Beta Particle Radiation Instrumentation and Sources

1 Page 1 NBSMeasurementServices: Calibrationof Beta-ParticleRadiation InstrumentationandSources JohnS.Pruitt ChristopherG.Soares MargareteEhrlich NBS Special Publication 250-21 U.S.DepartmentofCommerce NationalBureauofStandards Open at page → 3 Page 3 NBSMEASUREMENTSERVICES: CALIBRATIONOFBETA-PARTICLE RADIATIONINSTRUMENTATION ANDSOURCES JohnS.Pruitt ChristopherG.Soares MargareteEhrlich CenterforRadiationResearcli NationalMeasurementLaboratory NationalBureauofStandards... Open at page → 4 Page 4 LibraryofCongressCatalogCardNumber:88-600514 NationalBureauofStandardsSpecialPublication250-21 Natl.Bur.Stand.(U.S.),Spec.Publ.250-21,75pages(Apr.1988) CODEN:XNBSAV U.S.GOVERNMENTPRINTINGOFFICE WASHINGTON: 1988 Forsaleby... Open at page → 5 Page 5 PREFACE Thecalibration andrelatedmeasurement servicesoftheNationalBureau ofStandardsareintendedtoassistthemakersandusersofprecision measuringinstruments inachievingthehighestpossiblelevelsof accuracy,quality,andproductiv... Open at page → 6 Page 6 ABSTRACT InaprojectfundedjointlybytheNationalBureauofStandards(NBS)and theNuclearRegulatoryCommission(NRC),NBShasdeveloped acalibration facilityforbeta-particle instruments andsourcesusedinradiation- protectiondosimetry.... Open at page → 7 Page 7 TABLEOFCONTENTS Page Preface 111 Abstract 1v ListofTables v1 1 ListofFigures viii 1.HistoryandDescription ofService 1 1.1QuantityforReportingCalibrationResults 1 1.2SourcesandInstrumentsAcceptedforCalibration 1 1.3Proced... Open at page → 8 Page 8 TABLEOFCONTENTS(Continued) Page 4.4SpectralCharacterization byMeansofPulse-Height Distributions. 24 4.5Uncertainty intheCalibration ofBeta-ParticleSourcesand TransferIonizationChambersSubmittedtoNBS 31 5.Characterization... Open at page → 9 Page 9 LISTOFTABLES Page Table1.Characteristics ofAmersham-Buchler Beta-ParticleSources 4 Table2.TypicalExamplesforCorrectionFactorstoMeasured IonizationCurrents 11 Table3.ValuesofParameters aandBforAirDensityCorrectionFactor 1... Open at page → 10 Page 10 LISTOFFIGURES Page Figure1.Theoretical Beta-ParticleSpectrafortheRadionuclides Employed 5 Figure2.Beta-Particle CalibrationFacility 6 Figure3.Extrapolation IonizationChamber: CrossSectionthroughthe FrontPortion;Schematic... Open at page → 11 Page 11 1.HistoryandDescription ofService Between1982and1985,theNationalBureauofStandards(NBS),with partialsupportfromtheU.S.NuclearRegulatoryCommission,developed a facilitysuitedtoestablish aserviceforcalibratingcertainuser-own... Open at page → 12 Page 12 905r+90Yand204y]sources isreportedas3percent,thatfor^'^^Pmsourcesas 5percent,andthatforthin-window parallei-plateionizationchambersas 3percentwhencalibratedwiththe^°Sr+^^Yand 204-|-] sourcesand5percent whencalibratedwith... Open at page → 13 Page 13 (2)anextrapolation ionizationchambersuitedforthedetermination of absorbed-dose ratestowateratdistancesfromthebeta-particle sourcesappropriate forthestudyofradiation-protection instruments; (3)arugged(althoughthin-walled)... Open at page → 14 Page 14 Table1.Characteristics ofAmersham-Buchler Beta-Particle Sources (a)SourceStructureandActivity Radionuclide HalfLife Structure Source NominalActivity rlDt) ^ \\Kj 1 j ,UdLc 90sr+90Y 