1、Designation: E1026 041E1026 13 An American National StandardStandard Practice forUsing the Fricke Reference-Standard Dosimetry System1This standard is issued under the fixed designation E1026; the number immediately following the designation indicates the year oforiginal adoption or, in the case of
2、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 NOTEEquations 3 and 4 were corrected editorially in August 2005.1. Scope1.1 This practice covers the proce
3、dures for preparation, testing and using the acidic aqueous ferrous ammonium sulfate solutiondosimetry system to measure absorbed dose to water when exposed to ionizing radiation. The system consists of a dosimeter andappropriate analytical instrumentation. The system will be referred to as the Fric
4、ke system. It is classified as a reference-standarddosimetry system (see ISO/ASTM 51261).dosimetry system. The Fricke dosimetry system may be used as either a referencestandard dosimetry system or a routine dosimetry system.1.2 This practice is one of a set of standards that provides recommendations
5、 for properly implementing dosimetry in radiationprocessing, and describes a means of achieving compliance with the requirements of Practice E2628 for the Fricke dosimetrysystem. It is intended to be read in conjunction with Practice E2628.1.3 The practice describes the spectrophotometric analysis p
6、rocedures for the Fricke dosimeter.dosimetry system.1.4 This practice applies only to gamma rays, x-raysradiation, X-radiation (bremsstrahlung), and high-energy electrons.1.5 This practice applies provided the following are satisfied:1.5.1 The absorbed dose range shall be from 20 to 400 Gy (1).21.5.
7、2 The absorbed-dose rate does not exceed 106 Gys1 (2).1.5.3 For radioisotope gamma-raygamma sources, the initial photon energy is greater than 0.6 MeV. For x-raysX-radiation(bremsstrahlung), the initial energy of the electrons used to produce the photons is equal to or greater than 2 MeV. For electr
8、onbeams, the initial electron energy is greater than 8 MeV (see ICRU Reports 34 and 35). MeV.NOTE 1The lower energy limits given are appropriate for a cylindrical dosimeter ampoule of 12-mm outside12 mm diameter. Corrections for dosegradients across an ampoule of that diameter or less are notdisplac
9、ement effects and dose gradient across the ampoule may be required for electron beamsrequired.(3). The Fricke dosimetry system may be used at lower energies by employing thinner (in the beam direction) dosimeter containers (see ICRUReport 35).1.5.4 The irradiation temperature of the dosimeter should
10、 be within the range of 10 to 60C.1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitati
11、ons prior to use.2. Referenced Documents2.1 ASTM Standards:3C912 Practice for Designing a Process for Cleaning Technical GlassesD1193 Specification for Reagent WaterE170 Terminology Relating to Radiation Measurements and DosimetryE178 Practice for Dealing With Outlying ObservationsE275 Practice for
12、Describing and Measuring Performance of Ultraviolet and Visible SpectrophotometersE666 Practice for Calculating Absorbed Dose From Gamma or X Radiation1 This practice is under the jurisdiction ofASTM Committee E61 on Radiation Processing and is the direct responsibility of Subcommittee E61.02 on Dos
13、imetry Systems.Current edition approved Jan. 1, 2004Jan. 1, 2013. Published February 2004March 2013. Originally approved in 1984. Last previous edition approved in 20032004 asE1026 03.E1026 041. DOI: 10.1520/E1026-04E01.10.1520/E1026-13.2 The boldface numbers that appear in parentheses refer to a li
14、st of references at the end of this practice.3 For referenced ASTM and ISO/ASTM standards, visit the ASTM webiste, www.astm.org, or contact ASTM Customer Service at serviceastm.org. For Annual Bookof ASTM Standards volume information, refer to the standards Document Summary page on the ASTM website.
