CN103969675B - Digitize the baseline correction method and system of scintillation pulse - Google Patents
Digitize the baseline correction method and system of scintillation pulse Download PDFInfo
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Abstract
A kind of baseline correction method and system for digitizing scintillation pulse.This method is first by multi-Vt sampling method, and the time that carried out to scintillation pulse signal axially samples, and obtains the time threshold sampled point of scintillation pulse waveform；Then these time threshold sampled points are chosen, impulse waveform and identification model parameter are rebuild using the style characteristic of scintillation pulse, the baseline drift average of scintillation pulse is estimated accordingly；Baseline correction is carried out to scintillation pulse waveform finally according to the baseline drift average.The invention also discloses a kind of base line correction system for digitizing scintillation pulse, including digital sample module, needle position misalignment computing module and baseline correction module.The present invention can efficiently and accurately screen the baseline drift of scintillation pulse, realize and the quick real-time adaptive of baseline is corrected, improve the signal to noise ratio of scintillation pulse data measurement and the stability of data acquistion system.
Description
Technical field
The invention belongs to high-energy physics detector and field of signal processing, and in particular to a kind of base of digitlization scintillation pulse
Line bearing calibration and system, can be applied to high energy particle detection and medical imaging equipment.
Background technology
In most high energy particle field of detecting and medical imaging equipment, what data acquistion system was gathered and handled
Scintillation pulse is typically by high energy particle by scintillation crystal（Such as：X-ray, gamma-rays etc.）Visible ray is converted into, then again by light
Electrical part is converted into the electric impulse signal that can be measured, and typical scintillation pulse waveform is as shown in Figure 1 in the prior art.
To in the information extraction of scintillation pulse, due to the shadow by factors such as detector leakage current, scintillation pulse hangover, noise jammings
Ring, scintillation pulse is often to be superimposed upon on a unstable baseline.So not only result in scintillation pulse arrival time and arteries and veins
The inaccurate of elevation carrection is rushed, the signal to noise ratio of initial data is reduced, while also can be to crystal segmentation, chance event and scattering events
Rejecting produce indirect influence, especially to positron emission tomography instrument（Positron Emission Tomography,
Hereinafter referred to as PET）Resolution ratio, contrast and the signal to noise ratio of reconstruction image are affected greatly.Therefore, floated to reduce baseline
Move the influence to radiation detecting system stability and performance indications, it is necessary to baseline school is carried out before scintillation pulse information is extracted
Just.
Framework of the implementation of baseline correction often with front-end electronics circuit where data acquistion system is closely related.
It is traditional based in analog circuit or analog to digital hybrid circuit structure, a kind of baseline correction method being most widely used
It is base line restorer.Robinson propose earliest it is a kind of for unipolar signal base line restorer [L.B.Robinson,
“Reduction of baseline shift in pulse-amplitude measurements”,
Rev.Sci.Instrum.,Vol.32,p.1057,1961].Subsequent Chase [R.L.Chase and L.R.Poulo, " A
high precision DC restorer”,IEEE Trans.Nucl.Sci.,vol.NS-14,no.6,pp.83-88,
Dec.1967], Fairstein [E.Fairstein, " Gated baseline restorer with adjustable
Asymmetry ", IEEE Trans.Nucl.Sci., vol.NS-22, no.1, pp.463-466, Feb.1975] and Kuwata
[M.Kuwata,H.Maeda,and K.Husimi,“New baseline restorer based on feedforward
differential compensation”,IEEE Trans.Nucl.Sci.,vol.41,no.4,pp.1236-1239,
Aug.1994] etc. seminar propose various follow-on base line restorers in succession, to improve the efficiency of baseline correction.In addition,
Geronimo[G.De.Geronimo,P.O’Connor,and J.Grosholz,“A CMOS baseline holder(BLH)
For readout ASICs ", IEEE Trans.Nucl.Sci., vol.47, no.3, Jun.2000] it is also proposed one kind and be available for
The baseline retainer based on CMOS technology of selection.Although these circuits each not phase on details and functional characteristic is implemented
Together, but they have relied on analogue technique and grown up, the design optimizations of these circuits is often directed to a certain spy
Fixed panel detector structure and carry out, can not be changed once designing and completing according to application demand, flexibility, autgmentability and liter
Level property receives great restriction.
