CN119363116A

CN119363116A - Signal digitization method, device, computer storage medium and digital PET system

Info

Publication number: CN119363116A
Application number: CN202411910892.9A
Authority: CN
Inventors: 张博; 房磊; 李炳轩; 胡云; 朱标; 陈维操
Original assignee: Hefei Ruishi Digital Technology Co ltd
Current assignee: Hefei Ruishi Digital Technology Co ltd
Priority date: 2024-12-24
Filing date: 2024-12-24
Publication date: 2025-01-24

Abstract

The present application discloses a signal digitization method, device, computer storage medium and digital PET system. The signal digitization method includes: generating a counting step signal, the waveform of the counting step signal is shown as an amplitude that increases in a step-like manner with the number of microelements of the photoelectric conversion device that is excited; directly sampling the counting step signal to determine the time series corresponding to each state change in the counting step signal; and restoring the counting step signal according to the time series. The present application generates a counting step signal to replace the analog output scintillation pulse signal in the prior art, so that the incident photon sequence can be directly sampled with TDC, the time series of incident photon excitation can be recorded, the incident photons can be directly digitized and read out in the form of digital signals, the original information of the incident photon sequence is preserved to the greatest extent, and additional external digitization devices are saved, so that the system performance is improved while the cost is further reduced.

Description

Signal digitizing method, device, computer storage medium and digital PET system

Technical Field

The present invention relates to the field of medical imaging technologies, and in particular, to a signal digitizing method, apparatus, computer storage medium, and digital PET system.

Background

In positron emission tomography (Positron emission tomography, PET), gamma rays are converted by a scintillation crystal into a visible light signal, which is further converted by a photoelectric conversion device into a scintillation pulse signal, which is then sampled and processed to obtain a series of application images. In this process, the digitized quality of the scintillation pulse has a significant impact on the final imaging quality.

In the traditional PET digitizing process, a PMT (Photomultiplier tube, photomultiplier) is adopted to convert visible light signals converted by a scintillation crystal into analog electric signals, then filtering, shaping, amplifying, integrating and coincidence processing are carried out on the signals through a matched logic circuit, and coincidence events are further sent to a computer in a digitizing mode for image reconstruction. Compared with the traditional PET, the digital PET technology adopts a more efficient SiPM (Silicon photomultiplier ) to carry out photoelectric conversion, adopts a Multi-voltage threshold sampling (Multi-Voltage Threshold, MVT) method to directly digitize signals at the source of pulse sampling, and then utilizes a software algorithm to replace the traditional analog circuit to extract information and carry out image reconstruction. As shown in fig. 1, since the scintillation pulse signal in PET tends to have 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 generally obtained through TDCs (Time to digital converter, time-to-digital converter), one of the TDCs in each path is used to convert the time (T ₁、T₂、T₃、T₄) when the scintillation pulse crosses the corresponding threshold (V ₁、V₂、V₃、V₄) at the rising edge, and the other TDC is used to convert the time (T ₅、T₆、T₇、T₈) when the scintillation pulse is below the threshold at the falling edge, so that the waveform information of the scintillation pulse is inverted according to the corresponding voltage-time pair （V₁、T₁）、（V₂、T₂）、（V₃、T₃）、（V₄、T₄）、（V₄、T₅）、（V₃、T₆）、（V₂、T₇）、（V₁、T₈） information.

However, in the prior art digital PET technology, because SiPM is an integrated circuit-based photodetector, it includes an array of single photon avalanche diodes (Single Photon Avalanche Diode, also called Micro cells, abbreviated as MC), each of which is a photo-sensing pixel, and corresponding ancillary circuitry. The SiPM adopts a bias voltage application mode to make the MC operate in the geiger mode, and each MC has a state of only 1 or 0, which is essentially a digital signal, however, the actual operation thereof is to accumulate hundreds to thousands of binary signals of the MC to form an analog scintillation pulse signal output, and the digitizing of the final signal is completed outside the SiPM by the MVT method. On the other hand, the electronic components adopted in the digital circuit matched with the MVT method still have room for further optimization, and the overall processing efficiency of the system still has room for improvement, thereby further reducing the power consumption and the cost of the system.

Disclosure of Invention

Based on this, it is necessary to provide a signal digitizing method, apparatus, computer storage medium and digital PET system for at least one technical problem of the conventional scheme.

According to a first aspect of the application, a signal digitizing method is provided, comprising the steps of generating a counting step signal, wherein the waveform of the counting step signal is represented as a stepwise increase of amplitude along with the number of the micro elements of an excited photoelectric conversion device, directly sampling the counting step signal, determining a corresponding time sequence when each state in the counting step signal changes, and restoring the counting step signal according to the time sequence.

According to one embodiment of the application, the generating the count step signal includes outputting a unit step signal when the impulse response signal satisfies a trigger condition, and generating the count step signal based on the unit step signal.

According to one embodiment of the application, when the impulse response signal meets the trigger condition, the unit step signal is output, and the unit step signal is output according to the comparison result that the impulse response signal is not smaller than the trigger threshold value.

According to an embodiment of the present application, the unit step signal maintains a 0 output state when the micro element of the photoelectric conversion device is not excited, and the magnitude of the unit step signal rises by one unit and maintains the magnitude when the micro element is excited.

According to one embodiment of the application, the triggering condition comprises the steps of presetting a voltage, judging that the triggering condition is met when the impulse response signal is larger than the preset voltage, and outputting the unit step signal, or presetting a waveform characteristic, judging that the triggering condition is met when the waveform characteristic of the impulse response signal meets the preset waveform characteristic, and outputting the unit step signal.

According to one embodiment of the application, the preset waveform characteristics comprise that the maximum voltage value of the waveform reaches a preset voltage threshold value, the current amplitude value of the waveform reaches a preset current threshold value, or the accumulated voltage of the waveform reaches a preset amplitude value.

According to one embodiment of the application, the generating the count step signal based on the unit step signal includes summing the unit step signal to generate the count step signal.

According to one embodiment of the application, the unit step signals are added and processed, wherein the unit step signals are added and output through an in-phase proportion adding circuit to generate the counting step signals, or the unit step signals output correspondingly in different rows and columns are added and output through an adding circuit to generate the counting step signals, or the unit step signals are set with corresponding time delays and then added and processed to form the counting step signals.

According to one embodiment of the present application, when the micro-element of the photoelectric conversion device is not excited, the magnitude of the counting step signal is kept in a 0 state, when one of the micro-elements is excited, the magnitude of the counting step signal rises by one unit and is kept, and when n of the micro-elements are excited, the magnitude of the counting step signal rises by n units and is kept, and n is a positive integer.

According to one embodiment of the application, the step counting signal is directly sampled, and the corresponding time sequence of each state change in the step counting signal is determined, wherein the step counting signal comprises the steps of recording the time point of the jump of the amplitude value in the step counting signal and the jump times, and forming the time sequence according to the jump times.

According to one embodiment of the application, the time sequence comprises time point information corresponding to each jump of the counting step signal, jump frequency information formed by statistics of all time point information and source physical address information corresponding to each counting step signal.

According to one embodiment of the application, the step signal recovery according to the time sequence comprises determining a physical model corresponding to the step signal, and recovering the step signal according to the physical model and the time sequence.

According to one embodiment of the application, the signal digitizing method further comprises outputting a reset signal to zero out the impulse response signal after recovering the count step signal according to the time series.

According to a second aspect of the application, a signal digitizing method is provided, which comprises the steps of generating counting step signals by multiple channels respectively, wherein the waveform of the counting step signals is represented by stepwise increasing the amplitude along with the number of the micro elements of an excited photoelectric conversion device, synchronously and parallelly determining the time sequences corresponding to the state changes of the counting step signals in the channels respectively, and restoring the counting step signals according to the time sequences.

According to a third aspect of the present application, there is provided a signal digitizing apparatus comprising a count step signal generating unit configured to generate a count step signal, the waveform of the count step signal exhibiting a stepwise increase in amplitude with the number of micro-elements of an excited photoelectric conversion device, a sampling unit configured to directly sample the count step signal and determine a corresponding time sequence for each state change in the count step signal, and a reconstruction unit configured to restore the count step signal according to the time sequence.

According to one embodiment of the application, the counting step signal generating unit comprises a plurality of detecting modules and a signal processing module, wherein the detecting modules are used for outputting impulse response signals when photons are detected, and outputting unit step signals when the impulse response signals reach a trigger condition, and the signal processing module is respectively connected with the detecting modules and used for generating the counting step signals based on the unit step signals.

