CN101937093B - Method for correcting afterglow of scintillation detector - Google Patents
Method for correcting afterglow of scintillation detector Download PDFInfo
- Publication number
- CN101937093B CN101937093B CN 200910088619 CN200910088619A CN101937093B CN 101937093 B CN101937093 B CN 101937093B CN 200910088619 CN200910088619 CN 200910088619 CN 200910088619 A CN200910088619 A CN 200910088619A CN 101937093 B CN101937093 B CN 101937093B
- Authority
- CN
- China
- Prior art keywords
- detector
- measuring
- data
- signal data
- measuring process
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Abstract
The invention discloses a method for correcting afterglow of a scintillation detector, which can effectively reduce or even eliminate artifact which is formed in a scanned picture by scintillator afterglow, and can enable the scanned picture to truthfully reflect actual projection of a detected object. The method comprises the following steps of: setting the same integration time when measuring background data and signal data; a first measuring step of measuring the initial background data of the detector when rays do not emerge; a second measuring step of measuring the signal data of the detector when the rays emerge; a third measuring step of measuring the background data of the detector when the emerging rays stop; a fourth measuring step of measuring the signal data of the detector when the rays emerge; repeating the third measuring step and the fourth measuring step to finish scanning; and subtracting the last background data of the detector from the measured signal data of the detected when the rays emerge every time, and taking the data as the corrected signal data of the detector for subsequent image data processing.
Description
Technical field
The present invention relates to radiation checking technical, be specifically related to radiation scanning check system detector signal and process, particularly the method for correcting afterglow of X ray scintillation detector.
Background technology
Scintillation detector is a kind of ionizing radiation detector spare commonly used, mainly is comprised of scintillator and electrooptical device such as photodiode, photomultiplier etc.Send passage of scintillation light after the energy of scintillator absorption ionising radiation such as X ray, electrooptical device converts blinking light to electric signal.Scintillation detector is widely applied in radiation scanning check system such as X ray container scanning check system, and this moment, radiation source was the pulsed X-ray that is produced by electron linear accelerator.Form a fan-shaped detection faces by pulsed X-ray and detector array during work, tested object is placed between pulsed X-ray and detector array, the X ray that penetrates tested object lists at detector array and produces a row transmission projection, converts electric signal to and corrects through signals collecting and A/D conversion and follow-up brightness rectification and inconsistency the column data that (seeing the open communique CN1173169 of patent of invention) becomes scan image through detector.Along with the relative motion of tested object and fan-shaped detection faces, can obtain the multiple row scan-data and consist of final X ray transmission scan image.
Every column scan data should be all independent the generations in theory, and such scan-data could reflect the internal state of the tested object of correspondence position this moment.The scan-data before yet the twilight sunset phenomenon of scintillation detector makes each column scan data and obtains this column data is relevant.
The twilight sunset of scintillation detector is not to be synchronous the generation because scintillator wherein absorbs the process of ionising radiation and generation visible light, the luminous process of scintillator can't stop at once after X ray is turned off, progressively decay but defer to complicated index law, its attenuation process mainly comprises intrinsic decay of luminescence and twilight sunset.The intrinsic decay of luminescence depends on the architectural feature of scintillator, and its attenuation constant is commonly referred to as fluorescence decay time, such as CsI (Tl) scintillation crystal commonly used is 680ns to the fluorescence decay time of X ray.Twilight sunset is the decay of luminescence that causes due to the defective of scintillator inside or impurity, and general die-away time is very long, such as CsI (Tl) scintillation crystal also may be had by luminous residue after rays excite 3ms peaked 5%, this luminous residual be exactly twilight sunset.Affect scintillator twilight sunset factor a lot: the manufacturing process of scintillator, scintillator absorb the temperature of time of ray and dosage, environment etc. all can be to the exerting an influence of scintillator twilight sunset, and its time constant can be from several milliseconds to tens hours.
The persistence characteristic of scintillator has a strong impact on the picture quality of radiation scanning check system.Especially can cause image artifacts for quick check system.Due to the asynchronism(-nization) of cumulative absorbed dose or absorbed dose, easily cause the persistence characteristic difference of different passage scintillators, this difference may make the inconsistency of detector output correct inefficacy.