28.5y ^"^Srcarbonate 50mg/cm^Ag 1850(50... Open at page → 15 Page 15 Beta-Particle Energy,MeV Figure1.Theoretical Beta-Particle SpectrafortheRadionuclides Employed [2],PlottedisthenumberofbetaparticlesperMeVforonetransition fromtheoriginalstate,againstbeta-particle energyinMeV, 5 Open at page → 16 Page 16 Figure2.Beta-Particle CalibrationFacility. Thesource-support standis shownattheright,theextrapolation ionizationchamberattheleft,anda beamflatteningfiltersupportedbywiresin-between. Thepicturedflattening filterisforthe^'... Open at page → 17 Page 17 enoughtosimulate aphantomofinfinitesize. Theplateseparation ofthe ionizationchamberisvariableandcanbeaccuratelydeterminedbymeansofa micrometermeasurement (seescrewonendofchamberatleft). Thethin entrancewindowforthebetapa... Open at page → 18 Page 18 PMMA Brass Aluminum Graphite-Coated PTPFoi Electrodes: Collecting HighVoltage Guard Fig.3.Extrapolation IonizationChamber: CrossSectionthroughtheFront Portion;SchematicRepresentation. Thecollectingandguardelectrodes(grap... Open at page → 19 Page 19 Figure4showstheresultsofcurrentmeasurements asafunctionofplate separationwiththethreetypesofsources,afterapplication ofcertain corrections. Thesecorrections areintroduced ineq.(1)below,andare subsequentlydiscussed indeta... Open at page → 20 Page 20 < 20 LJ q: o IA 1 111 UJ 10 < o UJ h- O LlI (T CC 0o o PLATESEPARATION,mm Fig.4.CurrentMeasurements intheExtrapolation IonizationChamberasa FunctionofNominalElectrode-Plate Separation(MicrometerReadingof ChamberDepth). T... Open at page → 21 Page 21 Table2,TypicalExamplesforCorrectionFactorstoMeasuredIonization Currents(fromDataBooks863and868) ValueofCorrectionFactorfor SymbolCorrectiontoReferenceConditions 2oni 90sr+90Y A.ChamberCorrectionFactors ^foil entrancefoil... Open at page → 22 Page 22 (c) ^atten' correctionforattenuation inthechamberairgap,was determinedbymeasuringchambercurrentasafunctionofdistanceybetween sourceandchamberusingafixedairgapd=0.5mm. Itwasfoundthat,after multiplyingthecurrent Ibythesqua... Open at page → 23 Page 23 (g)^recom' correctionforionrecombination anddiffusion intheair insidethechamber, isusuallyquitesmallforprotection-level measurements. Itonlybecomesappreciable forlargeioncurrentsand/orsmallvoltages. It wascalculatedbymea... Open at page → 24 Page 24 correctionfactor(seecorrection (d)),andaandBareconstants. Table3 showsempiricalvaluesforaand3forallthreetypesofsources,withthe beamsattenuatedbyselectedthicknesses ofPTP.Thesecorrectionswere checkedbyactualmeasurements o... Open at page → 25 Page 25 whereW/e—energyrequiredtoproduceanionpairinair,injoulesper coulomb ; ^air^"" "'^^^''O*averagemassstoppingpowerofwatertothatofdryair, dimensionless ; pQ —densityofdryairatreferenceambientconditions (22°Cand 101.325kPa),in... Open at page → 26 Page 26 -> 1 in <- 14.5mm 1o 13mm t 1 1 Fig.5.DesignofPTWPara1lei-PlateTransferIonizationChamber. Witha potentialof100Vacrossthechamber,absorbed-dose ratestowaterfrom roughly0.3toover30mGy/h(0.5toover50mrad/min)canbemeasured. Du... Open at page → 27 Page 27 2.5.2PrincipleofUse Formeasurements, thefrontsurfaceofthechamberisplacedinthe calibrationplane,afterremovaloftheextrapolation chamber. Ionization currentismeasuredwithanelectrometer. Thecalibrationfactorofthe transfercha... Open at page → 28 Page 28 Operationofthefacility isdescribed insomedetailinthesubsequent partsofsection3.Forgeneralsafetyprecautions intheoperation of electronaccelerators seethepertinentliteraturelistedinsection11,which isonfileintheofficeoftheD... Open at page → 29 Page 29 Figure6.Monoenergetic ElectronBeam-Handling Arrangement. 