According to one embodiment of the application, the detection module comprises a photon detection sub-module and a threshold comparison sub-module, wherein the photon detection sub-module is used for outputting an impulse response signal when photons are detected, and the threshold comparison sub-module is connected with the photon detection sub-module and is used for outputting the unit step signal when the impulse response signal reaches a trigger condition.

According to one embodiment of the application, the preset waveform characteristics comprise that the maximum voltage value reaches a preset voltage threshold value, the current amplitude reaches a preset current threshold value, or the accumulated voltage reaches a preset amplitude value.

According to one embodiment of the application, the photon detection submodule comprises a single photon avalanche diode, a quenching tube and a quenching tube, wherein the cathode of the single photon avalanche diode is connected with an externally input reverse bias voltage, the drain electrode of the quenching tube is connected with the anode of the single photon avalanche diode, the source electrode of the quenching tube is grounded, and the grid electrode of the quenching tube is connected with an externally input direct current voltage.

According to one embodiment of the application, the signal processing module comprises an in-phase proportional addition circuit which is respectively connected with the detection modules and is used for adding and processing the unit step signals to generate the counting step signals.

According to one embodiment of the present application, the plurality of detection modules are respectively connected to the signal input end of the in-phase proportional addition circuit through corresponding input resistors, wherein the resistance value of each input resistor is the same.

According to one embodiment of the application, the in-phase proportional addition circuit comprises an operational amplifier, a feedback resistor and a grounding resistor, wherein the output end of each detection module is connected with the input resistor in a one-to-one correspondence manner and is connected with the positive input end of the operational amplifier, one end of the feedback resistor is connected with the positive input end of the operational amplifier, the other end of the feedback resistor is connected with the output end of the operational amplifier, and the negative input end of the operational amplifier is grounded through the grounding resistor.

According to one embodiment of the application, the sampling unit comprises a time-to-digital converter and a storage module, wherein the time-to-digital converter is configured to record time information of each jump of the amplitude value in the counting step signal, and the storage module is connected with the time-to-digital converter and is configured to package the time information and address information of a corresponding channel and output the time information and the address information of the corresponding channel in a time sequence mode.

According to one embodiment of the application, the signal digitizing device further comprises a reset module for outputting a reset signal to zero the impulse response signal.

According to one embodiment of the application, the signal digitizing apparatus further comprises a transmission unit, coupled to the sampling unit, configured for transmitting the acquired digitized sampled signal.

According to one embodiment of the application, the reconstruction unit of the signal digitizing device comprises a modeling module and a data processing module, wherein the modeling module is used for determining a physical model corresponding to the counting step signal, and the data processing module is connected with the modeling module and is configured to perform signal recovery processing on the time sequence based on the physical model and restore the counting step signal.

According to one embodiment of the application, the reconstruction unit further comprises a data conversion module connected with the data processing module for converting the count step signal into count information per unit time.

According to a fourth aspect of the present application, there is provided a signal digitizing apparatus comprising a plurality of count step signal generating units configured to generate count step signals whose waveforms appear to increase in magnitude stepwise with the number of micro-elements of an excited photoelectric conversion device, sampling units respectively connected to the count step signal generating units, the sampling units configured to directly sample the count step signals and determine a corresponding time sequence for each state change in the count step signals, and reconstruction units respectively connected to the sampling units, the reconstruction units configured to restore the count step signals according to the time sequences.

According to one embodiment of the present application, the sampling unit includes a plurality of TDCs and a storage module, the plurality of count step signal generating units are respectively connected to the same storage module through the TDCs, and the storage module is connected to the reconstruction unit.

According to a fifth aspect of the present application, there is provided a signal digitizing apparatus comprising a plurality of detection modules, each detection module comprising a plurality of count step signal generating units configured to generate count step signals, a plurality of sampling units, each sampling unit being connected to a plurality of the count step signal generating units in the same detection module, the sampling units being configured to directly sample the count step signals and to determine a corresponding time sequence for each state change in the count step signals, and a reconstruction unit, the reconstruction units being respectively connected to the sampling units, the reconstruction unit being configured to recover the count step signals according to the time sequences.

According to one embodiment of the present application, the sampling unit includes a plurality of TDCs and a storage module, the plurality of count step signal generating units in each of the detecting modules are respectively connected to the same storage module through the TDCs, and the plurality of storage modules are respectively connected to the reconstruction unit.

According to a sixth aspect of the present application there is provided a computer storage medium having stored thereon a computer program which when executed by a processor implements the steps of the signal digitisation method as described above.

According to a seventh aspect of the present application there is provided a computer program product comprising a computer program or instructions which, when executed by a processor, implement the steps of a signal digitising method as described above.

According to a seventh eighth aspect of the present application there is provided a digital PET system comprising a signal digitizing means as described above.

According to the signal digitizing method, device, computer storage medium and digital PET system provided by the application, the counting step signal is generated to replace the scintillation pulse signal which is output in the prior art in an analog manner, so that the incident photon sequence can be directly sampled by the TDC, the time sequence of the excitation of the incident photon is recorded, the direct digitization of the incident photon is realized, the original information of the incident photon sequence is read out in the form of a digital signal, the original information of the incident photon sequence is stored to the greatest extent, the complex process of integrating the signals output by the microelements into the analog scintillation pulse signal output and then sampling is avoided, and an additional external digitizing device is saved, so that the cost is reduced to a certain extent while the system performance is improved.

Drawings

In order to more clearly illustrate the embodiments of the present description or the technical solutions in the prior art, the following description will briefly explain the embodiments or the drawings needed in the description of the prior art, and it is obvious that the drawings in the following description are only some embodiments described in the present description, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.

FIG. 1 is a diagram of the prior art for digitizing a scintillation pulse signal;

FIG. 2 is a flow chart of a method for digitizing signals according to one embodiment of the application;

FIG. 3 is a flow chart of outputting a count step signal according to one embodiment of the present application;

FIG. 4 is a schematic diagram of counting step signals in one embodiment of the application;

FIG. 5 is a flow chart of the acquisition forming time sequence according to one embodiment of the application;

FIG. 6 is a schematic diagram illustrating a process of recovering a count step signal according to one embodiment of the present application;

FIG. 7 is a flowchart of a signal digitizing method according to another embodiment of the application;

FIG. 8 is a schematic diagram of a signal digitizing apparatus according to one embodiment of the application;

FIG. 9 is a schematic diagram of a photoelectric conversion device in a signal digitizing apparatus according to one embodiment of the application;

FIG. 10 is a schematic diagram of a signal processing module in the signal digitizing apparatus according to FIG. 9;

FIG. 11 is a schematic diagram of a signal digitizing apparatus according to one embodiment of the application;

FIG. 12 is a schematic diagram of a signal digitizing apparatus according to one embodiment of the application;

FIG. 13 is a schematic diagram of a signal digitizing apparatus according to one embodiment of the application;

FIG. 14 is a schematic diagram of a signal digitizing apparatus according to one embodiment of the application;

FIG. 15 is a schematic diagram of a signal digitizing apparatus according to one embodiment of the application;

FIG. 16 is a schematic diagram of a digitizing system for implementing a signal digitizing method according to another embodiment of the application;

fig. 17 is an internal structural view of a computer device according to one embodiment of the present application.

Detailed Description

In order that the above-recited objects, features and advantages of the present application will become more readily apparent, a more particular description of the application will be rendered by reference to the appended drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. The present application may be embodied in many other forms than described herein and similarly modified by those skilled in the art without departing from the spirit of the application, whereby the application is not limited to the specific embodiments disclosed below.

It will be understood that when an element is referred to as being "mounted" to another element, it can be directly mounted to the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "left," "right," and the like are used herein for illustrative purposes only.

Unless defined otherwise, 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 the application. The term "and/or" and/or "as used herein includes any and all combinations of one or more of the associated listed items.

In the prior digital PET technology, siPM with better photoelectric conversion performance is generally adopted as a photoelectric conversion device, each micro element in the SiPM is made to work in a Geiger mode by applying bias voltage, binary signals generated by hundreds to thousands of micro elements are accumulated to form an Analog scintillation pulse signal output in actual work, and devices/instruments other than the SiPM, such as an ADC (Analog-to-digital converter ) sampling circuit and a multi-voltage threshold (Multiple Voltage Threshold, MVT) acquisition card, digitize and reconstruct the SiPM signal, thereby extracting the charge quantity and arrival time information of the original SiPM signal and deducing the total number and arrival time of incident photons. However, the prior art essentially treats the binary signal (only 0 and 1 states of the infinitesimal) which is digitized as an analog signal, adds up, and then digitizes the binary signal, wherein the digital-analog-digital conversion process causes the original information of the incident photon sequence to be lost, and the incident photon time sequence cannot be recovered from the analog SiPM signal. In addition, hundreds to thousands of MC binary signals are accumulated to form an analog signal output, resulting in a series of analog signal processing circuits and analog-to-digital conversion circuits external to the SiPM to complete the digitization and reconstruction of the final signal, and the complexity of the circuits results in difficulty in further reduction of power consumption and volume, and in further breakthrough of system performance.