For this problem, two kinds of solutions are arranged generally, the first is used the scintillator of low twilight sunset, and such as using the CdWO4 scintillation crystal to substitute CsI (Tl) scintillation crystal, the former twilight sunset is only 0.1% after 3ms.Yet because the price of applicable low twilight sunset scintillator is often very high, can increase a lot of costs to thousands of or radiation scanning imaging systems several thousand passages easily.The another one solution is to measure in advance the time constant of scintillator twilight sunset, eliminates in the algorithm that image is processed.Yet because the factor that affects scintillator twilight sunset is a lot, especially because the cumulative absorbed dose of scintillator is all relevant with all measurement data before this measurement, therefore can increase the calculating of large amount of complex, this also increases a lot of difficult to practical application.
Summary of the invention
The object of the present invention is to provide the twilight sunset of scintillation detector in a kind of radiation scanning check system to correct way, especially can effectively reduce in using the radiogenic scanning imaging system of pulse and even eliminate scintillator twilight sunset to the impact of scan image.
In order to realize the foregoing invention purpose, the present invention proposes a kind of antidote of detector twilight sunset, comprises the steps:
At first be set in when measuring background data and measuring-signal data and have identical integral time;
Measure the 1st measuring process of the initial background data of detector without ray the time;
Constantly measure the 2nd measuring process of the signal data of detector at emerging ray;
Measure the 3rd measuring process of the background data of detector during stopping emerging ray;
Constantly measure the 4th measuring process of the signal data of detector at emerging ray;
Repeat above-mentioned the 3rd measuring process and the 4th measuring process until scanning is completed;
The detector background data of the last time before the signal data of the detector of measuring during each emerging ray deducts is used for follow-up view data with it as the detector signal data after correcting and processes.
The method for correcting afterglow of scintillation detector that utilizes the present invention to propose can effectively reduce and even eliminate the pseudo-shadow that scintillator twilight sunset forms in scan image, scan image is reflected truly be detected the actual projection of object.
Description of drawings:
Fig. 1 is the schematic diagram of scintillator twilight sunset.
Fig. 2 is the schematic diagram that a kind of X-ray scanning check system consists of.
Fig. 3 is the schematic diagram of detector signal output.
Fig. 4 is a schematic diagram of scan image deviation.
Fig. 5 is the process flow diagram of an embodiment of method for correcting afterglow of scintillation detector of the present invention.
Fig. 6 is the schematic diagram of signal output in detector method for correcting afterglow embodiment of the present invention.
Fig. 7 has carried out detector twilight sunset through method for correcting afterglow of the present invention to correct scan image schematic diagram afterwards.
Fig. 8 is the schematic diagram of another embodiment of scintillator method for correcting afterglow of the present invention.
Embodiment
Figure I is the schematic diagram of scintillator twilight sunset.The twilight sunset mechanism of production of scintillator is very complicated, manufacture process that it is generally acknowledged structure, impurity and the defective of twilight sunset and scintillator inside and scintillator is relevant, and is also relevant with the time length of the serviceability temperature of scintillator, the dosage that is ionized radiation irradiation and irradiation simultaneously.The damping time constant of scintillator twilight sunset even several hours from 1ms to hundreds of ms, often same scintillator has the multiple attenuance component from the short persistence to the long afterglow.Increase along with the illuminated time of scintillator, the one-tenth branch of long afterglow increases gradually, therefore can cause scintillation detector output background lifting step by step, and the part that this background is raised can cause to the output signal of detector harmful effect, and then form pseudo-shadow in scan image.Method for correcting afterglow of the present invention can reduce even eliminates the pseudo-shadow of scan image that the persistence characteristic due to detector causes.
Fig. 2 is the schematic diagram that a kind of X-ray scanning check system consists of.Wherein 201 is scintillation detector arrays, the 202nd, and signal acquisition circuit array, the 203rd, accelerator pulse x-ray source.Detector array 201 and Pulsed Xray source 203 form one certain thickness sector.Tested object 204 passes fan-shaped detection faces by 205 directions, and the X ray that penetrates tested object is converted through detector array 201 and signal acquisition circuit array 202 and becomes row and check data, and the data rows of different time is combined to form final check image.
