This standard recommends a method for measuring the attenuation performance of X-ray shielding materials. This standard applies to X-ray shielding materials with an X-ray tube voltage of (30-400) kV and a total filtration of (0.05-3.5) mmCu. GBZ/T 147-2002 Determination of attenuation performance of X-ray shielding materials GBZ/T147-2002 standard download decompression password: www.bzxz.net

Ics13.100
National Occupational Health Standard of the People's Republic of China GBZ/T147-2002
X-ray Protective Materials
Determination of Attenuation Properties
Determination of Attenuation Properties for Protective Materials Against X-rays Issued on April 8, 2002
Ministry of Health of the People's Republic of China
Implementation on June 1, 2002
Measurement Items and General Requirements
Terms and Definitions
Determination of Attenuation Properties
Quantity Determination
Explanation of Measurement Results
This standard is formulated in accordance with the Law of the People's Republic of China on the Prevention and Control of Occupational Diseases. In case of any inconsistency between the original standard GB16363-1996 and this standard, this standard shall prevail. This standard retains the practical and feasible part of the original standard GB16363-1996, namely the shielding performance requirements. At the same time, this standard refers to the International Electrotechnical Commission standard IEC1331-1:1994 "Medical diagnostic X-ray protection equipment Part 1: Determination of attenuation performance of protective materials", and wide beam measurement conditions are added based on this standard. 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: Lin Zhikai, Zhao Lancai, Cui Guangzhi, Jin Hui, Ge Shuqing This standard is interpreted by the Ministry of Health.
—Scope
Determination of attenuation performance of X-ray protective materials
This standard recommends the measurement method for attenuation performance of X-ray protective materials GBZ/T147-2002
This standard is applicable to X-ray protective materials with an X-ray tube voltage of (30~400) kV and a total filtration of (0.05~3.5) mmCu.
2 Terms and Definitions
The following terms and definitions apply to this standard. 2.1 Attenuation ratiobzxz.net
The ratio of the air kerma rate of nuclear radiation before and after attenuation by protective materials. 2.2 Lead equivalent
The attenuation equivalent expressed by the thickness of lead when lead is used as a reference material, and the unit is millimeter lead (mmPb). The lead equivalent of each unit thickness (mm) of protective material plate is called the specific lead equivalent, and the specific lead equivalent should be the best combination of attenuation performance, physical properties and performance.
2.3 Broad beam broad beam
A radiation beam condition in radiation measurement. When the solid angle of the radiation beam increases, the measured radiation does not increase significantly, but there is a scattering effect.
2.4 Narrow beam narrow beam
In order to measure the ideal radiation, a radiation beam with a solid angle as small as possible is used. Under this condition, the influence of scattered radiation tends to the minimum value, and lateral electronic balance is guaranteed when necessary. 3 Measurement Items and General Requirements
3.1 Attenuation Ratio
The measured protective material shall indicate the attenuation ratio, i.e., the multiple of the nuclear radiation attenuated by the protective material. 3.2 Accumulation Factor (Symbol: B)
The measured protective material shall indicate the accumulation factor B, i.e., the ratio of the corresponding radiation value at the center of the wide beam to the corresponding radiation value at the center of the narrow beam under the specified irradiation conditions. 3.3 Attenuation Equivalent (Symbol: 8)
The measured protective material shall indicate the thickness (mm) of the reference material to which the measured protective material is equivalent when it has the same attenuation degree as the reference material in the beam of specified line quality and under specified measurement conditions. 3.4 Lead Equivalent
The factory-produced X-ray protective material shall indicate its nominal lead equivalent and non-uniformity, and the line quality shall be indicated by the tube voltage and total filtration.