Aiming at the technical problems in the prior art, the application provides a signal digitizing method and device capable of further improving the system performance and matched application.

In some embodiments, the signal digitizing method may be performed by a signal digitizing apparatus. For example, the signal digitizing method may be stored in a storage device (e.g., a self-contained memory module of the detection device or an external memory device) in the form of a program or instructions that, when executed, implement the signal digitizing method. The signal digitizing apparatus for implementing the signal digitizing method disclosed in the present application may be a device (for example, a computer, a server, a cloud computing device, etc.) having a large amount of computing resources, or may be a device (for example, a hardware Circuit such as an FPGA (Field Programmable GATE ARRAY, programmable gate array) chip board, an ASIC (Application-SPECIFIC INTEGRATED Circuit) chip board, etc.) having limited computing resources.

Some preferred embodiments of the present application are described below with reference to the accompanying drawings. It should be noted that the following description is for illustrative purposes and is not intended to limit the scope of the present application.

Fig. 2 is a flow chart of a signal digitizing method according to one embodiment of the application, in which the signal digitizing method 200 may include the following steps 210 to 250.

Step 210, generating a counting step signal, wherein the waveform of the counting step signal is shown that the amplitude increases stepwise with the number of the micro-elements of the excited photoelectric conversion device.

Typically, the generation of the count step signal is implemented by a silicon photomultiplier (SiPM), where the SiPM includes a plurality of microelements, each of which can be excited in response to an incident high-energy photon and output a unit step signal, for example, the SiPM may include an array of several single photon avalanche diodes (Single Photon Avalanche Diode) or avalanche diodes (APDs) and corresponding auxiliary circuits, where each single photon avalanche diode or avalanche diode and its corresponding electronic component is a microcell, and how the generation of the count step signal by the unit step signal output by the plurality of microcells of the SiPM is further described in conjunction with the circuit structure in the device embodiment below, which is not repeated herein.

The waveform of the counting step signal shows that the amplitude increases stepwise with the number of the micro-elements of the excited photoelectric conversion device, for example, when the micro-elements are not excited, the voltage output state is always kept at 0, when one micro-element is excited, the amplitude of the counting step signal rises by one unit and keeps the amplitude, for example, the voltage amplitude rises by one unit for 4mV, when 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 rises by n units and keeps the amplitude, in other words, the total amplitude of the counting step signal divided by the amplitude of the unit step signal at a certain moment t represents the total number of the excited micro-elements in the SiPM at a cut-off moment.

In this embodiment, the counting step signal includes the number of excited microelements, or includes the number of generated unit step signals, and different statistical methods may be used to obtain the counting step signal based on the unit step signal. For example, a counter may be used to count the received count step signals to obtain the number of unit step signals, or scaling the magnitude of the received count step signals may be used to obtain the number of unit step signals.

Step 230, directly sampling the counting step signal, and determining the corresponding time sequence when each state in the counting step signal changes.

Since the counting step signal is formed by a plurality of unit step signals, the waveform is represented as a unit amplitude value which is increased by one unit amplitude value corresponding to the amplitude value of the waveform at each jump along with the increase of the number of the unit step signals, and the waveform is in a ladder shape as a whole. Therefore, unlike the scintillation pulse with relatively fast rising edge and slow falling edge in the prior art, the counting step signal has obvious amplitude jump points, and the time information of the signal amplitude jump can be directly recorded through a time-to-digital converter (TDC), and then the time information corresponding to each jump point is output in a time sequence mode. For example, a certain count step signal cumulatively includes 9 hops, and the amplitude of each hop is a unit amplitude, for example, 3mV, but the time corresponding to each hop may or may not be uniformly distributed, for example, the time corresponding to 9 hops is 10ps, 25ps, 35ps, 45ps, 60ps, 80ps, 90ps, 110ps and 120ps, respectively, and when the count step signal is sampled, the output time sequence is the time information sequence corresponding to each hop.

And 250, restoring the counting step signal information according to the time sequence.

In the present application, for different kinds of high-energy photons, such as gamma photons or neutrons, the amplitude of the unit step signal generated by different types of microelements in the SiPM may be different, for example, for gamma photons, the amplitude of the unit step signal may be 3mV, for neutrons, how much specific amplitude of the unit step signal may be 5mV may be determined according to previous experiments, and it should be clear to those skilled in the art that once the corresponding parameters of the high-energy photon type, the SiPM production process, the material, the type of microelement quenching, etc. are determined, the amplitude of the unit step signal generated after the single microelements are excited is fixed accordingly, which is not repeated herein.

After the amplitude of the unit step signal is determined according to the experiment and the prior physical model, the information of the count step signal can be restored according to the time sequence information acquired in the steps, namely, the signal waveform can be raised by one unit amplitude and kept at each amplitude jumping time point through computer software until the next jumping time point, and the signal waveform is raised by one unit amplitude and kept until the last jumping time point.

For further understanding of the signal digitizing method provided by the present application, the following description will refer to fig. 3-6.

As shown in fig. 3, the generating the count step signal may further include the following steps 211 to 212.

Step 211, outputting a unit step signal when the impulse response signal meets the trigger condition.

Without photon incidence, the bins in the array of bins of the SiPM are in an unexcited state (i.e., equivalent to 0 in binary) regardless of dark counts. When a photon train enters the SiPM, a portion of the bins are excited (i.e., corresponding to 1 in binary) and an impulse response signal is generated. In this embodiment, the triggering condition is set to assist in determining whether the micro-element receives a photon. When the impulse response signal meets the triggering condition, judging that the infinitesimal receives photons and outputting a unit step signal. The problems of false reading and the like of the infinitesimal caused by noise interference and the like can be reduced by presetting the triggering conditions.

In some specific embodiments, the trigger condition may be set according to different application scenarios. For example, a preset voltage can be correspondingly set on the infinitesimal, the photon acts with the infinitesimal to generate an impulse response signal, when the impulse response signal is larger than the preset voltage, the trigger condition is judged to be met, and a unit step signal is output, or when the waveform of the impulse response signal meets the preset characteristics, the trigger condition is judged to be met, for example, the maximum voltage value reaches a preset voltage threshold value, the current amplitude reaches a preset current threshold value, or after the accumulated voltage reaches a certain amplitude value, the unit step signal is output.

More specifically, when the voltage is preset, the micro-cells may be correspondingly connected to a comparison module, and the preset voltage of the comparison module is provided through a digital-to-analog converter integrated on the micro-cell chip. When the photon is detected by the microcell, an impulse response signal is output, the impulse response signal is transmitted into the comparison module, and when the amplitude of the impulse response signal reaches a preset voltage, the comparison module outputs a unit step signal. Similarly, when the current threshold value or a certain amplitude value is preset, the current threshold value or the certain amplitude value can be realized through corresponding electronic devices, which belongs to the technical field, and is easily realized according to the teaching of the present application, and is not repeated here.

The output unit step signal has the characteristics that when a microcell is not excited, the output state of 0 voltage is always kept, and when one microcell is excited, the amplitude of the unit step signal rises by one unit and keeps the amplitude, for example, the voltage amplitude rises by one unit of 4mV.

Specifically, when the impulse response signal satisfies the trigger condition, outputting the unit step signal may include steps 2111 to 2112 as follows.

Step 2111, comparing the impulse response signal to a trigger threshold.

In this embodiment, a trigger threshold may be set, and the magnitude of the trigger threshold and the magnitude of the impulse response signal are compared to assist in determining whether the micro element receives a valid photon, for example, when the method is applied to gamma photon detection, the magnitude of the impulse response signal generated by a single gamma photon is often the same, the trigger threshold may be set to be slightly lower than the magnitude by a digital-to-analog converter, and the impulse response signal output by the micro element is input into a comparison module and compared with the trigger threshold preset in the comparison module.

Step 2112, outputting a unit step signal in response to the comparison result that the impulse response signal is not less than the trigger threshold.

When the impulse response signal is greater than or equal to the trigger threshold, it may be determined that the impulse response signal satisfies the trigger condition, that is, in the present embodiment, a comparison result that the impulse response signal is greater than or equal to the trigger threshold may be defined as the trigger condition. A unit step signal may be output in response to a comparison of the impulse response signal being greater than or equal to the trigger threshold. Specifically, when any one of the infinitesimal detects a photon, an impulse response signal is output. The trigger threshold, when embodied, may be a trigger voltage V _t. The impulse response signal is transmitted to the comparator, and when the amplitude of the impulse response signal reaches the trigger voltage V _t, the comparator outputs a unit step signal.

