CN109633730B - Positioning system and positioning method of radioactive source - Google Patents
Positioning system and positioning method of radioactive source Download PDFInfo
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- CN109633730B CN109633730B CN201811549185.6A CN201811549185A CN109633730B CN 109633730 B CN109633730 B CN 109633730B CN 201811549185 A CN201811549185 A CN 201811549185A CN 109633730 B CN109633730 B CN 109633730B
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- 230000002285 radioactive effect Effects 0.000 title claims abstract description 50
- 238000000034 method Methods 0.000 title claims abstract description 17
- 230000005855 radiation Effects 0.000 claims abstract description 40
- 239000013078 crystal Substances 0.000 claims abstract description 29
- 238000001514 detection method Methods 0.000 claims abstract description 15
- 238000005070 sampling Methods 0.000 claims abstract description 15
- 238000012545 processing Methods 0.000 claims abstract description 14
- 230000003321 amplification Effects 0.000 claims abstract description 7
- 238000006243 chemical reaction Methods 0.000 claims abstract description 7
- 238000003199 nucleic acid amplification method Methods 0.000 claims abstract description 7
- 239000002245 particle Substances 0.000 claims description 12
- 239000000463 material Substances 0.000 claims description 5
- 230000009471 action Effects 0.000 claims description 4
- 238000013135 deep learning Methods 0.000 claims description 4
- 230000008901 benefit Effects 0.000 abstract description 4
- 238000009792 diffusion process Methods 0.000 abstract 1
- 238000010586 diagram Methods 0.000 description 4
- 238000012544 monitoring process Methods 0.000 description 3
- 241000282414 Homo sapiens Species 0.000 description 2
- 230000005251 gamma ray Effects 0.000 description 2
- 238000003384 imaging method Methods 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
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- 230000004927 fusion Effects 0.000 description 1
- 231100001261 hazardous Toxicity 0.000 description 1
- 230000005865 ionizing radiation Effects 0.000 description 1
- 239000012857 radioactive material Substances 0.000 description 1
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- 238000006467 substitution reaction Methods 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
- G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
- G01T1/16—Measuring radiation intensity
- G01T1/20—Measuring radiation intensity with scintillation detectors
- G01T1/202—Measuring radiation intensity with scintillation detectors the detector being a crystal
- G01T1/2023—Selection of materials
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
- G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
- G01T1/36—Measuring spectral distribution of X-rays or of nuclear radiation spectrometry
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Abstract
The invention discloses a positioning system and a positioning method of a radioactive source, wherein the positioning system comprises: the detector comprises a photomultiplier and a cylindrical scintillation crystal, and the cylindrical scintillation crystal is used for receiving the radioactive rays and generating a detection signal through the photomultiplier; the analog-to-digital converter is connected with the detector through the preamplifier; the signal processing module is used for generating a sampling waveform according to the detection signal after amplification and analog-to-digital conversion by utilizing the inconsistency of light generation and diffusion in the direction of the columnar scintillation crystal vertical to the bottom surface for signal discrimination so as to judge the distance between the acting position of the radioactive ray and the photomultiplier, and determining the incident direction of the radioactive source by counting the distance distribution condition of the acting position of the radioactive ray and the photomultiplier; wherein, the length of the columnar scintillation crystal in the direction vertical to the bottom surface is larger than the preset length. The invention has the following advantages: the equipment is simple and the cost is low; can be used for auxiliary radiation source positioning and avoiding blind search.
Description
Technical Field
The invention relates to the technical field of nuclear radiation detection, in particular to a positioning system and a positioning method of a radioactive source.
Background
The radioactive source is widely applied to various fields of national economy, including industry, agriculture, medicine and the like, and greatly benefits human beings. On the other hand, however, since the radiation source can emit high-energy rays or particles, such as gamma rays, neutrons, etc., which are ionizing radiation, the tissue of the cell is damaged, thereby injuring the human body. Radioactive source leaks, losses, or theft events occur at all times, and the use of radioactive sources is potentially hazardous, requiring significant monitoring or supervision in addition to the need for strict management of the radioactive source. When the radioactive source is leaked, lost or stolen, the radioactive source can be quickly searched and positioned, so that the harm and social effect brought by the radioactive source are reduced.
Radiation source monitoring is currently most used with dosimeters and spectrometers, but these devices generally have no positioning capability and require carpet searching or fusion calculations using multiple detector information.
