Tiêu chuẩn iso 04037 3 1999

Microsoft Word C023727E DOC A Reference number ISO 4037 3 1999(E) INTERNATIONAL STANDARD ISO 4037 3 First edition 1999 06 15 X and gamma reference radiation for calibrating dosemeters and doserate met[.]

Quantities and units

H product of Q and D at a point in tissue, where D is the absorbed dose at that point and Q the quality factor (ICRU 51 [7]):

NOTE 1 The unit of the dose equivalent is joules per kilogram (J ◊ kg -1 ) with the special name sievert (Sv).

NOTE 2 For the purpose of this part of ISO 4037, for photon and electron radiation, the quality factor has the value unity.

The H*(10) dose equivalent represents the dose at a specific point within a radiation field, reflecting the amount of radiation that would be received in a widespread, aligned field It is measured at a depth of 10 mm inside the ICRU sphere, on the radius opposite to the direction of the radiation beam This standardized measurement ensures accurate assessment of radiation exposure, making it essential for radiation protection and dosimetry.

NOTE 1 The unit of the ambient dose equivalent is joules per kilogram (J ◊ kg -1 ) with the special name sievert (Sv).

In the expanded and aligned field, the fluence and its energy distribution remain consistent throughout the entire volume of interest, matching the values recorded at the test point This indicates that the field is unidirectional, ensuring uniform radiation exposure across the targeted area.

H’ (0,07;Ω) dose equivalent that, at a point in a radiation field, would be produced by the corresponding expanded field in the ICRU sphere at a depth of 0,07 mm on a radius in a specified direction Ω

NOTE 1 The unit of the directional dose equivalent is joules per kilogram (J ◊ kg -1 ) with the special name sievert (Sv).

In a unidirectional magnetic field, the field direction can be characterized by the angle α, which is measured between the radius opposite to the incident field and a designated radius When the angle α is zero, the magnetic field component H' (0,07; 0) simplifies to H' (0,07), indicating a straightforward orientation of the field.

Note 3 indicates that within the expanded field, the fluence and its angular and energy distributions are consistent throughout the volume of interest, matching the values observed at the measurement point in the actual field.

H p (d) dose equivalent in soft tissue as defined in ICRU 51 [7] below a specified point on the body at an appropriate depth d

NOTE 1 The unit of the personal dose equivalent is joules per kilogram (J ◊ kg -1 ) with the special name sievert (Sv).

NOTE 2 Any statement of personal dose equivalent should include a specification of the depth, d, expressed in millimetres.

For weakly penetrating radiation, a skin depth of 0.07 mm is used to determine the personal dose equivalent, denoted as H p (0,07) In contrast, for strongly penetrating radiation, a depth of 10 mm is typically employed for dose measurement According to ICRU Report 47, the personal dose equivalent is defined to include the dose at a specific depth in a standardized tissue-equivalent phantom, with H p (d) used for calibration purposes.

Calibration factor and response determination

3.2.1 influence quantity influence parameter quantity which may have a bearing on the result of a measurement without being the subject of the measurement

The reading of a dosimeter equipped with an unsealed ionization chamber is affected by ambient temperature and pressure While measuring these environmental parameters is essential for accurate dose determination, it is not the primary goal of the measurement process Proper correction for temperature and pressure variations ensures reliable and precise dosimetry.

3.2.2 reference conditions reference conditions represent the set of influence quantities for which the calibration factor is valid without any correction

The measurement quantity should be selected freely based on the instrument's properties to ensure accurate calibration It is important to note that the quantity to be measured is not an influence quantity, as specified in section 3.2.1 Proper selection of the measurement value is essential for reliable calibration outcomes.

3.2.3 standard test conditions standard test conditions represent the range of values of a set of influence quantities under which a calibration or a determination of response is carried out

Calibration should ideally be performed under reference conditions; however, when this is not feasible—such as for ambient air pressure or temperature—a small interval around the reference values may be accepted Deviations from the reference calibration factor caused by these variations should, in principle, be corrected, but in practice, the acceptable uncertainty guides whether these influences require explicit correction or can be incorporated into the overall uncertainty During type testing, influence quantities not directly tested are fixed within the standard test condition intervals, which, along with the reference conditions specified in Tables A.1 and A.2 of ISO 4037 Annex A, ensure consistent and reliable calibration procedures.

3.2.4 calibration conditions conditions within the range of standard test conditions actually prevailing during the calibration

3.2.5 reference point ãdosemeterề point which is placed at the point of test for calibrating or testing purposes

NOTE The distance of measurement refers to the distance between the radiation source and the reference point of the dosemeter.

The 3.2.6 test point in a radiation field is the designated location where the dosemeter's reference point is positioned for calibration and testing purposes At this point, the conventional true value of the measured quantity is accurately known, ensuring precise and reliable dose measurements Proper identification of this test point is essential for maintaining calibration accuracy in radiation measurements.

3.2.7 reference direction direction, in the coordinate system of a dosemeter, with respect to which the angle to the direction of radiation incidence is measured in unidirectional fields

3.2.8 reference orientation ãdosemeterề orientation for which the direction of incident radiation coincides with the reference direction of the dosemeter

Copyright International Organization for Standardization

The conventional true value of a quantity represents the best estimate of the true magnitude of the measured quantity It is determined using primary or secondary standards, or by reference instruments calibrated against these standards This approach ensures measurement accuracy and reliability, forming the foundation for precise and consistent data in scientific and industrial applications.

NOTE A conventional true value is, in general, regarded as being sufficiently close to the true value for the difference to be insignificant for the given purpose.

EXAMPLE Within an organization, the result of a measurement obtained with a secondary standard instrument may be taken as the conventional true value of the quantity to be measured.

R ãdosemeterề quotient of its reading M and the conventional true value of the measured quantity; the type of response should be specified

EXAMPLE The response with respect to ambient dose equivalent H*(10):

NOTE 1 The value of the response may vary with the magnitude of the quantity to be measured In such cases, a dosemeter is said to be non-linear.

The response of a detector varies depending on the energy and directional distribution of incident radiation It is essential to consider the response as a function R(E, Ω), where E represents the energy of mono-energetic radiation and Ω indicates the direction of the incident radiation R(E) reflects the energy dependence of the response, while R(Ω) describes its angular dependence, with Ω expressed as the angle between the device’s reference direction and the external radiation source.

Some evaluation algorithms for multi-element detectors may not be additive when the dosemeter is exposed to a combination of radiations with different energies and angles of incidence In such cases, the sum of individual readings (M H1 + M H2) may not equal the measurement obtained from combined irradiation (MH1 + H2), indicating that the response function R(E,Ω) alone cannot fully characterize the dosemeter in complex radiation fields.

3.2.11 calibration quantitative determination, under a controlled set of standard test conditions, of the reading given by a dosemeter as a function of the value of the quantity to be measured

Routine calibration, often performed under simplified conditions, verifies the factory calibration or assesses the stability of calibration factors during long-term use of dosimeters It is typically based on procedures developed from type test results to ensure consistency with standard test conditions The primary goal of routine calibration is to provide accurate batch or individual calibration factors, helping maintain measurement reliability over time.