Step 212, generating a count step signal based on the unit step signal.

Typically, sipms comprise an array of m×n (m and n are both non-zero natural numbers) microelements and corresponding auxiliary circuits, each element will generate an impulse response signal correspondingly after detecting a photon, and the impulse response signal will output a unit step signal when meeting a trigger condition, so that the array of microelements can output a plurality of unit step signals when detecting.

The counting step signals are formed after a plurality of unit step signals are output in a certain form, for example, the unit step signals output by each microcell are added through an in-phase proportional adding circuit and then output to form the counting step signals, or the unit step signals output by a certain row and a certain column of corresponding microcells are added through an adding circuit and then output to form the counting step signals, or the unit step signals output by each microcell are set with corresponding delay and then added directly to form the counting step signals. For how to output the count step signal through the adder circuit, reference may be made to the embodiment of the apparatus of the present application, and details thereof will not be repeated here.

In one embodiment, the step of generating the count step signal based on the unit step signal may specifically include adding the unit step signal to obtain the count step signal. The nature of the generated count step signal will be further described in connection with fig. 4. In fig. 4, when a bin is not excited, it always maintains a 0 voltage output state, and the counting step signal has no output, and the amplitude is always 0 before time t ₁, when a bin is excited, the bin outputs a unit step signal, the amplitude of which is for example 4mV, and at this time, the amplitude of the counting step signal is also increased by one unit and kept at the amplitude, the amplitude is equal to the amplitude of the unit step signal, that is, at time t ₁, the amplitude of the counting step signal is increased by n ₁, and when two bins are excited, the amplitude of the counting step signal is increased by two units and kept at the amplitude, that is, at time t ₂, the amplitude of the counting step signal is increased by n ₂, and similarly, at times t ₃ and t ₄, the amplitude of the counting step signal is increased by n ₃ and n ₄, respectively. It is noted that, in the present application, the time when the micro-element is excited defaults to the time when the counting step signal jumps, and the same micro-element cannot be excited twice at the same time.

Further, as shown in fig. 5, the counting step signal is directly sampled, and the corresponding time sequence of each state change in the counting step signal is determined, which may further include the following steps 231 to 232.

And 231, recording the time point when the amplitude value in the counting step signal jumps and the jump times.

The waveform of the scintillation pulse in the prior art has a relatively fast rising edge and a slow falling edge, and the waveform exhibits a continuously varying pattern. Unlike the prior art, the counting step signal has an obvious amplitude jump point, and is shown as a unit amplitude value corresponding to the increase of the amplitude value of the waveform in each jump along with the increase of the number of the unit step signals, and the waveform is in a ladder shape as a whole. Therefore, the time information of the signal amplitude jump can be directly recorded through a time-to-digital converter (TDC), then the time information corresponding to each jump point is sequentially output, and the recorded jump time is the number of times of counting the jump of the step signal amplitude.

And 232, forming a time sequence of the jump time information according to the jump times.

The TDC can record the time information at the moment of signal amplitude change, the recorded time information after a complete counting step signal is collected is arranged according to the sequence, and a time sequence to be output is formed, wherein the time sequence comprises at least three information, namely time point information corresponding to each jump of the counting step signal, jump frequency information formed by statistics of all the time point information and physical address information corresponding to each SiPM.

Further, as shown in fig. 6, the step signal is recovered according to the time sequence, and the following steps 251 to 252 may be further included.

Step 251, determining a physical model corresponding to the counting step signal.

For different kinds of high-energy photons, such as gamma photons or neutrons, the amplitude of the unit step signal generated by different types of microelements in the SiPM may be different, for example, for gamma photons, the amplitude of the unit step signal may be 3mV, for neutrons, the amplitude of the unit step signal may be 5mV, and how much specific amplitude is can be determined according to previous experiments, it should be clear to those skilled in the art that once the corresponding parameters of the high-energy photon type, the SiPM production process, the material, the type of microelement quenching and the like are determined, the amplitude of the unit step signal generated after the single microelements are excited is fixed accordingly.

Therefore, the physical model that the counting step signal meets can be determined according to the type of high-energy photon (such as gamma photon and neutron), the production process of SiPM (such as P-N junction design and packaging), the micro-element material (such as avalanche diode and single photon avalanche diode), the matched quenching mode (such as resistance quenching or transistor controllable quenching), and the corresponding parameters of the unit step signal output circuit, once the related parameters are determined, the amplitude of each jump in the counting step signal can be determined according to the physical model. The physical model may be determined through a number of experiments, a priori knowledge, or simulations.

Step 252, recovering the count step signal according to the physical model and the time sequence.

After the amplitude of the unit step signal is determined, the information of the count step signal can be restored according to the time sequence information acquired in the steps, for example, the signal waveform is raised by one unit amplitude and kept at the time point of each amplitude jump through computer software until the next jump time point, and the signal waveform is raised by one unit amplitude and kept until the last jump time point.

Since the count step signal contains information on the number of unit step signals received, direct digitization of the SiPM incident photon sequence can be achieved using a digitization process.

The signal digitizing method provided by the application can directly digitize and output counting step signal information, does not need to set a plurality of thresholds to collect analog scintillation pulse signals, saves an additional external digitizing device, and stores the original information of the incident photon sequence to the greatest extent. The external computer can digitize the sampled signal in combination with a priori information about the sequence of incident photons, and accurately reconstruct the time sequence of incident photons by an algorithm.

In a further embodiment of the present application, after the step count signal is digitized and the digitized sample signal is output, the signal digitizing method may further include outputting a reset signal to zero the impulse response signal. Namely, after the current SiPM detection flow is completed, a reset signal is output to clear the micro element count completely, and the next detection is waited.

According to the signal digitizing method provided by the application, the counting step signal is used for replacing the scintillation pulse signal which is output in the analog in the prior art, so that the incident photon sequence can be directly sampled, the time sequence of the excitation of the incident photon is recorded, the direct digitization of the incident photon is realized, the direct reading of the incident photon sequence is realized in the form of a digital signal, the original information of the incident photon sequence is stored to the greatest extent, the complex process of integrating the signal which is output by the micro element into the analog scintillation pulse signal output and then sampling is avoided, and an additional external digitizing device is saved, so that the cost is reduced for a short time while the system performance is improved.

Fig. 7 is a flowchart of a signal digitizing method according to another embodiment of the application, which may include the following steps 710-740.

The multiple channels respectively generate a count step signal, and the waveform of the count step signal is shown that the amplitude increases stepwise with the number of the micro-elements of the excited photoelectric conversion device.

For PET devices, whether ring PET, flat panel PET, or other variable shape PET, there are often multiple detectors, possibly including multiple SiPM arrays in each detector, and multiple SiPM channels in each SiPM array, where the SiPM of each channel includes multiple microcell arrays, the method of generating the count step signal in the SiPM of a single channel may be described with reference to the above embodiments, and will not be repeated here.

Step 720, synchronously and parallelly determining time sequences corresponding to the state changes of the counting step signals in each channel.

For each channel, the signals in each channel can be digitized synchronously in a parallel mode, the generation and the digitization of the counting step signals in each channel are independent from each other and are not influenced by each other, meanwhile, each channel is allocated with an address, such as an ip address, by the system, and the time sequence information collected by each channel is packaged together with the address information and sent to a processor for processing.

Step 740, restoring the counting step signal information according to the time sequence.

After the time sequence information in each channel is sent to the processor, the processor may establish a task to restore the count step signal of each channel according to the method described in the above embodiments.

Further, after the counting step signals in each channel are restored, the method can be used for single event coincidence in PET or photon scattering matching, the output digital time sequence can be utilized to store the original information of the incident photon sequence to the greatest extent, the complex analog-digital conversion process is abandoned, the digitization of photon signals is directly realized, the signal information loss caused by complex conversion is avoided, and the photon time sequence information can be restored, so that the system performance is further improved.

Based on the description of the signal digitizing method embodiment, the application also provides a rapid, accurate and stable signal digitizing device. The apparatus may include apparatus (including distributed systems), software (applications), modules, components, servers, clients, etc. that employ the methods described in embodiments of the present specification in combination with the necessary apparatus to implement the hardware. Based on the same innovative concepts, embodiments of the present application provide for devices in one or more embodiments as described in the following examples. Because the implementation scheme and the method for solving the problem by the device are similar, the implementation of the device in the embodiment of the present disclosure may refer to the implementation of the foregoing method, and the repetition is not repeated. As used below, the term "module" or "module" may be a combination of software and/or hardware that implements the intended function. Although the means described in the following embodiments are preferably implemented in software, implementation in hardware, or a combination of software and hardware, is also possible.

