1、Designation:F254718Standard Test Method forDetermining the Attenuation Properties in a Primary X-rayBeam of Materials Used to Protect Against RadiationGenerated During the Use of X-ray Equipment1This standard is issued under the fixed designation F2547;the number immediately following the designatio
2、n indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method establishes procedures for
3、 measuringthe attenuation of X-rays by protective materials at acceleratingpotentials from 60 to 130 kVp.1.2 This test method provides attenuation values of primarybeam X-radiation.1.3 This test method applies to both leaded and non-leadedradiation protective clothing materials.1.4 This standard doe
4、s 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,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.5 This international st
5、andard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Ref
6、erenced Documents2.1 ASTM Standards:2F1494 Terminology Relating to Protective Clothing3.Terminology3.1 Definitions:3.1.1 attenuation,nfor radiological protective material,the reduction in the intensity of the X-ray beam resulting fromthe interactions between the X-ray beam and the protectivematerial
7、 that occur when the X-ray beam passes through theprotective material.3.1.1.1 DiscussionIn this test method,the attenuation iscalculated as 1 minus the ratio of the measured exposure witha protective material in the beam to the measured exposurewithout the protective material in the beam at a specif
8、icaccelerating potential.Multiplying the resulting value by 100gives percent attenuation.Attenuationpercent!5S1 2exposure with sampleexposure without sampleD3100(1)3.1.2 coeffcient of variation,nthe ratio of the standarddeviation of a sample to the sample mean.3.1.3 exposure,nfor radiological purpos
9、es,the amount ofionization in air at standard conditions caused by interactionwith X-rays,expressed in units of Roentgen(R)or milliroent-gen(mR).The SI units are Coulomb per kilogram(C/kg).1 Roentgen=2.58 104C/kg.3.1.4 half-value layer(HVL),nthe thickness of aluminum,in millimetres(commonly designat
10、ed mmAl),that reduces theintensity of the X-ray beam by one half.3.1.4.1 DiscussionThe HVLis dependent on the energy ofthe X-ray beam and,therefore,is different for X-rays producedat different accelerating potentials.3.1.5 ionization chamber,na device that measures theelectrical charge liberated dur
11、ing the ionization of air mol-ecules by electromagnetic radiation(X-rays for the purposes ofthis test method),expressed in units of coulombs per kilogramof air.3.1.6 kilovolts,peak(kVp),nthe maximum electrical po-tential across an X-ray tube during an exposure,expressed inkilovolts.3.1.7 lead equiva
12、lency,nfor radiological protectivematerial,the thickness in millimetres of lead(commonlydesignated mmPb)of greater than 99.9%purity that providesthe same attenuation as a given protective material.3.1.7.1 DiscussionThis test method provides the attenua-tion of the material and not the lead equivalen
13、cy.Determininglead equivalency would require testing lead of known thicknessand purity,and comparing the attenuation of the protectivematerial with the attenuation of the lead.The lead equivalencymay be determined based on published half or tenth thickness1This test method is under the jurisdiction
14、ofASTM Committee F23 on PersonalProtective Clothing and Equipment and is the direct responsibility of SubcommitteeF23.70 on Radiological Hazards.Current edition approved Jan.1,2018.Published January 2018.Originallyapproved in 2006.Last previous edition approved in 2013 as F2547 06(2013).DOI:10.1520/
15、F2547-18.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box
16、 C700,West Conshohocken,PA 19428-2959.United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.1 values.When lead equivalency is stated,the source of pub-lished values shall be stated as the basis of calculation.X 5 lnSIIoD2en(2)w