N conventional true value of the quantity the dosemeter is intended to measure, H, divided by the dosemeter’s reading, M, (corrected if necessary)

EXAMPLE The calibration factor with respect to personal dose equivalent is given by

NOTE 1 The calibration factor N is dimensionless when the instrument indicates the quantity to be measured A dosemeter

The reciprocal of the calibration factor represents the response under reference conditions Unlike the calibration factor, which is specific to these reference conditions, the response reflects the conditions present during the actual measurement This distinction is essential for accurate data interpretation in various environmental and technical assessments.

NOTE 3 The value of the calibration factor may vary with the magnitude of the quantity to be measured In such cases, a dosemeter is said to have a non-linear response.

3.2.13 normalization procedure in which the calibration factor is multiplied by a factor in order to achieve, over a certain range of influence quantities, a better estimate of the quantity to be measured

Normalization is practical when a dosimeter is primarily used under conditions that differ from reference conditions, as it adjusts for variations in response This process accounts for differences in dosimeter performance between standardized reference environments and actual operational conditions, ensuring accurate dose measurement in diverse scenarios Implementing normalization improves measurement reliability and consistency across different working conditions.

3.2.14 kerma-to-dose-equivalent conversion coefficient h K quotient of the dose equivalent, H, and the air kerma, K a , at a point in the radiation field: h K = H / K a (4)

NOTE 1 The conversion coefficients of clauses 5 and 6 averaged over spectral distributions are based on the mono-energetic data of ICRP 74 [17].

When discussing kerma-to-dose-equivalent conversion coefficients, it is essential to specify the type of dose equivalent, such as ambient, directional, or personal dose equivalent The conversion coefficient, h K, varies depending on the radiation energy and other factors, underscoring the importance of precise parameter definitions for accurate dose assessment.

The conversion coefficient, denoted as K(E), is essential for understanding the interaction of incident radiation, considering both H p (10;a) and H '(0.07;a) values, as well as the directional distribution of the radiation It is beneficial to analyze the conversion coefficient as a function of photon energy E at various angles of incidence, creating the so-called conversion function This fundamental data is crucial for accurately assessing radiation behavior and is widely used in radiation shielding and dosimetry calculations.

3.2.15 back-scatter factor ratio of air kerma in front of a phantom to the air kerma at the same position free in air

NOTE 1 The field is considered to be unidirectional with a direction of incidence perpendicular to the phantom surface.

The back-scatter factor varies based on several key parameters, including the test point’s location relative to the surface and beam axis, the beam diameter, phantom size, material composition, and radiation energy.

4 Procedures applicable to all area and personal dosemeters

General principles

All radiation qualities should be selected and produced according to ISO 4037-1, ensuring compliance with standardized parameters It is advisable to choose the appropriate radiation quality based on the specified energy, dose, or dose rate range of the dosemeter under test For simplicity, abbreviated names are used in this section of ISO 4037, reflecting the radiation qualities outlined in ISO 4037-1.

In X-ray radiation, the letters F, L, N, W, or H represent different radiation qualities: fluorescence, low air kerma rate, narrow, wide, or high air kerma rate series, respectively These are followed by the chemical symbol of the radiator responsible for fluorescence radiation and the generating potential for filtered X-ray radiation.

Reference radiations generated by radioactive sources are labeled with the letter "S" followed by the chemical symbol of the radionuclide, providing a standardized way to identify these emissions Conversely, reference radiations resulting from nuclear reactions are denoted by the letter "R" plus the chemical symbol of the target element responsible for emitting the radiation This notation system helps clearly distinguish between different types of reference radiations in nuclear and radiological contexts.

Table 1 outlines all the radiation qualities covered in this section of ISO 4037, including their mean energies (E) averaged over the fluence spectrum To ensure accurate dosimetry, measurements in these radiation fields must be conducted following the guidelines specified in ISO 4037-2.

Table 1 — Radiation qualities covered in this part of ISO 4037

Radionuclides High energy photon radiations radiation quality radionuclide

S-Co 60 Co 1 250 R-Ti (n,γ) capture in Ti 5,14 a

R-O 16 O (n,p) 16 N 6,61 a a Average taken over the spectral fluence.

In clauses 5 and 6 and annex A.2, the irradiation distance is defined as the measurement from the X-ray tube's focal spot or the radionuclide source's geometrical center to the test point, where the reference dosemeter is positioned For fluorescence X-radiation and R-C, R-F, or R-O radiations, the distance is measured from the radiator or target surface’s center to the test point If a range of distances is provided, the applicable conversion coefficients can be used within that range without alteration.

In clauses 5 and 6 and annex A.2, a specific notation is used to present conversion coefficients, which is explained in detail The example h' K (0.07; E, a) represents the conversion coefficient from air kerma (Kₐ) to the directional dose equivalent at a depth of 0.07 mm for photon radiation of energy E, with an angle a between the dosemeter's reference direction and the radiation incidence The prime symbol can be replaced by an asterisk for ambient dose equivalent or by the letter p for personal dose equivalent, depending on the context For radiation qualities with finite spectral width, the symbol E is replaced by a letter indicating a specific reference radiation series, such as F, L, N, W, H, S, or R, as detailed in Table 1.

Conversion coefficients for mono-energetic radiation, as listed in Tables 2, 8, 15, 21, 27, and A.3, are provided without any associated uncertainty For other tables in clauses 5 and 6, a standard uncertainty of ±2% should be assumed, reflecting potential variations between the spectrum used in calculations and the spectrum present at the testing location This approach ensures accurate interpretation of radiation conversion data for safety and measurement purposes.

For tube voltages below approximately 30 kV, particularly in high air kerma rate series, the actual conversion coefficients (h K *(10;E) and h pK (10;E,a)) can vary by more than 2% from the nominal values provided in the tables, depending on the specific experimental setup Certain combinations of radiation qualities and conversion coefficients—especially those sensitive to small energy distribution variations—are marked with an exclamation mark in the tables, indicating that the standard 2% uncertainty may not be adequate and more precise estimates or alternative values should be used If a radiation quality listed in Table 1 is not found in the conversion coefficient tables, reliable values cannot be provided for that quality.

At low photon energies, even small variations in the energy distribution can lead to significant changes in the calculated conversion coefficients This is because air kerma primarily depends on the low-energy portion of the spectrum, whereas ambient dose equivalent H*(10) and personal dose equivalent H p (10) are mainly influenced by the high-energy part of the spectrum Understanding these distinctions is crucial for accurate radiation dose assessment and calibration in radiological practices.

Variations in energy distribution between different experimental setups can result from factors such as anode angle, anode roughening, tungsten deposition on the tube window, the presence of a transmission monitor chamber, deviations in filter thickness, air path length between the focal spot and test point, and atmospheric pressure during measurement To optimize fluorescence radiation measurements and minimize scattered radiation, it may be necessary to use a thinner radiator or reduce the tube voltage.

Calibration and response determination must be performed under standard test conditions, ensuring consistency and accuracy The influence quantities’ ranges within these conditions are detailed in Tables A.1 and A.2, covering radiation-related parameters and other factors This standardized approach ensures reliable and reproducible measurement results.