In recent years, imaging detectors based on a code plate and detectors based on the Compton scattering principle are applied to radioactive source monitoring and searching, the imaging detectors can quickly lock radioactive sources, but the equipment is expensive and is not beneficial to popularization and application.
Disclosure of Invention
The present invention is directed to solving at least one of the above problems.
To this end, a first object of the invention is to propose a low-cost positioning system of a radioactive source, which allows the radioactive source to be positioned.
In order to achieve the above object, an embodiment of the present invention discloses a positioning system of a radiation source, including: the detector comprises a photomultiplier and a cylindrical scintillation crystal, the photomultiplier is coupled with the bottom surface of the cylindrical scintillation crystal, and the cylindrical scintillation crystal is used for receiving radioactive rays and generating detection signals through the photomultiplier; the analog-to-digital converter is connected with the detector through a preamplifier; the signal processing module is connected with the analog-to-digital converter and used for generating a sampling waveform according to the detection signal after amplification and analog-to-digital conversion, comparing the sampling waveform with a standard waveform of the radioactive source at different positions to judge the distance between the acting position of the radioactive ray and the photomultiplier tube, and determining the incident direction of the radioactive source by counting the distance distribution condition of the acting position of the radioactive ray and the photomultiplier tube; wherein, the length of the columnar scintillation crystal in the direction vertical to the bottom surface is larger than the preset length.
According to the positioning system of the radioactive source, the positioning system is based on the traditional gamma ray energy spectrometer, hardware improvement is not needed, equipment is simple, and cost is low; can be used for auxiliary radiation source positioning and avoiding blind search.
In addition, the positioning system of the radiation source according to the above embodiment of the present invention may further have the following additional technical features:
optionally, the signal processing module compares the standard waveform of the radiation source at different positions with the sampling waveform in at least one of template matching and least square algorithm deep learning.
Optionally, the columnar scintillation crystal is in the shape of a cuboid or a cylinder.
Optionally, the preset length is 10 cm.
Optionally, the crystal material of the columnar scintillation crystal is any one of NaI, CsI, GAGG, LSO, LYSO, BGO, GSO, and YSO.
The second purpose of the present invention is to provide a method for positioning a radioactive source, which can position the radioactive source.
In order to achieve the above object, an embodiment of the present invention discloses a positioning method for a radiation source, including the positioning system for a radiation source of the above embodiment, the positioning method for a radiation source includes the following steps: acquiring signal waveforms incident by a collimation source at different positions in advance, and storing the signal waveforms after processing; receiving the radioactive rays through the detector to generate detection signals, and processing the detection signals after amplification and analog-to-digital conversion to obtain sampling waveforms; obtaining the distance distribution condition between the acting position of the radioactive source ray and the photomultiplier according to the sampling waveform and the stored signal waveforms of the collimation source incident at different positions; and determining that the emitted rays of the radioactive source are incident from one end close to the photomultiplier or one end far away from the photomultiplier according to the distance distribution between the radioactive source ray acting position and the photomultiplier.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
FIG. 1 is a block diagram of a positioning system for a radiation source according to one embodiment of the present invention;
FIG. 2 is a schematic diagram of the structure of a detector in one embodiment of the invention;
FIG. 3 is a statistical histogram of decision locations for 1s particle waveforms in one embodiment of the present invention;
FIG. 4 is a flow chart of a method of positioning a radiation source according to one embodiment of the present invention.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.
In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on those shown in the drawings, and are used only for convenience in describing the present invention and for simplicity in description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
These and other aspects of embodiments of the invention will be apparent with reference to the following description and attached drawings. In the description and drawings, particular embodiments of the invention have been disclosed in detail as being indicative of some of the ways in which the principles of the embodiments of the invention may be practiced, but it is understood that the scope of the embodiments of the invention is not limited correspondingly. On the contrary, the embodiments of the invention include all changes, modifications and equivalents coming within the spirit and terms of the claims appended hereto.
The positioning system and the positioning method of the radioactive source of the present invention are described below with reference to the accompanying drawings.
FIG. 1 is a block diagram of a positioning system for a radiation source, in accordance with one embodiment of the present invention. As shown in FIG. 1, the positioning system of the radiation source according to the embodiment of the present invention includes a detector 100, a preamplifier 200, an analog-to-digital converter 300, and a signal processing module 400.