19 Open at page → 30 Page 30 rates(lessthan2/s). Whenonlyonemonitorwasused,themagnitudeofbeam wanderingandfluctuations inbeamintensitywerelargeenoughtolimit dosimetryreproducibility toabout15percentwhenthebeamwasturnedoff betweenindividualmeasuremen... Open at page → 31 Page 31 usedwerethosedescribed indetailinsection2.4.3. Theresultsareshown intable4.Sincethesourceshadbeeninitiallycalibrated atthePTB,it waspossibletocomparetheNBScalibrations withthoseobtainedatthePTBin asimilargeometryatthesam... Open at page → 32 Page 32 4.2.1DependenceofDoseRateonOff-AxisShiftofDetector Forthisstudy,thedetectorwasmovedhorizontallywithinthecalibra- tionplanesoastocovertheentirebeamcrosssection. Typicalresultsare showninfigure7.Alongthehorizontal linepass... Open at page → 33 Page 33 10 -5 0 5 10 DISTANCEFROMBEAMAXIS,cm 15 Fig.7.DegreeofNon-UniformityofDoseRatealongaHorizontal Linethrough theReferencePoint,Perpendicular totheBeamAxis.Reference distance: 30cmfor^osr+soy and20kji^20cmfor^'^'^Pm, -2-101... Open at page → 34 Page 34 4.3SpectralCharacterization byMeansofMeasurements asaFunctionofDepth inPlastic Measurements weremadeofionizationcurrentintheextrapolation ioniza- tionchancerasafunctionofthickness ofpolyethyleneterephthalate (PTP) addedt... Open at page → 35 Page 35 Figure9.IonizationCurrentasaFunctionofDepthinPTP. 25 Open at page → 36 Page 36 0 800 1600 ^2400 DEPTHINPOLYSTYRENE,mg/cm^ Figure10.Attenuation CurveinPolystyrene forthe2-mCi^osr+soySource. 26 Open at page → 37 Page 37 ENERGY.HaV Figure11. top:SpectrumofI'+^'PmSource,UsedwithFlatteningFilter. Distance: 20cm.Detectoruncol1imated, bottom: Spectrumof 20i+j-i source.UsedwithFlatteningFilter, ShowingInfluenceofLeadCollimatorwithCircular Ape... Open at page → 38 Page 38 1000 distance: 30cm aperture: 1.6nm ENERGY. lleV ENERGY.HcV Figure12.Spectrumof^Osp+soy Sources,ShowingInfluenceofFlattening FilterandofDetectorCollimator. Thetheoretical spectrumof isshown forcomparison, 28 Open at page → 39 Page 39 _ ;jidistance:50cm ENEKGY,HeV Figure13.Spectrumof^Osr+soySourcesUsedwithoutFlatteningFilter, ShowingInfluenceofSource-to-Detector Distance. Detectorcollimatorwith circularaperture,1.6-mmindiameter. 29 Open at page → 40 Page 40 UJ z z < X o a: UJ Q. CO 3 o o 10' z— r—r~n— r— i— i— i— -r— i — -]— i — t— \— r — r 0.98MeV 10^ 10' 1— \— r T— I— I— I— r /1.05MeV JL«J I I I I I L ' ' ' ' ' L 111 ,J L 1.0 2.0 ELECTRONENERGY,MeV Figure14.EnergyCalibrat... Open at page → 41 Page 41 (b)Influenceofsource-to-detector distancefor^QSr+^Qy .Figure13 showsthespectraldistributions atthethreedistancesspecifiedbythe sourcemanufacturer. Theeffectofdistance isseentoberelativelysmall. Therefore, achangeindistan... Open at page → 42 Page 42 Figure15.EffectofAddedPolystyreneAbsorbersonsosr+^oy Spectrum. Detectorcollimatorwithcircularaperture,1.6mmindiameter. 