A method for on-site verification of thermoluminescence detector dose

Abstract

The present invention provides a method for on-site verification of thermoluminescence detector dose, which specifically includes screening of thermoluminescence detectors for verification standards, signal attenuation characteristic testing, and thermoluminescence detector setting. The method for on-site verification of thermoluminescence detector dose disclosed by the present invention effectively controls the radiation performance change trend of a thermoluminescence dose measurement device by using an on-site verification standard based on a thermoluminescence detector, ensures that the value measured on-site is accurate and reliable, and can be measured directly on-site, thus solving the problems of being time-consuming, labor-intensive, and controlled by a calibration agency in regular inspection.

Description

Technical Field

[0001] The invention relates to the technical field of verification standards, and in particular to a method for on-site verification of thermoluminescence detector dosage. Background Art

[0002] Introduction to the role of thermoluminescent detector (TLD): Thermoluminescent detector is a device that uses the principle of thermoluminescence to record the cumulative radiation dose. One or more thermoluminescent detectors and an external structure together form a thermoluminescent dosimeter, which has the advantages of good energy response, high sensitivity, small environmental impact, convenient measurement and reading, and low price. It is mainly used in radiation dose monitoring, aerospace, archaeology, scientific research and other fields.

[0003] The background technology of the verification standard is that after the thermoluminescence detector (TLD) is irradiated with a certain dose, this energy will be stored. During the measurement process of the thermoluminescence reader, the detector is heated and the TLD releases this energy in the form of light. The amount of light emitted when heated is linearly related to the irradiated dose value within a certain range.

[0004] At present, there is no verification standard for thermoluminescent dose measurement systems, and it is impossible to conduct on-site verification of thermoluminescent dose measurement systems to determine the accuracy and other instrument performance of the device. For daily inspection, the customer's thermoluminescent dosimeter needs to be sent to the statutory metrology and verification agency by mail, transportation, etc., and the dosimeter is irradiated and returned for measurement and reading. The measurement and reading data are compared with the agreed value to achieve the radiation performance evaluation of the thermoluminescent dose measurement system.

[0005] The inspection process of thermoluminescence dose measurement system is complicated, and the reader is generally large and not suitable for inspection. The metrology guarantee of this type of equipment requires high professional skills, a long investment cycle, and daily maintenance requires more professional personnel. Moreover, the accuracy and reliability of the data cannot be guaranteed under on-site conditions.

[0006] Therefore, technicians in this field are committed to developing a method for on-site verification of thermoluminescence detector dose to address the deficiencies of the above-mentioned prior art. Summary of the invention

[0007] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is that the current existing verification standards cannot conduct on-site verification of the thermoluminescence dose measurement system, the inspection process of the thermoluminescence dose measurement system is complicated, and the accuracy and reliability of the data cannot be guaranteed under on-site conditions.

[0008] To achieve the above object, the present invention provides a method for on-site verification of thermoluminescence detector dose, which specifically comprises the following steps:

[0009] Step 1, checking the screening of standard thermoluminescence detectors;

[0010] Step 2: Signal attenuation characteristic test;

[0011] Step 3, setting the value of the thermoluminescence detector;

[0012] Furthermore, in step 1, the screening of the verification standard using a thermoluminescence detector specifically includes the following steps:

[0013] Step 1-1, inspect the appearance of the purchased thermoluminescence detectors, and retain the thermoluminescence detectors without defects;

[0014] Step 1-2, annealing the thermoluminescent detector, then rapidly cooling it and standing it for 24 hours;

[0015] Step 1-3, irradiate the thermoluminescence detector with a certain dose value in the reference radiation field and let it stand for 24 hours;

[0016] Step 1-4: Read the data, analyze the obtained results for consistency, remove outliers using the Raida criterion, and retain the thermoluminescence detectors with a dispersion value of <3%;

[0017] Step 1-5, repeat steps 1-2 to 1-4 for multiple times to confirm the final verification standard thermoluminescence detector;

[0018] Furthermore, in step 2, the signal attenuation characteristic test specifically includes the following steps:

[0019] Step 2-1, grouping the screened thermoluminescent detectors into a number of groups, and irradiating the thermoluminescent detectors with a certain dose value in a reference radiation field;

