BS ISO 4037-2-1998 X and gamma reference radiation for calibrating dosemeters and doserate meters and for determining their response as a function of photon energy Dosimetry for rat.pdf

1、BRITISH STANDARD BSISO 4037-2:1997 X and gamma reference radiation for calibrating dosemeters and doserate meters and for determining their response as a function of photon energy Part 2: Dosimetry for radiation protection over the energy ranges8keV to1,3MeV and4MeV to9MeV ICS 17.240BSISO4037-2:1997

2、 This British Standard, having been prepared under the directionof the Engineering SectorBoard, was published underthe authority of the Standards Board and comes intoeffect on 15 March1998 BSI 05-1999 ISBN 0 580 29311 4 National foreword This British Standard reproduces verbatim ISO4037-2:1997 and i

3、mplements it as the UK national standard. It supersedes BS5869:1980 which is withdrawn. The UK participation in its preparation was entrusted to Technical Committee NCE/2, Health physics instrumentation, which has the responsibility to: aid enquirers to understand the text; present to the responsibl

4、e international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. A list of organizations represented on this committee can be obtained on request

5、 to its secretary. Cross-references The British Standards which implement international or European publications referred to in this document may be found in the BSI Standards Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Find” facility of the

6、BSI Standards Electronic Catalogue. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summa

7、ry of pages This document comprises a front cover, an inside front cover, pages i and ii, theISOtitle page, pages ii to iv, pages 1 to 25 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on t

8、he inside front cover. Amendments issued since publication Amd. No. Date CommentsBSISO4037-2:1997 BSI 05-1999 i Contents Page National foreword Inside front cover Foreword iii Text of ISO 4037-2 1ii blankBSISO4037-2:1997 ii BSI 05-1999 Contents Page Foreword iii Introduction 1 1 Scope 1 2 Normative

9、references 1 3 Definitions 1 4 Apparatus 4 5 General procedures 4 6 Procedures applicable to ionization chambers 5 7 Additional procedures and precautions specific to gamma radiation dosimetry using radionuclide sources 7 8 Additional procedures and precautions specific to X-radiation dosimetry 8 9

10、Special procedures and precautions specific to fluorescence X-radiation Limitation of extraneous radiation in beams 9 10 Dosimetry of reference radiation at photon energies between4MeV and9MeV 10 11 Uncertainty of measurement 19 Annex A (informative) Determination by ionization chamber measurements

11、of air kerma under receptor-absent conditions and of absorbed dose to tissue (water) under receptor conditions 21 Annex B (informative) Bibliography 23 Figure 1 Example of a typical X-ray setup 9 Figure 2 Example of setup for calibration of fluence detectors by means of associated particle counting

12、19 16 Figure 3 Radiation geometries for in-phantom measurements, showing cross-sections through two types of phantom: a sphere of30cm diameter and a parallelepiped of30cm 30cm 20cm 17 Table 1 Typical values for the bremsstrahlung correction 12 Table 2 Values for attenuation and scatter correction, k

13、 att , for different types of ionization chamber 13 Table 3 Typical average restricted-mass collision-stopping powers of air relative to those of the wall materials 13 Table 4 Typical energy absorption coefficients for non air-equivalent wall materials relative to air 15 14 Descriptors: Nuclear radi

14、ation, radiation protection, radiation measuring instruments, exposure dose-rate meters, calibration, reference sources, gamma radiation, X rays, dosimetry.BSISO4037-2:1997 BSI 05-1999 iii Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standar

15、ds bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organi

16、zations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Draft International Standards adopted by the technical committees are cir

17、culated to the member bodies for voting. Publication as an International Standard requires approval by at least75% of the member bodies casting a vote. International Standard ISO4037-2 was prepared by Technical Committee ISO/TC85, Nuclear energy, Subcommittee SC2, Radiation protection. This first ed

18、ition of ISO4037-2, along with ISO4037-1, cancels and replaces the first edition of ISO4037:1979, which has been technically revised. ISO4037 consists of the following parts, under the general title X and gamma reference radiation for calibrating dosemeters and doserate meters and for determining th