32 Open at page → 43 Page 43 Theestimatesofeachtypearecombinedinquadrature, andthenthetwo resultsarecombinedinquadraturetogiveacombineduncertainty. The confineduncertainty inturnismultipliedbytwo(orthree),togivean overalluncertainty. Table5givesabre... Open at page → 44 Page 44 Table5.Uncertainties intheDetermination ofAbsorbed-Dose RatetoWater fromMeasurements withtheExtrapolation IonizationChamber Parameter SyrTt)ol PercentUncertainty ype A' 204T190Sr+90Y Type b'^ 90Sr+90Yi'^'Pm A.CorrectedIo... Open at page → 45 Page 45 Table6.Uncertainty intheCalibration ofBeta-Particle Sourcesand TransferIonizationChambersSubmittedtoNBS A.SourceCalibration PercentUncertainty ^ Parameter TypeA'* Type 20'*T1 i-7pm2oni90Sr+90Y 90sr+90Y Positioningofextra... Open at page → 46 Page 46 1 I 1 1 1 cm 1 1 1 n r> r> i 1 1 \— 1// e - \ // " o 1// o ca // «» nee '/yi. " 1/X^o «* '//O o // 1- o 1/1 5 // ^ — — c c // p o 1 o j o o f ' 1 c 1 ^ 1 _ V 1 - €> - O \ \ «< ^ o o CM I8\ 1 1 1 1 1 1 I 1 1 i\ \I'll o on... Open at page → 47 Page 47 showninthelastcolumnofthetablecorrespondtoamonitorcountingrateof 10^persecond. Atthetimeofwriting(February1988),representative values forRandforminimumabsorbed-dose levelsarebeingobtainedforthenew monitorsystem. Noassess... Open at page → 48 Page 48 13NNVH3U3dSlNnOO >- o a: UJ z lU z o a t- o 13NNVH3U3dSINHOO 13NNVHD«3dSlNflOD O toS a;o <U-r- c5 O4-> •f— jcX. t—<u i\ r i cc L. <U£_ <4-O +-> •r-O OOJ •-J •r--O «/>c cOJ O0) t-2 +->(-> O OJJ3 r— UJo; a >c ^+j 1iA O-i-... Open at page → 49 Page 49 0.09mm ALUMINUM uj9000 - z z < I o lU a. 0 0.5 1.0 1.5 ELECTRONENERGY.MeV 0.09mm ELECTRONENERGY.MeV Figure18.Degradation ofNominal1.5-MeVand2.5-MeVElectrons inDifferent Thicknesses ofAluminumAddedtothe0.09-mmAluminumExit... Open at page → 50 Page 50 gure19.Degradation inAirofNominal200-keVto2.5-MeVElectronsin DifferentThicknesses ofInterveningAirLayers. 40 Open at page → 51 Page 51 6.ExamplesofPracticalStudiesPerformedwiththeBeta-Particle Beams 6.1Compatibility ofDifferent ^OSr-t-^OySourceswithExistingStandards Sincespectralcharacteristics of^Osr+^Oybeta-particle sourcesmayvary widelywithsourcegeom... Open at page → 52 Page 52 CO o 13 o >- o O 0) o o o CO C- «J o. E o o no CO c o O Q. 00 O) (J Q. E O o CM o O o O 00 O CO 00 CO CO o o o CTiO Or-I AV o o O V o o o o (T3 U o o o 00 A CO 00 00 O) o o 4-> O CM A I — C7) <c o c: O O •• AV o o o o O... Open at page → 53 Page 53 Figure20.lonization-versus-Depth CurvesforThreeDifferenttypesof 90sr+90YSources. Solidline:Buchler-Amersham source;dashedline: Amershamexperimental source;dash-dotted line:specialhigh-activity source usedbytheNVLAPTestin... Open at page → 54 Page 54 Electronenergy,mcv Figure21.ComparisonofSpectrumoftheBuchler-AmershamandtheNVLAP TestingLaboratory's ^Osr+^oySources,onSemi-Logarithmic Scale. The ordinateswereadjustedforequaltotalnumberofcounts. 44 Open at page → 55 Page 55 10^ ELECTRONENERGY,MeV Figure22.ComparisonofSpectrumoftheAmershamExperimental andtheNVLAP TestingLabortory's^osp+soySources,onSemi-LogarithmicScale. The ordinateswereadjustedforequaltotalnumberofcounts. 45 Open at page → 56 Page 56 Figure23.Comparison ofSpectrumofAmershamExperimental ^^Sr+^^YSource, BareandShielded. Adding82mg/cm^ofaluminumtotheAmershamexperi- mentalsourcemakesitsspectrumsimilartothatoftheBuchler-Amersham source(fig.21). 