With the popularization and the extensive use of digital signal processing algorithm of various general digital equipment and electronic device,
Digitizing technique is just more and more being incorporated into the information extraction to scintillation pulse.At present, numeral is carried out to scintillation pulse
Changing the method for processing mainly has：Based on analogue-to-digital converters（Analog-to-Digital Converter, hereinafter referred to as
ADC）Equal interval sampling method and based on multi-Vt（Multi-Voltage Threshold, hereinafter referred to as MVT）Time
Axial sampling method.The former carries out equal interval sampling using fast A/D C to scintillation pulse signal and baseline, obtains pulse signal and base
The voltage amplitude sample point of line, wherein pulse amplitude are extracted available for pulse information, and baseline sample point can be carried out at average
Reason or statistical analysis are to carry out baseline correction [Hongdi Li, Chao Wang, Hossain Baghaei et al., " A
new statistics-based online baseline restorer for a high count rate fully
digital system”,IEEE Trans.Nucl.Sci.,vol.57,no.2,Apr.2010].With based on ADC at equal intervals
Sampling is different, and the time based on MVT, axial sampling method was known threshold reference voltage, to obtain the temporal information of sampled point, so
Event information [Qingguo Xie, the Chien-Min Kao, Zekai of scintillation pulse are extracted by digital signal processing algorithm afterwards
Hsiau et al.,“A new approach for pulse processing in positron emission
tomography”,IEEE Trans.Nucl.Sci.,vol.52,no.4,Aug.2005].The MVT method of samplings can effectively dash forward
The limitation of broken Shannon's sampling theorem, accurately and efficiently obtains event information [the Qingguo Xie, Chien-Min of scintillation pulse
Kao, Xi Wang et al., " Potentials of digitally sampling scintillation pulses in
timing determination in pet”,vol.56,no.5,Oct.2009].For the MVT method of samplings, it equally can be by
The interference problem obtained to baseline drift to scintillation pulse information, and existing baseline correction method can not be solved effectively at present
Certainly MVT baseline drift problem.
Therefore, for above-mentioned technical problem, it is necessary to propose a kind of baseline correction method of new digitlization scintillation pulse
And system, to overcome drawbacks described above.
The content of the invention
In view of this, it is an object of the invention to provide a kind of baseline correction method and system for digitizing scintillation pulse,
For solving the problems, such as front-end electronics baseline drift in high-energy physics particle detection and medical imaging equipment.This method passes through to dodging
Bright pulse carries out multi-Vt sampling, right with the digital signal processing algorithm of innovation using the priori of scintillation pulse
The baseline drift as caused by detector leakage current, pulse stretching and noise jamming etc. carries out effective, accurately and quickly adaptive
Correction, while improving the signal to noise ratio of scintillation pulse data measurement and the stability of data acquistion system.
To achieve the above object, the present invention provides following technical scheme：
A kind of baseline correction method for digitizing scintillation pulse, the baseline correction method step is as follows：
（1）Using multi-Vt sampling method, the time that carried out to scintillation pulse signal axially samples, and obtains scintillation pulse ripple
The digitized sampling point of shape；
（2）The corresponding digitized sampling point of each scintillation pulse is chosen, according to the style characteristic of scintillation pulse, pulse is rebuild
Waveform and identification model parameter, obtain the baseline drift amount of each scintillation pulse, then the baseline drift amount to gained is entered accordingly
Row analysis, obtains baseline drift average；
（3）Scintillation pulse waveform after reconstruction is subtracted into step（2）The baseline drift average of acquisition, completes baseline correction.
It is preferred that, in the baseline correction method of above-mentioned digitlization scintillation pulse, the step（1）Middle multi-Vt is adopted
Quadrat method is specially：Some threshold reference voltages are pre-set, record scintillation pulse voltage amplitude reaches each threshold voltage
Specific moment, each voltage threshold and corresponding triggered time are m- threshold value sampled point when constituting one.
It is preferred that, in the baseline correction method of above-mentioned digitlization scintillation pulse, the step（2）The shape of middle scintillation pulse
Shape characteristic is modeled acquisition according to the scintillation crystal and the classification of electrooptical device that are coupled.
It is preferred that, in the baseline correction method of above-mentioned digitlization scintillation pulse, the step（2）Middle identification model parameter
Refer to the style characteristic according to scintillation pulse, function approximation is carried out to the when m- threshold value sampled point of selected scintillation pulse waveform
Characteristic mathematical model is obtained, and therefrom extracts the parameter value for portraying scintillation pulse characteristic.
It is preferred that, in the baseline correction method of above-mentioned digitlization scintillation pulse, the step（2）Middle scintillation pulse baseline
Offset be found from the parameter value for portraying scintillation pulse characteristic of extraction description baseline values measure to.
It is preferred that, in the baseline correction method of above-mentioned digitlization scintillation pulse, the step（2）In to resulting each
The method that the needle position misalignment amount of individual scintillation pulse is analyzed is mean value computation or statistical analysis.