Fig. 3 is the schematic diagram of a scintillation detector signal output in above-mentioned scintillation detector array 201.Wherein P0 is the output of detector when there is no X ray, is also zero point or the initial background data of detector.P1 is detector output data when the X ray pulse is arranged to P7, these output data are the stack of X ray data for projection Ti and background data P0: Pi=Ti+P0, if background data P0 does not change in whole scanning process, data for projection Ti=Pi-P0, this is also the method (seeing the open communique CN1173169 of patent of invention) of traditional rectification detector background data.If there is previously described afterglow issues in detector, detector output data also comprises the twilight sunset data Ai of projection signal before except comprising data for projection Ti and background data P0, so Pi=Ti+P0+Ai.Due to the existence of twilight sunset, traditional background antidote can not obtain real data for projection.Because the twilight sunset data of detector are relevant with the history of detector raying irradiation, a row detector to any time, wherein the twilight sunset data Ai in each detector output data may be different at different time points, therefore through traditional measure rectifications, inconsistency is corrected and the scan image of background after correcting still exists and the true deviation of projected image (because the existence of Ai causes).
Fig. 4 is a schematic diagram of above-mentioned scan image deviation.Shown in figure to be a row detector reexamine an even object after scanning after a while the time the scan image sectional drawing.The twilight sunset data of other passage of channel C 1, C2 and C3 twilight sunset data and detector array have difference, cause scan image can not truly reflect actual projection.
Fig. 5 and Fig. 6 are respectively process flow diagram and the schematic diagram of an embodiment of method for correcting afterglow of scintillation detector of the present invention.Because background data and twilight sunset data all the integral time with signal acquisition circuit relevant, so identical integral time is used in all data acquisitions.Constantly measure the initial background data P0 of detector at the t0 that there is no ray, measure the output data Pi of detector in the emerging ray moment (t1, t2....), there is no a moment (ti of X ray before measuring Pi
-1During-ti) measure the background data Pia of detector.According to above-mentioned analysis as can be known, Pia=P0+Ai here is so have: Ti=Pi-Pia.For the container check system that uses the accelerator x-ray source, the time of origin of single accelerator pulse (pulsewidth) only has several microseconds, and adjacent two recurrent interval (ti
-1During-ti) several milliseconds are arranged to tens milliseconds, can insert a real-time sample-out count Pia fully in practical operation.
About the Measuring Time point problem of inserting for above-mentioned sample-out count Pia, theoretically, the background data Pia that the measurement of distance P i moment ti more closely obtains is truer, and the embodiment that the present invention provides has chosen ti
-1Intermediate point during-ti is constantly as the insertion point, 1/3rd, 1/4th before can certainly selected distance ti ... equi-time point.But, if the after time of detector with respect in relatively long situation of recurrent interval, choosing of above-mentioned different time points can't produce substantial effect to real sample-out count data pia.
Fig. 7 has carried out detector twilight sunset through method for correcting afterglow of the present invention to correct scan image schematic diagram afterwards.Contrast as can be known with Fig. 4, because the inconsistent image artifacts that causes of each detector twilight sunset data in detector array has obtained revising preferably.
Fig. 8 is the schematic diagram of another embodiment of scintillator method for correcting afterglow of the present invention.Sample-out count in this embodiment is not all will measure real-time background data before each emerging ray is measured the output data of detector constantly.The detector output that t2 in Fig. 8, t3, t5, t7 measure constantly when ray is arranged is adjacent and real-time background data that inserted before the above-mentioned moment with it not.This moment, the twilight sunset rectification of detector can be taked nearest sample-out count data of time before, such as T3=P3-A1.The benefit of this antidote is the X-ray scanning check system that can be used for correcting the non-pulse type, such as the afterglow of scintillation detector in X ray baggage screening system and X ray CT check system, whether hinder by tested object shading light and control because these system's X ray go out bundle and stop bundle.
Here needed is all to measure once background data in real time when each X ray stops bundle, and after the measurement data of the detector of X ray when beginning to go out to restraint continuously all use background data this time to correct, until X ray stops the real-time background data that Shu Shizai measures a new round and is used for the rectification of data afterwards next time.