19、eir response as a function of photon energy. Part 1: Radiation characteristics and production methods; Part 2: Dosimetry of X and gamma reference radiation for radiation protection over the energy ranges8keV to1,3MeV and4MeV to9MeV; Part 3: Calibration of area and personal dosemeters. Annex A and An

20、nex B of this part of ISO4037 are for information only.iv blank BSI 05-1999 1 BSISO4037-2:1997 Introduction The term “dosimetry” is used in this part of ISO4037 to describe the method by which the value of a physical quantity characterizing the interaction of radiation with matter may be measured at

21、 a given point by the use of a calibrated standard instrument. Dosimetry is the basis for the calibration of radiation protection instruments and devices and the determination of their response as a function of the energy of the radiation of interest. At present, the quantities in which photon secon

22、dary-standard instruments or sources are calibrated for use in radiological protection calibration laboratories relate to measurements made in free air, i.e.air kerma. NOTEThroughout this part of ISO4037, kerma is used as an abbreviation for air kerma. In order to correlate measured physical quantit

23、ies with the magnitude of a biological effect, a quantity of the dose equivalent type1 is required for use in radiation protection. ICRU has defined such quantities2 and a further International Standard will be issued containing tables of conversion coefficients from air kerma to these dose equivale

24、nt quantities (see ISO4037-3). 1 Scope This part of ISO4037 specifies the procedures for the dosimetry of X and gamma reference radiation for the calibration of radiation protection instruments over the energy range from approximately8keV to1,3MeV and from 4MeV to9MeV. The methods of production and

25、nominal kerma rates obtained from these reference radiations are given in ISO4037-1. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this part of ISO4037. At the time of the publication, the editions indicated were val

26、id. All standards are subject to revision, and parties to agreements based on the part of ISO4037 are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards.

27、 ISO4037-1:, X and gamma reference radiation for calibrating dosemeters and doserate meters and for determining their response as a function of photon energy Part 1: Radiation characteristics and production methods 1) . ISO4037-3:, X and gamma reference radiation for calibrating dosemeters and doser

28、ate meters and for determining their response as a function of photon energy Part 3: Calibration of area and personal dosemeters 2) . ICRU Report 33:1980, Radiation quantities and units. VIM, 1984, International Vocabulary of Basic and General Terms in Metrology, BIPM-IEC-ISO-OIML. 3 Definitions For

29、 the purposes of this part of ISO4037, the definitions given in ICRU Report33, in the International Vocabulary of Basic and General Terms in Metrology (VIM) and the following definitions apply. 3.1 reference conditions conditions of use for a measuring instrument prescribed for performance testing o

30、r conditions to ensure valid comparison of results of measurements VIM NOTEThe reference conditions generally specify reference values or reference ranges for the parameters affecting the measuring instrument. For the purposes of this part of ISO4037, the reference values for temperature, atmospheri

31、c pressure and relative humidity are as follows: ambient temperature: 293,15K; atmospheric pressure: 101,3kPa; relative humidity: 65%. 1) To be published. (Revision of ISO4037:1979) 2) To be published.BSISO4037-2:1997 2 BSI 05-1999 3.2 standard test conditions value (or range of values) of the influ

32、ence quantities VIM or instrument parameters that are specified for the dosimetry of the radiation fields NOTEThe range of values for ambient temperature, atmospheric pressure and relative humidity are as follows: ambient temperature: 291,15K to 295,15K; ambient pressure: 86kPa to106kPa; relative hu

33、midity: 30% to75%. Working outside this range may result in reduced accuracy. 3.3 ionization chamber ionization detector consisting of a chamber filled with a suitable gas, in which an electric field, insufficient to induce gas multiplication, is provided for the collection at the electrodes of char

