WO2023226306A1 - Procédé et appareil d'échantillonnage de signal pet numérique, dispositif et support de stockage - Google Patents

Procédé et appareil d'échantillonnage de signal pet numérique, dispositif et support de stockage Download PDF

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WO2023226306A1
WO2023226306A1 PCT/CN2022/129466 CN2022129466W WO2023226306A1 WO 2023226306 A1 WO2023226306 A1 WO 2023226306A1 CN 2022129466 W CN2022129466 W CN 2022129466W WO 2023226306 A1 WO2023226306 A1 WO 2023226306A1
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threshold
thresholds
sampling
time
signal
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PCT/CN2022/129466
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Chinese (zh)
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张博
房磊
谢庆国
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合肥锐世数字科技有限公司
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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/02—Arrangements for diagnosis sequentially in different planes; Stereoscopic radiation diagnosis
    • A61B6/03—Computed tomography [CT]
    • A61B6/037—Emission tomography
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/42—Arrangements for detecting radiation specially adapted for radiation diagnosis
    • A61B6/4208—Arrangements for detecting radiation specially adapted for radiation diagnosis characterised by using a particular type of detector
    • A61B6/4241—Arrangements for detecting radiation specially adapted for radiation diagnosis characterised by using a particular type of detector using energy resolving detectors, e.g. photon counting

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  • the present application relates to the field of positron emission computed tomography, and in particular to a digital PET signal sampling method, device, equipment and storage medium.
  • Positron emission tomography is a high-end nuclear medicine imaging equipment that is widely used in cancer diagnosis and treatment, brain science research, cardiology research, heavy ion radiotherapy monitoring and other fields, in which a large number of gamma ray detectors are used for signal sampling .
  • the Multi-Voltage Threshold (MVT) method proposed by Xie Qingguo's team completes the digitization of scintillation pulses by sampling the time point when the scintillation pulse crosses the threshold voltage.
  • the MVT method can directly digitize the scintillation pulse signal when the detector is sampling, thus making the detector modular and bringing PET into the digital PET era.
  • the key to the MVT method is to obtain the time information when the input waveform crosses the set threshold through TDC (time to digital conversion) technology, thereby inverting the waveform information.
  • This usually requires threshold comparison of multiple channels and subsequent time measurement, which requires a certain amount of internal FPGA time.
  • the waveform processing circuit output by a single SIPM detector is usually shown in Figure 1.
  • the waveform of a single channel corresponds to 4 channels of comparators (LVDS Comparator), which requires 8 input pins of the FPGA chip and 8 TDC measurement module for several channels, and an FPGA usually needs to process dozens or hundreds of channels of signals.
  • LVDS Comparator comparators
  • the FPGA chip used in PET can provide 115K logic resources and about 500 available LVDS pins, regardless of its tube size. Neither pins nor logic resources can handle the data of many channels. The logic resources are limited and the measurement accuracy of the TDC module is also restricted.
  • the purpose of the embodiments of the present application is to provide a digital PET signal sampling method, device, equipment and storage medium to solve at least one technical problem existing in the existing technology.
  • a signal sampling method for digital PET includes: presetting at least two thresholds that can be switched and selected; using the same comparison module to sequentially compare the to-be-processed scintillation pulse with at least two Threshold, determine at least two status signals corresponding to at least two thresholds when the flicker pulse to be processed crosses the threshold; use the same sampling module to sequentially sample the time of at least two status signals to obtain the corresponding flicker pulse threshold-time pair.
  • a signal sampling method for digital PET includes: presetting at least two sets of thresholds, each set of thresholds including at least two switchable thresholds; setting and at least two sets of thresholds in parallel.
  • a digital PET signal sampling device includes: an acquisition module for acquiring the scintillation pulse to be processed; a threshold value providing module for switching and selecting at least two preset thresholds ;
  • the comparison module is used to compare the flicker pulse to be processed with at least two thresholds in sequence, and determine at least two status signals corresponding to the at least two thresholds when the flicker pulse to be processed crosses the threshold;
  • the sampling module is used to compare at least two status signals in sequence Perform time sampling on each status signal to obtain the corresponding flicker pulse threshold-time pair.
  • a signal sampling device for digital PET includes: an acquisition module for acquiring scintillation pulses to be processed; at least two threshold value providing modules, wherein each threshold value providing module is used for Switching selects at least two preset thresholds; at least two comparison modules are set up in parallel, which correspond to at least two threshold providing modules one-to-one, wherein each comparison module is used to sequentially compare the flicker pulse to be processed with the corresponding threshold providing module.
  • At least two thresholds are used to determine at least two status signals corresponding to the at least two thresholds when the flicker pulse to be processed crosses the threshold; a sampling module is used to time-sample the status signal in sequence to obtain the corresponding flicker pulse threshold - The time is right.
  • a detector device includes: a detector and a digital PET signal sampling device as described in any one of the above, wherein the detector is configured to detect gamma rays and The flicker pulse signal to be processed is output to the signal sampling device for digital sampling processing.
  • a digital PET device including: a memory, a processor, and a computer program stored in the memory and executable on the processor.
  • the computer program is executed by the processor, any of the above items are implemented. The steps of the signal sampling method.
  • a computer-readable storage medium is provided.
  • a computer program is stored on the storage medium.
  • the computer program is executed by a processor, the steps of any one of the signal sampling methods described above are implemented.
  • FIG. 1 is an exemplary processing circuit diagram of multiple voltage threshold sampling according to the prior art
  • Figure 2 is an exemplary flow chart of a signal sampling method for digital PET shown according to some embodiments of the present application
  • Figure 3 is a schematic diagram illustrating an exemplary relationship between threshold voltage and flicker pulses to be processed according to some embodiments of the present application
  • Figure 4 is an exemplary flowchart of sequentially time sampling at least two status signals according to some embodiments of the present application
  • Figure 5 is an exemplary flow chart of scintillation pulse signal sampling according to other embodiments of the present application.
  • Figure 6 is an exemplary flowchart of sequentially time sampling status signals according to some embodiments of the present application.
  • Figure 7 is an exemplary module diagram of a digital PET signal sampling device according to some embodiments of this specification.
  • FIG. 8 is an exemplary module diagram of a digital PET signal sampling device according to some embodiments of this specification.
  • FIG. 2 is an exemplary flow chart of signal sampling of digital PET according to some embodiments of the present application.
  • the digital PET signal sampling method S200 may include the following steps.
  • Step S210 Preset at least two thresholds that can be switched and selected.
  • At least two thresholds may be used for comparison with the amplitude of the scintillation pulse to be processed.
  • the comparison results can be used for time sampling to determine the time point at which the amplitude of the scintillation pulse to be processed crosses a threshold. After these time points are matched with the corresponding thresholds, they can be used for waveform recovery during subsequent processing (for example, image reconstruction), such as recovering the area of the waveform, and then obtaining the waveform energy value.
  • the size of the threshold value is set to not exceed the maximum amplitude of the scintillation pulse to be processed, that is, the size of the threshold value is within the amplitude of the scintillation pulse to be processed.
  • FIG. 3 is a schematic diagram of an exemplary relationship between threshold voltage and scintillation pulses according to some embodiments of the present application, wherein 310 represents a scintillation pulse, which may be the to-be-processed scintillation pulse mentioned in this application.
  • the waveform of the scintillation pulse in the figure shows its characteristics, that is, the rise period is very short, usually only a few nanoseconds, before it rises to the highest point.
