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Ics13.100
National Occupational Health Standard of the People's Republic of China GBZ/T145-2002
Personal Film Dosimeter
Personal photographic dosemeters (IS01757:1996, EQT)
Issued on April 8, 2002
Ministry of Health of the People's Republic of China
Implementation on June 1, 2002
1 Scope
2 Normative references
3 Terms and definitions
4 Description of the appearance and design requirements of dosemeters
5 Classification and nomenclature
7 Performance requirements
8 Inspection methods
9 Identification
10 Labeling and additional instructions
1 (Normative Appendix) Conversion coefficients and angular correction factors Appendix A
3 (Normative Appendix) Evaluation of photon dose measured by personal film dosimeters Appendix B
This standard is formulated in accordance with the "Law of the People's Republic of China on the Prevention and Control of Occupational Diseases". This standard is equivalent to the international standard IS01757:1996 "Personaphotographic dose meters". This international standard is complete in content, mature in technology, reasonable in structure, clear in description, and highly operable. It can be fully used as a reference and application for personnel engaged in personal film dose monitoring in my country. At the same time, in order to suit the actual situation in my country, we have made appropriate additions, modifications and deletions to some of the original contents of the standard during the compilation process. We have modified some of the writing formats and standard expressions in accordance with Chinese habits. We have deleted Chapter 2\Normative Reference Documents\ and Chapter 3\Terms and Definitions\ of IS01757:1996;
-Deleted ISO1757:1996\Appendix C\;-Removed the original 3.8 and 3.16 of Chapter 3\Terms and Definitions\ of IS01757:1996, and changed them into the main text by removing the \notes:
-Added explanations for "OD (E)" and "OD (Eref)" in the original 8.2.4 of IS01757:1996.
Appendix A and Appendix B of this standard are normative appendices. This standard is proposed and managed by the Ministry of Health.
Drafting unit of this standard: Institute of Radiation Protection and Nuclear Safety Medicine, Chinese Center for Disease Control and Prevention
Main drafters of this standard: Hu Aiying, Cheng Ronglin, Wang Jianchao. The Ministry of Health is responsible for interpreting this standard.
1 Scope
Personal film dosimeter
GBZ/T145-2002
This standard specifies the physical properties of personal film dosimeters and the corresponding methods for testing these properties. This standard is applicable to personal film dosimeters with a range from 200μSv to 1Sv, and is particularly applicable to the measurement of external body doses, including:
Determination of personal doses caused by X or Y rays; Determination of personal doses caused by beta rays (regardless of whether they are accompanied by photon radiation). This standard does not apply to:
- Dosimeters with fluorescent intensifying screens:
Film dosimeters for measuring neutrons or other particles: - Film dosimeters for measuring personal doses caused by pulsed radiation sources (such as accelerators): - Film dosimeters for measuring mixed radiation fields of photons and neutrons: - Nuclear track emulsions.
2 Normative references
The clauses in the following documents become clauses of this standard through reference in this standard. For dated referenced documents, all subsequent amendments (excluding corrections) or revisions are not applicable to this standard. However, parties to agreements based on this standard are encouraged to study whether the latest versions of these documents can be used. For undated referenced documents, the latest versions apply to this standard.
Iso 4037-l:1996, X and gamma reference radiation for calibrating dosemeters anddoserate meters and for determining their response as a function of photonenergy-- Part l: Radiation characteristics and production methods. IEC 846:1989, BetaX and gamma radiation dose equivalent and dose equivalent ratemeters for use in radiation protection.3 Terms and Definitions
The following terms and definitions apply to this standard. 3.1
Personal film dosimeterpersonalphotographicdosemeter4
A dosimeter consisting of one or more photographic films placed in a film box containing one or more filters, whereby the radiation dose can be obtained from the optical density measurements of the photographic emulsion film under various filters. Note: This standard refers to "personal film dosimeter" as "dosemeter". 3.2
Filter
The part of the dosimeter that can change the intensity of the radiation incident on the photographic emulsion. 3.3
Transmission densityoptical transmission densityThe common logarithm of the ratio of the window flux to the sample transmission flux under the same beam geometry conditions. 3.4
Reflection densityoptical reflection densityThe common logarithm of the ratio of the absolute reflection flux of the standard sample to the reflection flux of the sample under the same beam geometry conditions. 3.5
characteristic curvecharacteristic curve describing the functional relationship between the optical density of a photographic emulsion obtained under given conditions for a given radiation of known energy and the calibration value under a specified filter.
