ANSI ISO ASTM 51707-2015 Standard Guide for Estimation of Measurement Uncertainty in Dosimetry for Radiation Processing.pdf

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1、ISO/ASTM 51707:2015(E)Standard Guide forEstimation of Measurement Uncertainty in Dosimetry forRadiation Processing1This standard is issued under the fixed designation ISO/ASTM 51707; the number immediately following the designation indicates theyear of original adoption or, in the case of revision,

2、the year of last revision.1. Scope1.1 This standard provides guidance on the use of conceptsdescribed in the JCGM Evaluation of Measurement Data Guide to the Expression of Uncertainty in Measurement(GUM) to estimate the uncertainties in the measurement ofabsorbed dose in radiation processing.1.2 Met

3、hods are given for identifying, evaluating and esti-mating the components of measurement uncertainty associatedwith the use of dosimetry systems and for calculating com-bined standard measurement uncertainty and expanded (over-all) uncertainty of dose measurements based on the GUMmethodology.1.3 Exa

4、mples are given on how to develop a measurementuncertainty budget and a statement of uncertainty.1.4 This document is one of a set of standards that providesrecommendations for properly implementing dosimetry inradiation processing, and provides guidance for achievingcompliance with the requirements

5、 of ISO/ASTM 52628 relatedto the evaluation and documentation of the uncertaintiesassociated with measurements made with a dosimetry system.It is intended to be read in conjunction with ISO/ASTM 52628,ISO/ASTM 51261 and ISO/ASTM 52701.1.5 This guide does not address the establishment of processspeci

6、fications or conformity assessment.1.6 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limit

7、ations prior to use.2. Referenced documents2.1 ASTM Standards:2E170 Terminology Relating to Radiation Measurements andDosimetryE456 Terminology Relating to Quality and Statistics2.2 ISO/ASTM Standards:251261 Practice for Calibration of Routine Dosimetry Sys-tems for Radiation Processing51608 Practic

8、e for Dosimetry in an X-Ray (Bremsstrahlung)Facility for Radiation Processing51649 Practice for Dosimetry in an Electron Beam Facilityfor Radiation Processing at Energies Between 300 keVand 25 MeV51702 Practice for Dosimetry in a Gamma Facility forRadiation Processing52628 Practice for Dosimetry in

9、Radiation Processing52701 Guide for Performance Characterization of Dosim-eters and Dosimetry systems for Use in Radiation Pro-cessing2.3 ISO Documents:ISO 11137-1 Sterilization of Health Care Products Radia-tion Requirements for Development, Validation andRoutine Control of a Sterilization Process3

10、ISO/IEC 17025 General Requirements for the Competenceof Testing and Calibration Laboratories41This guide is under the jurisdiction of ASTM Committee E61 on RadiationProcessing and is the direct responsibility of Subcommittee E61.01 on Dosimetry,and is also under the jurisdiction of ISO/TC 85/WG 3.Cu

11、rrent edition approved Sept. 8, 2014. Published February 2015. Originallypublished as ASTM E 170795. Last previous ASTM edition E 1707951. ASTME 1707951was adopted by ISO in 1998 with the intermediate designation ISO15572:1998(E). The present International Standard ISO/ASTM 51707:2015(E) is amajor r

12、evision of the last previous edition ISO/ASTM 51707:2005(E), whichreplaced ISO/ASTM 51707:2002(E).2For referenced ASTM and ISO/ASTM standards, visit the ASTM website,www.astm.org, or contact ASTM Customer Service at serviceastm.org. ForAnnual Book of ASTM Standards volume information, refer to the s

13、tandardsDocument Summary page on the ASTM website.3Available from Association for the Advancement of Medical Instrumentation,1110 North Glebe Road, Suite 220, Arlington, VA 22201-4795, U.S.A.4Available from International Organization for Standardization (ISO), 1, ch. dela Voie-Creuse, CP 56, CH-1211

14、 Geneva 20, Switzerland, http:/www.iso.org. ISO/ASTM International 2017 All rights reservedThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Gu

15、ides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.12.4 Joint Committee for Guides in Metrology (JCGM)Reports:JCGM 100:2008, GUM 1995, with minor correc-tions, Evaluation of measurement data Guide to theExpression of Uncertainty in Measurement

16、5JCGM 200:2008, VIM, International vocabulary of metrol-ogy Basis and general concepts and associated terms62.5 ICRU Reports:7ICRU Report 80 Dosimetry Systems for Use in RadiationProcessingICRU Report 85a Fundamental Quantities and Units forIonizing Radiation3. Terminology3.1 Definitions:NOTE 1For d