  • the decline period is longer, usually more than 100ns, and usually about 200 nanoseconds.
  • eight threshold voltages are set, and 310-1 to 310-8 represent eight different threshold voltages.
  • all eight threshold voltages are within the amplitude of the flicker pulse.
  • the eight threshold voltages can be 10mV, 50mV, 70mV, 90mV, 110mV, 120mV, 140mV, and 160mV respectively.
  • the scintillation pulses to be processed are usually acquired by a PET detector.
  • the PET detector usually includes mutually coupled scintillation crystals and photoelectric conversion devices, where the scintillation crystal is used to convert detected high-energy rays (such as gamma rays, Neutron rays, etc.) are converted into visible light signals.
  • Photoelectric conversion devices for example, photomultiplier tubes PMT, silicon photomultiplier tubes SiPM, etc.
  • the electrical signals pass through the electronics connected to the photoelectric conversion devices.
  • the device outputs a scintillation pulse signal.
  • the acquisition module can communicate with the detector to obtain the scintillation pulse to be processed.
  • a scintillation pulse usually has a rising edge and a falling edge, and the rising edge and falling edge can be represented by a function model.
  • a scintillation pulse corresponding to a gamma photon usually has a relatively fast rising edge and a relatively slow edge.
  • the rising edge can be characterized by a straight line function, and the falling edge can be characterized by an exponential function.
  • the preset switchable selection of at least two thresholds is implemented by a threshold providing module.
  • the threshold providing module is implemented by a circuit including a threshold control module and a threshold selection module.
  • the threshold control module controls the threshold selection module to adjust the preset threshold.
  • the threshold control module controls the threshold selection module through a control line.
  • the threshold control module includes a threshold controller, and the threshold selection module includes a data selector MUX (multiplexer).
  • MUX multiplexer
  • an 8-to-1 data selector MUX8 can be used to preset 8 A switchable threshold.
  • the threshold controller controls MUX8 to switch and select at least two thresholds, and the switched thresholds are transmitted to the LVDS comparator for amplitude comparison.
  • the threshold controller controls the threshold switching selection operation based on the comparison result between the amplitude of the scintillation pulse to be processed and the threshold currently selected by the data selector MUX8.
  • the threshold controller controls MUX8 through the control line.
  • Step S220 Use the same comparison module to sequentially compare the flicker pulse to be processed with at least two thresholds, and determine at least two status signals corresponding to at least two thresholds when the flicker pulse to be processed crosses the threshold.
  • the same comparison module is used to sequentially compare at least two preset thresholds with the amplitude of the scintillation pulse to be processed.
  • the comparison module is implemented by a circuit including a comparator, capable of comparing the received threshold size with the amplitude of the flicker pulse.
  • the comparator sequentially compares the flicker pulse to be processed with each threshold selected from at least two thresholds. the size of.
  • the comparison module 820 may be implemented by a circuit including a Low-Voltage Differential Signaling (LVDS) comparator.
  • LVDS Low-Voltage Differential Signaling
  • the flicker pulse generated by the detector can be input to the p terminal of the LVDS comparator pin (also called the positive terminal), and the currently selected threshold value can be input to the n terminal of the LVDS comparator pin (also called the positive terminal). can be called the negative terminal), thereby completing the comparison between the pulse waveform and the threshold.
  • LVDS Low-Voltage Differential Signaling
  • the scintillation pulse can cross the same threshold twice. Once is in the rising phase of the scintillation pulse, the amplitude of the scintillation pulse can cross the threshold and be higher than the threshold from low to high. Once is in the falling phase of the scintillation pulse, the amplitude of the scintillation pulse can cross the threshold and fall below the threshold from high to low. Regardless of the type of crossing, the comparison module can generate a transition and record the time when the amplitude crosses the threshold.
  • Figure 3 shows a schematic diagram of the principle of multi-voltage threshold sampling.
  • the scintillation pulse 310 will first cross and be higher than the threshold voltage 310-1, then continue upward, cross and be higher than the threshold voltage 310-2, and then will successively cross and be higher than the threshold voltage 310-3 ⁇ 310-8.
  • the flicker pulse 310 first crosses and falls below the threshold voltage 310-8. Then it continues downward, crossing and falling below the threshold voltage 310-7, and then crossing and falling below the threshold voltages 310-6 to 310-1 in sequence.
  • the pulse voltage 310 can undergo 16 state changes relative to the above eight threshold voltages.
  • the threshold when the threshold is set to a large value, such as when it is higher than the maximum amplitude of the signal, the amplitude of the scintillation pulse will never cross the preset threshold, and therefore the comparison module will not change state;
  • the threshold is set exactly equal to the maximum amplitude of the signal, the comparison module only changes state once. Therefore, usually those skilled in the art can reasonably set the size and number of thresholds based on limited experiments, so that the size intervals of the thresholds are more reasonable. Usually, if 2-8 evenly spaced thresholds are selected, the collected information will be closer The real state can accurately restore the pulse shape while reducing the number of channels and improving data processing efficiency. I will not go into details here.
  • the comparison module can compare the flicker pulse to be processed with the current threshold of the switched selection, and output a status signal.
  • the status signal may indicate a change in status of the pulse to be processed relative to the threshold (eg, from below the threshold to above and above the threshold or from above the threshold to above and below the threshold).
  • the time sampling mentioned in the subsequent parts of this application may refer to time measurement at the moment corresponding to the status signal.
  • Each status signal consists of a rising edge and a falling edge.
  • the rising edge corresponds to the time when the scintillation pulse to be processed crosses the threshold voltages 310-1 to 310-8 in sequence on the rising edge of the pulse
  • the falling edge corresponds to the time when the scintillation pulse to be processed crosses the threshold voltages 310-8 to 310-8 in sequence on the falling edge of the pulse.
  • 310-1 moment The rising edge indicates that the scintillation pulse to be processed has crossed over and is higher than the threshold voltage from bottom to top, and the falling edge represents that the scintillation pulse to be processed has crossed over and is below the threshold voltage from top to bottom.
  • the moment corresponding to the position of the rising edge and the falling edge may be the moment when the scintillation pulse crosses the threshold voltage.
  • Persons skilled in the art should understand that in the above embodiments, only voltage thresholds and voltage status signals are used as examples, and other thresholds and status changes are applicable in principle and will not be described again here.
  • the status signal includes a rising edge indicating that the flicker pulse to be processed crosses at least part of the at least two thresholds, including the lowest threshold, and a falling edge that crosses all of the at least two thresholds.
  • the status signal includes the rising edge corresponding to the moment when the flicker pulse to be processed crosses the lowest threshold voltage 310-1 on the rising edge of the pulse, and the flicker pulse to be processed sequentially crosses the threshold voltage 310-8 on the falling edge of the pulse.
  • the same comparison module is used to sequentially compare the flicker pulse to be processed with at least two thresholds, including sequentially switching between at least two thresholds according to the status signal, so that the same comparison module sequentially compares the pulse to be processed with at least The size of the different thresholds in the two thresholds.
  • sequential switching between at least two thresholds is performed according to the status signal, which is realized by the threshold value providing module.
  • the threshold value providing module selects and controls the threshold value input to the negative terminal of the LVDS comparator according to the status signal output by the LVDS comparator.
  • the flicker pulse to be processed is input to the positive terminal of the LVDS comparator, and the threshold voltage selected by the threshold providing module is input to the negative terminal of the LVDS comparator.
  • the status signal output by the LVDS comparator is 1.
  • the status signal output by the LVDS comparator is 0.