latentimage
The invisible change that occurs in a photographic emulsion after exposure to radiation that can directly or indirectly ionize, such as visible light, ultraviolet light, or nuclear radiation, which can be converted into a visible image after processing. 3.7
stabilityof latent imagethe degree to which a latent image formed on an emulsion of given optical characteristics can eventually be developed, regardless of the time between the formation of the latent image and the development of the emulsion, and regardless of the environmental conditions (temperature or humidity) during this period. 3.8
fading
The loss of the latent image (i.e., the latent information) over time between the formation of the latent image on the emulsion and the development of the image. This loss is strongly affected by environmental conditions such as temperature and humidity. 3.9
solarization
The phenomenon that light density decreases as the irradiance increases, usually under high-level irradiation conditions. 3.10
conventional true value (Q)conventional true valueThe best estimate of a quantity at a point of interest. 3.11
response (R)response
The ratio of the estimated value M of a quantity obtained from the detector reading to the conventional true value Q of the quantity3.12
sensitivity of a photographic emulsion (S) The ratio of the change in optical density △OD to the corresponding change △Q in the agreed true value of the calibration quantity. 3.13
The lower limit (of the nominal range) The value of the calibration quantity corresponding to the optical density obtained by adding twice the experimental standard deviation of the average optical density of the unexposed film.
The upper limit (of the nominal range) The value of the calibration quantity Q corresponding to the positive value of the photographic emulsion sensitivity (S = △OD/△Q), the transmitted optical density not less than 0.4Gy and the reflected optical density not less than 0.2Gy (taking into account saturation and negative sensitivity). 3.15
Coefficient of performance (P) The coefficient of performance (P) describes the deviation of a set of measured values from the agreed true value. For a series of n measurements xi, the value of P is given by: P = -
of(x,-x)
where x is the conventional true value of the standard quantity.
controlspecimens
film packages, film boxes or dosimeters of the same type and batch as those used in the sample test and used as reference. 3.17
calibration quantitycalibration quantity
a physical quantity used to measure the radiation used for irradiation in order to determine the properties of photographic emulsion after irradiation either alone or in a special film box.
conversion coefficientconversion coefficienta coefficient used to convert one physical quantity into another 4 Dosimeter Appearance Description and Design Requirements
A personal film dosimeter consists of two parts: a) Film package, including:
a photosensitive part enclosed in a protective packaging material, consisting of one or more layers of photosensitive emulsion coated on one or more layers of thin substrate. The protective layer of the film should not be removed before processing. 1) Protective packaging material to protect the photosensitive emulsion from light and, if necessary, from external chemical and mechanical factors.
b) Film box, a small box that can hold one or more films, with the help of which the measured radiation field and irradiation conditions can be created, and in many cases the box makes it possible to estimate the radiation energy. In order to avoid edge effects, the filter area should be large enough. 5 Classification and nomenclature
5.1 Classification
Personal film dosimeters with a range of 200μSv to 1Sv are classified as follows. 5.1.1 Dosimeter classes according to radiation energy range According to the type of radiation and the radiation energy range [within this energy range the response of the dosimeter can meet the performance test requirements of item k) in Table 1], personal film dosimeters can be divided into the following five classes: a) Class 1: Dosimeters for measuring X and gamma rays in the energy range of about 250keV to 9MeV. b) Class 2: Dosimeters for measuring X and gamma rays with an energy range of approximately 20keV to 250keV. 6
c) Class 3: Dosimeters for measuring X and gamma rays with an energy range of approximately 20keV to 9MeV. d) Class 4: Dosimeters for measuring beta radiation with a maximum energy of 0.5MeV to 4MeV. e) Class 5: Dosimeters for measuring beta radiation with a maximum energy of 1.5MeV to 4MeV. Note: Since the maximum photon energy has been extended to 50MeV, the response of class 1 and class 3 dosimeters is preferably extended to the response of 50MeV.
