Scintillation pulse signal digitization device and imaging system

Abstract

This application proposes a scintillation pulse signal digitization device and imaging system, comprising a threshold comparison unit, a peak capture unit, and a data processing unit. The threshold comparison unit outputs a threshold time digital signal corresponding to the pulse based on a preset threshold and input pulse information; the peak capture unit outputs a pulse peak digital signal based on the input pulse information; and the data processing unit controls the peak capture unit to output a peak digital signal based on the threshold time digital signal and the peak digital signal. This application obtains pulse peak information through a peak capture circuit, reducing the sensitivity of pulse fitting to the threshold during pulse information reconstruction, improving pulse fitting accuracy and the peak range of the fitted pulse, thereby achieving good pulse fitting accuracy within a relatively wider peak range, and thereby improving the detector's count rate.

Description

Technical Field

[0001] The present application relates to the field of signal sampling, and in particular to a scintillation pulse signal digitization device and imaging system. Background Art

[0002] Positron Emission Tomography (PET) is an imaging technique that utilizes radioactive elements. The process involves labeling a positron-emitting radionuclide with a compound that participates in the blood flow or metabolic processes of living tissue, and then injecting the labeled radionuclide compound into the subject. The positrons generated by the decay of the radionuclide in the body combine with negative electrons in the subject's body, annihilating electron pairs and producing a pair of gamma photons with equal energy and traveling in opposite directions. These gamma photons can be converted into visible light by a scintillation crystal. A photoelectric converter then converts the visible light into an electrical signal for sampling and image reconstruction, helping to identify areas of radionuclide enrichment, locate areas of active metabolism, and assess activity.

[0003] In PET or other related fields, the pulse signal needs to be sampled and processed before it is reconstructed. In the field of radiation detection and imaging, in order to reduce the cost of digital sampling of electrical signals, the prior art generally adopts a multi-voltage threshold (MVT) sampling method. The multi-voltage threshold sampling method is a mature method for high-speed pulse digitization. Without the need for a high-speed and expensive analog-to-digital converter, this method only needs to collect a number of arrival times and the corresponding reference voltages, and combine the prior information to completely restore the pulse. This method significantly reduces the cost of pulse digitization, especially the cost of digitizing scintillation pulses with a bandwidth of up to gigahertz. It is very suitable for application in positron emission tomography and has been successfully put into commercial application.

[0004] However, the multi-voltage threshold sampling method only collects a limited number of sampling points and cannot determine whether the collected sampling points are signal amplitude points, which may affect the sampling accuracy and the accuracy of subsequent signal restoration. Moreover, the performance of the multi-voltage threshold sampling method depends on the appropriate voltage threshold setting. An inappropriate threshold setting may significantly reduce the accuracy of pulse fitting. The dependence on threshold selection means that multi-voltage threshold sampling can only have sufficient fitting accuracy for waveforms with similar peaks. In addition, the multi-voltage threshold sampling method also has problems such as not being able to take into account large and small pulses, relatively insufficient counting rate, and the number of thresholds required is still too large. Summary of the Invention

[0005] The present application provides a scintillation pulse signal digitization device and an imaging system to solve at least one of the above problems.

[0006] According to one aspect of the present application, a device for digitizing a flicker pulse signal is proposed, comprising: a threshold comparison unit, which outputs a threshold time digital signal corresponding to a pulse based on a preset threshold and input pulse information, wherein the number of the thresholds does not exceed three; a peak capture unit, which outputs a peak digital signal of the pulse based on the pulse information; and a data processing unit, which controls the peak capture unit to output a peak digital signal based on the threshold time digital signal and the peak digital signal.

[0007] According to some embodiments, the preset threshold includes one or more of a voltage threshold, a current threshold, an energy threshold, and a magnetic field strength threshold.

[0008] According to some embodiments, the peak capture unit includes a peak acquisition module, a peak holding module, a peak feedback module, and a first output module, wherein: the peak acquisition module uses the input pulse information to output the peak value of the pulse; the peak holding module is used to save the peak value; the first output module outputs a digitized peak value based on the saved peak value; the peak feedback module provides a peak feedback signal to the peak acquisition module based on the peak value output by the peak acquisition module.