  • the output result of the LVDS comparator is connected to the threshold control module of the threshold providing module as a feedback input.
  • the threshold controller of the threshold control block controls the MUX8 of the threshold selection module through the control line according to the feedback input signal in the rising edge sequence (that is, ascending order) or The selection thresholds are switched sequentially in falling edge order (that is, in descending order).
  • the threshold controller controls MUX8 to continue to select the current threshold.
  • the threshold controller controls MUX8 according to The rising edge sequentially switches to the next threshold; when the rising edge sampling is completed, that is, it switches to the maximum threshold and completes the rising edge sampling, then the falling edge sampling of the threshold continues. This threshold is the first threshold in the falling edge sampling order.
  • the threshold controller controls MUX8 to continue to select the current threshold.
  • the threshold controller Control MUX8 to switch to the next threshold according to the falling edge sequence.
  • Step S230 Use the same sampling module to sequentially perform time sampling on at least two status signals to obtain the corresponding flicker pulse threshold-time pair.
  • time sampling may be time digital sampling for the moments corresponding to the rising edge and falling edge of the status signal and/or the delayed status signal.
  • time sampling time digitized sampling
  • time measurement time may be used interchangeably to mean determining the rising edge of each status signal and/or each delayed status signal after delay processing and This operation occurs at the time corresponding to the position of the falling edge.
  • the sampling module can be used to sample the times corresponding to the rising edge and falling edge of the above delayed status signal according to a certain sampling sequence.
  • the sampling module can be implemented by a circuit including a time-to-digital converter (TDC).
  • TDC time-to-digital converter
  • the time-to-digital converter TDC is communicatively connected with the comparison module, and the time-to-digital converter implements time sampling.
  • the sampling module can use TDC to sample the moment corresponding to the rising edge or falling edge of the input delayed status signal.
  • the scintillation pulse threshold-time pair may include a state change time obtained by performing time sampling on the state signal and the amplitude of the threshold corresponding to the state signal.
  • the status signal can be obtained by comparing it with the flicker pulse to be processed.
  • the TDC time measurement of the status signal can obtain two moments, including the time T 1 corresponding to the position of the rising edge and the position of the falling edge.
  • T 1 and T 2 may be referred to as state change times
  • the flicker pulse threshold-time pair may include (V 1 , T 1 ) and (V 1 , T 2 ).
  • the flicker pulse threshold-time pairs may be transmitted to other components for further processing.
  • the sampling results can be transmitted to the image processing components related to the PET equipment through wired or wireless communication methods for subsequent PET image reconstruction.
  • the digital PET signal sampling method in the embodiment of the present application is based on the realization of multi-threshold scintillation pulse waveform sampling through threshold switching.
  • the time sampling of scintillation pulses can be realized by using only one TDC of one sampling module, and the sampling module TDC is realized.
  • the multiplexing greatly saves computing resources and effectively reduces energy consumption. At the same time, the saved resources can improve the accuracy of time sampling, thereby improving system performance.
  • FIG. 4 is an exemplary flowchart of sequentially time sampling at least two status signals according to some embodiments of the present application. As shown in Figure 4, the process S400 of sequentially sampling at least two status signals in time may include the following operations:
  • Step S410 Perform first time sampling based on the time corresponding to the rising edge of the status signal corresponding to the lowest threshold.
  • the sampling module may be used to perform the first time sampling at the moment corresponding to the rising edge of the status signal corresponding to the lowest threshold in the first order. For example, referring to FIG. 3 , among the eight threshold voltages, the lowest threshold that is ranked first among the eight threshold voltages in ascending order is the threshold voltage 310-1. After the status signal corresponding to the lowest threshold is output from the comparison module, it will be input to the TDC for time sampling. In step S410, the LVDS comparator of the comparison module will first output the status signal corresponding to the threshold voltage 310-1 to TDC. The TDC can perform time sampling on the moment corresponding to the rising edge of the status signal to complete the first time sampling.
  • Step S420 determine whether the first time sampling is successful.
  • the TDC of the sampling module can output a feedback at the same time when sampling the status signal in time.
  • Feedback may include one or more combinations of numbers, letters, symbols, etc.
  • the feedback can be a 1 or a 0.
  • a 1 indicates that the flicker pulse is above and above the threshold
  • a 0 indicates that the flicker pulse is above and below the threshold voltage.
  • the signal sampling method After performing the first time sampling based on the lowest threshold at the moment corresponding to the rising edge of the status signal, the signal sampling method also includes:
  • the lowest threshold among the at least two preset thresholds is more critical, and the time corresponding to its corresponding status signal is usually used to determine the arrival time of the input ray particles received by the front-end detector.
  • a comparison is set Low, in the order of several mV, and prone to false triggering. It is necessary to further confirm whether the flicker pulse to be processed is a valid signal through subsequent thresholds.
  • determining whether the scintillation pulse to be processed is a valid signal includes the following steps:
  • the comparison module is used to compare the flash pulse to be processed and the verification threshold. If the verification status signal that the flash pulse to be processed crosses the verification threshold is not obtained, it is a false trigger signal; if the verification status signal that the flash pulse to be processed crosses the verification threshold is obtained, it is a false trigger signal. valid signal.
  • whether the rising edge position is a valid trigger can usually be determined by whether the flicker pulse waveform crosses a higher second threshold.
  • the rising edge sampling of the scintillation pulse waveform first determines whether the signal passes the minimum threshold. After completing the first time sampling, the false trigger signal is then eliminated by whether it passes the second threshold to obtain an effective rising edge starting point, which is the key to the subsequent particle arrival time. data.
  • the rising edge period of the scintillation pulse is very short, typically culminating in only a few nanoseconds.
  • the falling edge period is longer, usually more than 100ns, and usually about 200 nanoseconds. Therefore, after completing the first time sampling, during the switching process of the threshold providing module from the lowest threshold to the second threshold, the amplitude of the input flicker pulse waveform has crossed the level of the second threshold, so the threshold providing module completes the switching process from the lowest threshold to the second threshold. After the threshold of the second threshold is switched, it can be directly judged whether it is a valid signal. If it is a false trigger, it will return to the starting state.
  • the threshold will be directly set to the highest threshold and the waveform collection of the falling edge will be carried out.
  • the flicker pulse signal is a valid signal
  • the amplitude of the input flicker pulse waveform has crossed the level of the second threshold, therefore, regarding the rise of the flicker pulse
  • the first time sampling of the edge is performed based on the moment corresponding to the rising edge of the status signal corresponding to the lowest threshold. For example, in the example shown in Figure 3, during the switching process of the lowest threshold 310-1 to the second threshold 310-2 by the threshold value providing module, the input flicker pulse waveform amplitude has crossed the level of the second threshold 310-2. Therefore, the flash pulse signal is a valid signal.
  • the scintillation pulse signal is a valid signal
  • the first time sampling is only performed on the state signal corresponding to the lowest threshold voltage 510-1.
  • step S430 is executed. Otherwise, the process S400 will return to the initial state, execute step S410, and re-execute the first time sampling based on the moment corresponding to the rising edge of the status signal corresponding to the lowest threshold.
  • Step S430 Perform second time sampling based on descending order based on the time corresponding to the falling edge of the status signal.
  • the sampling module can sequentially perform second time sampling at the time corresponding to the falling edge of one or more delayed status signals.
  • the second order may be an arrangement order determined from large to small according to the magnitude of one or more thresholds. For example, continuing to refer to Figure 3, among the eight threshold voltages, the largest threshold voltage is 410-8, arranged from small to large.