A kind of base line correction system for digitizing scintillation pulse, it includes：
Digitized sampling module, for carrying out time axially sampling to scintillation pulse using the multi-Vt method of sampling,
Obtain the digitized sampling point of scintillation pulse；
Needle position misalignment computing module, for rebuilding scintillation pulse waveform, identification model parameter obtains the baseline of scintillation pulse
Drift value, and utilize the baseline drift average of statistical distribution calculating scintillation pulse；
Baseline correction module, for carrying out baseline correction to scintillation pulse, reduces the primary data information (pdi) of scintillation pulse.
It is preferred that, in the base line correction system of above-mentioned digitlization scintillation pulse, the digitized sampling module includes threshold
Threshold voltage setup module, threshold value discriminator module and time mark module, wherein,
Threshold voltage settings module is used for given threshold reference voltage, and threshold reference voltage is sent into threshold value discriminator mould
Block and time mark module；
Threshold value discriminator module is used to compare the magnitude relationship between scintillation pulse threshold voltage and threshold reference voltage, and
Logical pulse is produced when scintillation pulse voltage passes through threshold reference voltage, and the logical pulse time of delivery (TOD) of generation is marked into mould
Block carries out time mark；
Time mark module is used to carry out time mark to the logical pulse that threshold value discriminator module is exported, and by gained
Its corresponding threshold reference voltage makeup time-threshold value sampled point of timestamp is simultaneously sent to needle position misalignment computing module.
It is preferred that, in the base line correction system of above-mentioned digitlization scintillation pulse, the needle position misalignment computing module includes
Event accumulation rejects module, pulse and rebuilds module and needle position misalignment amount computing module, wherein,
Module is rejected in event accumulation to be used to differentiate and reject the pile-up events in scintillation pulse；
Module is rebuild in pulse to be used to rebuild the scintillation pulse waveform, identification model parameter, and reconstruction parameter value is transmitted
To needle position misalignment amount computing module；
The baseline that needle position misalignment amount computing module rebuilds the reconstruction parameter calculating scintillation pulse that module is obtained according to pulse is inclined
Shifting amount, then carries out statistic histogram analysis to the needle position misalignment amount in the range of a period of time, obtains the average base of scintillation pulse
Line deviation is simultaneously sent to baseline correction module.
It can be seen from the above technical proposal that the baseline correction method of the digitlization scintillation pulse of the embodiment of the present invention passes through
Multi-Vt sampling is carried out to scintillation pulse, using the priori of scintillation pulse, calculated with the Digital Signal Processing of innovation
Method, to as caused by detector leakage current, pulse stretching and noise jamming etc. baseline drift carry out effectively, accurately and quickly from
Correction is adapted to, while improving the signal to noise ratio of scintillation pulse data measurement and the stability of data acquistion system.
Brief description of the drawings
In order to illustrate more clearly about the embodiment of the present invention or technical scheme of the prior art, below will be to embodiment or existing
There is the accompanying drawing used required in technology description to be briefly described, it should be apparent that, it is for the present invention in describing below
Accompanying drawing is only some embodiments of the present invention, for those of ordinary skill in the art, is not paying creative work
Under the premise of, other accompanying drawings can also be obtained according to these accompanying drawings.
Fig. 1 is the schematic diagram of scintillation pulse signal common in the art；
Fig. 2 digitizes the flow chart of scintillation pulse baseline correction method for the present invention；
Fig. 3 digitizes to enter needle position misalignment value using statistical distribution method in scintillation pulse baseline correction method for the present invention
The result figure of row analysis；
Fig. 4 present invention digitlization scintillation pulse baseline correction methods are corrected to scintillation pulse baseline positive excursion
Design sketch.
Fig. 5 is digitized in scintillation pulse baseline correction method using the 4 threshold value MVT method of samplings to by LYSO/ for the present invention
The schematic diagram that the output scintillation pulse of PMT detectors is sampled and pulse shape is fitted；
Fig. 6 is digitized in scintillation pulse baseline correction method using the 4 threshold value MVT method of samplings to by LYSO/ for the present invention
The schematic diagram that the output scintillation pulse of SiPM detectors is sampled and pulse shape is fitted；
Fig. 7 digitizes the system construction drawing of scintillation pulse base line correction system for the present invention；
Fig. 8 is design sketch of the present invention to energy resolution, wherein, 8（a）For the energy resolution that the present invention is obtained is not used
The design sketch of rate, 8（b）For the design sketch of the energy resolution obtained using the present invention.