[0020] Step 2-2, put it in a shielding box after irradiation, take it out at different times after irradiation, and measure it;

[0021] Step 2-3: Obtain the dose response value R at different times relative to 24 hours by calculating the formula: x ;

[0022] Step 2-4, response value R x Detectors with a value between 0.98 and 1.02 meet the verification requirements;

[0023] Furthermore, in step 3, the thermoluminescence detector is set to a certain value, specifically comprising the following steps:

[0024] Step 3-1, group the verification standard thermoluminescence detectors according to actual needs;

[0025] Step 3-2, irradiating the thermoluminescent detectors of each group with corresponding doses in a reference radiation field of corresponding radiation type and energy;

[0026] Step 3-3: Use national measurement standards to determine the dose rate value at a certain point in the radiation field.

[0027]

[0028] Where: N k is the calibration factor of the standard ionization chamber traceable to the national standard; P is the ambient pressure during the measurement; T is the ambient temperature during the measurement; P0 is the ambient pressure under the reference standard conditions; T0 is the ambient temperature under the reference standard conditions; R k is the reading of the ionization chamber dose meter; h p,k (d) the conversion factor from air kerma to personal dose equivalent;

[0029] Step 3-4: Calculate the irradiation time required to meet the verification standard based on the actual required dose

[0030] Step 3-5, irradiate the corresponding dose under the corresponding radiation type and energy in accordance with the verification standard to obtain the verification standard with known dose value and energy;

[0031] Furthermore, in the step 1-2, the thermoluminescence detector annealing is conventional annealing;

[0032] Furthermore, the conventional annealing is 240° C., 10 min;

[0033] Further, in the steps 1-3, the reference radiation field includes X-rays, gamma rays, beta rays, protons, and electrons;

[0034] Furthermore, in the steps 1-3, the dose value is greater than or equal to 1mGy / 1mSv;

[0035] Further, in step 2-1, the reference radiation field includes X-rays, gamma rays, beta rays, protons, and electrons;

[0036] Furthermore, in step 2-1, the dose value is greater than or equal to 1mGy / 1mSv;

[0037] Further, in step 2-2, the different times are 12h, 24h, 3d, 7d, 14d, 30d, 45d, 60d, and 90d;

[0038] Furthermore, in step 2-3, the calculation formula is

[0039] Furthermore, in step 3-1, the actual demand groups are grouped according to different dose values ​​and different energies, and at least one background group is retained, and the number of thermoluminescence detectors in each group is n=10;

[0040] Further, the different dose values ​​are 0.1mSv to 10Sv;

[0041] Further, the different energies are 40keV to 1.25MeV;

[0042] Further, in step 3-3, the national metrology standards include a gamma-ray air kerma (protection level) standard device and a medium-energy X-ray air kerma (protection level) standard device;

[0043] In a specific implementation manner of the present invention, in the steps 1-3, the reference radiation field uses gamma rays;

[0044] In another specific embodiment of the present invention, in the steps 1-3, the reference radiation field uses X-rays;

[0045] In a specific embodiment of the present invention, in steps 1-3, the dosage value is 1mGy / 1mSv;

[0046] In another specific embodiment of the present invention, in the steps 1-3, the dosage value is 3mGy / 3mSv;

[0047] In a specific implementation manner of the present invention, in step 2-1, the reference radiation field uses gamma rays;

[0048] In another specific embodiment of the present invention, in step 2-1, the reference radiation field uses X-rays;

[0049] In a specific embodiment of the present invention, in step 2-1, the dose value is 1mGy / 1mSv;

[0050] In another specific embodiment of the present invention, in step 2-1, the dose value is 3mGy / 3mSv;

[0051] In a specific embodiment of the present invention, in step 3-1, the actual demand groups are 100mSv dose value and 662keV energy in one group, 1Sv dose value and 662keV energy in one group, and 10Sv dose value and 662keV energy in one group;

[0052] In another specific embodiment of the present invention, in step 3-1, the actual demand is grouped into 1 mSv dose value and 48 keV energy in one group, 1 mSv dose value and 65 keV energy in one group, and 1 mSv dose value and 100 keV energy in one group;