  • TDC can start performing the second time sampling according to the status signal corresponding to the threshold voltage 410-8, that is, the TDC acquisition threshold voltage is the moment corresponding to the falling edge of the status signal corresponding to 410-8.
  • the threshold providing module sequentially selects different thresholds in the second order from large to small thresholds, that is, in descending order. Based on this, the comparison module obtains the corresponding threshold voltage 410 For the status signals corresponding to -7 to 410-1, the TDC performs time sampling on the moments corresponding to the falling edges of the status signals corresponding to the threshold voltages 410-7 to 410-1, thereby completing the second time sampling, and the process S400 can end.
  • the sampling module is implemented by a circuit including a time-to-digital converter, and the time-to-digital converter implements time sampling.
  • dynamic threshold switching is achieved by using a threshold value providing module to switch between different set thresholds, and the LVDS comparator of only one comparison module can be used to sequentially compare the flicker pulses to be processed with the set ones.
  • this application effectively increases the number of sampling points while reducing the number of LVDS comparators, thereby reducing the number of pins and reducing the cost of the FPGA chip.
  • FIG. 5 is an exemplary flow chart of signal sampling of digital PET according to other embodiments of the present application.
  • the acquisition of the scintillation pulses to be processed, the characteristics and manifestations of the scintillation pulses, the manifestations of the thresholds, and the structures of the comparison module and the sampling module can all refer to the embodiment shown in Figure 2 and will not be described in detail in this embodiment.
  • the process S500 of the digital PET signal sampling method may include the following steps.
  • Step S510 Preset at least two sets of thresholds, each set of thresholds including at least two switchable thresholds.
  • each group of thresholds includes at least two switchable thresholds that are implemented by a threshold providing module.
  • One group of thresholds corresponds to a threshold passing module.
  • the threshold providing module is implemented by a circuit including a threshold control module and a threshold selection module.
  • the threshold The control module sequentially controls the threshold selection module according to the status signal to implement switching selection of at least two thresholds for each set of preset thresholds.
  • At least two sets of thresholds may be used for comparison with the amplitude of the scintillation pulse to be processed.
  • the comparison results can be used for time sampling to determine the time point at which the amplitude of the scintillation pulse to be processed crosses a threshold. After these time points are matched with the corresponding thresholds, they can be used for waveform recovery during subsequent processing (for example, image reconstruction), such as recovering the area of the waveform, and then obtaining the waveform energy value.
  • the threshold when the threshold is set to a large value, such as when it is higher than the maximum amplitude of the signal, the amplitude of the scintillation pulse will never cross the preset threshold, and therefore the comparison module will not change state;
  • the threshold is set exactly equal to the maximum amplitude of the signal, the comparison module only changes state once. Therefore, usually those skilled in the art can reasonably set the size and number of thresholds based on limited experiments, so that the size intervals of the thresholds are more reasonable. Usually, if 2-8 evenly spaced thresholds are selected, the collected information will be closer The real state can accurately restore the pulse shape while reducing the number of channels and improving data processing efficiency. I will not go into details here.
  • the number of thresholds in each group is set to 2-4, and the size of the threshold is set not to exceed the maximum amplitude of the scintillation pulse to be processed, that is, the size of the thresholds is within the amplitude of the scintillation pulse to be processed. .
  • FIG. 3 is a schematic diagram of an exemplary relationship between threshold voltage and scintillation pulse according to some embodiments of the present application, wherein 310 represents a scintillation pulse, which may be the one mentioned in this application.
  • Pending flash pulse The waveform of the scintillation pulse in the figure shows its characteristics, that is, the rise period is very short, usually only a few nanoseconds, before it rises to the highest point. The decline period is longer, usually more than 100ns, and usually about 200 nanoseconds.
  • eight threshold voltages are set, and 310-1 to 310-8 represent eight different threshold voltages. It can be seen that all eight threshold voltages are within the amplitude of the flicker pulse.
  • the 8 threshold voltages can be 10mV, 50mV, 70mV, 90mV, 110mV, 130mV, 150mV, 170mV respectively.
  • the 8 threshold voltages are divided into two groups.
  • the four threshold voltages of one group are 20mV, 40mV, 60mV, and 80mV, and the four threshold voltages of the second group are 100mV, 120mV, 140mV, and 160mV.
  • At least two sets of thresholds that are preset and switchable are implemented through at least two corresponding threshold value providing modules, and one threshold value providing module corresponds to one group of thresholds.
  • the threshold providing module is implemented by a circuit including a threshold control module and a threshold selection module.
  • the threshold control module controls the threshold selection module to switch and select a preset threshold.
  • the threshold control module controls the threshold selection module through a control line.
  • the threshold control module includes a threshold controller, and the threshold selection module includes a data selector MUX (multiplexer).
  • two threshold supply modules are specifically used to correspond to two sets of thresholds. Specifically, 2 data selectors MUX4 can be used.
  • Each MUX4 is preset with 4 switchable selection thresholds. Through the 2 data selectors MUX4, 8 switchable selection thresholds can be preset. After presetting the switchable threshold, the threshold controller controls MUX4 to switch and select at least 4 thresholds, and the switched thresholds are transmitted to the LVDS comparator for amplitude comparison. The threshold controller controls the threshold switching selection operation based on the comparison result between the amplitude of the scintillation pulse to be processed and the threshold currently selected by each data selector MUX4. The threshold controller controls MUX4 through the control line.
  • the threshold value providing module is used to switch between different set thresholds to achieve dynamic threshold switching, which can easily increase the number of sampling points and improve the subsequent image reconstruction effect.
  • the LVDS comparator using only one comparison module can be used to sequentially compare the size of the flicker pulse to be processed with the different set thresholds, and only one sampling module TDC is used for time sampling, which improves system performance.
  • at least two groups of thresholds are preset by using at least two threshold modules. Each group of thresholds includes at least two switchable thresholds, and each group of thresholds includes a minimum threshold. The minimum threshold of each group can be used as a rising edge sample. points, thereby increasing the number of sampling points.
  • Step S520 Set up in parallel at least two comparison modules corresponding to at least two sets of thresholds.
  • At least two comparison modules correspond to at least two sets of thresholds respectively, and each comparison module is set up in parallel and works independently of each other.
  • Each comparison module is communicatively connected with the corresponding threshold control module.
  • the pulses to be processed are respectively connected to the positive terminals of at least two comparison modules, the selected threshold value in each set of thresholds is connected to the negative terminal of the comparison module, and the at least two comparison modules are connected to the same sampling module.
  • each comparison module sequentially compares the flicker pulse to be processed with at least two thresholds corresponding to each group, and determines at least two states corresponding to the at least two thresholds of each group when the flicker pulse to be processed crosses the threshold. Signal.
  • each comparison module is used to sequentially compare the corresponding groups of at least two preset thresholds with the amplitude of the scintillation pulse to be processed.
  • the scintillation pulse can cross the same threshold twice. Once is in the rising phase of the scintillation pulse, the amplitude of the scintillation pulse can cross the threshold and be higher than the threshold from low to high. Once is in the falling phase of the scintillation pulse, the amplitude of the scintillation pulse can cross the threshold and fall below the threshold from high to low. Regardless of the type of crossing, the comparison module can generate a transition and record the time when the amplitude crosses the threshold.
  • Figure 3 shows a schematic diagram of the principle of multi-voltage threshold sampling. In this example, there are two sets of thresholds, each with 4 thresholds.
  • the lowest threshold is 310-1 and the highest threshold is 310-4.