15、This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior edi
16、tions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1E668 Practice for Application of Thermoluminesce
17、nce-Dosimetry (TLD) Systems for Determining Absorbed Dose inRadiation-Hardness Testing of Electronic DevicesE925 Practice for Monitoring the Calibration of Ultraviolet-Visible Spectrophotometers whose Spectral Bandwidth does notExceed 2 nmE958 Practice for Estimation of the Spectral Bandwidth of Ult
18、raviolet-Visible SpectrophotometersE2628 Practice for Dosimetry in Radiation Processing2.2 ISO/ASTM Standards:ISO/ASTM 51205 Method for Using the Ceric-Cerous Sulfate Dosimetry System3ISO/ASTM 51261 GuidePractice for Selection and Calibration of Routine Dosimetry Systems for Radiation ProcessingISO/
19、ASTM 51707 Guide for Estimating Uncertainties in Dosimetry for Radiation Processing2.3 ISO/IEC Standard:ISO/IEC 17025 General requirements for the competence of testing and calibration laboratories42.4 International Commission on Radiation Units and Measurements (ICRU) Reports:5ICRU Report 3414 The
20、Dosimetry of Pulsed RadiationRadiation Dosimetry: X Rays and Gamma Rays with Maximum PhotonEnergies Between 0.6 and 50 MeVICRU Report 35 Radiation Dosimetry: Electrons with Initial Energies Between 1 and 50 MeVICRU Report 60 Fundamental Quantities and Units for Ionizing Radiation4ICRU Report 64 Dosi
21、metry of High-Energy Photon Beams based on Standards of Absorbed Dose to WaterICRU Report 80 Dosimetry Systems for Use in Radiation ProcessingICRU Report 85a Fundamental Quantities and Units for Ionizing Radiation2.5 Joint Committee for Guides in Metrology (JCGM) Reports:6JCGM 100:2008 GUM 1995 , wi
22、th minor corrections, Evaluation of measurement data Guide to the Expression of Uncertaintyin Measurement2.6 National Research Council Canada (NRCC):PIRS-0815 The IRS Fricke Dosimetry System73. Terminology3.1 Definitions:3.1.1 Fricke Dosimetry Systemapproved laboratoryconsists of a liquid chemical d
23、osimeter (composed of ferrous sulfate orferrous ammonium sulfate in aqueous sulfuric acid solution), a spectrophotometer (to measure optical absorbance) and itsassociated reference standards, and procedures for its use.laboratory that is a recognized national metrology institute; or has beenformally
24、 accredited to ISO/IEC 17025; or has a quality system consistent with the requirements of ISO/IEC 17025.3.1.1.1 DiscussionThe Fricke dosimetry system is considered a reference-standard dosimetry system. Sodium chloride is usually added to dosimetricsolution to minimize the effects of organic impurit
25、ies.A recognized national metrology institute or other calibration laboratoryaccredited to ISO/IEC 17025 should be used in order to ensure traceability to a national or international standard. A calibrationcertificate provided by a laboratory not having formal recognition or accreditation will not n
26、ecessarily be proof of traceability toa national or international standard.3.1.2 molar linear absorption coeffcient (m)a constant relating the spectrophotometric absorbance (A) of an opticallyabsorbing molecular species at a given wavelength () per unit pathlength (d) to the molar concentration (c)
27、of that species insolution:m 5 Ad 3c! (1)Unit: m2molmol-13.1.3 net absorbance (A)change in measured optical absorbance at a selected wavelength determined as the absolutedifference between the pre-irradiation absorbance, Ao, and the post-irradiation absorbance, A as follows: A = |A Ao|3.1.3 radiatio
28、n chemical yield (G(x)the quotient of n(x) by , where n(x) is the mean amount of a specified entity, x, produced,destroyed, or changed by the mean energy, , imparted to the matter.4 Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http:/www.
29、ansi.org.5 Available from the International Commission on Radiation Units and Measurements (ICRU), 7910 Woodmont Ave., Suite 800,400, Bethesda, MD 20814.20841-3095,http:/www.icru.org.6 Document produced by Working Group 1 of the Joint Committee for Guides in Metrology (JCGM/WG1). Available free of c
30、harge at the BIPM website(http:/www.bipm.org).7 Available from the National Research Council, Ionizing Radiation Standards, Institute for National Measurement Standards, Ottawa, Ontario. K1A 0R6.E1026 132Gx! 5Snx!H D (2)Unit: molJ-13.1.4 reference standard dosimetry systemdosimetry system, generally
31、 having the highest metrological quality available at agiven location or in a given organization, from which measurements made there are derived.3.1.5 type I dosimeterdosimeter of high metrological quality, the response of which is affected by individual influencequantities in a well-defined way tha
32、t can be expressed in terms of independent correction factors.3.2 Definitions of other terms used in this standard that pertain to radiation measurement and dosimetry may be found inTerminology E170. Definitions in E170 are compatible with ICRU 60;85a; that document, therefore, may be used as an alt
33、ernativereference.4. Significance and Use4.1 The Fricke dosimetry system provides a reliable means for measurement of absorbed dose to water, based on a process ofoxidation of ferrous ions to ferric ions in acidic aqueous solution by ionizing radiation (34). In situations not requiring traceabilityt