Claims (4)
1. an antidote that uses the detector twilight sunset in the radiogenic scanning imaging system of pulse, comprise the steps:
At first be set in when measuring background data and measuring-signal data and have identical integral time;
Measure the 1st measuring process of the initial background data of detector without ray the time;
Constantly measure the 2nd measuring process of the signal data of detector at emerging ray;
Measure the 3rd measuring process of the background data of detector during stopping emerging ray;
Constantly measure the 4th measuring process of the signal data of detector at emerging ray;
Repeat above-mentioned the 3rd measuring process and the 4th measuring process until scanning is completed;
The detector background data of the last time before the signal data of the detector of measuring during each emerging ray deducts is used for follow-up view data with it as the detector signal data after correcting and processes.
2. the antidote of detector twilight sunset as claimed in claim 1, is characterized in that, the Measuring Time point of described the 3rd measuring process is arranged at the position of the intermediate point between recurrent interval of adjacent two measuring-signal data.
3. the antidote of detector twilight sunset as claimed in claim 1, it is characterized in that, the Measuring Time point of described the 3rd measuring process is arranged near position before current measuring-signal pulse, recurrent interval n adjacent two measuring-signal data /one, and wherein, n is the natural number greater than 2.
4. an antidote that uses the detector twilight sunset in the radiogenic scanning imaging system of pulse, comprise the steps:
At first be set in when measuring background data and measuring-signal data and have identical integral time;
Measure the 1st measuring process of the initial background data of detector without ray the time;
Constantly measure the 2nd measuring process of the signal data of detector at emerging ray;
Measure the 3rd measuring process of the background data of detector during stopping emerging ray;
Constantly measure the 4th measuring process of the signal data of detector at emerging ray;
Repeat above-mentioned the 3rd measuring process and the 4th measuring process until scanning is completed, and omit at least above-mentioned the 3rd measuring process more than n time in repeating above-mentioned the 3rd measuring process and the 4th measuring process process, wherein n is the natural number more than 2;
The detector background data of the last time before the signal data of the detector of measuring during each emerging ray deducts is used for follow-up view data with it as the detector signal data after correcting and processes.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200910088619 CN101937093B (en) | 2009-06-30 | 2009-06-30 | Method for correcting afterglow of scintillation detector |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200910088619 CN101937093B (en) | 2009-06-30 | 2009-06-30 | Method for correcting afterglow of scintillation detector |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN101937093A CN101937093A (en) | 2011-01-05 |
| CN101937093B true CN101937093B (en) | 2013-06-19 |
Family
ID=43390522
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 200910088619 Active CN101937093B (en) | 2009-06-30 | 2009-06-30 | Method for correcting afterglow of scintillation detector |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN101937093B (en) |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102360083B (en) * | 2011-08-19 | 2013-06-05 | 上海高晶影像科技有限公司 | Method for removing belt artifacts in images for line scanning X-ray security inspection equipment |
| CN103969677B (en) * | 2013-01-25 | 2016-09-07 | 中国科学技术大学 | Wide dynamic range neutron flux measurement system and method based on Pulse-Current pattern |
| CN103674981A (en) * | 2013-12-04 | 2014-03-26 | 中国科学院上海硅酸盐研究所 | Microsecond scintillation afterglow measuring device for scintillating material |
| CN108535770B (en) * | 2018-05-09 | 2024-01-02 | 同方威视技术股份有限公司 | Afterglow detection device and afterglow detection method |
| CN110274923B (en) * | 2019-07-22 | 2020-10-09 | 中国原子能科学研究院 | Synchronous data acquisition and calibration method and control system of high-energy X-ray CT equipment |
| CN114602822A (en) * | 2022-03-28 | 2022-06-10 | 同方威视技术股份有限公司 | Mineral dry separation equipment |
| CN114545488B (en) * | 2022-04-26 | 2022-07-22 | 江苏尚飞光电科技股份有限公司 | Scintillator afterglow measuring method |