  • the flicker pulse 310 will first cross and be higher than the threshold voltage 310-1, and then continue upward, cross and be higher than the threshold voltage. 310-2, and then will successively cross and be higher than the threshold voltage 310-3 ⁇ 310-4.
  • the flicker pulse 310 first crosses and falls below the threshold voltage 310-4. Then it continues downward, crossing and falling below the threshold voltage 310-3, and then crossing and falling below the threshold voltages 310-2 to 310-1 in sequence.
  • the pulse voltage 310 can undergo 16 state changes relative to the above eight threshold voltages.
  • the lowest threshold is 310-5 and the highest threshold is 310-8.
  • the flicker pulse 310 will first cross and be higher than the threshold voltage 310-5, and then continue upward, cross and be higher than the threshold voltage. 310-6, and then will successively cross and be higher than the threshold voltage 310-7 ⁇ 310-8.
  • the flicker pulse 310 first crosses and falls below the threshold voltage 310-8. Then it continues downward, crossing and falling below the threshold voltage 310-7, and then crossing and falling below the threshold voltages 310-6 to 310-5 in sequence.
  • the pulse voltage 310 can undergo 16 state changes relative to the above eight threshold voltages.
  • the comparison module can compare the flicker pulse to be processed with the current threshold of the switched selection, and output a status signal.
  • the status signal may indicate a change in status of the pulse to be processed relative to the threshold (eg, from below the threshold to above and above the threshold or from above the threshold to above and below the threshold).
  • the time sampling mentioned in the subsequent parts of this application may refer to time measurement at the moment corresponding to the status signal.
  • the plurality of status signals respectively correspond to threshold voltages 310-1 to 310-8. Each status signal consists of a rising edge and a falling edge.
  • the respective rising edges of the two sets of thresholds respectively correspond to the moments when the flicker pulse to be processed successively crosses the threshold voltages 310-1 ⁇ 310-4 and 310-1 ⁇ 310-8 on the rising edge of the pulse
  • the respective falling edges correspond to The processing is performed on the moments when the flicker pulses sequentially cross the threshold voltages 310-8 to 310-5 and 310-4 to 310-1 on the falling edges of the pulses.
  • the rising edge indicates that the scintillation pulse to be processed has crossed over and is higher than the threshold voltage from bottom to top
  • the falling edge represents that the scintillation pulse to be processed has crossed over and is below the threshold voltage from top to bottom.
  • the moment corresponding to the position of the rising edge and the falling edge may be the moment when the scintillation pulse crosses the threshold voltage.
  • Only voltage thresholds and voltage status signals are used as examples, and other thresholds and status changes are applicable in principle and will not be described again here.
  • the threshold is set to at least two groups, each group has a minimum threshold, and the information of the minimum threshold can be accurately collected.
  • the status signal includes a rising edge indicating that the flicker pulse to be processed crosses at least some of the thresholds in each set of at least two thresholds, including the lowest threshold, and a falling edge that crosses all thresholds in each set of at least two thresholds.
  • a comparison module is used to compare the flicker pulse to be processed with at least two thresholds of each group in each channel, including: sequentially switching between at least two thresholds of each group according to the status signal, so as to The comparison module corresponding to the set of thresholds is caused to sequentially compare the size of the pulse to be processed with different thresholds in at least two thresholds.
  • each threshold providing module is based on the status signal output by the LVDS comparator, and the input corresponds to the threshold providing module.
  • the threshold of the negative terminal of the LVDS comparator is selected for control.
  • a flicker pulse to be processed is input to the positive terminal of an LVDS comparator, and a corresponding threshold voltage switched and selected by a threshold providing module is input to the corresponding negative terminal of the LVDS comparator.
  • the output status signal of the LVDS comparator is 1, when the level of the flicker pulse to be processed is lower than the currently selected threshold level.
  • the status signal of the output of the LVDS comparator is 0.
  • the output result of the LVDS comparator is connected to the threshold control module of the corresponding threshold providing module as a feedback input.
  • the threshold controller of the threshold control block controls the MUX of the threshold selection module through the control line according to the feedback input signal in the rising edge sequence (that is, in ascending order). ) or falling edge order (i.e. descending order) to switch the selection thresholds sequentially.
  • another flicker pulse to be processed is input to the positive terminal of another LVDS comparator, and the corresponding threshold voltage switched and selected by the other threshold providing module is input to the corresponding negative terminal of another LVDS comparator.
  • the output status signal of the other LVDS comparator is 1.
  • the other LVDS comparator When the level of the flicker pulse to be processed is lower than the currently selected threshold level, the other LVDS comparator The output status signal of the device is 0. The output result of the other LVDS comparator is connected to the threshold control module of the corresponding threshold providing module as a feedback input.
  • the threshold controller of the threshold control block controls the MUX of the threshold selection module through the control line according to the feedback input signal in the rising edge sequence ( The selection thresholds are switched sequentially in ascending order) or falling edge order (descending order).
  • the threshold controller controls the MUX to continue to select the current threshold.
  • the rising edge uses Completed, immediately switch to the maximum threshold for falling edge sampling.
  • This threshold is the first threshold in the falling edge sampling order, that is, the maximum threshold for falling edge sampling.
  • the threshold controller controls the MUX to continue to select the current threshold.
  • the threshold controller controls the MUX to switch to the next threshold in sequence according to the falling edge.
  • Each comparison module is implemented by a circuit including a comparator, and the comparator sequentially compares the magnitude of the pulse to be processed with each threshold value switched and selected in a corresponding set of threshold values.
  • Step S540 Use the same sampling module to sequentially perform time sampling on the status signal to obtain the corresponding flicker pulse threshold-time pair.
  • time sampling may be time digital sampling for the moments corresponding to the positions of the rising edge and falling edge of the status signal.
  • time sampling time digitized sampling
  • time measurement can be used interchangeably to indicate the determination of the moment corresponding to the position of the rising edge and falling edge of each status signal after delay processing. operate.
  • the sampling module can be used to sample the times corresponding to the rising edge and falling edge of the above delayed status signal according to a certain sampling sequence.
  • the sampling module can be implemented by a circuit including a time-to-digital converter (TDC).
  • TDC time-to-digital converter
  • the time-to-digital converter is communicatively connected with at least two comparison modules.
  • the time-to-digital converter implements time sampling. .
  • the sampling module can use TDC to sample the moment corresponding to the rising edge or falling edge of the input status signal.
  • the scintillation pulse threshold-time pair may include a state change time obtained by performing time sampling on the state signal and the amplitude of the threshold corresponding to the state signal.
  • the status signal can be obtained by comparing it with the flicker pulse to be processed.
  • the TDC time measurement of the status signal can obtain two moments, including the time T 1 corresponding to the position of the rising edge and the position of the falling edge.
  • T 1 and T 2 may be referred to as state change times
  • the flicker pulse threshold-time pair may include (V 1 , T 1 ) and (V 1 , T 2 ).
  • the flicker pulse threshold-time pairs may be transmitted to other components for further processing.
  • the sampling results can be transmitted to the image processing components related to the PET equipment through wired or wireless communication methods for subsequent PET image reconstruction.
  • the time sampling of scintillation pulses can be achieved by using only one TDC of one sampling module, realizing the multiplexing of the sampling module TDC, greatly saving computing resources, and effectively Energy consumption is reduced, and the resources saved can improve the accuracy of time sampling, thereby improving system performance.