[0009] According to some embodiments, the peak acquisition module includes a first comparator, the peak holding module includes a third three-terminal switch, and the peak feedback module includes a first three-terminal switch, wherein the first terminal of the first comparator receives the pulse information; the output terminal of the first comparator and the control terminal of the third three-terminal switch are electrically connected to the first connection terminal; the control terminal of the first three-terminal switch is electrically connected to the first connection terminal; the first terminal of the first three-terminal switch is electrically connected to the second terminal of the first comparator; and the second terminal of the first three-terminal switch and the first terminal of the third three-terminal switch are electrically connected to the second connection terminal.

[0010] According to some embodiments, the first output module includes a cascaded voltage follower and an analog-to-digital converter, wherein: the voltage follower is used to isolate the influence of the data processing unit on the peak capture unit; the analog-to-digital converter is used to output a digitized peak value according to the peak value output by the voltage follower.

[0011] According to some embodiments, the peak value capturing unit further includes: a second output module, configured to control the analog-to-digital converter to capture the peak value according to the peak value output by the voltage follower.

[0012] According to some embodiments, the second output module includes a second comparator, the output end of the voltage follower and the first end of the voltage follower are electrically connected to the first end of the second comparator; the output end of the second comparator is electrically connected to the first end of the second comparator; and the second end of the second comparator is electrically connected to the second connection end.

[0013] According to some embodiments, the peak holding module further includes a first capacitor, a first terminal of the first capacitor and a second terminal of the third three-terminal switch are electrically connected to a third connection terminal; and a second terminal of the voltage follower is electrically connected to the third connection terminal.

[0014] According to some embodiments, the peak capture unit further includes a discharge module, which includes a second three-terminal switch, which receives a peak control signal for collecting the next pulse sent by the data processing unit; a first terminal of the second three-terminal switch is electrically connected to the third connection terminal; and a second terminal of the second three-terminal switch is electrically connected to the second terminal of the first capacitor.

[0015] According to some embodiments, the data processing unit transmits the received threshold time digital signal and the peak digital signal to a host computer so that the host computer performs pulse fitting.

[0016] According to one aspect of the present application, an imaging system is provided, comprising any of the above-mentioned scintillation pulse signal digitizing devices.

[0017] According to some embodiments, the imaging system further includes a fitting device, which uses the threshold time digital signal and the peak digital signal to complete the characterization of the pulse waveform.

[0018] The scintillation pulse signal digitization device proposed in this application obtains pulse peak information through a peak capture circuit. This reduces the threshold sensitivity of pulse fitting during pulse information reconstruction, improves pulse fitting accuracy and the peak range of the fitted pulse, and thus achieves good pulse fitting accuracy over a relatively wider peak range, thereby increasing the detector's count rate. Furthermore, compared to traditional multi-threshold sampling methods, the scintillation pulse signal digitization device proposed in this application requires fewer thresholds, resulting in a lower implementation cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for describing the embodiments.

[0020] Figure 1 A structural block diagram of a digitizing device for a scintillation pulse signal according to an exemplary embodiment of the present application is shown.

[0021] Figure 2A structural block diagram of a peak capture unit according to an exemplary embodiment of the present application is shown.

[0022] Figure 3 A peak capture circuit diagram according to an exemplary embodiment of the present application is shown.

[0023] Figure 4 A circuit diagram of a device for digitizing a scintillation pulse signal according to an exemplary embodiment of the present application is shown. DETAILED DESCRIPTION

[0024] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be embodied in many forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the concepts of the example embodiments to those skilled in the art. Like reference numerals in the drawings represent like or similar parts, and thus repetitive description thereof will be omitted.