Fig. 8 is a schematic structural diagram of a signal digitizing apparatus according to one embodiment of the present application, where the signal digitizing apparatus may include a count step signal generating unit 80, a sampling unit 90, and a reconstruction unit 100, where the count step signal generating unit 80 is configured to generate a count step signal, a waveform of the count step signal is represented by a stepwise increase in amplitude with a number of micro-elements of an excited photoelectric conversion device, the sampling unit 90 is configured to directly sample the count step signal and determine a corresponding time sequence for each state change in the count step signal, and the reconstruction unit 100 is configured to restore the count step signal according to the time sequence.

More specifically, the count step signal generation unit 80 may include a plurality of detection modules 810 and a signal processing module 820, wherein the plurality of detection modules 810 may output an impulse response signal when a photon is detected, and the detection modules 810 may also output a unit step signal when the impulse response signal reaches a trigger condition. In practical applications, the plurality of detection modules 810 in the signal digitizing apparatus may be arranged in an array of mxn (m and n are all positive integers).

In the absence of photon incidence, detection module 810 is in an unexcited state (i.e., equivalent to an output of 0 in binary) regardless of dark counts. When a photon train enters the signal digitizing apparatus, the detection module 810 receiving the photons is excited (i.e., the output is 1 in binary), and generates an impulse response signal. In this embodiment, by setting the trigger condition, it may be assisted in determining whether the detection module 810 receives a photon. When the impulse response signal satisfies the trigger condition, the determination detection module 810 receives the photon and outputs a unit step signal. By presetting the triggering conditions, the problems of false readings and the like of the detection module 810 caused by noise interference and the like can be reduced.

In some specific embodiments, the trigger condition may be set according to different application scenarios. For example, a preset voltage may be set on the infinitesimal in the detection module 810 correspondingly, the photon acts on the infinitesimal to generate an impulse response signal, when the impulse response signal is greater than the preset voltage, the detection module determines that the triggering condition is met, and the detection module outputs a unit step signal, or when the waveform of the impulse response signal meets the preset characteristic, it may be determined that the triggering condition is met, for example, the maximum voltage reaches a preset threshold, the current amplitude reaches a preset threshold, or the accumulated voltage reaches a certain amplitude, which belongs to those skilled in the art and is not listed here.

The generated unit step signal has the characteristics that when a microcell is not excited, it always maintains a 0 voltage output state, and when one microcell is excited, the magnitude of the unit step signal rises by one unit and maintains the magnitude, for example, the voltage magnitude rises by one unit of 4mV.

The signal processing module 820 is respectively connected to the plurality of detecting modules 810, and the signal processing module 820 can be used for generating a counting step signal based on the unit step signal.

When the plurality of detection modules 810 detect photons, a plurality of unit step signals are output, respectively. In this embodiment, the signal processing module 820 may generate a count step signal based on the unit step signal, and utilize the count step signal to count the number of received unit step signals.

Typically, sipms comprise an array of m×n (m and n are both positive integers) microelements and corresponding auxiliary circuits, each element will generate an impulse response signal correspondingly after detecting a photon, and the impulse response signal will output a unit step signal when meeting a trigger condition, so that the detection module array can output a plurality of unit step signals when detecting. The plurality of unit step signals are output in a certain form to form a counting step signal, for example, after each detection module 810 outputs the unit step signal, the signal processing module 820 adds the unit step signal through the in-phase proportion adding circuit to output the counting step signal, or after a certain row or a certain column of corresponding detection modules 810 outputs the unit step signal, the signal processing module 820 adds the unit step signal through the adding circuit to output the counting step signal, or the corresponding delay is set for the unit step signal output by each detection module, and then the counting step signal is directly added through the signal processing module 820.

The sampling unit 90 is connected to the signal processing module 820, and the sampling unit 90 may be configured to directly digitize the count step signal and output a digitized sampled signal. Since the count step signal contains information on the number of unit step signals received, the sampling unit 90 can utilize a digitizing method to achieve direct digitization of the SiPM incident photon sequence. The above-mentioned digital processing method may be any digital processing method described in the method embodiment of the present application, and will not be described herein.

Fig. 9 is a schematic structural diagram of a detection module 810 according to one embodiment of the present application, where the detection module 810 may include a photon detection submodule 8110 and a threshold comparison submodule 8120.

Photon detection submodule 8110 may be used to output an impulse response signal when a photon is detected. Referring to fig. 9, photon detection sub-module 8110 may include a single photon avalanche diode D1 and a quench tube Q1. The cathode of the single photon avalanche diode D1 is connected with the externally input reverse bias voltage, the anode of the single photon avalanche diode D1 is connected to the ground through a quenching tube Q1, the drain electrode of the quenching tube Q1 is connected with the anode of the single photon avalanche diode D1, the source electrode of the quenching tube Q1 is grounded, the grid electrode of the quenching tube Q1 is connected with the externally input direct current voltage V _q, and the direct current voltage V _q can be used for controlling the pulse width of the quenching tube.

A threshold comparison sub-module 8120 may be coupled to the photon detection sub-module 8110, the threshold comparison sub-module 8120 may be configured to output a unit step signal when the impulse response signal reaches a trigger condition. Referring to fig. 9, the threshold comparison sub-module 8120 may include a comparator U1. The output terminal of the photon detection sub-module 8110 may be connected to the positive input terminal of the comparator U1, and the negative input terminal of the comparator U1 is connected to the externally input trigger voltage V _t.

When the single photon avalanche diode D1 detects a photon, the single photon avalanche diode D1 outputs an impulse response signal. The impulse response signal is transmitted to the positive input of the comparator U1, and the comparator U1 compares the impulse response signal with the trigger voltage V _t. When the amplitude of the impulse response signal reaches the trigger voltage V _t, the comparator U1 outputs a unit step signal V _ij, where i and j represent the number of rows and columns in the array of micro-elements, respectively, j=1, 2,3,... The trigger voltages V _t of the plurality of detection modules 810 may be identical, and the trigger voltages V _t of the plurality of detection modules 810 may be provided by a digital-to-Analog Converter (DAC) integrated on-chip.

Fig. 10 is a schematic diagram of a signal processing module 820 according to one embodiment of the present application, in which the signal processing module 820 may include an in-phase proportional adding circuit 8210.

The in-phase proportional adding circuit 8210 may be respectively connected to the N detecting modules 810, and the in-phase proportional adding circuit 8210 may be configured to add up the unit step signals output by any detecting module 810 to generate a count step signal.

In one embodiment, the output terminals of the plurality of detection modules 810 may be connected to the signal input terminals of the in-phase proportional adding circuit 8210 through a plurality of input resistors 8220, respectively. Referring to fig. 10, the in-phase proportional addition circuit 8210 may include an operational amplifier U ₂, a feedback resistor R _f, and a ground resistor Rs. The unit step signals output by the N detection modules 810 may be V _i1、V_i2、...、V_iN respectively, the output ends of the N detection modules 810 are connected to the positive input end of the operational amplifier U ₂ through the input resistor 8220 (R ₁、R₂、...、R_N in the drawing) in a one-to-one correspondence manner, one end of the feedback resistor R _f is connected to the positive input end of the operational amplifier U ₂, the other end of the feedback resistor R _f is connected to the output end of the operational amplifier U ₂, and the negative input end of the operational amplifier U ₂ is grounded through the grounding resistor Rs.

The operational amplifier U ₂ may sum the plurality of unit step signals to output the count step signal Vo. Specifically, the count step signal Vo=R_f×(V_i1/R₁+V_i2/R₂+V_i3/R₃+...V_iN/R_N), corresponds to multiplying the unit step signal output by each detection module 810 by a proportional sum output. The N input resistors 8220 have the same resistance, so that the ratio of the unit step signals output by each detection module 810 is the same, and the voltage input by each detection module 810 to the in-phase ratio adder 8210 is ensured to be the same. Because of the time difference between photon arrival times, each detection module 810 outputs a unit step signal, and therefore, a count step signal with a time-varying amplitude is generated at the output of the in-phase proportional adder 8210. For example, when two detection modules 810 are triggered at 1ns and 2ns respectively, the in-phase proportional adding circuit 8210 outputs a count step signal with a unit amplitude of a ₀ at 1ns and holds the count step signal, and when the unit step signal output by the second triggered detection module 810 is added at 2ns, the count step signal amplitude output by the in-phase proportional adding circuit 8210 at 2ns becomes 2a ₀, so that a stepped count step signal is formed.