5.1.2 Classification of dosimeters according to water vapor tolerance According to the different tolerance of dosimeters to water vapor, personal film dosimeters can be divided into the following two categories: a) Class W: Dosimeters that can meet the performance test requirements of item g) (tolerance to water vapor or/and photochemical agents) in Table 1.
b) Class Y: Dosimeters that do not meet the performance test requirements of item g) in Table 1. 5.2 Nomenclature
Personal film dosimeters should be named with reference to international standards based on the dosimeter's range of radiation type and energy, its tolerance to water vapor, and the amount of photographic emulsion. For example: Personal film dosimeter IS01757-1-W-3. 6 Quantities
6.1 In order to obtain and report the results of the performance tests a) to h) in Table 1, the calibration quantity used should be air kerma or tissue absorbed dose, whichever is selected depending on the specific radiation type. Since these items are essentially relative tests, all exposures can be carried out in free air or on a human body model unless otherwise specified. 6.2 When the test result depends on the response performance of the personal film dosimeter to radiation energy and radiation incidence angle [see k) and i) in Table 1, the test result should be expressed in personal dose equivalent (see Appendix A). 7 Performance requirements
7.1 The performance of personal film dosimeters shall meet the requirements specified in the items in Table 1. 7.2 The film manufacturer shall test the properties of the photographic emulsion in items a) to g) of Table 1 and provide information on the results of these performance tests.
7.3 The film box manufacturer shall test the physical properties of the film box in item h) of Table 1 and provide information on the results of these performance tests.
7.4 The organization responsible for selecting the film and film box and assembling them into the dosimeter shall test the properties of items i) to k) of Table 1 (in most cases these tests are completed by a designated performance testing laboratory) and provide information on the results of these performance tests.
8 Test methods
8.1 General test conditions
The test methods listed in this standard are sometimes intended to evaluate the performance of the entire dosimeter consisting of film and film box, and sometimes they are intended to evaluate only the performance of the film in the film box, the film box or the photographic emulsion on the film. Table 1
Test performance
Performance requirements of personal film dosimeter
Test method
a) Emulsion optical density uniformity
(belonging to photosensitive emulsion)
This test aims to ensure the uniformity of film emulsion.
b) Latent image stability
(belonging to photosensitive emulsion)
This test aims to test the decay behavior of the latent image under normal test conditions to ensure that the storage dose information is retained during the normal wearing period of the dosimeter.
c) Anti-aging
(belonging to photosensitive emulsion)
This test aims to identify the tolerance of film emulsion to abnormal storage conditions before use.
d) Photon Energy Effect
(For Photographic Emulsion)
This test is intended to identify the difference in the effect of different
photon energies on the optical density of film photosensitivity
e) Nominal Range
(For Photographic Emulsion)
The nominal range test of the dosimeter is intended to verify the satisfaction of the minimum requirements for the dose
metering range. wwW.bzxz.Net
Test Performance
f) Optical Opacity
(For Negative Film)
Grades 1 to 5:
1) For each emulsion sample, the difference between the maximum and minimum values of the measured values of the transmitted optical density and the reflected optical density over the entire surface should be less than 0.05.
2) The standard deviation of the mean optical density of the samples shall be less than 0.02 for transmitted optical density and less than 0.05 for reflected optical density.
The deviation obtained when comparing the test sample with the control sample shall not be greater than 10% of the calibration amount.
1) Artificial aging
The deviation obtained when comparing the test sample with the control sample shall not be greater than 20% of the calibration amount. The coefficient of variation of the mean optical density of the fog background level relative to the control sample value shall not exceed 0.10.
2) Natural aging
Same as a) and b).
The variation in the ratio of the calibration amounts that lead to the same optical density results for each batch of film shall not be greater than 10% of the nominal range of the latex.
1) Lower limit
The optical density value corresponding to the lower limit of the calibration amount is the mean optical density of the fog background plus at least 2 times the standard deviation of the fog background.
2) Upper limit (saturation and negative sensitivity are taken into account) The upper limit of the nominal range is determined based on the maximum value of the calibration value Q. At this time, the sensitivity S=AOD/Ag of the photosensitive emulsion should be positive, and the transmitted light density should be at least 0.4Gy, while the reflected light density should be at least 0.2Gyl. No streaks or unevenness should be observed on the processed test film. The average optical density on the effective area of the sample film is 8.2.1
Test method
g) Water vapour resistance of packaging materials
(belongs to film)
This test is only for W-type
dosemeters.
h)
Quality control of filters and plastic boxes
(belongs to film boxes)
i) Angular response
(belongs to dosimeters)
This test aims to evaluate the angular response of the dosimeter relative to the
normal incidence (0°) of the radiation.
i) Back irradiation of dosimeters
(belongs to dosimeters)
Comparison of the response of the dosimeter when the radiation is
normally incident and when irradiated
from the back (i.e. in the reverse direction).