[0025] The described features, structures or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, many specific details are provided to provide a full understanding of the embodiments of the present disclosure. However, those skilled in the art will appreciate that the technical solutions of the present disclosure may be practiced without one or more of these specific details, or other modes, components, materials, devices or operations may be employed. In these cases, well-known structures, methods, devices, implementations, materials or operations will not be shown or described in detail.

[0026] The flowcharts shown in the accompanying drawings are for illustrative purposes only and do not necessarily include all contents and operations / steps, nor must they be executed in the order described. For example, some operations / steps may be decomposed, while others may be combined or partially combined. Therefore, the actual execution order may vary depending on the actual situation.

[0027] The terms "first," "second," and the like in the specification and claims of this application and the accompanying drawings are used to distinguish between different objects, not to describe a particular order. Furthermore, the terms "including," "having," and any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or elements is not limited to the listed steps or elements but may optionally include steps or elements not listed, or may optionally include other steps or elements inherent to the process, method, product, or apparatus.

[0028] The specific embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0029] The traditional multi-threshold sampling process is divided into three processes: sampling point acquisition, nonlinear fitting, and energy calculation. In the nonlinear fitting process, the constraints of the sampling points are formed in the area with steeper gradients, so their constraints are limited and can only constrain information near the threshold sampling. The constraints are poor at places far away from these sampling points, and thus the errors are large. For example, the peak of the pulse has a large error due to the lack of constraints, especially when the thresholds are far apart. The traditional multi-threshold sampling method is very sensitive to the threshold, and the choice of the threshold directly affects the quality of the fitting. It only has sufficient fitting accuracy for pulses with peak values ​​in a specific range, and the energy resolution is low. According to the embodiments of the present application, by obtaining additional peak information, good fitting accuracy is achieved for pulses within a relatively wide peak range.

[0030] According to an embodiment of the present application, effective constraints are imposed at the key point position, i.e., the peak value, and the peak value itself is more critical information for energy characterization than at the edge. Therefore, introducing the peak value is to complete a strong constraint, and thus the accuracy is higher. Thus, when calculating energy, the energy resolution is higher and the dynamic measurement range is larger. Moreover, the present application is completed based on traditional multi-threshold sampling, so it does not affect the count rate. Under various threshold settings, the pulse has a good fitting effect, and has higher energy resolution and higher count rate.

[0031] Furthermore, traditional multi-threshold sampling methods require a large number of thresholds, typically four or more, and their implementation costs remain high. According to other embodiments of the present application, the nonlinear sampling fitting process can be completed with only one or two thresholds. Four thresholds, however, contain redundant information compared to the present invention's technical solution. Therefore, the scintillation pulse signal digitization device proposed in this application requires fewer thresholds, resulting in higher accuracy and lower implementation costs.

[0032] Figure 1 The following is a block diagram of a digitizing device for a scintillation pulse signal according to an exemplary embodiment of the present application. Figure 1 , a structural block diagram of a digitizing device for a scintillation pulse signal according to an exemplary embodiment of the present application is described in detail.

[0033] like Figure 1 As shown, the digitizing device for a scintillation pulse signal includes a threshold comparison unit 101 , a peak value capture unit 103 and a data processing unit 105 .

[0034] The threshold comparison unit 101 compares the input pulse information with at least one preset threshold, such as a voltage threshold, to obtain the time when the pulse reaches the threshold, and outputs a threshold time digital signal to the data processing unit 105. The threshold time digital signal includes the threshold information and time information corresponding to when the pulse reaches or crosses the preset threshold, such as voltage-time pair information.

[0035] According to some embodiments, the preset threshold value may include one or more of a voltage threshold value, a current threshold value, an energy threshold value, and a magnetic field strength threshold value. Since the pulse signal may be an electrical signal (e.g., an electrical pulse signal), an optical signal, an acoustic signal, etc., the preset threshold value may be an electrical threshold value, such as a voltage threshold value, a current threshold value, or other threshold values, such as a magnetic threshold value such as a magnetic field strength, an energy threshold value, or one or more of the above threshold values. The preset threshold value may be set according to the characteristics of the pulse signal (e.g., a trigger level, a pulse amplitude), or may be set according to a pre-statistical empirical value of the amplitude of the pulse signal. Those skilled in the art may make a choice based on the actual situation, and this is not limited here.