In a specific embodiment, the signal digitizing apparatus includes 32×32 square arranged detection modules 810 (as shown in fig. 9, n=32), and the total number of detection modules 810 is 32×32=1024. After each detection module 810 converts the impulse response signal into a unit step signal with a digital logic high level, 1024 detection modules 810 are connected to an in-phase proportional adding circuit 8210, and the unit step signal is converted into a counting step signal through the in-phase proportional adding circuit 8210. If the power supply of the in-phase proportional adding circuit 8210 is 4.1V, the voltage range output by the in-phase proportional adding circuit 210 is 0-4.1V. When the number of triggered detection modules 810 ranges from 0 to 1024, a ₀ = 4.1V/1024 ≡4mV.

Fig. 11 is a schematic structural diagram of a sampling unit 90 according to one embodiment of the present application, where the sampling unit 90 may include a TDC and a memory module.

As the counting step signal has obvious amplitude jump points, the waveform is expressed as that the amplitude of the waveform rises by one unit amplitude along with the rising of the number of the unit step signals, and each jump corresponds to the rising of the amplitude of the waveform, and the waveform is in a ladder shape as a whole. Therefore, in this embodiment, the count step signal generated by the count step signal generating unit 80 may be directly input into a time-to-digital converter (TDC), the time information of each jump of the amplitude value in the count step signal is recorded through the TDC, then the time information corresponding to each jump point is sent and stored in the storage module, and the storage module matches the time sequence and the information such as the channel number/address and outputs in a packed form.

The memory module may be a FIFO (First Input First Output) memory, which is connected to the TDC, and the FIFO memory may be used to count threshold-time pairs based on the time sequence of the TDC output and the output P groups. The FIFO memory may centralize the jump time information recorded by the TDC for stacking and storing. The FIFO memory is a kind of first-in first-out dual-port buffer, i.e. the first data entered therein is shifted out first, and can buffer continuous data streams, preventing data loss during entry and storage operations.

After the counting step signal is input into the sampling unit, the TDC records the jump time of the counting step signal in sequence, the FIFO memory stores the data in a centralized way, and a subsequent external computer can restore the whole counting pulse signal through prior information.

In one embodiment, the signal digitizing apparatus may further include a reset module, which may be configured to output a reset signal to clear the impulse response signal. After the TDC and the storage module both complete the operation and output a time-series frame (each channel outputs a gray code with a length of about 30 bits), the reset module may output a reset signal to clear the count of the detection module 810 entirely to wait for the next detection operation.

Fig. 12 is a schematic structural diagram of a signal digitizing apparatus according to another embodiment of the present application, where the signal digitizing apparatus may be applied to a PET system, a SPECT system, or the like, and the apparatus includes a plurality of counting step signal generating units, each of which may generate a counting step signal as described in the foregoing embodiment, for example, in the embodiment of fig. 12, the apparatus includes three counting step signal generating units, each of which may generate a corresponding counting step signal after receiving photons, each of which is output to a corresponding connected TDC, and the plurality of TDCs may be simultaneously connected to the same storage module.

Fig. 13 is a schematic structural diagram of a signal digitizing device in another embodiment of the present application, which is similar to that in the embodiment of fig. 12, and may be suitable for a system having a plurality of detection modules, such as a PET system, a SPECT system, etc., where each detection module includes a plurality of counting step signal generating units, each counting step signal generating unit may generate a counting step signal as described in the foregoing embodiment, unlike the embodiment of fig. 13, where the detection modules may be divided into a plurality of groups, each group of detection modules may include two counting step signal generating units, respectively, and each counting step signal generating unit may be connected with the same storage module through a TDC, each counting step signal generating unit may generate a corresponding counting step signal after receiving photons, each counting step signal may be output to the TDC correspondingly connected, and two or more TDCs may be simultaneously connected with the same storage module.

According to the signal digitizing device provided by the application, the counting step signal is generated to replace the scintillation pulse signal which is output in the prior art in an analog manner, so that the incident photon sequence can be directly sampled by the TDC, the time sequence of the excitation of the incident photon is recorded, the direct digitization of the incident photon is realized, the direct digitization of the incident photon sequence is read out in the form of a digital signal, the original information of the incident photon sequence is stored to the greatest extent, the complex process of integrating the signal which is output by the micro element into the analog scintillation pulse signal output and then sampling is avoided, and an additional external digitizing device is saved, so that the cost is reduced to the first degree while the system performance is improved.

Fig. 14 is a schematic structural diagram of a signal digitizing apparatus according to one embodiment of the application, wherein the signal digitizing apparatus may include a transmission unit 910 and a reconstruction unit 100.

The transmission unit 910 may be configured to transmit the acquired digitized sample signal. The reconstruction unit 100 may be connected to the transmission unit 910, the reconstruction unit 100 may be configured to reconstruct the digitized sampled signal according to the a priori information to recover the count step signal, and the reconstruction unit 100 may be configured to convert the count step signal into count information for a unit time.

The digitized sample signal may refer to the digitized sample signal acquired with the sampling unit in the above-described embodiments. In this embodiment, the signal digitizing means may read the digitized sample signal of the sampling unit through the transmission unit 910. After the digitized sampled signal is obtained, the reconstruction unit 100 may analyze the signal characteristics of the count step signal through prior information, such as a prior physical model, so as to reconstruct the digitized signal according to the prior information and restore the count step signal. For example, the digitized sampled signal is reconstructed according to a function or shape model in which the count step signal corresponds, and the count step signal is restored. Further, the counting step signal is converted, and counting information of unit time is obtained.

According to the signal digitizing device, the digitized sampling signal is reconstructed according to the priori information, so that the original information of the incident photon sequence is stored to the greatest extent, the incident photon time sequence is accurately recovered, and the digitized reconstruction of the counting step signal is realized on the premise of not losing photon detection efficiency.

Fig. 15 is a schematic structural diagram of a signal digitizing apparatus according to another embodiment of the application, wherein the reconstruction unit 100 may include a modeling module 1510 and a data processing module 1520.

The modeling module 1510 may be used to determine a physical model for which the count step signal corresponds. The data processing module 1520 may be connected to the modeling module 1510, and the data processing module 1520 may be configured to perform signal recovery processing on the digitized sampled signal based on the physical model to recover the count step signal.

According to the above embodiment of the signal digitizing apparatus, the counting step signal is subject to a physical model. The voltage amplitude of the count step signal is the count number x a ₀, and the modeling module 1510 may set a corresponding physical model according to the characteristic of the count step signal, for example, may represent the count step signal by using a stepped exponential model or an approximate linear function model. Further, the data processing module 1520 may perform signal recovery processing on the digitized sampled signal based on the physical model determined by the modeling module 1510 by using a signal processing method such as a fitting algorithm or a neural network algorithm, and recover the count step signal from the time series of the digitized sampled signal.

In one embodiment, the reconstruction unit 100 may further include a data conversion module 1530. The data conversion module 1530 may be coupled to the data processing module 1520, and the data conversion module 1530 may be configured to convert the count step signal into count per unit time information.

It should be understood that the apparatus shown in fig. 8-15 and modules thereof may be implemented in a variety of ways. For example, in some embodiments, the apparatus and its modules may be implemented in hardware, software, or a combination of software and hardware. Wherein the hardware portions may be implemented using dedicated logic and the software portions may be stored in a memory for execution by a suitable instruction execution device, such as a microprocessor or dedicated design hardware. Those skilled in the art will appreciate that the methods and apparatus described above may be implemented using computer executable instructions and/or embodied in processor control code, such as provided on a carrier medium such as a magnetic 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 apparatus and the modules thereof in the present specification may be implemented not only by a hardware circuit such as a very large scale integrated circuit or gate array, a semiconductor such as a logic chip, a transistor, or the like, or a programmable hardware device such as a field programmable gate array, a programmable logic device, or the like, but also by software executed by various types of processors, for example, and may be implemented by a combination of the above hardware circuit and software (e.g., firmware).

It should be noted that the above description of the module is for convenience of description only, and is not intended to limit the description of the present application to the scope of the illustrated embodiments. It will be appreciated by those skilled in the art that it is possible, after understanding the principles of the apparatus, to combine the individual modules arbitrarily or to construct a subsystem in connection with other modules without departing from such principles. For example, each module may share one memory module, or each module may have a respective memory module. Such variations are within the scope of the present description.

Fig. 16 is a schematic diagram of a signal digitizing system for implementing a signal digitizing method according to one embodiment of the application. Referring to fig. 16, the signal digitizing system S00 may include a processing component S20 that further includes one or more processors, and memory resources represented by a memory S22 for storing instructions, such as applications, executable by the processors of the processing component S20. The application program stored in the memory S22 may include one or more instructions, each module corresponding to a set of instructions. Further, the processing component S20 is configured to execute instructions to perform the signal digitizing method described above.