Wherein the detector 100 includes a photomultiplier tube and a cylindrical scintillation crystal. The photomultiplier is coupled to the bottom surface of a cylindrical scintillation crystal for receiving the radiation and generating a detection signal via the photomultiplier. Wherein, the length of the columnar scintillation crystal in the direction vertical to the bottom surface is larger than the preset length.
FIG. 2 is a schematic diagram of a detector according to an embodiment of the present invention. As shown in fig. 2, the detector 100 includes a photomultiplier tube 1, a columnar scintillation crystal 2, and a light shielding case 3 provided outside the photomultiplier tube 1 for shielding external light.
In one embodiment of the invention, the columnar scintillation crystal 2 is in the shape of a cuboid or a cylinder.
In one embodiment of the present invention, the crystal material of the columnar scintillation crystal 2 is any one of NaI, CsI, GAGG, LSO, LYSO, BGO, GSO, and YSO.
In one embodiment of the invention, the predetermined length is 10 cm.
In one example of the present invention, the columnar scintillation crystal 2 is a NaI rectangular parallelepiped with dimensions of 10cm × 10cm × 40cm, wherein a 3.5-inch photomultiplier tube 1 is coupled to a 10cm × 10cm end face.
The preamplifier 200 is used for signal amplification of the sampling signal.
The analog-to-digital converter 300 is used for analog-to-digital conversion of the amplified signal.
The signal processing module 400 is connected to the analog-to-digital converter 300, and is configured to generate a sampling waveform according to the amplified and analog-to-digital converted detection signal, compare the sampling waveform with a standard waveform of the radiation source at different positions to determine a distance between the radiation source acting position and the photomultiplier tube, and determine an incident direction of the radiation source by counting a distance distribution between the radiation source acting position and the photomultiplier tube.
Specifically, the columnar scintillation crystal 2 is irradiated with collimated Na22 radiation source at different positions, and standard waveforms at the respective positions are obtained. The example is divided into three positions: far away from one end of the photomultiplier, in the middle of the crystal and near one end of the photomultiplier, 100 ten thousand waveforms are collected at each position.
And acquiring data, and judging that each waveform is compared with each position standard waveform, so as to judge whether each particle incidence position is far away from one end of the photomultiplier, or in the middle of the crystal, or close to one end of the photomultiplier.
In one embodiment of the present invention, the comparison of the standard waveform of the radiation source at different positions with the sampled waveform by the signal processing module 400 includes at least one of template matching, least squares algorithm and deep learning.
In one example of the invention, the signal processing module 400 employs a least squares algorithm for waveform comparison. The method specifically comprises the following steps: and averaging 100 ten thousand waveforms at three positions to obtain three standard waveforms, respectively calculating the square sum of differences of each point of the particle waveform at the position to be judged and the three standard waveforms, and taking the position of the standard waveform with the minimum square sum of the differences as the particle incidence position.
In another example of the present invention, the signal processing module 400 employs a deep learning method for waveform comparison. The method specifically comprises the following steps: training 100 ten thousand waveforms at three positions to obtain a model, and inputting the waveform of the particle to be judged into the model to obtain the action position of the particle.
FIG. 3 is a statistical histogram of the decision locations of the 1s particle waveforms in one embodiment of the invention. As shown in fig. 3, the statistical histogram distribution of the action positions of all the particles incident within 1s is counted, so as to determine whether the radiation source is incident in a direction close to the PMT or in a direction away from the PMT, i.e., if the number of events at the particle action position near one end of the PMT (e.g., position 1) is the largest, the radiation source is near one end of the PMT, and if the number of events at position 1 in fig. 3 is the largest, the radiation source is near one end of the PMT (i.e., position 1); conversely, the particle effect position the radiation source is at the end away from the PMT if the number of events is greatest at a position away from the end of the PMT (e.g., position 3). In one example of the present invention, a positioning system of the radioactive source is installed in the ground of the pedestrian passageway, and it can be determined whether the suspect with the radioactive material passes through the detector from the left side or the right side.
According to the positioning system of the radioactive source, the positioning system is based on the traditional gamma ray energy spectrometer, hardware improvement is not needed, equipment is simple, and cost is low; can be used for auxiliary radiation source positioning and avoiding blind search.
FIG. 4 is a flow chart of a method of positioning a radiation source according to one embodiment of the present invention. As shown in fig. 4, the positioning method of a radiation source according to an embodiment of the present invention includes the positioning system of a radiation source according to the above embodiment, and the positioning method of a radiation source includes the following steps:
s1: and acquiring and storing signal waveforms incident by the collimation source at different positions in advance.