When measuring the effect of a single influence quantity on a response, all other influencing factors must be kept constant under standard test conditions unless stated otherwise, ensuring accurate and reliable results.

In certain cases, it is crucial to vary the influence quantity while maintaining a constant instrument response, especially when assessing energy dependence in dosemeters with counter tubes within high dead time ranges Performing measurements at a constant indication rather than at a constant dose rate allows for more accurate evaluation of radiation qualities Similarly, thermoluminescence dosemeters with supra-linearity benefit from this approach However, it is generally recommended to test instruments under conditions where their response to dose or dose rate is essentially linear for more reliable results.

4.1.5 Point of test and reference point

Measurements must be conducted by positioning the dosemeter's reference point at the test location, ensuring accurate and consistent results The manufacturer should specify both the reference point and the reference direction for the dosemeter, with the reference point marked on the device's exterior whenever possible If marking the reference point on the dosemeter is not feasible, it should be clearly indicated in the accompanying documentation Additionally, all distances between the radiation source and the dosemeter should be measured from the radiation source to the dosemeter's reference point to ensure precise assessment.

When testing a dosemeter without specific information about the reference point or reference direction, the testing laboratory must determine and fix these parameters The chosen reference point and direction shall be documented clearly in the test certificate to ensure transparency and accuracy of the testing process.

Methods for the determination of the calibration factor and the response

4.2.1 Operation of the standard instrument

The standard instrument must operate according to its calibration certificate and instruction manual, including zero control, warm-up time, battery check, and correction factors The interval between periodic calibrations should comply with national regulations; if none exist, calibrations should be performed at least every three years to ensure accuracy and reliability.

Regular measurements should be conducted using a radioactive check source or calibrated radiation field to ensure that the reproducibility of the standard instrument remains within ±2% of its certified value Corrections for radioactive decay and deviations in air density from the reference standard must be applied as needed to maintain measurement accuracy.

When performing sequential irradiation of the standard instrument and the dosemeter under test, it is essential to determine whether a monitor is required, based on the stability of the radiation source's output This decision should reference specific guidelines: use a monitor according to sections 4.2.3.1 and 4.2.3.2 if stability necessitates it, or proceed without a monitor as outlined in sections 4.2.2.1 and 4.2.2.2 if the radiation source demonstrates consistent output Ensuring the correct application of these procedures enhances the accuracy and reliability of dose measurements in radiation testing.

Standard radiation measurement instruments can be categorized into two types: those measuring basic dosimetric quantities such as air kerma, and those directly measuring the quantity used for calibration For instruments measuring air kerma, a suitable conversion coefficient (h) must be applied in the relevant formulas, whereas for instruments directly measuring the calibration quantity, the coefficient h is considered equal to unity.

4.2.2 Measurements without a monitor for the source output

In general, a monitor is not needed in reference radiation fields produced by radioactive sources For X-radiation reference fields, the use of a monitor is usually recommended.

This procedure can be implemented when the air kerma rate in the radiation field remains stable throughout the calibration period, ensuring accurate results The calibration factor, N B, for a dosemeter positioned at the test point for the same duration as the standard instrument, is determined by a specific calculation Ensuring a consistent air kerma rate and proper timing between the dosemeter and standard instrument are essential for precise calibration.

= (5) h kerma-to-dose-equivalent conversion coefficient;

N A calibration factor of the standard instrument;

N B calibration factor of the dosemeter under calibration;

M A measured value of the standard instrument, i.e reading multiplied by the correction factor for differences in air density, where applicable;

M B measured value of the dosemeter under calibration, i.e reading multiplied by the correction factor for differences in air density, where applicable.

4.2.2.2 Determination of the response as a function of energy and angle of incidence

Under conditions not necessarily identical to the reference conditions, the response of a dosemeter is determined by

The correction factors, denoted as kE and ka, are applied to the standard instrument readings to account for variations in radiation quality and the direction of radiation incidence These adjustments ensure accurate measurements by compensating for differences between reference conditions and those present during the actual measurement Proper application of these correction factors is essential for precise radiation assessment, aligning measurements with standardized conditions for reliable results.

Often, the response of the dosemeter is given as its relative response, r, with respect to its response under reference conditions. r = R

R r is the response under reference conditions.

NOTE The relative response can be a useful quantity for describing the variation of response as a function of photon energy or angle of incidence (see also 3.2.10).

4.2.3 Measurements with a monitor for the source output

To account for moderate variations in the air kerma rate over time, a monitor can be utilized alongside sequential irradiation of the standard instrument and dosemeter This approach is commonly used with X-ray units to correct for fluctuations by alternating the placement of the standard and dosemeter at the test point The measured values for the standard instrument (M A) and dosemeter (M B), positioned sequentially, should be related to the monitor's readings The calibration factor for the dosemeter (N B) can then be determined based on these measurements and the monitor's data, ensuring accurate dose measurement and calibration.

The equation (8) involves m_A, the measured monitor reading during the standard instrument irradiation, and m_B, the measured monitor reading during the calibration of the dosemeter Additionally, h and N_A are parameters defined as in section 4.2.2.1, which are essential for accurate calibration calculations This process ensures precise dose measurements by comparing monitored values from standard and test irradiations.

In practical calibration scenarios, performing irradiations of the standard instrument and the dosemeter in quick succession ensures that ambient conditions remain consistent, eliminating the need for corrections to sync the monitor's indicated value with reference conditions.

NOTE 2 In cases where the monitor has a good long-term stability (see also 4037-2:1997, subclause 8.2) it may serve as the reference instrument after having been calibrated by the standard instrument.

4.2.3.2 Determination of the response as a function of energy and angle of incidence (see 4.2.2.2)

The relative response is obtained using equation (7).

4.2.4 Measurements by simultaneous irradiation of standard instrument and dosemeter

In certain situations, calibrations can be conducted through simultaneous irradiation of the standard instrument and the device under test in the field This method involves positioning both instruments symmetrically along the radiation field axis at an equal distance from the source Ensuring an adequate distance between the two detectors is crucial to prevent their readings from significantly influencing each other, maintaining accurate calibration results.

To ensure accurate measurements and eliminate the effects of radiation field asymmetry, it is essential to repeat measurements after swapping the positions of the two instruments The calibration factor, N_B, is then determined by calculating the geometric mean of the readings obtained, providing a reliable basis for calibration.

(10) where the symbols are as defined in 4.2.2.1 and the indices 1 and 2 refer to the two irradiations.

This procedure is mainly applicable to cases where no phantom is needed, specifically for area dosemeters It is particularly useful for reference radiations generated by accelerators or when working with uncollimated sources, as outlined in ISO 4037-1 standards.

4.2.4.2 Determination of the response as a function of energy and angle of incidence

A 2 Ê ËÁ ˆ ¯˜ Ê ËÁ ˆ ¯˜ (11) where the symbols are as defined in 4.2.2.1 and 4.2.2.2 and the indices 1 and 2 refer to the two irradiations.

The relative response is obtained by using equation (7).