The operations and/or methods described in the embodiments of the present specification as being implemented by one processor may also be implemented by a plurality of processors collectively or individually. For example, if in the present description the processor of the processing device performs step 1 and step 2, it should be understood that step 1 and step 2 may also be performed jointly or independently by two different processors of the processing device (e.g., a first processor performs step 1, a second processor performs step 2, or the first and second processors jointly perform step 1 and step 2).

The signal digitizing system S00 may further include a power supply assembly S24 configured to perform power management of the signal digitizing system S00, a wired or wireless network interface S26 configured to connect the signal digitizing system S00 to a network, and an input output (I/O) interface S28. The signal digitizing system S00 may operate based on an operating system stored in the memory S22, such as Windows Server, mac OS X, unix, linux, freeBSD or the like.

In an exemplary embodiment, a computer readable storage medium is also provided, such as a memory S22, comprising instructions executable by a processor of the signal digitizing system S00 to perform the above method. The storage medium may be a computer readable storage medium, which may be, for example, ROM, random Access Memory (RAM), CD-ROM, magnetic tape, floppy disk, optical data storage device, etc.

In an exemplary embodiment, a computer program product is also provided, comprising instructions therein, which are executable by a processor of the signal digitizing system S00 to perform the above method.

In one embodiment, a computer device is provided, which may be a server, and an internal structure diagram thereof may be shown in fig. 17, and fig. 17 is an internal structure diagram of the computer device in one embodiment of the present application. The computer device includes a processor, a memory, and a network interface connected by a system bus. Wherein the processor of the computer device is configured to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an 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 media. The database of the computer equipment is used for storing data related to users and tasks used in the signal digitizing method. The network interface of the computer device is used for communicating with an external terminal through a network connection. The computer program is executed by a processor to implement a signal digitizing method.

It will be appreciated by those skilled in the art that the structure shown in FIG. 17 is merely a block diagram of some of the structures associated with the present inventive arrangements and is not limiting of the computer device to which the present inventive arrangements may be applied, and that a particular computer device may include more or fewer components than shown, or may combine some of the components, or have a different arrangement of components.

Those skilled in the art will appreciate that implementing all or part of the above-described embodiment methods may be accomplished by way of a computer program stored on a non-transitory computer readable storage medium, which when executed, may comprise the steps of the embodiments of the methods described above. Any reference to memory, database, or other medium used in embodiments provided herein may include at least one of non-volatile and volatile memory. The nonvolatile Memory may include Read-Only Memory (ROM), magnetic tape, floppy disk, flash Memory, optical Memory, high density embedded nonvolatile Memory, resistive random access Memory (ReRAM), magneto-resistive random access Memory (Magnetoresistive Random Access Memory, MRAM), ferroelectric Memory (Ferroelectric Random Access Memory, FRAM), phase change Memory (PHASE CHANGE Memory, PCM), graphene Memory, and the like. Volatile memory can include random access memory (Random Access Memory, RAM) or external cache memory, and the like. By way of illustration, and not limitation, RAM can be in various forms such as static random access memory (Static Random Access Memory, SRAM) or dynamic random access memory (Dynamic Random Access Memory, DRAM), etc. The databases referred to in the embodiments provided herein may include at least one of a relational database and a non-relational database. The non-relational database may include, but is not limited to, a blockchain-based distributed database, and the like. The processor referred to in the embodiments provided in the present application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic unit, a data processing logic unit based on quantum computing, or the like, but is not limited thereto.

In this specification, each embodiment is described in a progressive manner, and the same or similar parts of each embodiment are referred to each other, and each embodiment mainly describes differences from other embodiments. In particular, for a hardware+program class embodiment, since it is substantially similar to a method embodiment, the description is relatively simple, and reference is made to the description of a method embodiment for relevant points.

It should be noted that the descriptions of the apparatus, the electronic device, the server, and the like according to the method embodiments may further include other implementations, and specific implementations may refer to descriptions of related method embodiments. Meanwhile, new embodiments formed by combining features of the embodiments of the method, the device, the equipment and the server still fall within the implementation scope covered by the present application, and are not described in detail herein.

In the description herein, reference to the terms "one embodiment," "an embodiment," and/or "some embodiments," "other embodiments," "ideal embodiments," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, a schematic description of the above terms does not necessarily refer to the same embodiment or example, and certain features, structures, or characteristics of one or more embodiments of the present specification may be combined as appropriate.

The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.

The above examples illustrate only a few embodiments of the invention, which are described in detail and are not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.

Having described the basic concepts herein, it will be apparent to those skilled in the art that the foregoing detailed disclosure is by way of example only and is not intended to be limiting. Although not explicitly described herein, various modifications, improvements, and adaptations to the present disclosure may occur to one skilled in the art. Such modifications, improvements, and modifications are intended to be suggested within this specification, and therefore, such modifications, improvements, and modifications are intended to be included within the spirit and scope of the exemplary embodiments of the present invention.

Furthermore, those skilled in the art will appreciate that the various aspects of the specification can be illustrated and described in terms of several patentable categories or circumstances, including any novel and useful procedures, machines, products, or materials, or any novel and useful modifications thereof. Accordingly, aspects of the present description may be performed entirely by hardware, entirely by software (including firmware, resident software, micro-code, etc.), or by a combination of hardware and software. The above hardware or software may be referred to as a "data block," module, "" engine, "" module, "" component, "or" system. Furthermore, aspects of the specification may take the form of a computer product, comprising computer-readable program code, embodied in one or more computer-readable media.

The computer storage medium may contain a propagated data signal with the computer program code embodied therein, for example, on a baseband or as part of a carrier wave. The propagated signal may take on a variety of forms, including electro-magnetic, optical, etc., or any suitable combination thereof. A computer storage medium may be any computer readable medium that can communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device. Program code located on a computer storage medium may be propagated through any suitable medium, including radio, cable, fiber optic cable, RF, or the like, or a combination of any of the foregoing.

The computer program code necessary for operation of portions of the present description may be written in any one or more programming languages, including an object oriented programming language such as Java, scala, smalltalk, eiffel, JADE, emerald, C ++, c#, vb net, python, and the like, a conventional programming language such as C language, visual Basic, fortran 3003, perl, COBOL 3002, PHP, ABAP, a dynamic programming language such as Python, ruby, and Groovy, or the like. The program code may execute entirely on the user's computer or as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user's computer through any form of network, such as a Local Area Network (LAN) or a Wide Area Network (WAN), or the connection may be made to an external computer (for example, through the Internet), or the use of services such as software as a service (SaaS) in a cloud computing environment.

Furthermore, the order in which the elements and sequences are processed, the use of numerical letters, or other designations in the description are not intended to limit the order in which the processes and methods of the description are performed unless explicitly recited in the claims. While certain presently useful inventive embodiments have been discussed in the foregoing disclosure, by way of various examples, it is to be understood that such details are merely illustrative and that the appended claims are not limited to the disclosed embodiments, but, on the contrary, are intended to cover all modifications and equivalent arrangements included within the spirit and scope of the embodiments of the present disclosure. For example, while the system components described above may be implemented by hardware devices, they may also be implemented solely by software solutions, such as installing the described system on an existing server or mobile device.

Likewise, it should be noted that in order to simplify the presentation disclosed in this specification and thereby aid in understanding one or more inventive embodiments, various features are sometimes grouped together in a single embodiment, figure, or description thereof. This method of disclosure does not imply that the subject matter of the present description requires more features than are set forth in the claims. Indeed, less than all of the features of a single embodiment disclosed above.

In some embodiments, numbers describing the components, number of attributes are used, it being understood that such numbers being used in the description of embodiments are modified in some examples by the modifier "about," approximately, "or" substantially. Unless otherwise indicated, "about," "approximately," or "substantially" indicate that the number allows for a 20% variation. Accordingly, in some embodiments, numerical parameters set forth in the specification and claims are approximations that may vary depending upon the desired properties sought to be obtained by the individual embodiments. In some embodiments, the numerical parameters should take into account the specified significant digits and employ a method for preserving the general number of digits. Although the numerical ranges and parameters set forth herein are approximations that may be employed in some embodiments to confirm the breadth of the range, in particular embodiments, the setting of such numerical values is as precise as possible.

Each patent, patent application publication, and other material, such as articles, books, specifications, publications, documents, etc., referred to in this specification is incorporated herein by reference in its entirety. Except for application history documents that are inconsistent or conflicting with the content of this specification, documents that are currently or later attached to this specification in which the broadest scope of the claims to this specification is limited are also. It is noted that, if the description, definition, and/or use of a term in an attached material in this specification does not conform to or conflict with what is described in this specification, the description, definition, and/or use of the term in this specification controls.