  • multi-threshold flicker pulse waveform sampling can be achieved through threshold switching, which can easily increase the number of sampling points and improve the subsequent data processing effect.
  • FIG. 6 is an exemplary flowchart of sequentially time sampling a status signal according to some embodiments of the present application. As shown in Figure 6, the process S600 of sequentially sampling the status signal in time may include the following operations:
  • Step S610 Based on the first sequence, perform first time sampling on the moments corresponding to the rising edges of the plurality of status signals.
  • the first order may be an arrangement order determined from small to large according to the lowest threshold size of each group of thresholds of at least two groups of thresholds.
  • the sampling module may first perform the first time sampling at the moment corresponding to the rising edge of the delay status signal corresponding to the lowest threshold in the first order. For example, referring to Figure 3, among the two sets of threshold voltages, the lowest threshold of the first set of thresholds is 310-1, and the lowest threshold of the second set of thresholds is 310-5. The lowest threshold voltage is ranked first from small to large. 310-1; the second ranked one is the lowest threshold voltage 310-5. After each status signal 310-1 and 310-5 is output from the comparison module, it will be input to the TDC of the sampling module for time sampling.
  • step S610 the status signal 310-5 is generated after the status signal 310-1.
  • the status signal 310-1 is first sent to the TDC.
  • the TDC first performs time sampling on the moment corresponding to the rising edge of the status signal corresponding to the first lowest threshold 310-1. .
  • the TDC performs time sampling on the moment corresponding to the rising edge of the status signal corresponding to the second lowest threshold 310-5 in the first order, thereby completing the first time sampling.
  • Step S620 Determine whether the first time sampling is successful.
  • the TDC of the sampling module 840 can output a feedback at the same time when performing time sampling on the delayed status signal.
  • Feedback may include one or more combinations of numbers, letters, symbols, etc.
  • the feedback can be a 1 or a 0.
  • a 1 indicates that the flicker pulse is above and above the threshold
  • a 0 indicates that the flicker pulse is above and below the threshold voltage.
  • performing first time sampling on the moments corresponding to rising edges of multiple status signals in sequence based on the first sequence includes:
  • the smallest of the at least two preset thresholds is critical, and the time corresponding to its corresponding status signal is usually used to determine the arrival time of the input ray particles received by the front-end detector.
  • the setting is relatively low, on the order of several mV, and is prone to false triggering. It is necessary to further confirm whether the flicker pulse to be processed is a valid signal through subsequent thresholds.
  • determining whether the scintillation pulse to be processed is a valid signal includes the following steps:
  • determining whether the scintillation pulse to be processed is a valid signal includes the following steps:
  • the comparison module corresponding to the verification group uses the comparison module corresponding to the verification group to compare the flicker pulse to be processed and the verification threshold. If the verification status signal that the flicker pulse to be processed crosses the verification threshold is not obtained, it is a false trigger signal; if the verification status signal that the flicker pulse to be processed crosses the verification threshold is obtained, The status signal is a valid signal.
  • whether the rising edge position is a valid trigger can usually be determined by whether the flicker pulse waveform crosses a higher second threshold.
  • the rising edge sampling of the waveform of the scintillation pulse first determines whether the signal passes the minimum minimum threshold. After completing the first time sampling of the minimum minimum threshold, the false trigger signal is then eliminated by whether it passes the second threshold to obtain a valid rising edge starting point. As the key data for subsequent particle arrival time.
  • the rising edge period of the scintillation pulse is very short, typically culminating in only a few nanoseconds.
  • the falling edge period is longer, usually more than 100ns, and usually about 200 nanoseconds. Therefore, after completing the first time sampling of the lowest threshold of the group with the smallest lowest threshold among at least two groups of thresholds, during the process of switching the lowest threshold of the group to the second threshold by the threshold providing module, the input flicker pulse waveform amplitude The level of the second threshold has been crossed. Therefore, after the threshold providing module completes the threshold switching from the lowest threshold to the second threshold, it can directly determine whether it is a valid signal. If it is a false trigger, it will return to the starting state.
  • the threshold providing module switches the lowest threshold 310-1 of the group.
  • the verification threshold that is, the second threshold 310-2. If the verification status signal that the flicker pulse to be processed crosses the second threshold 310-2 of the verification threshold is not obtained, it is a false trigger signal; if the flicker pulse to be processed crosses the verification threshold 310-2, it is a false trigger signal.
  • the verification status signal of the second threshold 310-2 is a valid signal, and then the first time sampling is performed at the moment corresponding to the rising edge of the delay status signal corresponding to the lowest threshold 310-5 of the second set of thresholds. After completion, the first time sampling Time sampling completed.
  • the process S600 may proceed to step S630. Otherwise, the process S600 will return to the execution step S610, and re-execute the first time sampling based on the first sequence at the moments corresponding to the rising edges of the plurality of status signals.
  • Step S630 Based on the second order, perform second time sampling sequentially on the time corresponding to the falling edge of the status signal.
  • the sampling module can sequentially perform the second time sampling at the time corresponding to the falling edge of the status signal.
  • the second order may be an arrangement order determined from large to small according to the size of each threshold of at least two sets of thresholds.
  • the eight threshold voltages are divided into two groups, the first group is 310-1 ⁇ 310-4, and the ones arranged from large to small are 310-4, 310-3, 310-2, 310- 1; the second group is 310-5 ⁇ 310-8, arranged from largest to smallest, it is 310-8, 310-7, 310-6, 310-5.
  • the highest threshold of the first set of thresholds is 310-4, and the highest threshold of the second set of thresholds is 310-8, and the threshold 310-8 is greater than 310-4.
  • TDC can start performing the second time sampling based on the status signal corresponding to the maximum value in each group of highest thresholds, for example, start execution based on the status signal corresponding to the highest threshold 310-8 of the second group of thresholds. Second time sampling, TDC collects the moment corresponding to the falling edge 5' of status signal 310-8.
  • TDC sequentially samples the falling edge moments of the status signals corresponding to the thresholds 310-7 to 310-1 in the second order of each group of thresholds from large to small. Time sampling is performed, thereby completing the second time sampling, and the process S600 may end.
  • At least two sets of thresholds are preset by using at least two threshold modules, each set of thresholds includes at least two switchable thresholds, and each set of thresholds includes a minimum threshold, and the minimum thresholds of each set are It can be used as a rising edge sampling point, thereby increasing the number of sampling points; since each set of thresholds can achieve dynamic threshold switching, only at least two comparison modules corresponding to the number of threshold sets (i.e., the number of threshold providing modules) can be used to sequentially compare the to-be-processed Compared with the existing technology that uses multiple LVDS comparators that correspond to the number of preset thresholds, this application effectively increases the number of sampling points while reducing the size of the LVDS comparators.
  • the time difference/time interval corresponding to each status signal can be obtained through the delay module, and then the time difference/time interval is superimposed on the status signal to delay the positions of its rising edge and falling edge at the same time. This achieves the purpose of staggering each status signal.
  • performing delay processing on multiple status signals refers to performing delay processing on a part of the status signals, for example, performing delay processing on at least one group of status signals among each group of thresholds except the group with the smallest minimum threshold.
  • the status signal is delayed so that the rising edges of the status signal corresponding to the lowest threshold of each group are staggered. Staggering means that the rising edge or falling edge transition time points of the status signal are spaced apart so that they can be recognized by the minimum identification unit of the time-to-digital converter.