34、ges associated with the ions and the electrons produced in the sensitive volume of the detector by the ionizing radiation 3 NOTEThe ionization chamber includes the sensitive volume, the collecting and polarizing electrodes, the guard electrode, if any, the chamber wall, the parts of the insulator ad

35、jacent to the sensitive volume and any necessary caps to ensure electron equilibrium. 3.4 ionization chamber assembly ionization chamber and all other parts to which the chamber is permanently attached, except the measuring assembly NOTEFor a cable-connected chamber, it includes the stem, the electr

36、ical fitting and any permanently attached cable or pre-amplifier. For a thin-window chamber, it includes any block of material in which the ionization chamber is permanently embedded. 3.5 measuring assembly device for measuring the current or charge from the ionization chamber and converting it into

37、 a form suitable for display, control or storage 3.6 reference point of the ionization chamber point to which the measurement of the distance from the radiation source to the chamber at a given orientation refers NOTEThe reference point should be marked on the assembly by the manufacturer of the ins

38、trument. If this proves impossible, the reference point should be indicated in the accompanying documentation supplied with the instrument. 3.7 point of test location of the reference point of the ionization chamber for calibration purposes and at which the conventionally true kerma rate (see3.11) i

39、s known 3.8 chamber orientation effect change in the ionization current from the ionization chamber as the directional incidence of the reference radiation is varied 3.9 calibration factorratio of the conventional true value of the quantity the instrument is intended to measure divided by the indica

40、tion of the instrument, corrected to stated reference conditions 3.10 calibration factorfactor which converts the ionization current or charge, corrected to reference conditions, to the conventional true value of the dosimetric quantity at the reference point of the chamber BSI 05-1999 3 BSISO4037-2

41、:1997 3.11 true value value which characterizes a quantity perfectly defined, in the conditions which exist when that quantity is considered NOTEThe true value of a quantity is an ideal concept and, in general, cannot be known exactly. Indeed, quantum effects may preclude the existence of a unique t

42、rue value VIM. 3.12 conventional true value of a quantity best estimate of the value of the quantity to be measured, determined by a primary or secondary standard or by a reference instrument that has been calibrated against a primary or secondary standard EXAMPLE: Within an organization, the result

43、 of a measurement obtained with a secondary standard instrument may be taken as the conventional true value of the quantity to be measured. NOTEA conventional true value is, in general, regarded as being sufficiently close to the true value for the difference to be insignificant for the given purpos

44、e. 3.13 response ratio between the indication of the measuring assembly and the conventional true value of the measured quantity at the position of the reference point in space NOTEThe response usally varies with the spectral and directional distribution of the incident radiation. 3.14 response time

45、 time interval between the instant when a stimulus is subjected to a specified abrupt change and the instant when the response reaches and remains within specified limits of its final steady value VIM 3.15 deviation from linearity percentage deviation from linearity given by: =100 (mQ/Mq1) where M a

46、nd Q refer to the indication and input at a chosen test point, respectively; m is the indication observed for some other input signal q. NOTEFor multirange instruments, the above definition is applicable to each range. 3.16 leakage current total detector current flowing at the operating bias in the

47、absence of radiation 3 3.17 zero drift slow variation with time of the indication of the measuring assembly when the input is short-circuited 3.18 zero shift sudden change in the scale reading of either polarity of a measuring assembly when the setting control is changed from the “zero” mode to the

48、“measure” mode, with the input connected to an ionization chamber in the absence of ionizing radiation other than ambient radiation 3.19 primary standard standard of a particular quantity which has the highest metrological qualities in a given field 3.20 secondary standard standard, the value of whi

49、ch is fixed by direct or indirect comparison with a primary standardBSISO4037-2:1997 4 BSI 05-1999 4 Apparatus 4.1 General The instrument to be used for the measurement of the reference radiation shall be a secondary standard or other appropriate instrument. Generally this comprises an ionization chamber assembly and measuring assembly. In some applications, for example the determination of low kerma rates, other devices such as scintillation dosemeters are used. For high energies from4MeV to9MeV (see10.2 and10.6.3) o