Embodiment
The invention discloses a kind of baseline correction method and system for digitizing scintillation pulse, for solving high-energy physics grain
Front-end electronics system baseline drift problem in sub- field of detecting and medical imaging equipment.This method to scintillation pulse by carrying out
Multi-Vt is sampled, using the priori of scintillation pulse, with the digital signal processing algorithm of innovation, to being leaked by detector
Baseline drift caused by electric current, pulse stretching and noise jamming etc. carry out effectively, accurately and quickly adaptively correcting, carry simultaneously
The signal to noise ratio of high scintillation pulse data measurement and the stability of data acquistion system.
Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is retouched in detail
State, it is clear that described embodiment is only a part of embodiment of the invention, rather than whole embodiments.Based on the present invention
In embodiment, the every other implementation that those of ordinary skill in the art are obtained on the premise of creative work is not made
Example, belongs to the scope of protection of the invention.
As shown in Fig. 2 the baseline correction method of digitlization scintillation pulse disclosed by the invention comprises the following steps：
（1）Using multi-Vt sampling method, the time that carried out to scintillation pulse signal axially samples, and obtains scintillation pulse ripple
The digitized sampling point of shape；
（2）The corresponding digitized sampling point of each scintillation pulse is chosen, according to the style characteristic of scintillation pulse, pulse is rebuild
Waveform and identification model parameter, obtain the baseline drift amount of each scintillation pulse, then the baseline drift amount to gained is entered accordingly
Row analysis, obtains baseline drift average；
（3）Scintillation pulse waveform after reconstruction is subtracted into step（2）The baseline drift average of acquisition, completes baseline correction.
Wherein, the step（1）The middle multi-Vt method of sampling is specially：Some threshold reference voltages are pre-set,
Record scintillation pulse voltage amplitude reaches specific moment of each threshold voltage, and each voltage threshold and corresponding triggered time be
M- threshold value sampled point when constituting one.
Wherein, the step（2）The style characteristic of middle scintillation pulse is according to the scintillation crystal and optical-electrical converter coupled
The classification of part is modeled acquisition, i.e., according to the scintillation crystal and electrooptical device classification coupled, obtains corresponding flicker
Pulse shape characteristic model.
Wherein, the step（2）Middle identification model parameter refers to the style characteristic according to scintillation pulse, to selected flicker
The when m- threshold value sampled point of impulse waveform carries out function approximation and obtains characteristic mathematical model, and therefrom scintillation pulse is portrayed in extraction
The parameter value of characteristic.
Wherein, the step（2）Middle scintillation pulse needle position misalignment amount is the parameter for portraying scintillation pulse characteristic from extraction
Measuring for description baseline values is found in value.
Wherein, the step（2）In the method analyzed the needle position misalignment amount of each resulting scintillation pulse be
Mean value computation or statistical analysis.
Wherein, in order to reduce noise, pulse shape error of fitting and event accumulation etc. influence factor to baseline drift amount
The interference of calculating process, is necessary to analyze multiple baseline values, common method includes before baseline correction is carried out：
It is worth calculating, statistical analysis etc..As shown in figure 3, Fig. 3 digitizes for the present invention uses statistical in scintillation pulse baseline correction method
The result figure that analysis method is analyzed needle position misalignment value.
Fig. 4 present invention digitlization scintillation pulse baseline correction methods are corrected to scintillation pulse baseline positive excursion
Design sketch.Wherein, solid line 11 is to carry out what sampling reconstruction was obtained to the scintillation pulse that LYSO/PMT detectors are exported with oscillograph
Waveform；Dotted line 12 is the ripple obtained according to scintillation pulse models fitting in the case where not using baseline correction method proposed by the present invention
Shape, it can be seen that the waveform after fitting has obvious needle position misalignment situation；Dotted line 13 is to use baseline correction proposed by the present invention
Under method, the waveform obtained according to scintillation pulse models fitting, it can be seen that this base line non-drifting situation.
Because scintillation crystal is different with the characteristic of electrooptical device, the coupling of its plurality of classes form has different arteries and veins
Rush shape characterization form.Specific method is entered below to the explaination of row pulse shape forms of characterization.