[0036] According to some embodiments, the threshold comparison unit 101 compares the input pulse information with one, two or three preset thresholds, such as voltage thresholds, to obtain the time when the pulse reaches the threshold, and outputs a threshold time digital signal to the data processing unit 105, which includes the threshold information and time information corresponding to when the pulse reaches or crosses the above-mentioned preset threshold, such as voltage-time pair information.

[0037] According to some embodiments, the threshold comparison unit 101 includes a comparator and a TDC (Time to Digital Converter) circuit, where the number of comparators is equal to the number of thresholds, and each comparator corresponds to two TDC circuits. The comparator compares the input pulse information with the threshold and sends the result to the TDC circuit electrically connected to it. The TDC circuit converts the time when the pulse reaches the rising edge or falling edge threshold, respectively, into a threshold time digital signal, which is then sent to the data processing unit 105.

[0038] According to some embodiments, the number of comparators in threshold comparison unit 101 is 1, 2, or 3, preferably 1 or 2, so that the corresponding thresholds are fewer than those in traditional multi-threshold sampling. Since pulse data from a large number of channels needs to be collected in a short period of time during high-speed pulse information digitization, especially during data acquisition for positron emission tomography (PET), the number of thresholds significantly affects the total number of sampling points. When two thresholds are used, the number of data collected is at least doubled compared to traditional multi-threshold sampling methods. Therefore, reducing the number of thresholds by one is of great significance in improving acquisition efficiency, reducing circuit complexity, lowering the performance requirements of back-end data processing chips, and reducing system costs.

[0039] The peak value capturing unit 103 outputs a peak value digital signal of the pulse according to the input pulse information.

[0040] The internal structure of the peak capture unit 103 is as follows: Figure 2As shown, I will not go into details here.

[0041] The data processing unit 105 controls the peak value capturing unit to output the peak value digital signal according to the received threshold time digital signal and the peak value digital signal.

[0042] According to some embodiments, the data processing unit 105 receives the threshold time digital signal sent by the threshold comparison unit 101 and the peak digital signal sent by the peak capture unit 103, and sends them to the host computer so that the host computer can perform pulse information reconstruction and energy spectrum analysis.

[0043] According to some other embodiments, the data processing unit 105 further outputs a control signal to the peak value capturing unit 103 so that the peak value capturing unit 103 captures the next pulse signal.

[0044] According to some embodiments, the data processing unit 105 is implemented using FPGA.

[0045] according to Figure 1 In the illustrated embodiment, pulse peak information is obtained through a peak capture unit, reducing the threshold sensitivity of pulse fitting during pulse information reconstruction. This improves pulse fitting accuracy and the peak range of the fitted pulses, thereby achieving good pulse fitting accuracy over a relatively wider peak range, thereby increasing the detector's count rate. Furthermore, compared to traditional multi-threshold sampling methods, the scintillation pulse signal digitization device proposed in this application requires fewer thresholds, resulting in lower implementation costs.

[0046] Figure 2 A structural block diagram of a peak capture unit according to an exemplary embodiment of the present application is shown below. Figure 2 , a peak capture unit according to an exemplary embodiment of the present application is described in detail.

[0047] like Figure 2 The peak value capturing unit shown includes a peak value acquisition module 1031 , a peak value holding module 1033 , a first output module 1035 and a peak value feedback module 1037 .

[0048] According to some embodiments of the present application, the peak value acquisition module 1031 uses input pulse information to output the peak value of the pulse; the peak value holding module 1033 is used to store the peak value output by the peak value acquisition module 1031; and the first output module 1035 converts the peak value stored by the peak value holding module 1033 into a digitized peak value and outputs it to the data processing unit 105. The peak value feedback module provides a peak value feedback signal to the peak value acquisition module 1031 based on the peak value output by the peak value acquisition module 1031. That is, when the pulse input by the peak value acquisition module 1031 reaches the peak value, the peak value acquisition module 1031 stops outputting the signal.