4.2.5 Determination of the calibration factor and the response in a known gamma radiation field

For a gamma radiation field in which the air kerma rate at the point of test is known, the calibration factor of a dosemeter under calibration, N B , is obtained by

M B measured value (under reference conditions) of the dosemeter under calibration; h is as defined in 4.2.2.1.

5 Particular procedures for area dosemeters

General principles

These principles specify the calibration procedures for portable and installed area dosemeters in reference radiations, encompassing both active and passive devices, while excluding in-situ calibrations of installed dosemeters Area dosemeters should be irradiated in free air without a phantom to ensure accurate measurements Response measurements may be required across a photon energy range of 8 keV to 9 MeV, with irradiation distances varying based on equipment used Conversion coefficients h, detailed in subclauses 5.3.1 and 5.3.2, facilitate the transformation of air kerma to operational quantities H*(10) and H'(0,07), crucial for ISO reference radiations involving broad parallel beams and mono-energetic photons without scattered radiation.

Calibration procedures are typically conducted using divergent radiation beams, with conversion coefficients adjusted to a specified reference distance between the source and the test point When a reference distance is provided along with an incident radiation angle α, this angle represents the discrepancy between the reference orientation and the actual orientation of the dosimeter in the field Properly accounting for divergence and angles ensures accurate dosimetry and reliable radiation measurement results.

Quantities to be measured

For area dosemeters, the quantities to be measured shall be the ambient dose equivalent, H*(10), and directional dose equivalent, H '(0,07).

Conversion coefficients

5.3.1 Conversion coefficients from air kerma to H'(0,07)

5.3.1.3 Low air kerma rate series

5.3.1.6 High air kerma rate series

Table 2 — Conversion coefficient h' K (0,07;E,αα) from air kerma, K a , to the dose equivalent H'(0,07) for mono-energetic and parallel photon radiation (expanded field) and the ICRU sphere

Table 3 — Conversion coefficient h' K (0,07;F,αα) and h' K (0,07;S,αα) from air kerma, K a , to the dose equivalent

H'(0,07) for radiation qualities given in ISO 4037-1 (expanded field) and the ICRU sphere, reference distance 2 m

Table 4 — Conversion coefficient h' K (0,07;L,αα) from air kerma, K a , to the dose equivalent H'(0,07) for radiation qualities given in ISO 4037-1 (expanded field) and the ICRU sphere, reference distance 2 m

Table 5 — Conversion coefficient h' K (0,07;N,αα) from air kerma, K a , to the dose equivalent H'(0,07) for radiation qualities given in ISO 4037-1 (expanded field) and the ICRU sphere, reference distance 2 m

Table 6 — Conversion coefficient h' K (0,07;W,αα) from air kerma, K a , to the dose equivalent H'(0,07) for radiation qualities given in ISO 4037-1 (expanded field) and the ICRU sphere, reference distance 2 m

Table 7 — Conversion coefficient h' K (0,07;H,αα) from air kerma, K a , to the dose equivalent H'(0,07) for radiation qualities given in ISO 4037-1 (expanded field) and the ICRU sphere, reference distance 2 m

5.3.2 Conversion coefficient from air kerma to H*(10)

Table 8 — Conversion coefficient h* K (10) from air kerma, K a , to ambient dose equivalent H*(10) for mono-energetic and parallel photon radiation (expanded and aligned field) and the ICRU sphere

Photon energy keV h* K (10) Sv/Gy

Table 9 — Conversion coefficient h* K (10;F) from air kerma, K a , to ambient dose equivalent H*(10) for radiation qualities given in ISO 4037-1 (expanded and aligned field) and the ICRU sphere, reference distance 2 m.

F-U 1,0 - 3,0 1,65 a With these radiation qualities, care needs to be taken as energy impurities may have a substantial influence on the numerical values of conversion coefficients (see 4.1.2).

Table 10 — Conversion coefficient h* K (10;L) from air kerma, K a , to ambient dose equivalent H*(10) for radiation qualities given in ISO 4037-1 (expanded and aligned field) and the ICRU sphere, reference distance 2 m

L-240 1,0 - 3,0 1,38 a With these radiation qualities, care needs to be taken as variations in energy distribution may have a substantial influence

Table 11 — Conversion coefficient h* K (10;N) from air kerma, K a , to ambient dose equivalent H*(10) for radiation qualities given in ISO 4037-1 (expanded and aligned field) and the ICRU sphere, reference distance 2 m

N-300 1,0 - 3,0 1,35 a With these radiation qualities, care needs to be taken as variations in energy distribuition may have a substantial influence on the numerical values of conversion coefficients (see 4.1.2).

Table 12 — Conversion coefficient h* K (10;W) from air kerma, K a , to ambient dose equivalent H*(10) for radiation qualities given in ISO 4037-1 (expanded and aligned field) and the ICRU sphere, reference distance 2 m

Table 13 — Conversion coefficient h* K (10;H) from air kerma, K a , to ambient dose equivalent H*(10) for radiation qualities given in ISO 4037-1 (expanded and aligned field) and the ICRU sphere, reference distance 2 m

5.3.2.7 Radionuclides and high energy reference radiations

Table 14 — Conversion coefficient h* K (10;S) and h* K (10;R) from air kerma, K a , to ambient dose equivalent

H*(10) for radiation qualities given in ISO 4037-1 (expanded and aligned field) and the ICRU sphere for collimated beams, reference distance 2 m.

Build-up layer thickness mm kPMMA h* K (10;S) h* K (10;R) Sv/Gy

When using an uncollimated irradiation geometry, the irradiation distance should also be in the range recommended in ISO 4037-2 for this parameter.

6 Particular procedures for personal dosemeters

General principles

Calibration principles for personal dosemeters, including whole body and extremity devices, require irradiation on a phantom to ensure accuracy Response measurements should be conducted across a photon energy range of 8 keV to 9 MeV and at various distances to guarantee reliable dose assessment in different radiation conditions.

Subclauses 6.4.2 and 6.4.3 contain conversion coefficients h pK (d) to convert air kerma free in air to the operational quantities H p (0,07) and H p (10) defined in 3.1.2.3 These conversion coefficients pertain to the nominal photon

If the energy distribution of the reference radiation differs from the nominal distribution, compliance with clause 4.1.2 is required to ensure accurate dose measurements The initial reference data for conversion coefficients of mono-energetic photons, applicable to broad parallel beams without scattered radiation, are provided in Tables 15, 21, 27, and A.3, serving as essential references for calibration and quality assurance in radiological practices.

Quantities to be measured

For individual monitoring, the key quantities to measure are the personal dose equivalents H p (0,07) and H p (10), with the depth chosen according to the dosemeter’s properties Conversion coefficients in Tables 15 to 30 facilitate the translation of air kerma (K a) to personal dose equivalents (H p (d)), tailored to different depths and phantom types Specifically, for d = 0.07 mm, coefficients are provided for both rod and pillar phantoms, while the coefficients for d = 10 mm correspond to specific phantom models, ensuring accurate dose assessment.