[0053] In a specific embodiment of the present invention, in step 3-3, the national measurement standard is a gamma-ray air kerma (protection level) standard device;

[0054] In another specific embodiment of the present invention, in step 3-3, the national measurement standard is a medium energy X-ray air kerma (protection level) standard device;

[0055] By adopting the above scheme, the on-site verification method of thermoluminescence detector dose disclosed in the present invention has the following advantages:

[0056] (1) The on-site verification method of the thermoluminescence detector dose of the present invention effectively controls the radiation performance change trend of the thermoluminescence dose measurement device by using the on-site verification standard based on the thermoluminescence detector. Once a deviation is found, it can be adjusted in time, and the on-site measured value can be guaranteed to be accurate and reliable through the verification standard;

[0057] (2) The on-site verification method of the thermoluminescence detector dose of the present invention avoids the need to mail or transport the thermoluminescence dose measurement system in conventional inspections, and can be measured directly on-site without being controlled by the inspection date or measurement agency, thus solving the problem of time-consuming and labor-intensive regular inspections and being controlled by the calibration agency.

[0058] In summary, the on-site verification method of the thermoluminescence detector dose disclosed in the present invention effectively controls the radiation performance change trend of the thermoluminescence dose measurement device by using the on-site verification standard based on the thermoluminescence detector, ensures that the on-site measured value is accurate and reliable, and can be measured directly on-site, thus solving the problems of time-consuming and labor-intensive regular inspections and being controlled by the calibration agency.

[0059] The concept, specific technical scheme and technical effects of the present invention will be further described below in conjunction with specific implementation methods to fully understand the purpose, characteristics and effects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 This is a method for on-site verification of thermoluminescence detector dosage according to the present invention, and an overall flow chart;

[0061] Figure 2 For example Figure 1 Screening of thermoluminescence detectors for verification standards, flow chart;

[0062] Figure 3 For example Figure 1 Signal attenuation characteristic test, flow chart;

[0063] Figure 4 For example Figure 1 Thermoluminescence detector setting, flow chart. DETAILED DESCRIPTION

[0064] The following introduces several preferred embodiments of the present invention to make its technical content clearer and easier to understand. The present invention can be embodied in many different forms of embodiments, which are exemplary descriptions, and the protection scope of the present invention is not limited to the embodiments mentioned in the text.

[0065] If there are experimental methods without specific conditions, they are usually implemented according to conventional conditions, such as those in the relevant instructions or manuals.

[0066] Example 1: A method for on-site verification of thermoluminescence detector dose

[0067] Step 1, checking the screening of standard thermoluminescence detectors;

[0068] Step 1-1, inspect the appearance of the purchased thermoluminescence detectors, and retain the thermoluminescence detectors without defects;

[0069] Step 1-2, annealing the thermoluminescent detector, then rapidly cooling it and standing it for 24 hours;

[0070] Step 1-3, irradiate the thermoluminescence detector with 1 mGy / 1 mSv in a gamma-ray reference radiation field and let it stand for 24 hours;

[0071] Step 1-4: Read the data, analyze the obtained results for consistency, remove outliers using the Raida criterion, and retain the thermoluminescence detectors with a dispersion value of <3%;

[0072] Step 1-5, repeat steps 1-2 to 1-4 for multiple times to confirm the final verification standard thermoluminescence detector;

[0073] Step 2: Signal attenuation characteristic test;

[0074] Step 2-1, grouping the screened thermoluminescent detectors into several groups, and irradiating the thermoluminescent detectors with 1 mGy / 1 mSv in a gamma-ray radiation field;

[0075] Step 2-2, put it in a shielding box after irradiation, take it out at 12h, 24h, 3d, 7d, 14d, 30d, 45d, 60d, and 90d after irradiation, and measure it;

[0076] Step 2-3: Obtain the dose response value R at different times relative to 24 hours by calculating the formula: x ;

[0077] Step 2-4, response value R x Detectors with a value between 0.98 and 1.02 meet the verification requirements;

[0078] Step 3, setting the value of the thermoluminescence detector;

[0079] Step 3-1, group the verification standard thermoluminescence detectors according to actual needs, 100mSv dose value, 662keV energy in one group, 1Sv dose value, 662keV energy in one group, 10Sv dose value, 662keV energy in one group;