| CN115932932A (en) * | 2022-11-03 | 2023-04-07 | 宁波虔东科浩光电科技有限公司 | Signal processing method of scintillator detection array and imaging device |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5331682A (en) * | 1991-11-25 | 1994-07-19 | General Electric Company | Radiation detector offset and afterglow compensation technique |
| US5666393A (en) * | 1994-02-17 | 1997-09-09 | Annis; Martin | Method and apparatus for reducing afterglow noise in an X-ray inspection system |
| DE19751298A1 (en) * | 1996-12-20 | 1998-06-25 | Siemens Ag | Diagnostic X-ray imaging arrangement |
| CN1380544A (en) * | 2001-04-12 | 2002-11-20 | 清华大学 | Method for correcting data nonuniformity in radiation imaging system |
| CN1447636A (en) * | 2002-03-26 | 2003-10-08 | 西门子公司 | Method of suppressing ghost in X-ray image and related X-ray appts. |
-
2009
- 2009-06-30 CN CN 200910088619 patent/CN101937093B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5331682A (en) * | 1991-11-25 | 1994-07-19 | General Electric Company | Radiation detector offset and afterglow compensation technique |
| US5666393A (en) * | 1994-02-17 | 1997-09-09 | Annis; Martin | Method and apparatus for reducing afterglow noise in an X-ray inspection system |
| DE19751298A1 (en) * | 1996-12-20 | 1998-06-25 | Siemens Ag | Diagnostic X-ray imaging arrangement |
| CN1380544A (en) * | 2001-04-12 | 2002-11-20 | 清华大学 | Method for correcting data nonuniformity in radiation imaging system |
| CN1447636A (en) * | 2002-03-26 | 2003-10-08 | 西门子公司 | Method of suppressing ghost in X-ray image and related X-ray appts. |
Also Published As
| Publication number | Publication date |
|---|---|
| CN101937093A (en) | 2011-01-05 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN101937093B (en) | Method for correcting afterglow of scintillation detector | |
| US11644586B2 (en) | Method and system for evaluating the working condition of a detector | |
| CN101074935B (en) | Detector array and its apparatus | |
| US7129495B2 (en) | Method and apparatus for timing calibration in a PET scanner | |
| CN101365962B (en) | Calibrating the coincidence timing utilized in time-of-flight measurements in positron emission tomography | |
| CN103675886B (en) | scintillation detector gain control | |
| US6232604B1 (en) | Analog time adjustment for coincidence detection electronics | |
| US20070270693A1 (en) | Timing Calibration for Tof-Pet Scanner | |
| CN102809756B (en) | A method for correcting count rate drift in a quantum-counting detector and an x-ray system | |
| CN101292174A (en) | Pmt gain and energy calibrations using lutetium background radiation | |
| EP3033637B1 (en) | A hybrid method based on simulation and experimental data to normalize pet data | |
| CN106539591A (en) | PET flight time state quality detection methods and PET scan device | |
| EP1747482B1 (en) | Stabilization of a scintillation detector | |
| CN103221841A (en) | PET calibrations with varying coincidence windows | |
| US8664616B2 (en) | Count correction in a photon counting imaging system | |
| US8274055B2 (en) | Radiation signal-processing unit and radiation detector provided with the same | |
| US20070057189A1 (en) | Method and system for calibrating a time of flight positron emission tomography system | |
| JP7239921B2 (en) | Positron annihilation spectrometer | |
| US20150219771A1 (en) | Systems and methods for scintillators having polished and roughened surfaces | |
| US8805652B2 (en) | Charge calibrator and system incorporating the same | |
| JP2015094624A (en) | Radiation detection system, data processing apparatus, radiation detection method, and wave height value distribution data processing program | |
| DE102015201494B4 (en) | Determining function data of an X-ray detector | |
| US20110155900A1 (en) | Systems and methods for generating calibration maps for non-pixelated gamma detectors | |
| Presti et al. | Development of a scintillation-fiber detector for real-time particle tracking | |
| Presti et al. | Design and characterization of a real time, large area, high spatial resolution particle tracker based on scintillating fibers |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| TR01 | Transfer of patent right |
Effective date of registration: 20181126 Address after: Building 10, 18 Garden Road, Miyun Economic Development Zone, Beijing 100084 Co-patentee after: Nuctech Company Limited Patentee after: Tongfang Weishi Technology (Beijing) Co., Ltd. Address before: 100084 Beijing city Haidian District Shuangqing Road with Party building A block 2 layer Patentee before: Nuctech Company Limited |
|
| TR01 | Transfer of patent right |