30 cm ¥ 30 cm ¥ 15 cm slab phantom of the four component ICRU tissue with a density of 1 g cm -3 All conversion coefficients pertain to the reference radiations recommended in ISO 4037-1.

NOTE Conversion coefficients from air kerma to H p (0,07) in the ICRU slab phantom are given in A.2.

Experimental conditions

Calibration of personal dosemeters should be conducted using appropriate phantoms that consider radiation energy, incidence direction, and measurement depth, ensuring accurate dose assessment For extremity dosemeters, a depth of 0.07 mm is typically used; finger dosemeters should be calibrated with the ISO rod phantom, a 19 mm diameter, 300 mm long PMMA cylinder, while wrist or ankle dosemeters require the ISO pillar phantom, a water-filled hollow cylinder with 73 mm outer diameter, 300 mm length, 2.5 mm thick walls, and 10 mm end face thickness These phantoms replicate human tissue and ensure precise calibration for dose measurement, including Hp(10) measurements on the body.

The ISO water slab phantom should be constructed with dimensions of 30 cm by 30 cm by 15 cm, featuring PMMA walls with a front wall thickness of 2.5 mm and other walls 10 mm thick, filled with water When employing reference radiations with a mean energy equal to or higher than that of radionuclide 137 Cs, a solid PMMA slab of identical outer dimensions can be used as an alternative.

When using these phantoms as described, no correction factors are needed for the instrument's readings, as differences in back-scatter properties between the phantoms and ICRU tissue are negligible, ensuring accurate measurements without adjustments.

Routine calibrations do not always need to be performed on a phantom; simpler methods such as free in air or using different radiation types can be acceptable Any such simplifications must be justified beforehand by demonstrating that they produce results equivalent to those obtained using the standard procedures outlined in ISO 4037 or that any differences can be reliably corrected, which can be verified through type testing.

In low-energy radiation fields, the dose equivalent H p (0,07) is relevant for assessing trunk exposure; however, interpreting values from dosemeters worn on the trunk requires caution Radiation absorption by clothing can cause significant discrepancies between the measured H p (0,07) and the actual dose received, potentially leading to underestimation or overestimation of exposure.

6.3.2 Geometrical considerations in divergent beams

When selecting the test point, it should be positioned at a sufficient distance from the source to ensure the irradiated field in the measurement plane covers the entire front face of the phantom, enabling accurate measurement The measurement process involves placing the reference point of the standard instrument at the test point, followed by positioning the dosemeter under test with its reference direction aligned parallel to the radiation beam Extremity dosemeters should be attached to the phantom in the same manner as they are worn on the body during normal use, ensuring realistic measurements The slab phantom must be oriented so its front surface contacts the rear of the dosemeter and is perpendicular to the beam axis for precise irradiation conditions Calibration or response values are obtained using the specified formulas, reflecting the condition that the phantom is present during irradiation, mirroring the standard instrument setup When evaluating the impact of radiation incidence angle, the assembly of the dosemeter and phantom should be rotated around the test point as shown in referenced diagrams to assess directional influence.

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In ISO 4037, the personal dosemeter and phantom are treated collectively as the device under testing, with the reference point aligned to that of the dosemeter The key measurement pertains to the dose equivalent at a specified depth, d, within the reference phantom, measured without the influence of the dosemeter.

The concept aligns with the definition of H p, which involves determining the dose equivalent at a non-accessible point inside the body, with placing the dosemeter's reference point at the test location offering practical benefits This setup ensures accurate measurement of primary radiation dose from the source regardless of beam divergence, as the primary dose often dominates the total dose, including scattered radiation from the phantom Consequently, the calibration factor remains unaffected by the distance between the source and test point Additionally, positioning the reference point and test point together simplifies experimental assessments of how the dosemeter responds to different radiation incident directions, eliminating the need for corrections related to distance variations caused by rotation angles.

For effective irradiation of the slab phantom, it is practical to rotate the phantom around a single axis, allowing for precise exposure Additionally, positioning the dosimeter in two mutually perpendicular orientations on the phantom's surface ensures accurate dose measurements This approach simplifies the process while maintaining reliable and comprehensive data collection.

6.3.3 Simultaneous irradiation of several dosemeters

When multiple personal dosemeters are irradiated simultaneously on the front face of the slab phantom, they should be positioned within a circle of diameter d_F, which corresponds to the approximate 98% isodose contour relative to the dose at the phantom's center The value of d_F varies based on radiation quality and is detailed in Tables 28 to 33; using smaller irradiation distances than those specified in Tables 16 to 20 results in a reduced d_F Additionally, variations in distances between the dosemeters' reference points and the radiation source must be considered according to section 4.1.5 to ensure accurate dosimetry.

To accurately assess the response of multiple dosemeters based on the radiation incidence direction, it is essential to position their reference points along the axis of rotation This setup ensures consistent and reliable measurements, facilitating comprehensive evaluation of dosemeters' performance under varying radiation angles Proper alignment along the rotation axis is crucial for precise, simultaneous dose measurement in radiation detection and dosimetry studies.

When implementing this simplified procedure, it is important to consider two key effects First, placing multiple dosemeters on the phantom surface can lead to reduced back-scatter because of attenuation of the primary radiation as it passes through the dosemeters Second, variations in the distances between the reference points and the radiation source may need to be taken into account to ensure accurate measurements.

Differences in distance should be carefully considered as outlined in section 4.1.4 Before implementing this practice, it must be verified that the results are within 2% of those obtained when a single dosemeter is irradiated at the center of the phantom Ensuring accuracy in dose measurement is essential when adjusting positioning methods in radiation dosimetry.

Certain dosemeters are highly sensitive to minor variations in the back-scattered photon field, often due to the use of energy-dependent detectors or the algorithms converting detector signals into dose equivalent values To ensure accurate calibration, it is recommended to use only a single dosemeter mounted on the phantom surface in such cases.

6.3.4 Influence of the orientation on the values of H p (0,07)

The value of H p (0,07) in a radiation field depends on the incident radiation's direction, with measurements taken using pillar and rod phantoms that feature two mutually perpendicular axes intersecting the dosemeter’s reference point When rotated by 60° around either axis, the photon energy-specific factor h pK (0,07;E,a) remains within 0.95 to 1.05 of the normal incidence value, as shown in Figure A.2 based on references [11] and [12] For smaller angles, these variations are even less significant Given the minimal impact of angular variation on the true value of H p (0,07), ISO 4037 assumes that H p (0,07) is independent of radiation incidence direction for angles up to 60°, with larger angles beyond this range not considered.

Conversion coefficients

The conversion coefficients outlined in sections 6.4.2 to 6.4.4 pertain to the rod, pillar, and slab phantoms constructed from ICRU tissue standards Calibration of individual dosemeters must be performed using the specified phantom described in section 6.3.1, suitable for the type of instrument under testing These phantoms are considered to be made of ICRU tissue, and no adjustments are necessary for potential differences in backscatter properties between the actual phantom used and the ICRU tissue phantom with the same shape.