Finally, it should be understood that the embodiments described in this specification are merely illustrative of the principles of the embodiments of this specification. Other variations are possible within the scope of this description. Thus, by way of example, and not limitation, alternative configurations of embodiments of the present specification may be considered as consistent with the teachings of the present specification. Accordingly, the embodiments of the present specification are not limited to only the embodiments explicitly described and depicted in the present specification.

Claims

1. A signal digitization method, comprising:

Generate a counting step signal, wherein the waveform of the counting step signal shows that the amplitude increases in a step-like manner along with the number of micro-elements of the photoelectric conversion device being excited;

Directly sampling the counting step signal to determine a time series corresponding to each state change in the counting step signal;

The count step signal is restored according to the time series.

2. The signal digitization method according to claim 1, wherein generating a counting step signal comprises:

When the impulse response signal meets the trigger condition, a unit step signal is output;

A count step signal is generated based on the unit step signal.

3. The signal digitization method according to claim 2, characterized in that when the impulse response signal meets the trigger condition, outputting a unit step signal comprises:

comparing the impulse response signal with a trigger threshold;

In response to a comparison result that the impulse response signal is not less than the trigger threshold, a unit step signal is output.

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

5. The signal digitization method according to claim 3, wherein the trigger condition comprises:

A voltage is preset, and when the pulse response signal is greater than the preset voltage, it is determined that a trigger condition is met, and the unit step signal is output; or

A waveform feature is preset, and when the waveform feature of the impulse response signal meets the preset waveform feature, it is determined that a trigger condition is 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 accumulated voltage of the waveform reaches a preset amplitude.

7. The signal digitization method according to claim 2, characterized in that generating a counting step signal based on the unit step signal comprises:

The unit step signal is summed to generate the counting step signal.

8. The signal digitization method according to claim 7, characterized in that the adding process of the unit step signal comprises:

A plurality of the unit step signals are added together by an in-phase proportional adding circuit and then output to generate the counting step signal; or

The unit step signals outputted corresponding to different rows and columns are respectively added up by an adding circuit and then outputted to generate the counting step signal; or

A corresponding delay is set for each unit step signal, and then the delays are added together to form the counting step signal.

9. The signal digitization method according to claim 8 is characterized in that when the microelement of the photoelectric conversion device is not excited, the amplitude of the counting step signal remains at 0; when one of the microelement is excited, the amplitude of the counting step signal rises by one unit and maintains the amplitude; when n of the microelement are excited, the amplitude of the counting step signal rises by n units and maintains the amplitude, where n is a positive integer.

10. The signal digitization method according to claim 1, characterized in that directly sampling the count step signal to determine the time series corresponding to each state change in the count step signal comprises:

Recording the time point when the amplitude of the counting step signal changes and the number of changes;

The time point information of the jump is formed into a time series according to the number of jumps.

11. The signal digitization method according to claim 10 is characterized in that the time series includes: the time point information corresponding to each jump of the counting step signal, the jump number information formed by statistics of 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 restoring the counting step signal according to the time series comprises:

Determine the physical model corresponding to the counting step signal;

The count step signal is restored according to the physical model and the time series.

13. The signal digitization method according to claim 2, characterized in that after restoring the count step signal according to the time series, the signal digitization method further comprises:

Output a reset signal to clear the pulse response signal.

14. A signal digitization method, comprising:

The multiple channels respectively generate counting step signals, wherein the waveform of the counting step signals is characterized in that the amplitude increases in a step-like manner along with the number of micro-elements of the photoelectric conversion device being excited;

Synchronously and in parallel determine the time series corresponding to the state changes of the counting step signal in each channel;

The count step signal is restored according to the time series.

15. A signal digitization device, comprising:

A counting step signal generating unit, wherein the counting step signal generating unit is configured to generate a counting step signal, wherein the waveform of the counting step signal is characterized in that the amplitude increases in a step-like manner as the number of micro-elements of the photoelectric conversion device being excited increases;

a sampling unit, the sampling unit being configured to directly sample the counting step signal and determine a time series corresponding to each state change in the counting step signal; and

A reconstruction unit is configured to restore the counting step signal according to the time series.

16. The signal digitizing device according to claim 15, characterized in that the counting step signal generating unit comprises:

A plurality of detection modules, configured to output an impulse response signal when a photon is detected, and output a unit step signal when the impulse response signal reaches a trigger condition;

The signal processing modules are respectively connected to the plurality of detection modules and are used to generate a counting step signal based on the unit step signal.

17. The signal digitization device according to claim 16, wherein the detection module comprises:

A photon detection submodule, used to output a pulse response signal when a photon is detected;

The threshold comparison submodule is connected to the photon detection submodule and is used to output the unit step signal when the pulse response signal reaches a trigger condition.

18. The signal digitization device according to claim 16, wherein the trigger condition comprises:

A voltage is preset, and when the pulse response signal is greater than the preset voltage, it is determined that the trigger condition is met, and the unit step signal is output; or

A waveform feature is preset, and when the waveform feature of the impulse response signal meets the preset waveform feature, it is determined that the trigger condition is met, and the unit step signal is output.

19. The signal digitizing device according to claim 18, wherein the preset waveform features include:

The maximum voltage reaches a preset voltage threshold, the current amplitude reaches a preset current threshold, or the accumulated voltage reaches a preset amplitude.

20. The signal digitization device according to claim 17, wherein the photon detection submodule comprises:

A single-photon avalanche diode, wherein the cathode of the single-photon avalanche diode is connected to an externally input reverse bias voltage;

A quenching tube, wherein the drain of the quenching tube is connected to the anode of the single-photon avalanche diode, the source of the quenching tube is grounded, and the gate of the quenching tube is connected to an externally inputted DC voltage.

21. The signal digitizing device according to claim 16, wherein the signal processing module comprises:

The in-phase proportional adding circuit is connected to the plurality of detection modules respectively, and is used for performing sum processing on the unit step signal to generate the counting step signal.

22. The signal digitization device according to claim 21 is characterized in that the plurality of detection modules are respectively connected to the signal input end of the in-phase proportional addition circuit through corresponding input resistors, wherein the resistance value of each input resistor is the same.

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

24. The signal digitizing device according to claim 15, wherein the sampling unit comprises:

A time-to-digital converter, the time-to-digital converter being configured to record time information of each amplitude jump in the counting step signal;

A storage module is connected to the time-to-digital converter, and the storage module 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 digitizing device according to claim 16, characterized in that the signal digitizing device further comprises:

The reset module is used to output a reset signal to clear the pulse response signal.

26. The signal digitizing device according to any one of claims 15 to 25, further comprising:

A transmission unit is connected to the sampling unit and is configured to transmit the acquired digital sampling signal.

27. The signal digitizing device according to any one of claims 15 to 25, characterized in that the reconstruction unit comprises:

A modeling module, used for determining a physical model corresponding to the counting step signal;

The data processing module is connected to the modeling module and 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 digitizing device according to claim 27, wherein the reconstruction unit further comprises:

The data conversion module is connected to the data processing module and is used to convert the counting step signal into unit time counting information.

29. A signal digitization device, comprising:

A plurality of counting step signal generating units, wherein the counting step signal generating units are configured to generate counting step signals, wherein the waveform of the counting step signal is characterized in that the amplitude increases in a step-wise manner as the number of micro-elements of the photoelectric conversion device being excited increases;

a sampling unit, each of which is connected to the counting step signal generating unit, and is configured to directly sample the counting step signal and determine a time series corresponding to each state change in the counting step signal; and

A reconstruction unit, wherein the reconstruction unit is connected to the sampling units respectively, and the reconstruction unit is configured to restore the counting step signal according to the time series.

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

31. A signal digitization device, comprising:

A plurality of detection modules, each of which comprises a plurality of counting step signal generating units, and the counting step signal generating units are configured to generate counting step signals;

A plurality of sampling units, each of which is connected to a plurality of the counting step signal generating units in the same detection module, and the sampling unit is configured to directly sample the counting step signal and determine a time series corresponding to each state change in the counting step signal; and

32. The signal digitization device according to claim 31 is characterized in that the sampling unit includes multiple TDCs and storage modules, and the multiple counting step signal generating 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, wherein when the computer program is executed by a processor, the steps of the signal digitization method according to any one of claims 1 to 14 are implemented.

34. A computer program product, characterized in that it comprises a computer program or instructions, characterized in that when the computer program or instructions are executed by a processor, the steps of the signal digitization method according to any one of claims 1 to 14 are implemented.

35. A digital PET system, characterized by comprising the signal digitization device according to any one of claims 15-32.