Test performance
k) Energy response
The difference between the average optical density of the control sample and the average optical density of the control sample should not exceed 3 times the standard deviation of the average optical density of the control sample.
1) Latent image decay
Compared with the control sample, the average deviation should not exceed 10% of the value of the calibration amount.
2) Response change
Same as above.
3) Fog background optical density change
Compared with the control sample, the average background deviation should not exceed 0.05.
1) Material thickness uniformity
For each filter and film box sample, the difference between the maximum and minimum optical density of the photosensitive emulsion under the filter due to material thickness variation should be less than 5% of the average optical density. For the same filter or film box sample, the standard deviation of its average optical density should be less than 2% of the average optical density. 2) Influence of (natural) radionuclides that may be contained in the filter
The difference in the mean optical density between the film sample and the standard film under the filter should not exceed 0.05.
Let H(E, α) be the agreed true value of the personal dose equivalent (deep or superficial), where E is the average energy of the radiation and a is the angle of the measurement point in the human body model: H,(E,a) is the personal dose equivalent measured when the dosimeter is tested. Therefore, the angular response R(E,α)=H,(E,α)/H'.(E,a) can be obtained. In this way, the ratio R(E,α)/R(EO) can also be calculated. These ratios should not exceed the following range of values:
No experiment is required for level 5,
All levels.
(for levels 1 and 2):
(for level 3);
(for level 4):
The dose meter under test shall measure and state the ratio of its response when the radiation is irradiated from the back to that when it is irradiated from the front. To
Levels 1 to 4:
Verification method
(for dose meters)
This test is intended to determine the energy response of the dose meter.
It is basically performed once as a type
test and is repeated only when there are important changes in the
system (e.g. filters, algorithms).
① Let H'.E,O) be the agreed true value of personal dose equivalent when the average energy E and radiation are irradiated vertically (0°) at the measuring point of the human model used for the test, and H,(E,0) be the personal dose equivalent value (deep or superficial) measured by the ith one of the n dosimeters, then the absolute value of the performance coefficient |P[H.,(E,0) - H,(E,0)]
(for level 1);
(for level 2);
(for levels 3 and 4).
② The relative deviation should satisfy:
H,,(E,O)-H(E,O)/H(E,0)
③ The coefficient of variation
Hp(E,O)
(for levels 1 and 2);
(for levels 3 and 4).
Z[H,/(E,0) -H,(E,0)2
should not be greater than 0.35 for all levels of dosimeters [where H,(E,0) is the average value of H(E,O)].
Level 4:
Only test for superficial personal dose equivalent Hp (0.07). Level 5:
No test required.
Note: If the optical density of different filter parts is carefully calculated to meet the performance requirements in the radiation energy range of interest, this algorithm should be useful to all users of each dosimeter.
8.1.1 Test samples and control samples
The method of providing test samples and control samples (see 3.16) should be the same as the manufacturer's dedicated method. The control samples should come from the same batch of products from the same manufacturer as the test samples, and in particular, the number and material of filters for both are required to be the same.
Depending on the test items, the entire dosimeter or only the exposed film may be irradiated. Unless otherwise specified, it shall be indicated whether the test is conducted on a human model. 8.1.2 Pre-test conditions
Before any test, the dosimeters to be tested or used as control samples shall be placed in an atmospheric environment with a room temperature of 20±2°C and a relative humidity of 45%-75% for 4-20 hours. The air kerma rate background shall not exceed 0.25μGy/h. 8.1.3 Normal test conditions
Unless otherwise specified, the test shall be conducted at a room temperature of 20±2°C and a relative humidity of 45%-75%, with normal (vertical) incident angle. The air kerma rate background should not exceed 0.25μGy/h8.1.4 Reference radiation
8.1.4.11 to level 3 dose meter
For X and radiation tests, the radiation should be selected according to the conditions listed in Tables 2 to 4 so as to cover the nominal energy range of the dose meter to be tested. The characteristics of these radiations, the methods of generating them and the geometric conditions can all be found in IS04037-1. According to the required energy and dose rate, the reference beam of high-energy radiation (photon radiation energy 4MeV to 9MeV) can be selected from the following methods introduced in IS04037-1: a) 4.44MeV y-ray beam obtained by \c(p,py)c reaction by bombarding carbon target with 5MeV protons; b) 6.13MeV y-ray beam obtained by \F(p,a)\o reaction by bombarding fluorine target with protons: c) 6MeV and 9MeV y-ray beams obtained by capture reaction using thermal neutrons and titanium and nickel. During the irradiation, the air around the sample should be in electron balance. If this requirement cannot be achieved due to environmental reasons, some suitable building materials should be placed in front of the sample to ensure electron balance (or short-term electron balance in the case of high-energy electron radiation).