3.5 Non-uniformity
The non-uniformity of the attenuation equivalent of the protective material shall not exceed ±10%. 4 Measurement of Quantities
This chapter mainly stipulates that when measuring the attenuation performance of protective materials, relevant radiation quantities and geometric quantities should be measured according to wide beam measurement conditions and narrow beam measurement conditions. At the same time, requirements are put forward for the location of radiation detectors, test instruments, test objects, and line quality. 4
Give the attenuation performance of protective materials based on the measured relevant radiation quantities. 4.1 Radiation Quantity
When measuring the attenuation performance, the air kerma rate should be measured according to the requirements in Table 1. Table 1
Air kerma rate to be measured
Air kerma rate
Attenuation performance
Attenuation ratio
Accumulation factor
Attenuation equivalent
Lead equivalent
Inhomogeneity
K, is the air kerma rate measured in a wide beam after attenuation in accordance with Article 4.3; K. is the air kerma rate measured in a wide beam without attenuation in accordance with Article 4.3: K. is the air kerma rate measured in a narrow beam after attenuation in accordance with Article 4.4; ks
K is the air kerma rate at the center of the wide beam between the radiation source and the test object measured according to Figure 1; K is the same as K after passing through the beam limiting system as shown in Figure 1. The air kerma rate outside the wide beam measured at the same distance from the radiation source;
K, is the air kerma rate outside the radiation beam limited by the aperture within the initial wide beam projection as shown in Figure 1;
K1s is the attenuated wide beam air kerma rate measured at the same distance from the radiation source as K. 4.2 Geometric quantities
The geometric quantities shown should be measured in accordance with the requirements in Table 2. 4.3 Measurements under wide beam conditions
4.3.1 Under wide beam conditions, measurements should be made in accordance with the requirements of Figure 1. Clause
4.3.2 During the measurement, the air kerma rate Koc should not be greater than 5% of the air kerma rate Kc, that is: Kc≤ 0.05 × K.
4.3.3 During the measurement, the air kerma rate K, should not be greater than 1% of the air kerma rate K1, that is: K, ≤ 0.01 × K1s
Attenuation performance
Attenuation ratio
Accumulation factor
Attenuation equivalent
Lead equivalent
Non-uniformity
Table 2 Geometric quantities to be measured
c is the correction factor for the deviation of the distance of the measuring point K from the radiation source (see Figure 2). c is determined according to the following formula: 1500+a
a is the distance from the far side plane of the test object to the reference point of the radiation detector as shown in Figure 2 by the center of the narrow beam. a shall not be less than 10 times the square root of the cross-section A;
b is the distance from the far plane of the test object to the reference point of the radiation detector at the center of the wide beam shown in Figure 1; A is the cross-section of the narrow beam at the far plane of the test object shown in Figure 2; W is the distance between the reference point of the radiation detector and any adjacent object or wall (see Figures 1 and 2). 4.4 Measurement under narrow beam conditions
4.4.1 Under narrow beam conditions, measurements shall be made in accordance with the requirements of Figure 2. 4.4.2 On the far side of the test object, the diameter of the radiation beam shall be 20 mm ± 1 mm. 4.4.3 When determining uniformity in accordance with Section 6.5.1, the narrow beam shall be limited to a diameter of no more than 10 mm on the far side of the test object. 4.5 Position of the radiation detector
The distance W shall not be less than 700 mm.
When determining the attenuation ratio, the air kerma rate K and Ko shall be measured with and without the test object. The distance b from the far side plane of the test object 4.5.1
to the reference point of the radiation detector shall be 50mm±1mm (see Figure 1). 4.5.2 In the measurement of air kerma rate K., for the measurement of the accumulation factor, the distance from the far side of the test object to the reference point of the radiation detector shall not be less than 10 times the square root of the cross section A. 4.6 Test instrument
4.6.1 The response dependence of the radiation detector of the test instrument on the incident direction of the ray on the hemispherical surface is very small and shall be ignored. 4.6.2 When the radiation detector measures X-rays with a tube voltage of 40kV to 400kV, the response dependence of the detector on the ray energy must not exceed ±20%.
4.6.3 The diameter and length of the sensitive volume of the radiation detector shall not exceed 50mm4.6.4 The X-ray high voltage generator shall meet the requirements of the experimental tube voltage, and the actual value of its experimental tube voltage shall not be less than 90% of the specified experimental tube voltage.