[0080] Step 3-2, irradiating the thermoluminescent detectors of each group with corresponding doses in a reference radiation field of corresponding radiation type and energy;

[0081] Step 3-3, use the gamma-ray air kerma (protection level) standard device to determine the dose rate value at a certain point in the radiation field,

[0082] Step 3-4: Calculate the irradiation time required to meet the verification standard based on the actual required dose

[0083] Step 3-5: irradiate the corresponding dose under the corresponding radiation type and energy against the verification standard to obtain the verification standard with known dose value and energy.

[0084] Example 2: A method for on-site verification of thermoluminescence detector dose

[0085] Step 1, checking the screening of standard thermoluminescence detectors;

[0086] Step 1-1, inspect the appearance of the purchased thermoluminescence detectors, and retain the thermoluminescence detectors without defects;

[0087] Step 1-2, annealing the thermoluminescent detector, then rapidly cooling it and standing it for 24 hours;

[0088] Step 1-3, irradiate the thermoluminescence detector with 3mGy / 3mSv in an X-ray radiation field and let it stand for 24h;

[0089] Step 1-4: Read the data, analyze the obtained results for consistency, remove outliers using the Raida criterion, and retain the thermoluminescence detectors with a dispersion value of <3%;

[0090] Step 1-5, repeat steps 1-2 to 1-4 for multiple times to confirm the final verification standard thermoluminescence detector;

[0091] Step 2: Signal attenuation characteristic test;

[0092] Step 2-1, grouping the screened thermoluminescence detectors into several groups, and irradiating the thermoluminescence detectors with 3mGy / 3mSv in an X-ray radiation field;

[0093] Step 2-2, put it in a shielding box after irradiation, take it out at 12h, 24h, 3d, 7d, 14d, 30d, 45d, 60d, and 90d after irradiation, and measure it;

[0094] Step 2-3: Obtain the dose response value R at different times relative to 24 hours by calculating the formula: x ;

[0095] Step 2-4, response value R x Detectors with a value between 0.98 and 1.02 meet the verification requirements;

[0096] Step 3, setting the value of the thermoluminescence detector;

[0097] Step 3-1, group the verification standard thermoluminescence detectors according to actual needs, 1mSv dose value, 48keV energy in one group, 1mSv dose value, 65keV energy in one group, 1mSv dose value, 100keV energy in one group;

[0098] Step 3-2, irradiating the thermoluminescent detectors of each group with corresponding doses in a reference radiation field of corresponding radiation type and energy;

[0099] Step 3-3, using the medium energy X-ray air kerma (protection level) standard device to determine the dose rate value at a certain point in the radiation field;

[0100] Step 3-4: Calculate the irradiation time required to meet the verification standard based on the actual required dose

[0101] Step 3-5: irradiate the corresponding dose under the corresponding radiation type and energy against the verification standard to obtain the verification standard with known dose value and energy.

[0102] Comparative Example 3: Inspection and Verification Method of Existing Thermoluminescence Dose Measurement System

[0103] Step 1, annealing the thermoluminescence detector, placing it in a thermoluminescence dose box, and packaging it together with the thermoluminescence reader;

[0104] Step 2: Send it to the legal metrology verification agency for testing by mailing, transportation, etc.

[0105] Step 3: After irradiation, the dosimeter is read using a thermoluminescence reader, and the reading data is compared with the agreed value to evaluate the radiation performance of the thermoluminescence dose measurement system.

[0106] It shows that the inspection process of the thermoluminescent dose measurement system is complicated, and the reader is generally large in size, which is not suitable for inspection. The metrological guarantee of this type of equipment requires high professional skills, a long investment cycle, and daily maintenance requires more professional personnel, and the accuracy and reliability of the data cannot be guaranteed under field conditions. Therefore, by checking the measuring instrument during the verification standard, the performance change trend of the instrument can be effectively controlled. Once a deviation is found, it can be adjusted in time. On-site measurement is not subject to the control of the inspection date and the metrological agency, avoiding the need to mail and transport the thermoluminescent dose measurement system in routine inspection, solving the problem of time-consuming, labor-intensive, and controlled by the calibration agency in regular inspection, and ensuring the timeliness of national defense metrology traceability, solving the problem of on-site value traceability, that is, under complex on-site conditions, there is no condition to provide quality assurance under the original value traceability system, and the on-site measured value can be guaranteed to be accurate and reliable through verification standards.