Calibration procedures are typically conducted using divergent radiation beams, with conversion coefficients adjusted to a standardized reference distance between the radiation source and the testing point When a reference distance and an irradiation angle are specified, the angle (a) represents the difference between the reference orientation and the actual orientation of the dosimeter in the field Proper understanding of these parameters ensures accurate dose measurement and reliable calibration in radiation safety practices.

A PMMA build-up plate measuring 30 cm × 30 cm should be positioned with its rear face 15 cm in front of the dosemeter's reference point This plate must remain stationary during any rotation of the dosemeter or dosemeter phantom assembly, ensuring accurate and consistent measurements (see 4.1.8 and Figure A.1).

6.4.2 Conversion coefficients from air kerma to H p (0,07) in the rod phantom consisting of ICRU tissue 6.4.2.1 Mono-energetic radiations

Table 15 — Conversion coefficient h pK (0,07;E) from air kerma, K a , to the dose equivalent H p (0,07) for mono-energetic and parallel photon radiation and the rod phantom

Table 16 — Conversion coefficient h pK (0,07;F) and h pK (0,07;S) from air kerma, K a , to the dose equivalent

H p (0,07) for radiation qualities given in ISO 4037-1 and the rod phantom, reference distance 2 m

Irradiation distance m h p K (0,07;F) and h p K (0,07;S) Sv/Gy

Table 17 — Conversion coefficient h pK (0,07;L) from air kerma, K a , to the dose equivalent H p (0,07) for radiation qualities given in ISO 4037-1 and the rod phantom, reference distance 2 m

Table 18 — Conversion coefficient h pK (0,07;N) from air kerma, K a , to the dose equivalent H p (0,07) for radiation qualities given by ISO 4037-1 and the rod phantom, reference distance 2 m

Table 19 — Conversion coefficient h pK (0,07;W) from air kerma, K a , to the dose equivalent H p (0,07) for radiation qualities given in ISO 4037-1 and the rod phantom, reference distance 2 m

Table 20 — Conversion coefficient h pK (0,07;H) from air kerma, K a , to the dose equivalent H p (0,07) for radiation qualities given in ISO 4037-1 and the rod phantom, reference distance 2 m

6.4.3 Conversion coefficients from air kerma to H p (0,07) in the pillar phantom consisting of ICRU tissue 6.4.3.1 Mono-energetic radiations

Table 21 — Conversion coefficient h pK (0,07;E) from air kerma, K a , to the dose equivalent H p (0,07) for mono-energetic and parallel photon radiation and the pillar phantom

Table 22 — Conversion coefficient h pK (0,07;F) and h pK (0,07;S) from air kerma, K a , to the dose equivalent

H p (0,07) for radiation qualities given in ISO 4037-1 and the pillar phantom, reference distance 2 m

Table 23 — Conversion coefficient h pK (0,07;L) from air kerma, K a , to the dose equivalent H p (0,07) for radiation qualities given in ISO 4037-1 and the pillar phantom, reference distance 2 m

Table 24 — Conversion coefficient h pK (0,07;N) from air kerma, K a , to the dose equivalent H p (0,07) for radiation qualities given by ISO 4037-1 and the pillar phantom, reference distance 2 m

Table 25 — Conversion coefficient h pK (0,07;W) from air kerma, K a , to the dose equivalent H p (0,07) for radiation qualities given in ISO 4037-1 and the pillar phantom, reference distance 2 m

Table 26 — Conversion coefficient h pK (0,07;H) from air kerma, K a , to the dose equivalent H p (0,07) for radiation qualities given in ISO 4037-1 and the pillar phantom, reference distance 2 m

6.4.4 Conversion coefficient from air kerma to H p (10) in the ICRU slab phantom

Table 27 — Conversion coefficient h pK (10;E,αα) from air kerma, K a , to the dose equivalent H p (10) for mono-energetic and parallel photon radiation and the slab phantom

Photon energy keV h p K (10;E,α) in Sv/Gy for angle of incidence of

Table 28 — Conversion coefficient h pK (10;F,αα) from air kerma, K a , to the dose equivalent H p (10) for radiation qualities given in ISO 4037-1 and the slab phantom, reference distance 2 m

Irradiation distance d F cm (see 6.3.3) h p K (10;F,α) in Sv/Gy for angle of incidence of m 0° 10° 20° 30° 40° 45° 50° 60° 70° 80°

F-U 1,0 - 3,0 11 1,82 1,81 1,80 1,77 1,72 1,69 1,65 1,51 1,29 0,87 a With these radiation qualities, care needs to be taken as energy impurities may have a substantial influence on the numerical values of conversion coefficients (see 4.1.2).

Table 29 — Conversion coefficient h pK (10;L,αα) from air kerma, K a , to the dose equivalent H p (10) for radiation qualities given in ISO 4037-1 and the slab phantom, reference distance 2 m

Irradiation distance d F cm (see 6.3.3) h p K (10;L,α) in Sv/Gy for angle of incidence of m 0° 10° 20° 30° 40° 45° 50° 60° 70° 80°

L-240 1,0 - 3,0 13 1,47 1,47 1,47 1,46 1,44 1,42 1,40 1,33 1,20 0,87 a With these radiation qualities, care needs to be taken as variations in energy distribution may have a substantial influence on the numerical values of conversion coefficients (see 4.1.2).

Table 30 — Conversion coefficient h pK (10;N,αα) from air kerma, K a , to the dose equivalent H p (10) for radiation qualities given in ISO 4037-1 and the slab phantom, reference distance 2 m

Irradiation distance d F cm (see 6.3.3) h p K (10;N,α) in Sv/Gy for angle of incidence of m 0° 10° 20° 30° 40° 45° 50° 60° 70° 80°

N-300 1,0 - 3,0 15 1,42 1,42 1,42 1,41 1,40 1,38 1,36 1,30 1,19 0,87 a With these radiation qualities, care needs to be taken as variations in energy distribution may have a substantial influence on the numerical values of conversion coefficients (see 4.1.2).

Table 31 — Conversion coefficient h pK (10;W,αα) from air kerma, K a , to the dose equivalent H p (10) for radiation qualities given in ISO 4037-1 and the slab phantom, reference distance 2 m

Irradiation distance d F cm (see 6.3.3) h p K (10;W,α) in Sv/Gy for angle of incidence of m 0° 10° 20° 30° 40° 45° 50° 60° 70° 80°

Table 32 — Conversion coefficient h pK (10;H,αα) from air kerma, K a , to the dose equivalent H p (10) for radiation qualities given in ISO 4037-1 and the slab phantom, reference distance 2m

Irradiation distance d F cm (see 6.3.3) h p K (10;H,α) in Sv/Gy for angle of incidence of m 0° 10° 20° 30° 40° 45° 50° 60° 70° 80°

H-300 1,0 - 3,0 15 1,59 1,59 1,58 1,57 1,53 1,51 1,48 1,39 1,23 0,86 a With this radiation quality, care needs to be taken as variations in energy distribution may have a substantial influence on the numerical values of conversion coefficients (see 4.1.2).