4.6.5 The chemical purity of the standard lead sheet should be 99.99% and the thickness accuracy should be ±0.01mm. 6
Black dot old surface
Unit: mm
Figure 1 Schematic diagram of wide beam measurement conditions
4.6.6 Filtering conditions
Limited system
Test object
Size of cut-off A
Selection of test object
For X-ray protection materials with tube voltage below 120kV (including 120kV), the experimental tube voltage is 80～120kV, and the total filtration is 2.5mmAl. For X-ray protection materials with tube voltage above 120kV, the most commonly used tube voltage is used, and the total filtration is in accordance with the provisions of Table 3.
Table 3 Standardized line quality
X-ray tube voltage
Total filtration
*Percent ripple rate does not exceed 4%;
**2.5mmAl can be used instead
4.7 Test object
4.7.1 Under wide beam measurement conditions, the test object must be a plate of the material to be tested, and its size must be at least 500mm×500mm. 4.7.2 Under narrow beam measurement conditions, the test object must be a plate of the material to be tested, with a size of at least 100 mm × 100 mm7
4.7.3 When used to determine the attenuation rate, test objects of various thicknesses can be obtained by stacking several layers of material of equal or different thicknesses.
4.8 Linear quality
The attenuation performance should be determined based on one or more of the line qualities given in Table 3, burn point color test plane
Unit: mm
Figure 2 Schematic diagram of true penetration measurement conditions
5 Determination of attenuation performance
Limiting system
Test object
Dimensions of surface A
Parameter points of the test instrument
The constancy of the air kerma rate of the radiation beam must be monitored during all measurements. If the fluctuation of the air kerma rate exceeds 5% of the average value, the measurement result must be corrected. 5.1 Attenuation ratio
5.1.1 The attenuation ratio F shall be determined in accordance with the following formula: 5.1.2 The attenuation ratio shall be expressed numerically and the radiation quality shall be expressed in terms of the X-ray tube voltage and the total filtration (see Clause 6). ·
5.2 Cumulative factor
5.2.1 The cumulative factor B shall be determined in accordance with the following formula: B=
where c is the correction factor for the deviation in the distance of the measuring point K° from the radiation source. 5.2.2 The cumulative factor shall be expressed numerically and the radiation quality shall be expressed in terms of the X-ray tube voltage and the total filtration (see Clause 6). 5.3 Attenuation equivalent
5.3.1 The attenuation equivalent shall be determined by measuring the K° of the material under test and comparing it with the thickness of a reference material that produces the same K° value.
5.3.2 The attenuation equivalent must be expressed as the thickness of the reference material (mm), together with the chemical symbol or other reference material identification, and the line quality expressed in terms of the X-ray tube voltage and total filtration (see Clause 6). 5.4 Lead equivalent
5.4.1 When the reference material is lead, the measured attenuation equivalent is the lead equivalent. 5.5 Inhomogeneity
5.5.1 The inhomogeneity of the protective material shall be determined by the measured value K obtained on the area of ​​the test object under the conditions of Clauses 4.4.3 and 4.6.3 and the corresponding attenuation value 8;.
5.5.2 The 8 value should be measured under the following conditions: a) Measured at 5 to 10 representative locations; b) Continuously measured in representative directions over the entire test object area. 5.5.3 The non-uniformity of the protective material should be expressed in terms of the single measured value 8 of the attenuation equivalent; the maximum deviation from its average value 8:
5.5.4 The allowable deviation of the non-uniformity should be indicated in the same unit as the attenuation equivalent, S
For example:
3mm±0.2mmPb
(See Chapter 6)
6. Explanation of the measurement results
6.1 If the attenuation performance measured according to this standard complies with this standard, it should be stated in the test document, for example: Attenuation ratio
Accumulation factor
Attenuation equivalent
Lead equivalent
2×102:
2mmFe:
1 mmPb
1.2mmCu ;
0.7mmCu:
0.25mmCu;
2.5mmAl.
Attenuation equivalent and non-uniformity
2mm±0.1mmFe
6.2 The following markings shall be placed at appropriate locations on X-ray shielding materials: a) Product name;
b) Product model;
c) Product specifications;
Lead equivalent;
Production date;
Manufacturer name and address.
Tip: This standard content only shows part of the intercepted content of the complete standard. If you need the complete standard, please go to the top to download the complete standard document for free.