Method example one：
S101：According to the scintillation crystal and electrooptical device classification coupled, corresponding scintillation pulse shape is obtained special
Property model；
In the case of being coupled for LYSO scintillation crystals with linear photoconductor multiplier tube PMT, influence of noise is not being considered
Under, the mathematical modeling of scintillation pulse shape is contemplated that into be made up of the rising edge and the trailing edge of exponential damping ramped, its
Expression formula is as follows：
Wherein, parameter LineKrFor the slope and LineK of rising edge straight liner>0, parameter LineBrIt is cutting for rising edge straight line
Away from can be any number；Parameter ExpKfFor damping time constant and ExpKf>0, parameter ExpBfIt can be any number；Ginseng
Number BaseL is the baseline parameter of scintillation pulse, can be any number；tsFor the initial time of scintillation pulse；tpFor scintillation pulse
Time to peak.Therefore, a preferable scintillation pulse can be by five model feature value LineKr、LineBr、ExpKf、
ExpBfDescribed with BaseL, at the beginning of scintillation pulse signal between, time to peak, peak amplitude, twilight sunset constant and baseline
The information such as value can be calculated by this five model feature values and obtained, and formula is as follows：
（a）Scintillation pulse initial time ts
It can be tried to achieve by equation below：
（b）Scintillation pulse time to peak tp
It can be tried to achieve by equation below：
LineKr×tp+LineBr=exp(-ExpKf×tp+ExpBf)+BaseL；
（c）Scintillation pulse peak amplitude Vp
It can be tried to achieve by equation below：
Vp=LineKr×tp+LineBr；
（d）Twilight sunset Changshu τ
It can be tried to achieve by equation below：
τ=1/ExpKf；
（e）Baseline value Bval
Bval=BaseL。
S102：The corresponding digitized sampling point of each single flash pulse is chosen, according to scintillation pulse in step S101
Shape, rebuilds impulse waveform and identification model parameter, the baseline drift amount of each single flash pulse is estimated accordingly successively；
（a）To ramping along the when m- threshold value sampled point produced for scintillation pulse, it is fitted according to equation below：
V(t)=LineKr×t+LineBr
Wherein, parameter LineKrFor the slope and LineK of rising edge straight liner>0, parameter LineBrIt is cutting for rising edge straight line
Away from can be any number；T is the time value obtained when threshold reference voltage is V (t) using the MVT method of samplings.This method is also
Scintillation pulse rising edge can be rebuild according to other scintillation pulse models.
（b）The when m- threshold value sampled point produced to the trailing edge of the exponential damping of scintillation pulse, is carried out according to equation below
Fitting：
V(t)=exp(-ExpKf×t+ExpBf)+BaseL
Wherein, parameter ExpKfFor damping time constant and ExpKf>0, parameter ExpBfIt can be any number；Parameter
BaseL is the baseline parameter of scintillation pulse, can be any number；T is that MVT sampling sides are used when threshold reference voltage is V (t)
The time value that method is obtained.This method can also be rebuild according to other scintillation pulse models to scintillation pulse trailing edge.
（c）Five aspect of model amounts are extracted from the impulse waveform mathematic(al) representation of reconstruction, scintillation pulse letter is obtained accordingly
Between at the beginning of number, the information such as time to peak, peak amplitude, twilight sunset constant and baseline value；
Specifically it refer to shown in Fig. 5, Fig. 5 uses 4 threshold value MVT sampling sides to digitize in scintillation pulse baseline correction method
Method by LYSO/PMT detectors to exporting the schematic diagram that scintillation pulse is sampled and pulse shape is fitted.Wherein, the table of solid line 21
Show to export after scintillation pulse is sampled LYSO/PMT detectors by oscillograph and rebuild obtained waveform；Round dot 22 is to use MVT
Method carries out the obtained sampled point of sampling under the reference threshold voltage of setting to scintillation pulse；Dotted line 23 is to be given according to the present invention
Ramp edge and the index decreased gone out is fitted obtained waveform along scintillation pulse model.It can be seen that according to
The waveform that scintillation pulse models fitting is obtained can preferably approach the waveform obtained by oscillograph sampling reconstruction, while also confirming
The coupling of different scintillation crystals and electrooptical device classification needs to obtain corresponding scintillation pulse model.
S103：The baseline drift amount data set of gained is analyzed, to obtain baseline drift average.
Method example two：
S201：According to the scintillation crystal and electrooptical device classification coupled, corresponding scintillation pulse shape is obtained special
Property model；
In the case of being coupled for LYSO scintillation crystals with non-linear silicon photoelectric multiplier SiPM, scintillation pulse shape
Mathematical modeling can be approximately by quick index rising edge and the index decreased of decay along constituting, its expression formula is as follows：
Wherein, parameter ArFor the amplitude coefficient of index rising edge, ExpKrFor the time constant and ExpK of index rising edger>
0, parameter BrIt can be any number；Parameter AfFor the amplitude coefficient on index decreased edge, parameter ExpKfFor index decreased edge when
Between constant and ExpKf>0, parameter BaseL are the baseline parameter of scintillation pulse, can be any number；tsFor rising for scintillation pulse
Time beginning；tpFor the time to peak of scintillation pulse.Therefore, a preferable scintillation pulse can be by six model feature value Ar、
ExpKr、Br、Af、ExpKfDescribed with BaseL, at the beginning of scintillation pulse signal between, time to peak, peak amplitude and baseline
The information such as value can be calculated by this six model feature values and obtained, and formula is as follows：
（a）Scintillation pulse initial time ts
It can be tried to achieve by equation below：
（b）Scintillation pulse time to peak tp
It can be tried to achieve by equation below：
Ar×exp(-ExpKr×tp)+Br=Af×exp(-ExpKf×tp)+BaseL；
（c）Scintillation pulse peak amplitude Vp
It can be tried to achieve by equation below：
Vp=Ar×exp(-ExpKr×tp)+Br；
（d）Baseline value Bval
Bval=BaseL.