S2: and receiving the radioactive rays through a detector to generate a detection signal, and processing the detection signal after amplification and analog-to-digital conversion to obtain a sampling waveform.
S3: and obtaining the distance distribution condition between the acting position of the radioactive source ray and the photomultiplier according to the sampling waveform and the stored signal waveforms of the collimation source incident at different positions.
S4: according to the distance distribution between the acting position of the radioactive source ray and the photomultiplier, the emitted ray of the radioactive source is determined to be incident from one end close to the photomultiplier or from one end far away from the photomultiplier.
It should be noted that, a specific implementation of the positioning method for a radiation source according to the embodiment of the present invention is similar to a specific implementation of the positioning system for a radiation source according to the embodiment of the present invention, and specific reference is specifically made to the description of the positioning system portion for a radiation source, and in order to reduce redundancy, no further description is given.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
While embodiments of the invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.
Claims (6)
1. A positioning system for a radiation source, comprising:
the detector comprises a photomultiplier and a cylindrical scintillation crystal, the photomultiplier is coupled with the bottom surface of the cylindrical scintillation crystal, and the cylindrical scintillation crystal is used for receiving radioactive rays and generating detection signals through the photomultiplier;
the analog-to-digital converter is connected with the detector through a preamplifier;
the signal processing module is connected with the analog-to-digital converter and used for generating a sampling waveform according to the detection signal after amplification and analog-to-digital conversion, comparing the sampling waveform with a standard waveform of the radioactive source at different positions to judge the distance between the acting position of the radioactive ray and the photomultiplier tube, and determining the incident direction of the radioactive source by counting the distance distribution condition of the acting position of the radioactive ray and the photomultiplier tube;
judging whether the incidence direction of a radioactive source is close to the photomultiplier or far away from the photomultiplier according to the distribution of the action positions of all particles counted by the photomultiplier;
wherein, the length of the columnar scintillation crystal in the direction vertical to the bottom surface is larger than the preset length.
2. The radiation source positioning system of claim 1, wherein the signal processing module compares the standard waveform of the radiation source at different positions with the sampled waveform by at least one of template matching, least squares algorithm, and deep learning.
3. The radiation source positioning system of claim 1, wherein the cylindrical scintillation crystal is in the shape of a cuboid or a cylinder.
4. The radiation source positioning system of claim 1, wherein the predetermined length is 10 cm.
5. The positioning system of a radiation source according to claim 1, wherein the crystal material of the columnar scintillation crystal is any one of NaI, CsI, GAGG, LSO, LYSO, BGO, GSO, and YSO.
6. A positioning method of a radioactive source, comprising the positioning system of a radioactive source according to any one of claims 1 to 5, comprising the steps of:
acquiring and storing signal waveforms of the collimation source incident at different positions in advance;
receiving the radioactive rays through the detector to generate detection signals, and processing the detection signals after amplification and analog-to-digital conversion to obtain sampling waveforms;
obtaining the distance distribution condition between the acting position of the radioactive source ray and the photomultiplier according to the sampling waveform and the stored signal waveforms of the collimation source incident at different positions;
and determining that the emitted rays of the radioactive source are incident from one end close to the photomultiplier or one end far away from the photomultiplier according to the distance distribution between the radioactive source ray acting position and the photomultiplier.
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| JPS63148189A (en) * | 1986-12-11 | 1988-06-21 | Hamamatsu Photonics Kk | Radiation detector |
| JP4338177B2 (en) * | 2003-03-12 | 2009-10-07 | 独立行政法人放射線医学総合研究所 | 3D radiation position detector |
| JP5709439B2 (en) * | 2010-08-30 | 2015-04-30 | キヤノン株式会社 | 3D radiation position detector |
| CN105339810B (en) * | 2013-06-28 | 2019-02-01 | 皇家飞利浦有限公司 | Semiconductor scintillation detector |
| CN103616713B (en) * | 2013-11-25 | 2016-06-29 | 中国科学院高能物理研究所 | detector and detection system |
| CN105068109B (en) * | 2015-07-28 | 2017-08-01 | 济南中威仪器有限公司 | It is a kind of to be used to search the localization method for losing radioactive source |
| CN108205154B (en) * | 2017-12-21 | 2019-11-08 | 北京科技大学 | A kind of radioactive source localization method |
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