Average energy
Narrow spectrum "A" series\
Additional filter thickness\
1) The narrow spectrum series is particularly suitable for energy response tests of dosimeters. 2) The total filtration includes a fixed filter adjusted to 4mm aluminum Table 3
Average energy
Broad spectrum "B" series\
Additional filter thickness2)
Note: 1) The broad spectrum series should be used when it is not possible to obtain the radiation intensity that meets the conditions by other methods. 2) Total filtration includes fixed filtration adjusted to 4 mm aluminum Table 4
Radionuclides
8.1.4.2 4 to 5 grade dosimeters
Radionuclide series
Y radiation energy (keV)
1173.3 and 1332.5
Half-life (a)
When performing the following tests, the radiation energy of the irradiated dosimeters shall be within the energy range covered by these dosimeters. 11
The beta radiation used for the test shall be selected from the radiation described in IS06980 so as to cover the useful energy range of the test dosimeters.
8.1.5 Radiation field strength
The radiation field strength used for calibration shall be large enough to make the change of the latent image during irradiation negligible. 8.2 Method
8.2.1 Test for uniformity of optical density of latex [see Table 1-a] The latex of each batch of film shall be tested for 1.0 optical density and a suitable reference radiation for the test shall be selected from the following radiations:
a) Class 1: Radiation of 137Cs or Co;
b) Class 2: Any reference radiation selected from 8.1.4 with an energy range below 250keV; c) Class 3: Any reference radiation selected from 8.1.4. d) Class 4 or 5: Beta radiation from a Sr/Y source (see IS06980) is preferred. For each batch of latex, 10 film packages are randomly selected and irradiated to obtain a calibration value corresponding to an optical density of 1.0. For each latex, the optical density is measured at 10 different points evenly distributed on its surface. The difference between the maximum and minimum optical density of each sample is determined and the average value and its standard deviation are calculated. The density measurement is carried out on the same film surface using conventional operating methods. This test may be affected by different irradiation conditions and development methods. Therefore, the influence of these two factors should be minimized to ensure the validity of the test results. 8.2.2 Latent image stability test [see Table 1-b] This anti-fading test shall be carried out on the latex of each batch of film. For each latex test, prepare two groups of samples, each group of 5 film packages, each group is marked with the letters A and B to distinguish them, the latter is used as a control sample.
Irradiate group A with reference radiation (see 8.1.4). In this way, its optical density value should be on the collimated straight line part of the characteristic curve of the test latex.
Store the samples of groups A and B under normal test conditions for 30 days. At the end of the storage period, the unirradiated group B is irradiated with the same calibration value as group A. After standing for 24 hours, all films are processed together. 8.2.3 Anti-aging test [see Table 1-c]
8.2.3.1 Artificial aging
This test shall be carried out on the latex of each batch of film. For each latex test, eight groups of samples, each containing three film packages, are prepared and the groups are marked with letters A to H. The samples of groups A to D are placed in a drying oven (without desiccant) at a temperature of 50 ± 1 ° C and open to the atmosphere for 7 days, while the samples of groups E to H are placed under normal test conditions (see 8.1.3). Within 4 to 20 hours after the heat treatment, groups A to C and groups E to G (control samples) are irradiated with a reference radiation under the following conditions: a) the film packages of groups A and E are irradiated with a calibration value corresponding to 1/4 of the latex range: b) the film packages of groups B and F are irradiated with a calibration value corresponding to 1/2 of the latex range: c) the film packages of groups C and G are irradiated with a calibration value corresponding to 4/5 of the latex range. The film packages of group D and the control samples of group H are heat treated together, but neither is irradiated. Develop all the above films at the same time, determine the calibration of each group of irradiated films, calculate the average calibration of the test sample group and the control sample group, and compare the two averages. Determine and compare the average background optical density of the two groups of unirradiated films. 8.2.3.2 Natural aging
Take a number of film packages sufficient for the tests a) and b) in Table 1 and store them for 1 month under the conditions provided by the manufacturer. Complete these tests according to the methods given in 8.2.1 and 8.2.2. 12
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