise stated, "approximately," "approximately," or "generally" indicates that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximate values, which may be changed depending on the characteristics required by individual embodiments. In some embodiments, numerical parameters should take into account specified significant digits and employ a general method of digit reservation. Although the numerical ranges and parameters used to confirm their breadth of range in some embodiments of this specification are approximate values, in specific embodiments, such values ​​are set as precisely as feasible.

[0175] For each patent, patent application, patent application publication, and other material, such as articles, books, specifications, publications, and documents, referenced in this specification, the entire contents of which are incorporated herein by reference. This excludes historical application documents that are inconsistent with or conflict with the content of this specification, as well as documents that limit the broadest scope of the claims in this specification (currently or subsequently appended to this specification). It should be noted that in the event of any inconsistency or conflict between the descriptions, definitions, and / or terminology used in the supplementary materials to this specification and the content of this specification, the descriptions, definitions, and / or terminology used in this specification shall prevail.

[0176] Finally, it should be understood that the embodiments described in this specification are merely illustrative of the principles of the embodiments described herein. Other variations may also fall within the scope of this specification. Therefore, alternative configurations of the embodiments described herein are intended to be illustrative rather than limiting, and should be considered consistent with the teachings of this specification. Accordingly, the embodiments described herein are not limited to those explicitly introduced and described herein.

Claims

1. A signal digitization method, characterized in that, include: A counting step signal is generated, the waveform of which shows that the amplitude increases stepwise with the number of micro-elements of the excited photoelectric conversion device. The counting step signal is sampled directly to determine the time sequence corresponding to each state change in the counting step signal; The counting step signal is reconstructed based on the time series.

2. The signal digitization method according to claim 1, characterized in that, The generation of the counting step signal includes: When the pulse response signal meets the triggering condition, a unit step signal is output; A counting step signal is generated based on the unit step signal.

3. The signal digitization method according to claim 2, characterized in that, The step signal output when the pulse response signal meets the triggering condition includes: Compare the pulse response signal with the trigger threshold; In response to the comparison result that the pulse response signal is not less than the trigger threshold, a unit step signal is output.

4. The signal digitization method according to claim 3, characterized in that, The unit step signal maintains a 0 output state when the micro-element of the photoelectric conversion device is not excited, and when the micro-element is excited, the amplitude of the unit step signal increases by one unit and maintains the amplitude.

5. The signal digitization method according to claim 3, characterized in that, The triggering conditions include: A preset voltage is established. When the pulse response signal exceeds the preset voltage, the trigger condition is determined to be met, and the unit step signal is output; or A preset waveform characteristic is defined. When the waveform characteristic of the pulse response signal matches the preset waveform characteristic, the trigger condition is determined to be met, and the unit step signal is output.

6. The signal digitization method according to claim 5, characterized in that, The preset waveform features include: The maximum voltage value of the waveform reaches a preset voltage threshold, the current amplitude of the waveform reaches a preset current threshold, or the cumulative voltage of the waveform reaches a preset amplitude.

7. The signal digitization method according to claim 2, characterized in that, The generation of a counted step signal based on the unit step signal includes: The unit step signal is summed to generate the counted step signal.

8. The signal digitization method according to claim 7, characterized in that, The summation process of the unit step signal includes: Multiple unit step signals are summed by an in-phase proportional adder circuit to generate the counted step signal; or The unit step signals output from different rows and columns are summed using an adder circuit to generate the counted step signal; or Each unit step signal is set with a corresponding delay, and then they are summed to form the counted step signal.

9. The signal digitization method according to claim 8, characterized in that, When the micro-element of the photoelectric conversion device is not excited, the amplitude of the counting step signal remains at 0. When one micro-element is excited, the amplitude of the counting step signal increases by one unit and remains at that amplitude. When n micro-elements are excited, the amplitude of the counting step signal increases by n units and remains at that amplitude, where n is a positive integer.

10. The signal digitization method according to claim 1, characterized in that, The step of directly sampling the counting step signal to determine the time series corresponding to each state change in the counting step signal includes: Record the time points and number of amplitude jumps in the counted step signal; The time information of the jumps is formed into a time series based on the number of jumps.

11. The signal digitization method according to claim 10, characterized in that, The time series includes: the time point information corresponding to each jump of the counting step signal, the jump count information formed by statistically analyzing all time point information, and the source physical address information corresponding to each counting step signal.

12. The signal digitization method according to claim 1, characterized in that, The step of reconstructing the counting step signal based on the time series includes: Determine the physical model corresponding to the counting step signal; The counting step signal is reconstructed based on the physical model and the time series.

13. The signal digitization method according to claim 2, characterized in that, After reconstructing the counting step signal based on the time series, the signal digitization method further includes: The output reset signal clears the pulse response signal to zero.

14. A signal digitization method, characterized in that, include: Multiple channels generate counting step signals respectively, and the waveform of the counting step signals shows that the amplitude increases stepwise with the number of micro-elements of the excited photoelectric conversion device. The time series corresponding to the state changes of the counting step signal in each channel are determined synchronously and in parallel. The counting step signal is reconstructed based on the time series.

15. A signal digitization device, characterized in that, include: A counting step signal generation unit is configured to generate a counting step signal, wherein the waveform of the counting step signal shows that the amplitude increases in a stepwise manner with the number of micro-elements of the excited photoelectric conversion device. A sampling unit is configured to directly sample the counting step signal and determine the time sequence corresponding to each state change in the counting step signal; as well as A reconstruction unit configured to reconstruct the counting step signal based on the time series.