34、o national standards, this system can be used for absolute determination of absorbed dose, dose without calibration, as the radiationchemical yield of ferric ions is well characterized.characterized (see Appendix X3).4.1.1 In situations requiring traceability to national standards, response of the F
35、ricke system shall be verified by means ofcomparison of expected and measured dose values. This verification process requires irradiation of dosimeters in a calibrationfacility having measurement traceability to nationally or internationally recognized standards.4.2 The dosimeter is an air-saturated
36、 solution of ferrous sulfate or ferrous ammonium sulfate that indicates absorbed dose byan increase in optical absorbance at a specified wavelength. A temperature-controlled calibrated spectrophotometer is used tomeasure the absorbance.absorbance (ICRU 80).4.3 The Fricke dosimeter response is depend
37、ent on irradiation temperature and measurement temperature. Thus, correctionsmay have to be applied to the radiation chemical yield (G) for irradiation temperature and to the molar linear absorption coefficient() for measurement temperatures.4.4 The absorbed dose in materials other than water may be
38、 calculated using procedures given in Practices E666 and E668, andISO/ASTM 51261, if the material is irradiated under equivalent conditions.4.5 There are two factors associated with use of the Fricke system at energies below those specified in 1.4.3:4.5.1 The radiation chemical yield changes signifi
39、cantly at low photon energies (4), and4.5.2 For electron energy below 8 MeV, dosimeter response requires correction for dose gradients across the dosimeter with adimension in the beam direction of 12 mm (see ICRU Report 35).4.6 The lower energy limits given (refer to 1.4.3) are appropriate for a cyl
40、indrical dosimeter ampoule of 12-mm outsidediameter. With some difficulty, the Fricke system may be used at lower energies by employing thinner (in the beam direction)dosimeters (see ICRU Report 35). Below the lower limits for energy, there will be significant dose gradients across the ampoulewall.
41、In addition, it is difficult to perform accurate calculations for a cylindrical ampoule.5. Effect of Influence Quantities5.1 The Fricke dosimeter response (change in optical absorbance) to a given radiation dose is dependent on irradiationtemperature and measurement temperature. Thus, corrections ma
42、y have to be applied for changes to the radiation chemical yield(G) for irradiation temperature and to the molar linear absorption coefficient () for measurement temperatures. both (Fe3+) andG(Fe3+) increase with increase in temperature. The subscripts indicate the temperature of irradiation and mea
43、surement, asapplicable.Tmeas 525110.0069 Tmeas 225!# (3)GTirrad 5G25110.0012 Tirrad225!# (4)5.2 The radiation chemical yield depends on the type and energy of the radiation employed and, in particular, changessignificantly at low photon energies (5).6. Interferences6.1 The Fricke dosimetric solution
44、 dosimeter response is extremely sensitive to impurities, impurities in the solution,particularly organic impurities. Even in trace quantities, impurities can cause a detectable change in the observed response. Forhigh accuracy, organic materials shall not be used for any component in contact with t
45、he solution, unless it has been demonstratedthat the materials do not affect the dosimeter response.6.2 Traces of metal ions in the irradiated and unirradiated dosimetric solutions can also affect dosimeter response. Therefore,do not use metal in any component in contact with the solutions.E1026 133
46、6.3 If flame sealing sealed ampoules are used as the dosimeters, exercise care in filling ampoules to avoid depositing solutionin the ampoule neck. Subsequent heating during sealing of the ampoule may cause undesirable chemical change in the dosimetricsolution remaining inside the ampoulesampoule ne
47、ck. For the same reason, exercise care to avoid heating the body of the ampouleduring sealing.6.4 Thermal oxidation (as indicated by an increase in optical absorbance), in the absence of radiation, is a function of ambienttemperature. At normal laboratory temperatures (about 20 to 25C), this effect
48、may be significant if there is a long period of timebetween solution preparation and photometric measurement. This interference is discussed further in 8.49.3.6.5 The dosimetric solution is somewhat sensitive to ultraviolet light and should be kept in the dark for long-term storage. Nospecial precau
49、tions are required during routine handling under normal laboratory lighting conditions, but strong UV sources suchas sunlight should be avoided.7. Apparatus7.1 For the analysis of the dosimetric solution, use a high-precision spectrophotometer capable of measuring absorbance valuesup to 2 with an uncertainty of no more than 61 % in the region of 300 nm. Use a quartz cuvette with 5- or 10-mm pathlengthfor spectrophotometric measurement of the solution. The cuvette capacity must be small enough to allow it to be thoroughly rin