[0107] The on-site verification method of the thermoluminescence detector dose in other embodiments of the present invention has similar beneficial effects as described above;

[0108] The on-site verification method of the thermoluminescence detector dose in other embodiments of the present invention has similar beneficial effects as described above.

[0109] The preferred specific embodiments of the present invention are described in detail above. It should be understood that ordinary technicians in the field can make many modifications and changes based on the concept of the present invention without creative work. Therefore, all technical solutions that can be obtained by technicians in the technical field based on the concept of the present invention through logical analysis, reasoning or limited experiments on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A method for on-site verification of thermoluminescence detector dose, characterized in that: The specific steps include: Step 1, checking the screening of standard thermoluminescence detectors; Step 2: Signal attenuation characteristic test; Step 3, setting the value of the thermoluminescence detector; The step 1 specifically includes the following steps: Step 1-1, inspect the appearance of the purchased thermoluminescence detectors, and retain the thermoluminescence detectors without defects; Step 1-2, annealing the thermoluminescent detector, then rapidly cooling it and standing it for 24 hours; Step 1-3, irradiate the thermoluminescence detector with a certain dose value in the reference radiation field and let it stand for 24 hours; Step 1-4: Read the data, analyze the obtained results for consistency, remove outliers using the Raida criterion, and retain the thermoluminescence detectors with a dispersion value of <3%; Step 1-5, repeat steps 1-2 to 1-4 for multiple times to confirm the final verification standard thermoluminescence detector; The step 2 specifically includes the following steps: Step 2-1, grouping the screened thermoluminescent detectors into a number of groups, and irradiating the thermoluminescent detectors with a certain dose value in a reference radiation field; Step 2-2, put it in a shielding box after irradiation, take it out at different times after irradiation, and measure it; Step 2-3: Obtain the dose response value R at different times relative to 24 hours by calculating the formula: x ; Step 2-4, response value R x Detectors with a value between 0.98 and 1.02 meet the verification requirements; The step 3 specifically includes the following steps: Step 3-1, group the verification standard thermoluminescence detectors according to actual needs; Step 3-2, irradiating the thermoluminescent detectors of each group with corresponding doses in a reference radiation field of corresponding radiation type and energy; Step 3-3, determine the dose rate value at a certain point in the radiation field using national measurement standards; Step 3-4: Calculate the irradiation time required to meet the verification standard based on the actual required dose Step 3-5: irradiate the verification standard with a corresponding dose under the corresponding radiation type and energy to obtain a verification standard with a known dose value and energy.

2. A method for on-site verification of thermoluminescence detector dose as claimed in claim 1, characterized in that: In the steps 1-2, The thermoluminescence detector annealing is conventional annealing; The conventional annealing is 240°C for 10 min; In the steps 1-3, The reference radiation field includes X-rays, gamma rays, beta rays, protons, and electrons; The dosage value is greater than or equal to 1 mGy / 1 mSv.

3. A method for on-site verification of thermoluminescence detector dose as claimed in claim 1, characterized in that: In the step 2-1, The reference radiation field includes X-rays, gamma rays, beta rays, protons, and electrons; The dose value is greater than or equal to 1mGy / 1mSv; In the step 2-2, The different times are 12h, 24h, 3d, 7d, 14d, 30d, 45d, 60d, and 90d; In the steps 2-3, The calculation formula is 4. A method for on-site verification of thermoluminescence detector dose as claimed in claim 1, characterized in that: In the step 3-1, The actual demand grouping is grouped according to different dose values ​​and different energies, and at least one group of background is retained, and the number of thermoluminescence detectors in each group is n=10; The different dose values ​​are 0.1mSv to 10Sv; The different energies are 40keV to 1.25MeV; In the step 3-3, The national metrological standards include a gamma-ray air kerma protection level standard device and a medium-energy X-ray air kerma protection level standard device.

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