[0049] According to some embodiments, the peak acquisition module 1031 includes a first comparator, the peak holding module 1033 includes a third three-terminal switch, and the peak feedback module 1037 includes a first three-terminal switch, wherein the first terminal of the first comparator receives pulse information, the output terminal of the first comparator and the control terminal of the third three-terminal switch are electrically connected to the first connection terminal, the control terminal of the first three-terminal switch is electrically connected to the first connection terminal, the first terminal of the first three-terminal switch is electrically connected to the second terminal of the first comparator, and the second terminal of the first three-terminal switch and the first terminal of the third three-terminal switch are electrically connected to the second connection terminal.

[0050] According to some embodiments, the first output module 1035 includes a cascaded voltage follower and an analog-to-digital converter, wherein the voltage follower is used to isolate the influence of the data processing unit 105 on the peak capture unit 103, and the analog-to-digital converter is used to convert the peak value output by the voltage follower into a digital peak value and output it to the data processing unit 105.

[0051] According to some embodiments, the peak capture unit further includes a second output module, configured to control an analog-to-digital converter to capture a peak value according to a peak value output by the voltage follower.

[0052] According to some embodiments, the second output module includes a second comparator, and the output end of the voltage follower and the first end of the voltage follower are electrically connected to the first end of the second comparator, the output end of the second comparator is electrically connected to the first end of the second comparator; the second end of the second comparator is electrically connected to the second connection end described above.

[0053] According to some embodiments, the peak holding module 1033 further includes a first capacitor, and the first end of the first capacitor and the second end of the third three-terminal switch are electrically connected to the third connection terminal mentioned above; the second end of the voltage follower is electrically connected to the third connection terminal.

[0054] According to some embodiments, the peak capture unit 103 further includes a discharge module configured to receive a control signal from the data processing unit 105 to control the discharge of the first capacitor so that the peak capture unit 103 can collect a peak control signal of a next pulse.

[0055] According to some embodiments, the discharge module includes a second three-terminal switch, and the second three-terminal switch receives a peak control signal for collecting the next pulse sent by the data processing unit 105, a first terminal of the second three-terminal switch is electrically connected to the third connection terminal mentioned above, and a second terminal of the second three-terminal switch is electrically connected to the second terminal of the first capacitor.

[0056] according to Figure 2The peak capture unit shown collects the pulse peak value through the peak acquisition module and the peak feedback module, and saves it in the peak holding module, so that the first output module converts the peak value into a peak digital signal and sends it to the data processing unit, so that effective constraints are performed at the peak value, so that the calculated energy accuracy is higher when the energy is calculated subsequently.

[0057] Figure 3 A peak capture circuit diagram according to an exemplary embodiment of the present application is shown. Figure 3 , a peak capture circuit according to an exemplary embodiment of the present application is described in detail.

[0058] like Figure 3 As shown, the pulse signal is input to the non-inverting input terminal of the comparator U1 through the input interface and the protection resistor R2. The comparator U1 is used as the peak acquisition module 1031 to collect the pulse peak value. In the rising phase of the pulse signal, the collected pulse information is input to the transistor Q1 and the transistor Q3 respectively.

[0059] like Figure 3 As shown, the control terminal of transistor Q1 receives the pulse peak value output by comparator U1, and its emitter is connected to the inverting input terminal of comparator U1. Transistor Q1 serves as peak feedback module 1037. When the pulse reaches its peak value, the potential of the inverting input terminal of comparator U1 is maximum. When the pulse enters the falling edge, because the potential of the non-inverting input terminal of comparator U1 is lower than that of the inverting input terminal, comparator U1 does not output a signal, thus allowing comparator U1 to collect the peak value.

[0060] Transistor Q3, capacitor C1 and resistor R7 form a peak holding module 1033, wherein resistor R7 is used for filtering, capacitor C1 is used to store charge and collect peak potential, and transistor Q3 is used as a clamp to prevent charge loss in capacitor C1.