17、efinitions quoted here from VIM, only the text of thedefinition is kept here. Any NOTES or EXAMPLES are not included.They can be reviewed by referring to VIM (JCGM 200:2008).3.2 Definitions:3.2.1 approved laboratorylaboratory that is a recognizednational metrology institute; or has been formally acc

18、redited toISO/IEC 17025; or has a quality system consistent with therequirements of ISO/IEC 17025.3.2.1.1 DiscussionA recognized national metrology insti-tute or other calibration laboratory accredited to ISO/IEC17025 should be used for irradiation of dosimeters or dosemeasurements for calibration i

19、n order to ensure traceability toa national or international standard. A calibration certificateprovided by a laboratory not having formal recognition oraccreditation will not necessarily be proof of traceability to anational or international standard.3.2.2 arithmetic mean, average GUM, C.2.19sum of

20、values divided by the number of values:x 51n(ixi, i 5 1, 2, 3 n (1)where:xi= individual values of parameters with i =1,2,3.n.3.2.2.1 DiscussionThe term mean is used generallywhen referring to a population parameter and the term aver-age when referring to the result of a calculation on the dataobtain

21、ed in a sample.3.2.3 calibration curve VIM, 4.31expression of therelation between indication and corresponding measured quan-tity value.3.2.3.1 DiscussionIn radiation processing standards, theterm “dosimeter response” is generally used for “indication”.3.2.4 coeffcient of variation (CV)sample standa

22、rd devia-tion expressed as a percentage of sample average value (see3.2.2 and 3.2.19):CV 5Sx3100 % (2)3.2.5 combined standard measurement uncertainty VIM,2.31standard measurement uncertainty that is obtained us-ing the individual standard measurement uncertainties associ-ated with the input quantiti

23、es in a measurement model.3.2.5.1 Discussion(1) It is also referred to as combined standard uncertainty.(2) In case of correlations of input quantities in a measure-ment model, covariances must also be taken into account whencalculating the combined standard measurement uncertainty.3.2.6 coverage fa

24、ctor (k) VIM, 2.38number larger thanone by which a combined standard measurement uncertainty ismultiplied to obtain an expanded measurement uncertainty.3.2.6.1 DiscussionA coverage factor, k, is typically in therange of 2 to 3 (see 5.2.4).3.2.7 expanded uncertainty GUM, 2.3.5quantity defin-ing the i

25、nterval about the result of a measurement that may beexpected to encompass a large fraction of the distribution ofvalues that could reasonably be attributed to the measurand.3.2.7.1 DiscussionExpanded uncertainty is obtained bymultiplying the combined standard uncertainty by a coveragefactor, the va

26、lue of which determines the magnitude of thefraction. Expanded uncertainty is also referred to as overalluncertainty.3.2.8 influence quantity VIM, 2.52quantity that, in adirect measurement, does not affect the quantity that is actuallymeasured, but affects the relation between the indication andthe

27、measurement result.3.2.8.1 DiscussionIn radiation processing dosimetry, thisterm includes temperature, relative humidity, time intervals,light, radiation energy, absorbed dose rate, and other factorsthat might affect dosimeter response, as well as quantitiesassociated with the measurement instrument

28、.3.2.9 level of confidenceprobability that the value of aparameter will fall within the given range.3.2.10 measurand VIM, 2.3quantity intended to be mea-sured.3.2.10.1 DiscussionIn radiation processing dosimetry, themeasurand is the absorbed dose (Gy) or simply dose.3.2.11 measurement VIM, 2.1proces

29、s of experimentallyobtaining one or more quantity values that can reasonably beattributed to a quantity.3.2.12 measurement uncertainty VIM, 2.26non-negativeparameter characterizing the dispersion of the quantity valuesbeing attributed to a measurand, based on the information used.3.2.12.1 Discussion

30、(1) Measurement uncertainty includes components arisingfrom systematic effects, such as components associated withcorrections and the assigned quantity values of measurement5Document produced by Working Group 1 of the Joint Committee for Guides inMetrology (JCGM/WG 1). Available free of charge at th

31、e BIPM website (http:/www.bipm.org).6Document produced by Working Group 2 of the Joint Committee for Guides inMetrology (JCGM/WG 2). Available free of charge at the BIPM website (http:/www.bipm.org).7Available from International Commission on Radiation Units andMeasurements, 7910 Woodmont Ave., Suit

32、e 800 Bethesda, MD 20814, U.S.A.ISO/ASTM 51707:2015(E)2 ISO/ASTM International 2017 All rights reserved standards, as well as the definitional uncertainty. Sometimesestimated systematic effects are not corrected for but, instead,associated measurement uncertainty components are incorpo-rated.(2) The