  • the time interval between the rising edges of the status signal corresponding to the lowest threshold value of each group after delay processing and/or the time interval between the corresponding falling edges is greater than the minimum identification unit of the time-to-digital converter, and the minimum identification unit
  • the unit can have various sizes depending on the technical means. For example, according to the current technical level, usually a time interval greater than 10 ns can meet the minimum identification unit requirements of the time-to-digital converter in the existing technology.
  • Figure 7 is an exemplary module diagram of a signal sampling device for digital PET shown in some embodiments of this specification.
  • the digital PET signal sampling device can realize high-performance pulse sampling.
  • the signal sampling device 700 may include an acquisition module 710 for acquiring the scintillation pulse to be processed; a threshold value providing module 720 for switching and selecting at least two preset thresholds; a comparison module 730 for sequentially comparing the to-be-processed scintillation pulses.
  • the acquisition module 710 may be used to acquire pulses to be processed.
  • the acquisition module 1010 can acquire the scintillation pulse to be processed by communicating with the detector.
  • the threshold providing module 720 may be used to provide 7 switchable selections of at least two thresholds.
  • the threshold value providing module includes a threshold value control module and a threshold value selection module.
  • the threshold value control module sequentially controls the threshold value selection module according to the status signal to implement switching selection of at least two preset thresholds.
  • the threshold control module controls the threshold selection module through a control line.
  • the threshold control module includes a threshold controller, and the threshold selection module includes a data selector MUX (multiplexer). In the embodiment of the present application, one data selector MUX8 or two data selectors set in parallel can be used. MUX4, which presets 8 switchable selectable thresholds.
  • the threshold controller controls the data selector MUX to switch and select at least two thresholds, and the switched and selected thresholds are transmitted to the LVDS comparator for amplitude comparison.
  • the threshold controller controls the switching selection operation of the threshold based on the comparison result between the amplitude of the scintillation pulse to be processed and the threshold currently selected by the data selector MUX.
  • the threshold controller controls the MUX through the control line.
  • the comparison module 730 may be configured to sequentially compare the flicker pulse to be processed with at least two thresholds, and determine at least two status signals respectively corresponding to the at least two thresholds when the flicker pulse to be processed crosses the threshold.
  • the comparison module includes a comparator that sequentially compares the magnitude of the flicker pulse to be processed with each threshold selected by the threshold providing module from at least two thresholds.
  • the comparison module 730 may be implemented by a circuit including a Low-Voltage Differential Signaling (LVDS) comparator.
  • LVDS Low-Voltage Differential Signaling
  • the comparison module 730 may be implemented by a circuit including a Low-Voltage Differential Signaling (LVDS) comparator.
  • the scintillation pulse generated by the photodetector can be input to the LVDS pin p terminal (also called the positive terminal), and the threshold voltage can be input to the LVDS pin n terminal (also called the negative terminal), so that Complete the comparison between the pulse waveform and the threshold voltage.
  • An LVDS comparator can be used to sequentially compare the flicker pulses to be processed with at least two preset switchable thresholds. In this way, the number of input pins is effectively reduced and system performance is improved.
  • the comparison module 730 outputs a status signal after comparing the flicker pulse to be processed with the switched selected threshold.
  • the status signal may indicate a change in status of the pulse to be processed relative to the threshold (eg, from below the threshold voltage to above and above the threshold voltage or from above the threshold voltage to above and below the threshold voltage).
  • the status signal includes a rising edge indicating that the flicker pulse to be processed crosses at least part of the at least two thresholds, including the lowest threshold, and a falling edge crosses all of the at least two thresholds.
  • the sampling module 740 can perform time sampling on the status signal respectively according to a certain sampling order, and obtain one or more corresponding flicker pulse threshold-time pairs.
  • the sampling module 740 includes a time-to-digital converter (TDC).
  • TDC time-to-digital converter
  • the time-to-digital converter TDC is communicatively connected with the comparison module 1030.
  • the time-to-digital converter implements time sampling.
  • the sampling module 740 may use TDC to sample the time corresponding to the position of the rising edge or falling edge of the input status signal.
  • the sampling module 740 may be configured to perform a first time sampling on the moment corresponding to the rising edge of the status signal based on the lowest threshold; determine whether the first time sampling is successful; and sequentially sample the time corresponding to the falling edge of the status signal based on descending order. Perform second time sampling.
  • the lowest threshold is the threshold that ranks first based on at least two thresholds in the order determined from small to large. If the first time sampling is successful, the sampling module 740 may perform the second time sampling at the moment corresponding to the falling edge of the status signal corresponding to the threshold voltage ranked first in the order of threshold values from large to small. That is, starting from the highest threshold, the second time sampling is performed on the delayed state signal corresponding to each threshold in descending order, until the state signal corresponding to the last threshold in the second order completes the second time sampling. If unsuccessful, re-execute the second time sampling. In some embodiments, the sampling module 740 may first obtain the sampling feedback that performs the first time sampling based on the lowest threshold at the moment corresponding to the rising edge of the status signal. If it is determined that the sampling feedback indicates that the first time sampling is successful, continue to perform the second time sampling based on the descending order at the time corresponding to the falling edge of the status signal.
  • the sampling module is also used to determine whether the signal to be processed is valid after performing the first time sampling based on the lowest threshold at the moment corresponding to the rising edge of the status signal, and to control the time sampling process accordingly, including: determining whether the flicker pulse to be processed is valid. signal; if yes, output the feedback signal synchronously and start switching to perform the second time sampling based on the moment corresponding to the falling edge of the status signal in descending order; if not, return to the initial state and re-execute the first time sampling.
  • the flicker pulse threshold-time pair includes a state change time obtained by time sampling of the state signal and a threshold corresponding to the state change time.
  • a state change time obtained by time sampling of the state signal and a threshold corresponding to the state change time.
  • dynamic threshold switching is achieved by using a threshold value providing module to switch between different set thresholds, and the LVDS comparator of only one comparison module can be used to sequentially compare the flicker pulses to be processed with the set ones.
  • this application effectively increases the number of sampling points while reducing the number of LVDS comparators, thereby reducing the number of pins and reducing the cost of the FPGA chip.
  • FIG. 8 is an exemplary module diagram of a signal sampling device for digital PET according to some embodiments of this specification.
  • the signal sampling device 800 may include: an acquisition module 810, used to acquire the scintillation pulse to be processed; at least two threshold value providing modules 820, wherein each threshold value providing module is used to switch and select at least two preset thresholds ; At least two comparison modules 830 are arranged in parallel, which correspond to at least two threshold value providing modules. Each comparison module is used to sequentially compare the flicker pulse to be processed with at least two thresholds provided by the corresponding threshold value providing module, and determine the to-be-processed scintillation pulse.
  • At least two status signals respectively corresponding to at least two thresholds are processed; a sampling module 840 is used to sequentially time sample the status signals to obtain the corresponding scintillation pulse threshold-time pair.
  • At least two comparison modules 830 are each connected to one sampling module 840 . Multiple thresholds can be compared sequentially through each comparison module 830, and only one sampling module is provided, which reduces the number of pins and improves system performance.
  • the comparison module 830 includes a comparator that sequentially compares the size of the flicker pulse to be processed with each threshold selected from at least two thresholds provided by the corresponding threshold providing module.
  • the sampling module 840 can perform time sampling on the status signal respectively according to a certain sampling order to obtain one or more corresponding flicker pulse threshold-time pairs.
  • the sampling module 840 includes a time-to-digital converter (Time-to-Digital Converter, TDC).
  • TDC Time-to-Digital Converter
  • the time-to-digital converter TDC is communicatively connected with at least two comparison modules 830.