[0061] like Figure 3 As shown, the collector of transistor Q1 is grounded via resistor R1 and connected to power supply AVDD via resistor R3. Transistor Q3 is connected to power supply AVDD via resistor R6 to control the current in transistors Q1 and Q3, thereby accelerating the charging time of capacitor C1. Resistors R1, R3, and R6 act as a static bias to prevent excessive charging current in capacitor C1.

[0062] The operational amplifier U3 and the analog-to-digital converter ADC serve as the first output module 1035, outputting a peak digital signal to the data processing unit 105. The non-inverting input of the operational amplifier U3 is connected to the emitter of the transistor Q3 to receive the peak value and send the peak value to the analog-to-digital converter ADC. The analog-to-digital converter ADC converts the peak signal into a peak digital signal and sends it to the data processing unit 105, i.e., the FPGA.

[0063] Since the operational amplifier has a relatively strong load capability, the operational amplifier U3 is used as a voltage follower to isolate the influence of the back-end circuit on the front-end circuit.

[0064] like Figure 3 As shown, the output and inverting input of operational amplifier U3 are connected to the non-inverting input of operational amplifier U2 via resistor R8. The output of operational amplifier U2 is connected to the non-inverting input of operational amplifier U2 via resistor R9. The inverting input of operational amplifier U2 is connected to power supply AVDD and ground via resistor R11, respectively. Resistors R8 and R9 provide hysteresis voltage for operational amplifier U2, while resistors R10 and R11 provide voltage division for operational amplifier U2, so that the inverting input of operational amplifier U2 maintains a fixed threshold voltage.

[0065] The operational amplifier U3 serves as a second output module, and is used to output a trigger signal to control the analog-to-digital converter ADC to collect the peak information of the pulse. That is, when the peak value of the pulse is greater than the threshold, the analog-to-digital converter ADC is controlled to collect the peak information of the pulse.

[0066] like Figure 3 As shown, the control terminal of transistor Q2 receives the peak value control signal for collecting the next pulse from data processing unit 105, that is, the FPGA, through resistor R5. The collector of transistor Q2 is connected to the emitter of transistor Q3 through resistor R4, and the emitter of transistor Q2 is grounded. Resistors R4 and R5 are used for current limiting.

[0067] Since the pulse width of the scintillation pulse is short, at high counting rates, it is necessary to Figure 3 The transistor Q2 shown is used as a discharge module to release the charge held by the capacitor C1 in a timely manner after the analog-to-digital converter ADC completes peak acquisition. The switching principle of the transistor is used to implement discharge control, so that the peak holding module 1033 composed of the transistor Q3, capacitor C1, and resistor R7 is reset and starts to collect the peak value of the next pulse.

[0068] According to some embodiments, the peak capture circuit begins capturing peak values ​​when a preset voltage threshold is triggered. A reset is initiated after a fixed interval, for example, a pulse duration of 200 ns. According to some embodiments, the reset may last for a period of time, for example, 100 ns.

[0069] It should be noted that in order to save costs, Figure 3 The operational amplifier shown in the figure is replaced by a transistor, which includes an NPN transistor, a PNP transistor, a CMOS transistor, or a PMOS transistor.

[0070] In addition, the analog-to-digital converter ADC is used to perform short-time sampling of the stable state of the peak capture circuit. Therefore, the analog-to-digital converter ADC can also use a cost-effective low-speed analog-to-digital converter ADC to reduce costs.

[0071] according to Figure 3 The peak capture circuit shown collects the pulse peak value through the comparator U1 and the transistor Q1, and stores it in the peak holding module composed of the transistor Q3, the capacitor C1, and the resistor R7. The analog-to-digital converter ADC converts the peak value into a peak digital signal and sends it to the data processing unit FPGA, so that effective constraints are placed on the subsequent peak value calculation. When the energy is calculated later, the energy resolution is higher and the dynamic measurement range is larger, which reduces the sensitivity of the pulse fitting to the voltage threshold when reconstructing the pulse information.