S202：The corresponding digitized sampling point of each single flash pulse is chosen, according to the shape of scintillation pulse in step 201
Shape model, rebuilds impulse waveform and identification model parameter, the baseline drift amount of each single flash pulse is estimated accordingly successively；
（a）The when m- threshold value sampled point produced to the index rising edge of scintillation pulse, is fitted according to equation below：
V(t)=Ar×exp(-ExpKr×t)+Br
Wherein, parameter ArFor the amplitude coefficient of index rising edge, ExpKrFor the time constant and ExpK of index rising edger>
0, parameter BrIt can be any number；T is the time value obtained when threshold reference voltage is V (t) using the MVT method of samplings.This
Method can also be rebuild according to other scintillation pulse models to scintillation pulse rising edge.
（b）The when m- threshold value sampled point produced to the trailing edge of the exponential damping of scintillation pulse, is carried out according to equation below
Fitting：
V(t)=Af×exp(-ExpKf×t)+BaseL
Wherein, parameter AfFor the amplitude coefficient on index decreased edge, parameter ExpKfTime constant for index decreased edge and
ExpKf>0；Parameter BaseL is the baseline parameter of scintillation pulse, can be any number；T is threshold reference voltage when being V (t)
The time value obtained using the MVT method of samplings.This method can also be entered according to other scintillation pulse models to scintillation pulse trailing edge
Row is rebuild.
（c）Six aspect of model amounts are extracted from the impulse waveform mathematic(al) representation of reconstruction, scintillation pulse letter is obtained accordingly
Between at the beginning of number, the information such as time to peak, peak amplitude and baseline value；
Specifically it refer to shown in Fig. 6, Fig. 6 is for the present invention using the MVT method of samplings of 4 threshold values to LYSO/SiPM detectors
The scintillation pulse of output is digitized the schematic diagram of sampling and pulse shape fitting.Wherein, solid line 31 is with oscillograph pair
The waveform that the scintillation pulse of LYSO/SiPM detectors output is rebuild after being sampled；Round dot 32 is the ginseng in setting with MVT methods
Examine the sampled point for the scintillation pulse that LYSO/SiPM detectors are exported sample under threshold voltage and obtaining；According to dotted line 33
The index rising edge and index decreased that the present invention is provided are fitted obtained waveform along scintillation pulse model to sampled point.From figure
In as can be seen that the waveform that is obtained according to scintillation pulse models fitting can preferably approach what is obtained by oscillograph sampling reconstruction
Waveform, while the coupling for also having confirmed different scintillation crystals and electrooptical device classification needs to obtain corresponding scintillation pulse
Model.
S203：The baseline drift amount data set of gained is analyzed, to obtain baseline drift average.
As shown in fig. 7, the base line correction system of digitlization scintillation pulse disclosed by the invention, it includes：
Digitized sampling module 100, for axially being adopted to the scintillation pulse progress time using the multi-Vt method of sampling
Sample, obtains the digitized sampling point of scintillation pulse；
Needle position misalignment computing module 200, for rebuilding scintillation pulse waveform, identification model parameter obtains scintillation pulse
Baseline drift amount, and utilize the baseline drift average of statistical distribution calculating scintillation pulse；
Baseline correction module 300, for scintillation pulse carry out baseline correction, reduce scintillation pulse original number it is believed that
Breath.
In the base line correction system of above-mentioned digitlization scintillation pulse, 100 points of digitized sampling module is 3 submodules, point
Wei not threshold voltage setup module 110, threshold value discriminator module 120 and time mark module 130.
Wherein, threshold voltage settings module 110 is used for given threshold reference voltage, and threshold reference voltage is sent into threshold value
Discriminator module 120 and time mark module 130.
Wherein, threshold value discriminator module 120 is used to compare big between scintillation pulse threshold voltage and threshold reference voltage
Small relation, and logical pulse is produced when scintillation pulse voltage passes through threshold reference voltage, and the logical pulse of generation is sent to
Time mark module 130 carries out time mark.