6.4.4.7 Radionuclide sources and high energy photon radiations

Table 33 — Conversion coefficient h pK (10;S,αα) and h pK (10;R,αα) from air kerma, K a , to the dose equivalent

H p (10) for radiation qualities given in ISO 4037-1 and the slab phantom Radiation quality

Build- up. layer k PMMA h p K (10;S,α) and h p K (10;R,α) in Sv/Gy for angle of incidence of m 0° 10° 20° 30° 40° 45° 50° 60° 70° 80°

Records and certificates

National regulations typically define specific requirements for calibration records and certificates, including their required formats and detailed content They also specify the calibration frequency to ensure ongoing measurement accuracy and outline the mandatory duration for retaining calibration records Adhering to these regulations ensures compliance, traceability, and the integrity of calibration processes.

Calibration records must comprehensively document the date and place of calibration, dosemeter description including type and serial number, and ownership details They should specify information about radiation sources and secondary standard instruments used, along with reference, calibration, or standard test conditions The results of the calibration, the name of the individual performing the process, and any special observations must also be included to ensure accurate and traceable calibration documentation.

Statement of uncertainties

The statement of uncertainty shall be consistent with the approaches recommended by the ISO Guide to the Expression of Uncertainty in Measurement (1993).

When evaluating component uncertainties, several factors must be considered, including the uncertainty of the conventional true value from calibration certificates and positioning accuracy assessments by the test laboratory Additional uncertainties arise from irradiation distances, typically 1% for distances over 2 meters, and from conversion coefficients, usually 2%, with specific conditions outlined in relevant clauses Field inhomogeneities caused by beam divergence and the 'heel effect' can introduce a 2% uncertainty at distances greater than 2 meters The effects of simultaneous irradiation of multiple dosimeters and simplified procedures may contribute up to 2% each, while the use of build-up plates adds approximately 1%, and long-term variations of standard instrument response can also impact results with an upper limit of 2% These guideline values are based on a 68% confidence level, as detailed in ISO 4037-2, ensuring accurate and reliable dosimetry measurements.

A.1 Statement of reference conditions and required standard test conditions

Table A.1 — Reference conditions and standard test conditions for radiological parameters

Influence quantities Reference conditions Standard test conditions

Angle of radiation incidence Reference orientation

Radiation background Ambient dose equivalent rate

H 10 0,1 àSv h -1 or less if practical

H 10 less than 0,25 àSv h -1 a Another radiation quality may be used if the rated energy range of the dosemeter does not comprise the energy of the photons emitted by 137 Cs.

Table A.2 — Reference conditions and standard test conditions for other parameters

Influence quantities Reference conditions Standard test conditions

Atmospheric pressure 101,3 kPa 86 kPa to 106 kPa a

Power supply voltage Nominal power supply voltage Nominal power supply voltage ± 3 %

Frequency b Nominal frequency Nominal frequency ± 1 % b

A.C power supply Sinusoidal Sinusoidal with total wave-form harmonic distortion less than 5 % b

Electromagnetic field of external origin

Negligible Less than the lowest value that causes interference

Magnetic induction of external origin

Negligible interference occurs when the induced magnetic field is less than twice the Earth's magnetic field, ensuring minimal impact on device performance Assembly controls are essential to establish normal operation, with specific setup procedures to ensure accuracy Test values should be documented accurately, with calibration data provided for temperate climates; adjustments may be necessary for different environmental conditions In higher altitudes, a lower pressure limit of 70 kPa can be acceptable These guidelines primarily pertain to assemblies operated from the main voltage supply, emphasizing the importance of proper setup and environmental considerations for reliable operation.

A.2 Conversion coefficients from air kerma to H p (0,07) in the ICRU slab phantom

Table A.3 — Conversion coefficient h pK (0,07;E,αα) from air kerma, K a , to the dose equivalent H p (0,07) for mono-energetic and parallel photon radiation (expanded field) and the slab phantom

Energy h p K (0,07;E,α) in Sv/Gy for angle of incidence of keV 0° 10° 20° 30° 40° 45° 50° 60° 70° 80°

Table A.4 — Conversion coefficient h pK (0,07;F,αα) and h pK (0,07;S,αα) from air kerma, K a , to the dose equivalent H p (0,07) for radiation qualities given in ISO 4037-1 and the slab phantom, reference distance 2 m Radiation quality

Irradiation distance d F cm (see 6.3.3) h p K (0,07;F,α) and h p K (0,07;S,α) in Sv /Gy for angle of incidence of m 0° 10° 20° 30° 40° 45° 50° 60° 70° 80°

A.2.3 Low air kerma rate series

Table A.5 — Conversion coefficient h pK (0,07;L,αα) from air kerma, K a , to the dose equivalent H p (0,07) for radiation qualities given in ISO 4037-1 and the slab phantom, reference distance 2 m

Irradiation distance d F cm (see 6.3.3) h p K (0,07;L,α) in Sv/Gy for angle of incidence of m 0° 10° 20° 30° 40° 45° 50° 60° 70° 80°

Table A.6 — Conversion coefficient h pK (0,07;N,αα) from air kerma, K a , to the dose equivalent H p (0,07) for radiation qualities given by ISO 4037-1 and the slab phantom, reference distance 2 m

Irradiation distance d F cm (see 6.3.3) h p K (0,07;N,α) in Sv/Gy for angle of incidence of m 0° 10° 20° 30° 40° 45° 50° 60° 70° 80°

Table A.7 — Conversion coefficient h pK (0,07;W,αα) from air kerma, K a , to the dose equivalent H p (0,07) for radiation qualities given in ISO 4037-1 and the slab phantom, reference distance 2 m

Irradiation distance d F cm (see 6.3.3) h p K (0,07;W,α) in Sv/Gy for angle of incidence of m 0° 10° 20° 30° 40° 45° 50° 60° 70° 80°

A.2.6 High air kerma rate series

Table A.8 — Conversion coefficient h pK (0,07;H,αα) from air kerma, K a , to the dose equivalent H p (0,07) for radiation qualities given in ISO 4037-1 and the slab phantom, reference distance 2 m

Irradiation distance d F cm (see 6.3.3) h p K (0,07;H,α) in Sv/Gy for angle of incidence of m 0° 10° 20° 30° 40° 45° 50° 60° 70° 80°

A.3 Effects associated with electron ranges

Electrons with energies above approximately 65 keV can penetrate 0.07 mm of ICRU tissue, while electrons with energies exceeding 2 MeV can reach depths of 10 mm This is crucial for understanding secondary electron generation in reference radiations, as their energies influence tissue penetration The electron ranges surpass the measurement depths, meaning the dose equivalent at these depths can vary significantly from values predicted under transient secondary electron equilibrium conditions Therefore, calculating dose using the kerma approximation—which assumes energy transfer occurs precisely at the interaction point—may not provide accurate results in these situations.

Figures A.3 a) and A.3 b) give examples of depth ionization curves obtained in the R-Ni and R-F reference radiation fields, respectively, showing that transient secondary electron equilibrium is achieved only at depths greater than about 3 cm Depending on the nature of the radiation source and on the kind and geometry of materials between the source and point of test, the depth dose curve may rise or fall with increasing depth as long as the conditions of electron equilibrium are not fulfilled or, as most radiation detectors do not work under conditions of electron equilibrium, as long as build-up is not completed A rise in the depth dose curve indicates that the electron fluence in the photon beam is smaller than it would be under equilibrium conditions and vice versa In the following, the term ''build-up'' is used in a generic sense implying that the depth dose curve may rise or fall with increasing depth (see Figures A.3a) and A.3b).