[0072] Figure 4 A sampling circuit diagram of a scintillation pulse digitization device according to an exemplary embodiment of the present application is shown. Figure 4 , a sampling circuit of a scintillation pulse digitization device according to an exemplary embodiment of the present application is described in detail.

[0073] like Figure 4 The sampling circuit shown in FIG. 1 includes a threshold comparison unit 101, a peak capture unit 103, and a data processing unit 105. The threshold comparison unit 101 includes two comparators and four TDC circuits, and the peak capture unit 103 includes the following: Figure 3 In the peak capture circuit shown, the data processing unit 105 includes an FPGA.

[0074] like Figure 4 As shown, the comparator in threshold comparison unit 101 inputs two voltage thresholds and a pulse signal. Each comparator is connected to two TDC circuits. The TDC circuit uses the fixed delay of the internal cells to form a long chain. When each cell is triggered, it outputs an output flag. The position of the output flag can be used to determine the duration of the signal. The output signal of the comparator enters the TDC circuit, which converts the time when the pulse reaches the threshold into a digital signal. The TDC circuit is then transmitted to the host computer using the FPGA for pulse information reconstruction.

[0075] The peak capture circuit as the peak capture unit 103 outputs the peak digital signal of the pulse according to the input pulse information and transmits it to the host computer using FPGA, so that when the pulse information is reconstructed, a strong constraint is formed at the peak to make the energy resolution higher and the dynamic measurement range larger.

[0076] The FPGA of the data processing unit 105 transmits the threshold time digital signal and the peak digital signal to the host computer, so that when the pulse information is reconstructed, the sensitivity of the pulse fitting to the threshold is reduced, the fitting accuracy and the peak range of the fitted pulse are improved, and the counting rate of the detector is thereby improved.

[0077] According to some embodiments, the FPGA of the data processing unit 105 is Figure 3 The peak value capturing unit 103 shown outputs a control signal for capturing the peak value of the next pulse, so as to control the peak value capturing unit 103 to capture the peak value of the next pulse.

[0078] According to the embodiments of the present application, peak capture and threshold sampling are combined based on an FPGA. Compared to traditional multi-threshold sampling methods, pulse peak information is obtained, thereby reducing the sensitivity of pulse fitting to thresholds, improving fitting accuracy and the peak range of the fitted pulses, and thus increasing the detector count rate. Furthermore, according to the embodiments of the present application, the number of thresholds required is reduced compared to traditional multi-threshold sampling methods, reducing implementation costs.

[0079] According to some embodiments of the present application, an imaging system is provided, which may include the above-mentioned scintillation pulse signal digitizing device.

[0080] According to other embodiments, the imaging system also includes a pulse signal fitting device, and the digitization device of the scintillation pulse signal transmits the obtained threshold time digital signal and peak digital signal to the pulse signal fitting device. The pulse signal fitting device uses the obtained threshold time digital signal and peak digital signal to form a strong constraint at the peak value, thereby completing the accurate characterization of the final pulse waveform.

[0081] The systems, devices, units, and the like described in the above embodiments may be implemented by semiconductor chips, computer chips, and / or physical devices, or by products having certain functions. For ease of description, the above devices are described separately by function, with each unit described separately. Of course, when implementing this application, the functions of each unit may be implemented in the same or multiple chips.

[0082] Although the present application provides the method operation steps described in the above embodiments or flow charts, more or fewer operation steps may be included in the method based on routine or no creative work. In the steps where there is no necessary causal relationship in logic, the execution order of these steps is not limited to the execution order provided in the embodiments of the present application.

[0083] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. The above embodiments are described to facilitate ordinary technicians in this technical field to understand and use this application. It is obvious that those familiar with the technology in this field can easily make various modifications to these embodiments and apply the general principles described here to other embodiments without having to go through creative work. Therefore, this application is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of this application without departing from the scope of this application should be within the scope of protection of this application.