Wherein, time mark module 130 is used to carry out time mark to the logical pulse that threshold value discriminator module 120 is exported
Note, and by its corresponding threshold reference voltage makeup time-threshold value sampled point of the timestamp of gained and it is sent to needle position misalignment
Computing module 200.
In the base line correction system of above-mentioned digitlization scintillation pulse, needle position misalignment computing module 200 includes event accumulation and picked
Except module 220 and needle position misalignment amount computing module 230 are rebuild in module 210, pulse.
Wherein, event accumulation rejects module 210 and is used to differentiate and reject the pile-up events in scintillation pulse.
Wherein, pulse rebuilds module 220 and is used to rebuild the scintillation pulse waveform, identification model parameter, and joins rebuilding
Numerical value is sent to needle position misalignment amount computing module 230.
Wherein, needle position misalignment amount computing module 230 rebuilds the reconstruction parameter calculating flicker arteries and veins that module 220 is obtained according to pulse
The needle position misalignment amount of punching, then carries out statistic histogram analysis to the needle position misalignment amount in the range of a period of time, obtains flicker arteries and veins
The average baselining offset of punching is simultaneously sent to baseline correction module 300.
Below by way of a specific embodiment data to the present invention digitlization scintillation pulse baseline correction method and
System does further checking, wherein, be related to some parameters, these parameters need for specific processing data be adjusted with up to
To good performance, the parameter of this application instance processes data is listed below.
Step（1）6 threshold reference voltages are set in middle multi thresholds reference voltage sampling method, and specific voltage magnitude is respectively
1.5mV, 21.5mV, 41.5mV, 61.5mV, 81.5,101.5；The digit pulse of importing is to use single LYSO（Yttrium luetcium silicate dodges
Bright crystal）Crystal bar and Hammatsu R9800PMT（Photomultiplier）Couple the scintillation pulse collected.Sample rate is
20GSps, impulse smaple number is 3000, and each impulse waveform sample point is 4000.Energy spectrum is average in 511keV
The rising edge of a pulse time is about 1ns, and detector damping time constant is about 47ns.
Step（2）Scintillation pulse in middle method example one is to be coupled by LYSO crystal bar with Hamamatsu R9800PMT
Produce, scintillation pulse model, which is used, ramps edge and exponential damping trailing edge composition；
Step（2）Scintillation pulse in middle method example two is to be coupled by LYSO crystal bar with SensL Array4 SiPM
Produce, scintillation pulse model is constituted using index rising edge and exponential damping trailing edge；
Step（2）In statistical is carried out to the baseline drift amount of 3000 scintillation pulses that is exported by LYSO/PMT detectors
Analysis, needle position misalignment amount is -10mv；
Specifically it refer to shown in Fig. 8, Fig. 8 is to use the correction situation under the inventive method to energy resolution,（a）For
The energy resolution 22.3% obtained when not carrying out baseline correction under the MVT method of samplings,（b）To have carried out base under the MVT method of samplings
The energy resolution 18.1% that line correction is obtained.
It is obvious to a person skilled in the art that the invention is not restricted to the details of above-mentioned one exemplary embodiment, Er Qie
In the case of without departing substantially from spirit or essential attributes of the invention, the present invention can be realized in other specific forms.Therefore, no matter
From the point of view of which point, embodiment all should be regarded as exemplary, and be nonrestrictive, the scope of the present invention is by appended power
Profit is required rather than described above is limited, it is intended that all in the implication and scope of the equivalency of claim by falling
Change is included in the present invention.Any reference in claim should not be considered as to the claim involved by limitation.
Moreover, it will be appreciated that although the present specification is described in terms of embodiments, not each embodiment is only wrapped
Containing an independent technical scheme, this narrating mode of specification is only that for clarity, those skilled in the art should
Using specification as an entirety, the technical solutions in the various embodiments may also be suitably combined, forms those skilled in the art
It may be appreciated other embodiment.
Claims (3)
1. a kind of baseline correction method for digitizing scintillation pulse, it is characterised in that：The baseline correction method step is as follows：
(1) multi-Vt sampling method is used, the time that carried out to scintillation pulse signal axially samples, and obtains scintillation pulse waveform
Digitized sampling point, the multi-Vt sampling method is specially：Some threshold reference voltages are pre-set, scintillation pulse is recorded
Voltage amplitude reaches the specific moment of each threshold voltage, and each voltage threshold and corresponding triggered time are when constituting one
M- threshold value sampled point；
(2) the corresponding digitized sampling point of each scintillation pulse is chosen, according to the scintillation crystal and electrooptical device coupled
Classification be modeled, obtain the style characteristic of corresponding scintillation pulse, rebuild impulse waveform and according to the shape of scintillation pulse
Characteristic, function approximation is carried out to the when m- threshold value sampled point of selected scintillation pulse waveform and obtains characteristic mathematical model, and from institute
The parameter value that characteristic mathematical model extraction portrays the style characteristic of scintillation pulse is stated, description baseline water is found from the parameter value
Flat baseline value, obtains the baseline drift amount of each scintillation pulse accordingly, and then the baseline drift amount to gained is analyzed, and is obtained
Obtain baseline drift average；
(3) the scintillation pulse waveform after reconstruction is subtracted to the baseline drift average of step (2) acquisition, baseline correction is completed.