  • the time-to-digital converter implements time sampling.
  • the sampling module 840 can use TDC to sample the time corresponding to the position of the rising edge or falling edge of the input status signal.
  • the sampling module 840 is configured to: perform first time sampling on the moments corresponding to the rising edges of multiple status signals based on the first order; determine whether the first time sampling is successful; and perform first time sampling on the status signals based on the second order.
  • the second time sampling is performed at the moment corresponding to the falling edge of .
  • the first order may be an arrangement order determined from small to large according to the lowest threshold size of each group of thresholds of at least two groups of thresholds.
  • the sampling module may first perform the first time sampling at the moment corresponding to the rising edge of the delay status signal corresponding to the lowest threshold in the first order. For example, referring to Figure 3, among the two sets of threshold voltages, the lowest threshold of the first set of thresholds is 310-1, and the lowest threshold of the second set of thresholds is 310-5. The lowest threshold voltage is ranked first from small to large. 310-1; the second ranked one is the lowest threshold voltage 310-5. After each status signal 310-1 and 310-5 is output from the comparison module, it will be input to the TDC of the sampling module for time sampling.
  • TDC first performs time sampling on the moment corresponding to the rising edge of the status signal corresponding to the first lowest threshold 310-1. Then, the TDC performs time sampling on the moment corresponding to the rising edge of the status signal corresponding to the second lowest threshold 310-5 in the first order, thereby completing the first time sampling.
  • the sampling module when the sampling module performs the first time sampling at the moments corresponding to the rising edges of multiple status signals based on the first order, it is also used to determine whether the signal to be processed is valid, and to control the time sampling process accordingly, It includes: after performing the first time sampling at the moment corresponding to the rising edge of the delayed status signal corresponding to the lowest threshold value in the first order, determining whether the flicker pulse to be processed is a valid signal; if so, synchronously outputting the feedback signal and based on the first sequence The first time sampling is performed at the moment corresponding to the rising edge of the status signal corresponding to the other lowest threshold value in at least two sets of thresholds; if not, the initial state is returned and the first time sampling is re-executed.
  • the flicker pulse threshold-time pair includes a state change time obtained by time sampling of the state signal and a threshold corresponding to the state change time.
  • a state change time obtained by time sampling of the state signal and a threshold corresponding to the state change time.
  • At least two sets of thresholds are preset by using at least two threshold modules, each set of thresholds includes at least two switchable thresholds, and each set of thresholds includes a minimum threshold, and the minimum thresholds of each set are It can be used as a rising edge sampling point, thereby increasing the number of sampling points; since each set of thresholds can achieve dynamic threshold switching, only at least two comparison modules corresponding to the number of threshold sets (i.e., the number of threshold providing modules) can be used to sequentially compare the to-be-processed Compared with the existing technology that uses multiple LVDS comparators that correspond to the number of preset thresholds, this application effectively increases the number of sampling points while reducing the size of the LVDS comparators.
  • a detector device is also provided.
  • the detector device includes: a detector and a signal sampling device as provided in any of the above embodiments, wherein the detector is configured to detect rays and output the scintillation pulse signal to be processed to the signal sampling device for digital sampling processing.
  • the detector is configured to detect rays and output the scintillation pulse signal to be processed to the signal sampling device for digital sampling processing.
  • a digital device which includes the signal sampling device provided in any of the above embodiments.
  • a digital device which includes: a memory, a processor, and a computer program stored in the memory and executable on the processor.
  • the computer program is executed by the processor, the implementation is as provided in any of the above embodiments. The steps of the signal sampling method.
  • a computer-readable storage medium is also provided, characterized in that a computer program is stored on the storage medium, and when the computer program is executed by a processor, the steps of the signal sampling method provided in any of the above embodiments are implemented.
  • aspects of this specification may be entirely executed by hardware, may be entirely executed by software (including firmware, resident software, microcode, etc.), or may be executed by a combination of hardware and software.
  • the above hardware or software may be referred to as "data block”, “module”, “engine”, “unit”, “component” or “system”.
  • aspects of this specification may be represented by a computer product including computer-readable program code located on one or more computer-readable media.
  • Computer storage media may contain a propagated data signal embodying the computer program code, such as at baseband or as part of a carrier wave.
  • the propagated signal may have multiple manifestations, including electromagnetic form, optical form, etc., or a suitable combination.
  • Computer storage media may be any computer-readable media other than computer-readable storage media that enables communication, propagation, or transfer of a program for use in connection with an instruction execution system, apparatus, or device.
  • Program code located on a computer storage medium may be transmitted via any suitable medium, including radio, electrical cable, fiber optic cable, RF, or similar media, or a combination of any of the foregoing.
  • the computer program coding required to operate each part of this manual can be written in any one or more programming languages, including object-oriented programming languages such as Java, Scala, Smalltalk, Eiffel, JADE, Emerald, C++, C#, VB.NET, Python etc., conventional procedural programming languages such as C language, Visual Basic, Fortran 3003, Perl, COBOLN3002, PHP, ABAP, dynamic programming languages such as Python, Ruby and Groovy, or other programming languages.
  • the program code may run entirely on the user's computer, as a stand-alone software package, or partially on the user's computer and partially on a remote computer, or entirely on the remote computer or server.
  • the remote computer can be connected to the user computer via any form of network, such as a local area network (LAN) or a wide area network (WAN), or to an external computer (e.g. via the Internet), or in a cloud computing environment, or as a service Use software as a service (SaaS).
  • LAN local area network
  • WAN wide area network
  • SaaS service Use software as a service
  • numbers are used to describe the quantities of components and properties. It should be understood that such numbers used to describe the embodiments are modified by the modifiers "about”, “approximately” or “substantially” in some examples. Grooming. Unless otherwise stated, “about,” “approximately,” or “substantially” means that the stated number is allowed to vary by ⁇ 20%. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximations that may vary depending on the desired features of the individual embodiment. In some embodiments, numerical parameters should account for the specified number of significant digits and use general digit preservation methods. Although the numerical ranges and parameters used to identify the breadth of ranges in some embodiments of this specification are approximations, in specific embodiments, such numerical values are set as accurately as is feasible.

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  • Nuclear Medicine (AREA)

Abstract

La présente demande divulgue un procédé et un appareil d'échantillonnage de signal PET numérique, un dispositif et un support de stockage. Le procédé d'échantillonnage de signal comprend : le préréglage d'au moins deux seuils alternatifs ; la comparaison d'une impulsion de scintillation à traiter avec lesdits au moins deux seuils en séquence en utilisant le même module de comparaison pour déterminer au moins deux signaux d'état correspondant respectivement auxdits au moins deux seuils lorsque ladite impulsion de scintillation dépasse les seuils ; et la réalisation d'un échantillonnage temporel sur lesdits au moins deux signaux d'état en séquence en utilisant le même module d'échantillonnage pour acquérir des paires seuil-temps d'impulsion de scintillation correspondantes. La présente demande peut réduire le nombre de broches et réaliser un multiplexage du module d'échantillonnage tout en garantissant la précision d'échantillonnage, ce qui permet d'économiser considérablement les ressources logiques.
PCT/CN2022/129466 2022-05-26 2022-11-03 Procédé et appareil d'échantillonnage de signal pet numérique, dispositif et support de stockage WO2023226306A1 (fr)

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CN115951391A (zh) * 2022-11-30 2023-04-11 苏州瑞派宁科技有限公司 闪烁脉冲的处理方法、装置、设备及存储介质

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