33、 parameter may be, for example, a standard devia-tion called standard measurement uncertainty (or a specifiedmultiple of it), or the half-width of an interval, having a statedcoverage probability.(3) Measurement uncertainty comprises, in general, manycomponents. Some of these may be evaluated by Typ

34、e Aevaluation of measurement uncertainty from the statisticaldistribution of the quantity values from series of measurementsand can be characterized by standard deviations. The othercomponents, which may be evaluated by Type B evaluation ofmeasurement uncertainty, can also be characterized by stan-d

35、ard deviations, evaluated from probability density functionsbased on experience or other information.(4) In general, for a given set of information, it is under-stood that the measurement uncertainty is associated with astated quantity value attributed to the measurand. A modifica-tion of this value

36、 results in a modification of the associateduncertainty.3.2.13 metrological traceability VIM, 2.41property of ameasurement result whereby the result can be related to areference through a documented unbroken chain ofcalibrations, each contributing to the measurement uncertainty.3.2.13.1 Discussion(1

37、) The unbroken chain of calibrations is referred to as“traceability chain”.(2) Metrological traceability of a measurement result doesnot ensure that the measurement uncertainty is adequate for agiven purpose or that there is an absence of mistakes.(3) The abbreviated term “traceability” is sometimes

38、 usedto mean metrological traceability as well as other concepts,such as sample traceability, document traceability, instru-ment traceability or material traceability, where the history(“trace”) of an item is meant. Therefore, the full term of“metrological traceability” is preferred if there is any

39、risk ofconfusion.3.2.14 quadraturemethod used in estimating combinedstandard uncertainty from independent sources by taking thepositive square root of the sum of the squares of individualcomponents of uncertainty, for example, coefficient of varia-tion.3.2.15 quantity VIM, 1.1property of a phenomeno

40、n,body, or substance, where the property has a magnitude thatcan be expressed as a number and a reference.3.2.16 quantity value VIM, 1.19number and referencetogether expressing magnitude of a quantity.3.2.16.1 DiscussionFor example, absorbed dose of 25kGy.3.2.17 repeatability (of results of measurem

41、ents) GUM,B.2.15closeness of the agreement between the results ofsuccessive measurements of the same measurand carried outunder the same conditions of measurement.3.2.17.1 Discussion(1) These conditions are called repeatability conditions.(2) Repeatability conditions include: the same measure-ment p

42、rocedure, the same observer, the same measuringinstrument used under the same conditions, the same location,repetition over a short period of time.(3) Repeatability may be expressed quantitatively in termsof the dispersion characteristics of the results.3.2.18 reproducibility (of results of measurem

43、ents) GUM,B.2.16closeness of the agreement between the results ofmeasurements of the same measurand carried out underchanged conditions of measurement.3.2.18.1 Discussion(1) A valid statement of reproducibility requires specifica-tion of the conditions changed.(2) The changed conditions may include:

44、 principle ofmeasurements, method of measurement, observer, measuringinstrument, reference standard, location, conditions of use andtime.(3) Reproducibility may be expressed quantitatively interms of the dispersion characteristics of the results.3.2.19 sample standard deviation (S) adapted from GUM,

45、C.2.21measure of dispersion of values of the same mea-surand expressed as the positive square root of the samplevariance.3.2.20 sample variance GUM, C.2.20measure ofdispersion, which is the sum of the squared deviations ofobservations from their average divided by (n 1), given by theexpression:S25(x

46、i2 x!2n 2 1!(3)where:xi= individual value of parameter with i = 1, 2 . n, andx = mean of n values of parameter (see 3.2.2).3.2.21 standard measurement uncertainty VIM, 2.30measurement uncertainty expressed as a standard deviation.3.2.21.1 DiscussionAlso referred to as standard uncer-tainty of measur

47、ement or standard uncertainty.3.2.22 true value VIM, 2.11quantity value consistentwith the definition of a quantity.3.2.22.1 DiscussionTrue value is by its nature indetermi-nate and only an idealized concept. In this guide the terms “truevalue of a measurand” and “value of a measurand” are viewedas

48、equivalent (see 5.1.1).3.2.23 Type A evaluation of measurement uncertainty VIM,2.28evaluation of a component of measurement uncertaintyby a statistical analysis of measured quantity values obtainedunder defined measurement conditions.3.2.24 Type B evaluation of measurement uncertainty VIM,2.29evalua

49、tion of a component of measurement uncertaintydetermined by means other than a Type A evaluation ofmeasurement uncertainty.3.2.25 uncertainty budget VIM, 2.33statement of a mea-surement uncertainty, of the components of that measurementuncertainty, and of their calculation and combination.ISO/ASTM 51707:2015(E)3 ISO/ASTM International 2017 All rights reserved