The depths of measurement for area and individual monitoring recommended by the ICRU are 0,07 mm and

10 mm, irrespective of whether the build-up is completed in the depth of interest Therefore, it is not reasonable to use conversion coefficients assuming electronic equilibrium and hence completed build-up On the other hand, the sign and magnitude of the deviations of the dose from its value under electronic equilibrium depend on the particular experimental set-up actually being used, which excludes the use of universally applicable conversion coefficients.

In ISO 4037, the solution for assessing reference photon radiation fields with energies above 65 keV and 2 MeV involves measuring air kerma at the test point and converting it to the relevant dose equivalent using specified conversion coefficients These coefficients, found in Tables 2 to 33 or A.3 to A.8, are only valid under conditions of secondary electron equilibrium, which requires the radiation field to be appropriately set up To ensure accurate measurements, the test instrument must be irradiated in a field where secondary electrons are in equilibrium, and if necessary, a tissue-equivalent material such as a PMMA layer should be added to achieve full build-up around the detector.

To accurately measure the instrument's reading relative to the true dose equivalent, a PMMA plate with a 30 cm x 30 cm cross-section should be placed in front of the dosemeter's reference point The influence of the PMMA plate on photon scattering and attenuation is corrected using the factor k PMMA Typically, the plate should be positioned immediately in front of the detector, but for studying response variations with different radiation angles, it can be placed at a certain distance to facilitate rotation of the dosemeter or its assembly, while keeping the plate stationary, ensuring complete build-up at various angles with a single k PMMA value.

This calibration procedure ensures that measurement results are unaffected by potential deviations from complete build-up, providing reliable performance in photon fields under electronic equilibrium conditions However, it does not guarantee accurate dose equivalent measurements in mixed photon and electron fields, especially when the electron range exceeds the measurement depth For precise dose equivalent assessment in such conditions, calibration in appropriate electron reference radiation fields for H(0.07) and H(10) per ISO 6980-1 is necessary, though this falls outside the scope of ISO 4037.

2 Build-up layer if required

Figure A.1 — Arrangement for the calibration of personal dosemeters at angle a

NOTE Direction 1 represents a rotation around the cylinder axis and direction 2 around the axis perpendicular to the cylinder axis and to the direction of radiation incidence.

Figure A.2 — Variation of H p (0,07;E,60°) / H p (0,07;E,0°) for the rod (19 mm) and the pillar phantom (73 mm) as a function of photon energy

2 Depth in water, in centimetres

3 Depth in PMMA, in grams per square centimetre

Figure A.3 — Examples of build-up curves in high energy photon fields

[1] International Commission on Radiation Units and Measurements, Determination of Dose Equivalents Resulting from External Radiation Sources, ICRU Report 39, Bethesda, MD, 1985.

[2] ICRU Rapport 39, 1987, Détermination des équivalents de dose dus aux sources externes de rayonnements.

[3] International Commission on Radiation Units and Measurements, Determination of Dose Equivalents Resulting from External Radiation Sources — Part 2, ICRU Report 43, Bethesda, MD, 1988.

[4] International Commission on Radiation Units and Measurements, Measurement of Dose Equivalents from External Photon and Electron Radiations, ICRU Report 47, Bethesda, MD, 1992.

[5] International Atomic Energy Agency, International Basic Safety Standards for Protection against Ionizing Radiation and for the Safety of Radiation Sources, Safety Series Report No 115-1, 1994.

[6] International Commission on Radiological Protection, Recommendations of the ICRP, Publication 60, Annals of the ICRP 21, No.1-3, Pergamon Press, New York, 1991.

[7] International Commission on Radiation Units and Measurements, Quantities and Units in Radiation Protection Dosimetry, ICRU Report 51, Bethesda, MD, 1993.

KRAMER et al (1994) discuss the current status of an ISO working document focusing on the calibration and type testing of radiation protection dosemeters for photons Their study emphasizes the importance of standardized testing procedures to ensure accurate dose measurement in radiation protection The article highlights ongoing efforts to develop globally accepted protocols that enhance the consistency and reliability of photon dosemeters, ultimately improving radiation safety standards across various industries.

[9] KRAMER, H.M., On the use of conversion coefficients from air kerma to the ICRU quantities for low energy X-ray spectra, Radiation Protection Dosimetry, 54,(1994) pp 213-215.

[10] ALBERTS, W.G., AMBROSI, P., BệHM, J., DIETZE, G., HOHLFELD, K and WILL, W., Neue Dosis-Meògrửòen im Strahlenschutz, PTB-Bericht Dos-23, Braunschweig, (1994), ISSN 0172-7095, ISBN 3-89429-507-4.

[11] TILL, E., ZANKL, M and DREXLER, G., Angular dependence of depth doses in a tissue slab irradiated with monoenergetic photons GSF-Bericht 27/95, München, (1995).

[12] GROòWENDT, B., Angular-Dependence Factors and Kerma to Dose Equivalent Conversion Coefficients for Cylindrical Phantoms Irradiated by Plane-Parallel Extended Monoenergetic Photon Beams, Radiation Protection Dosimetry, 59, (1995), p 165.

Grodwendt (1995) provides crucial conversion coefficients from air kerma to dose equivalent for cylindrical phantoms exposed to extended plane-parallel photon beams at oblique incidence This study enhances the accuracy of radiation dosimetry by accounting for beam angle and phantom geometry, which are essential for precise dose assessments in radiation protection scenarios.

The study by Dimbylow, Francis, and Bartlett (1989) focuses on calibrating photon personal dosemeters using ICRU operational quantities It emphasizes the importance of accurate phantom backscatter and depth-dose distribution calculations to ensure reliable dose measurements, as detailed in NRPB Report 230 published by the National Radiological Protection Board.

[15] WILLIAMS, G., SWANSON, W.P., KRAGH, P and DREXLER, G., Calculation and Analysis of Photon Dose Equivalent Distributions in the ICRU Sphere, GSF-Bericht S-958, Gesellschaft für Strahlen- und Umwelt- forschung, München (1983), ISSN 0721-1694.

[16] ICRU Report 56, 1997, Dosimetry of External Beta Rays for Radiation Protection.

[17] International Commision on Radiological Protection, Conversion Coefficients for use in Radiological Protection against External Radiation, ICRP Publication 74, Pergamon Press, 1997.

[18] ICRU Report 33, 1980, Measurements, Quantities and Units.

[19] ISO 6980:1996, Reference beta radiations for calibrating dosimeters and dose-rate meters and for determining their response as a function of beta-radiation energy.

Tiêu đề	X and Gamma Reference Radiation for Calibrating Dosemeters and Doserate Meters
Chuyên ngành	Radiation
Thể loại	Tiêu chuẩn
Năm xuất bản	1999

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