[0084] The embodiments of the present application are described in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only intended to help understand the method and core ideas of the present application. At the same time, changes or modifications made by those skilled in the art based on the ideas of the present application, the specific implementation methods, and the scope of application of the present application, all fall within the scope of protection of the present application. In summary, the contents of this specification should not be construed as limiting the present application.

Claims

1. A digitizing device for a scintillation pulse signal, characterized in that: include: A threshold comparison unit, which outputs a threshold time digital signal corresponding to the pulse according to a preset threshold and input pulse information, wherein the number of the thresholds does not exceed three; A peak value capture unit outputs a peak value digital signal of the pulse according to the pulse information; and A data processing unit generates a control signal based on the threshold time digital signal and the peak digital signal to control the peak capture unit to output the peak digital signal of the next pulse; the data processing unit transmits the received threshold time digital signal and the peak digital signal to a host computer so that the host computer performs pulse fitting.

2. The scintillation pulse signal digitizing device according to claim 1, characterized in that: The preset threshold value includes one or more of a voltage threshold value, a current threshold value, an energy threshold value, and a magnetic field strength threshold value.

3. The scintillation pulse signal digitizing device according to claim 1, characterized in that: The peak capture unit includes a peak acquisition module, a peak hold module, a peak feedback module and a first output module, wherein: The peak value acquisition module outputs the peak value of the pulse using the input pulse information; The peak holding module is used to store the peak value; The first output module outputs a digitized peak value according to the stored peak value; The peak feedback module provides a peak feedback signal to the peak acquisition module according to the peak value output by the peak acquisition module.

4. The scintillation pulse signal digitizing device according to claim 3, characterized in that: The peak acquisition module includes a first comparator, the peak holding module includes a third three-terminal switch, and the peak feedback module includes a first three-terminal switch, wherein: The first terminal of the first comparator receives the pulse information; The output terminal of the first comparator and the control terminal of the third three-terminal switch are electrically connected to the first connection terminal; The control end of the first three-terminal switch is electrically connected to the first connection end; A first terminal of the first three-terminal switch is electrically connected to a second terminal of the first comparator; The second terminal of the first three-terminal switch and the first terminal of the third three-terminal switch are electrically connected to the second connection terminal.

5. The scintillation pulse signal digitizing device according to claim 4, characterized in that: The first output module includes a cascaded voltage follower and an analog-to-digital converter, wherein: The analog-to-digital converter outputs a digitized peak value according to the peak value output by the voltage follower.

6. The scintillation pulse signal digitizing device according to claim 5, characterized in that: The peak capture unit also includes: The second output module controls the analog-to-digital converter to collect the peak value according to the peak value output by the voltage follower.

7. The scintillation pulse signal digitizing device according to claim 6, characterized in that: The second output module includes a second comparator, The output terminal of the voltage follower and the first terminal of the voltage follower are electrically connected to the first terminal of the second comparator; The output terminal of the second comparator is electrically connected to the first terminal of the second comparator; The second terminal of the second comparator is electrically connected to the second connection terminal.

8. The scintillation pulse signal digitizing device according to claim 7, characterized in that: The peak holding module further includes a first capacitor, The first terminal of the first capacitor and the second terminal of the third three-terminal switch are electrically connected to the third connection terminal; The second terminal of the voltage follower is electrically connected to the third connection terminal.

9. The scintillation pulse signal digitizing device according to claim 8, characterized in that: The peak capture unit further includes a discharge module, which includes a second three-terminal switch. The second three-terminal switch receives a peak value control signal for collecting a next pulse sent by the data processing unit; The first terminal of the second three-terminal switch is electrically connected to the third connection terminal; The second terminal of the second three-terminal switch is electrically connected to the second terminal of the first capacitor.

10. An imaging system, characterized in that: A device for digitizing a scintillation pulse signal comprising the device according to any one of claims 1 to 9.

11. The imaging system according to claim 10, wherein: The imaging system further comprises a fitting device, The fitting device uses the threshold time digital signal and the peak value digital signal to complete the characterization of the pulse waveform.

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