1、Designation:F 947 85(Reapproved 1996)Standard Test Method forDetermining Low-Level X-Radiation Sensitivity ofPhotographic Films1This standard is issued under the fixed designation F 947;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision
2、,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon(e)indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method determines the maximum x-ray sensi-tivity coefficient(slope of diffuse visual density versus
3、 x-rayexposure)of film/processing combinations for low quantitiesof x-ray exposure to silver halide photographic film.Thiscoefficient can be used to assess the relative susceptibility offilms to damage from x-ray exposure,such as that encounteredin airport and similar security screening systems.1.2
4、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 limitations prior to use.2.Referenced Documents
5、2.1ANSI Standard2PH2.19(1976)American National Standard Conditions forDiffuse and Doubly-Diffuse Transmission Measurements(Transmission Density)3.Significance and Use3.1 The x-ray sensitivity coefficient is used to estimate theamount of x-ray exposure that would produce a visuallysignificant effect
6、on a film.This value may be useful inestablishing maximum allowable x-ray doses for classes of filmproducts,for example,consumer color films,scientific andx-ray films,etc.4.Calibration and Standardization4.1 Radiant Energy Quality:4.1.1 Tungsten target x-ray tubes shall be used to exposetest films.I
7、nherent filtration of the tube plus an additionalaluminum3filter located as close to the x-ray tube as possibleshall provide a total filtration equivalent to 3.7 6 0.5 mm ofaluminum.4.1.2 The kilovoltage applied to the x-ray tube shall beadjusted to yield a half-value layer(HVL)of 3.4 6 0.5 mm ofalu
8、minum as determined with a radiation measuring devicehaving a quantum energy response flat within 65%over theeffective energy range from 30 to 100 keV.That is,with themeasuring device at or adjacent to the film exposing position,the tube kilovoltage shall be adjusted4such that the introduc-tion of 3
9、.4 mm of aluminum3into the x-ray beam close to thetube,in addition to the filtration specified in 4.1.1,will reducethe measured x-ray intensity to 50 6 1%of its value withoutthis HVL aluminum in the beam.The HVL aluminum must ofcourse be removed for subsequent film exposure and exposuremeasurement.4
10、.2 Secondary X-Rays:4.2.1 To minimize secondary radiation during dosimetryand exposure of test films,x-ray beams shall be diaphragmedto as small a size as will properly include the exposure area forthe films(and exposure measuring device,if included).Exceptfor a 1 mm minimum thickness sheet of lead
11、for backing thefilm container,the lightest supports possible of low-atomic-number material shall be used for supporting the film andexposure measuring device.Other materials in the x-ray beamshall be kept at least 50 cm distant from the film.The amountof secondary radiation reaching the film and mea
12、suring deviceshall be less than 3%of the primary x-rays.4.2.2 The presence of secondary(scattered)radiation shallbe tested by plotting the inverse square root of the exposurerate as a function of distance from the source.Absence ofsignificant secondary radiation is indicated when the resultingplot i
13、s a straight line passing through the origin.Such radiationis excessive if the point corresponding to the observed expo-sure rate at the distance used for film exposures is more than3%below the best straight line from the origin among theplotted points.Measurements shall be made at enough dis-tances
14、 to provide a reliable indication of secondary radiationreaching the exposure plane and shall include distances ap-proximately equally spaced from one-half that between the1This test method is under the jurisdiction of ASTM Committee F-12 onSecurity Systems and Equipment and is the direct responsibi
15、lity of SubcommitteeF12.60 on Controlled Access Security,Search and Screening Equipment.Current edition approved July 26,1985.Published October 1985.2Available from American National Standards Institute,11 W.42nd St.,13thFloor,New York,NY 10036.3Aluminum Association Alloy 1100,or the equivalent.4The
16、 HVL specification should be satisfied with approximately 80 kV constantpotential,approximately 80 kVp 3-phase,or approximately 95 kVp single phaseapplied to the x-ray tube.1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.x-ray tube focal spot and exposure plane to at least 10%beyond the exposure plane,if possible(film container and leadbacking removal).5.Conditioning5.1 The temperature of the film during exposure shall be 206 5C.The m