2. the baseline correction method of digitlization scintillation pulse according to claim 1, it is characterised in that：The step (2)
In the method analyzed the needle position misalignment amount of each resulting scintillation pulse be mean value computation or statistical analysis.
3. a kind of base line correction system for digitizing scintillation pulse, it is characterised in that：Including：
Digitized sampling module, for carrying out time axially sampling to scintillation pulse using the multi-Vt method of sampling, is obtained
The digitized sampling point of scintillation pulse；
Needle position misalignment computing module, for rebuilding scintillation pulse waveform, identification model parameter obtains the baseline drift of scintillation pulse
Amount, and utilize the baseline drift average of statistical distribution calculating scintillation pulse；Baseline correction module, for carrying out base to scintillation pulse
Line is corrected, and reduces the primary data information (pdi) of scintillation pulse；The needle position misalignment computing module includes event accumulation and rejects module, arteries and veins
Module and needle position misalignment amount computing module are rebuild in punching, wherein, module is rejected in event accumulation to be used to differentiate and reject in scintillation pulse
Pile-up events；Module is rebuild in pulse to be used to rebuild the scintillation pulse waveform, identification model parameter, and reconstruction parameter value is passed
It is sent to needle position misalignment amount computing module；Needle position misalignment amount computing module rebuilds the reconstruction parameter calculating sudden strain of a muscle that module is obtained according to pulse
The needle position misalignment amount of bright pulse, then carries out statistic histogram analysis to the needle position misalignment amount in the range of a period of time, is dodged
The average baselining offset of bright pulse is simultaneously sent to baseline correction module；
The digitized sampling module includes threshold voltage setup module, threshold value discriminator module and time mark module, wherein,
Threshold voltage settings module is used for given threshold reference voltage, and threshold reference voltage is sent into threshold value discriminator module and time
Mark module；Threshold value discriminator module is used to compare the magnitude relationship between scintillation pulse threshold voltage and threshold reference voltage,
And logical pulse is produced when scintillation pulse voltage passes through threshold reference voltage, and the logical pulse time of delivery (TOD) of generation is marked
Module carries out time mark；Time mark module is used to carry out time mark to the logical pulse that threshold value discriminator module is exported,
And by its corresponding threshold reference voltage makeup time-threshold value sampled point of the timestamp of gained and it is sent to needle position misalignment calculating
Module.
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| CN201310045576.5A CN103969675B (en) | 2013-02-05 | 2013-02-05 | Digitize the baseline correction method and system of scintillation pulse |
| PCT/CN2013/073126 WO2014121548A1 (en) | 2013-02-05 | 2013-03-25 | Method and system for correcting baseline of digitized scintillation pulse |
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| CN105824817B (en) | 2015-01-05 | 2019-05-21 | 苏州瑞派宁科技有限公司 | A kind of digitizing solution of scintillation pulse |
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| CN105629290B (en) * | 2016-02-16 | 2018-12-04 | 北京中科坤润科技有限公司 | A kind of number core pulse signal Mexico hat wavelet manufacturing process |
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| CN105866011B (en) * | 2016-03-31 | 2018-10-26 | 艾康生物技术(杭州)有限公司 | The particle counting methods of pulse base value calculating method and blood cell analysis machine |
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| CN107260197B (en) | 2017-07-10 | 2020-11-10 | 东软医疗系统股份有限公司 | Time correction method, device and equipment |
| CN109350098B (en) * | 2018-08-27 | 2021-02-26 | 苏州瑞派宁科技有限公司 | Method for determining fitting mode of signal, method for reconstructing signal and device |
| CN109444559B (en) * | 2018-10-26 | 2021-02-05 | 苏州瑞迈斯医疗科技有限公司 | Pulse signal sampling method, pulse signal reconstruction method and pulse signal reconstruction device |
| CN110327063B (en) * | 2019-06-10 | 2023-05-12 | 沈阳智核医疗科技有限公司 | Energy correction method, device, console device and PET system |
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