16. The signal digitization device according to claim 15, characterized in that, The counting step signal generation unit includes: Multiple detection modules are used to output a pulse response signal when a photon is detected, and to output a unit step signal when the pulse response signal reaches the trigger condition; The signal processing module is connected to multiple detection modules and is used to generate a counted step signal based on the unit step signal.

17. The signal digitization device according to claim 16, characterized in that, The detection module includes: The photon detection submodule is used to output a pulse response signal when a photon is detected; The threshold comparison submodule, connected to the photon detection submodule, is used to output the unit step signal when the pulse response signal reaches the trigger condition.

18. The signal digitization device according to claim 16, characterized in that, The triggering conditions include: A preset voltage is established. When the pulse response signal exceeds the preset voltage, the trigger condition is determined to be met, and the unit step signal is output; or A preset waveform characteristic is defined. When the waveform characteristic of the pulse response signal matches the preset waveform characteristic, the trigger condition is determined to be met, and the unit step signal is output.

19. The signal digitization device according to claim 18, characterized in that, The preset waveform features include: The maximum voltage reaches the preset voltage threshold, the current amplitude reaches the preset current threshold, or the cumulative voltage reaches the preset amplitude.

20. The signal digitization device according to claim 17, characterized in that, The photon detection submodule includes: A single-photon avalanche diode, wherein the cathode of the single-photon avalanche diode is connected to an externally input reverse-biased voltage; The quenching diode has its drain connected to the anode of the single-photon avalanche diode, its source grounded, and its gate connected to an externally input DC voltage.

21. The signal digitization device according to claim 16, characterized in that, The signal processing module includes: The in-phase proportional adder circuit is connected to multiple detection modules respectively, and is used to sum the unit step signal to generate the count step signal.

22. The signal digitization device according to claim 21, characterized in that, Each of the aforementioned detection modules is connected to the signal input terminal of the in-phase proportional adder circuit through a corresponding input resistor, wherein the resistance value of each input resistor is the same.

23. The signal digitization device according to claim 22, characterized in that, The in-phase proportional adder circuit includes an operational amplifier, a feedback resistor, and a grounding resistor. The output terminal of each detection module is connected to the input resistor and then to the positive input terminal of the operational amplifier. One end of the feedback resistor is connected to the positive input terminal of the operational amplifier, and the other end is connected to the output terminal of the operational amplifier. The negative input terminal of the operational amplifier is grounded through the grounding resistor.

24. The signal digitization device according to claim 15, characterized in that, The sampling unit includes: A time-to-digital converter, configured to record the timing information of each amplitude jump in the counting step signal; A storage module is connected to the time-to-digital converter and is configured to package the time information and the address information of the corresponding channel and output them in the form of a time series.

25. The signal digitization device according to claim 16, characterized in that, The signal digitization device also includes: The reset module is used to output a reset signal to clear the pulse response signal.

26. The signal digitization device according to any one of claims 15-25, characterized in that, Also includes: A transmission unit, connected to the sampling unit, is configured to transmit the acquired digital sampling signal.

27. The signal digitization device according to any one of claims 15-25, characterized in that, The reconstruction unit includes: The modeling module is used to determine the physical model corresponding to the counting step signal; The data processing module, connected to the modeling module, is configured to perform signal recovery processing on the time series based on the physical model to restore the counting step signal.

28. The signal digitization device according to claim 27, characterized in that, The reconstruction unit also includes: The data conversion module, connected to the data processing module, is used to convert the counting step signal into counting information per unit time.

29. A signal digitization device, characterized in that, include: Multiple counting step signal generation units are configured to generate counting step signals, wherein the waveform of the counting step signals shows that the amplitude increases in a stepwise manner with the number of micro-elements of the excited photoelectric conversion device. A sampling unit is connected to the counting step signal generation unit. The sampling unit is configured to directly sample the counting step signal and determine the time sequence corresponding to each state change in the counting step signal. as well as A reconstruction unit is connected to the sampling unit, and the reconstruction unit is configured to reconstruct the counting step signal according to the time series.

30. The signal digitization device according to claim 29, characterized in that, The sampling unit includes multiple TDCs and a storage module. The multiple counting step signal generation units are respectively connected to the same storage module through the TDCs, and the storage module is connected to the reconstruction unit.

31. A signal digitization device, characterized in that, include: Multiple detection modules, each of which includes multiple counting step signal generation units, the counting step signal generation units being configured to generate counting step signals; Multiple sampling units, each of which is connected to multiple counting step signal generation units in the same detection module, wherein the sampling unit is configured to directly sample the counting step signal and determine the time sequence corresponding to each state change in the counting step signal; as well as A reconstruction unit is connected to the sampling unit, and the reconstruction unit is configured to reconstruct the counting step signal according to the time series.

32. The signal digitization device according to claim 31, characterized in that, The sampling unit includes multiple TDCs and a storage module. The multiple counting step signal generation units in each of the detection modules are respectively connected to the same storage module through the TDC, and the multiple storage modules are respectively connected to the reconstruction unit.

33. A computer storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the signal digitization method according to any one of claims 1 to 14.

34. A computer program product, comprising a computer program or instructions, characterized in that, When the computer program or instructions are executed by a processor, they implement the steps of the signal digitization method according to any one of claims 1 to 14.

35. A digital PET system, characterized in that, Includes the signal digitization device as described in any one of claims 15-32.

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