46 Open at page → 57 Page 57 (b)thattheDOEcriterion istooloose,sinceitdoesnotdiscriminate betweentheoperationally verydifferentNVLAPandAmershamexperimental sources,whiletheISOcriteriondoes. Thehighbackgroundnoiseshownin figure20fortheexperimental Am... Open at page → 58 Page 58 largewith350-keVelectronsaswith^^'^Csgammaradiation. "Response"here isdefinedasscalereading(indication) oftheinstrumentdividedby absorbed-dose rate. 7.3RoleofNearlyMonoenergeticElectronSourcesintheDevelopment ofaNew Gene... Open at page → 59 Page 59 Theradiationhazardisonlymoderateforsourceswiththeactivitylevel thatwillbecalibrated inthefacilityinquestion,sinceevenadirect exposureoftheskinforabrieftimewouldnotbeserious,withthepossible exceptionoftheeyes.Howeverdirec... Open at page → 60 Page 60 9.References [1]Mantel,J.Thebetarayspectrumandtheaveragebetaenergyofseveral isotopesofinterest inmedicineandbiology. Int.J.Appl.Radiat, Isotopes. 23,407-413(1972). [2]Cross,W.G.;Ing,H.;Freedman, N.Ashortatlasofbeta-raysp... Open at page → 61 Page 61 [14]AmericanNationalStandardfordosimetry—personneldosimetry performance—criteriafortesting. Am.Nat.StandardsInstituteANSI N13.11-1983. [15]Referencebetaradiations forcalibratingdosimetersanddose-ratemeters andfordetermin... Open at page → 62 Page 62 Appendices Appendix 1.SampleofCalibrationReportForm(Seesec.1.3) DG8751/87 O.S.DEPARTMENTOFCOMMERCE Page 1of2 DB873/170 NATIONALBUREAUOFSTANDARDS TEN240032 GAITHERSBURG ,MD20899 1987Sep14 REPORTOFTEST 0.5mCi204 Beta-Parti... Open at page → 63 Page 63 Appendix 1,continued DG8751/87 Page2of2 1987Sep14 temperatureandpressureof22°Cand101.325kPa(1standardatmosphere). Iftheairdensitydifferssignificantly fromthedensityatthereference temperatureandpressure,itmaybenecessaryto... Open at page → 64 Page 64 Appendix 2.ReportofaTriptoaDOELaboratorybyJ .S.Pruitt ThecalibrationatthislaboratoryoftheBuchler ^Pmsourceis consideredimportantbecauseitsresultsprovideatestofthevalidityof therecentlydevelopedhigh-altitude air-densityco... Open at page → 65 Page 65 Appendix 2,continued Page2of4 where0.05848and-0.06168areaveragedDVMreadingsforoppositechamberpotential polarities, 0.9987istheDVMcalibration factor,100.17x10"^^ isthecapacitance of the100-pFcapacitor infarads,and50isthei... Open at page → 66 Page 66 Appendix 2 ,continued Page3of4 wheredistheair-gapsettinginmillimeters and±HVisthechamberpotential in volts. ThelistedvaluesofIwerefittedtoaleast-squares straightlineasafunctionof airgapsetting, d,andtheslopeofthislinewas... Open at page → 67 Page 67 Appendix 2,continued Page4of4 d,mm 2.5 1.5 0.5 ±HV Q- I; 25 0.02477 -0.02601 0.9964 1,0048 1.0025 1.0125 15 0.01339 -0.01603 0.9963 1.0029 1.0038 1.0131 5 0.00524 -0.00580 0.9960 1.0010 1.0107 1.0139 I,fA 5.166 2.992 1.1... Open at page → 68 Page 68 Appendix 3 . MeasurementAssuranceStudyby.MeansofPTWTransfer IonizationChamber,Model20A7"'' (Seesection6.2) DG8555/86 DB868/107 TFN236381 1986JUN19 Page1of2 U.S.DEPARTMENTOFCOMMERCE NATIONALBUREAUOFSTANDARDS GAITHERSBURG... Open at page → 69 Page 69 Appendix3,continued DG8555/86 1986JUN19 Page2of2 Eachchambercalibration (inGy//iC)istheratioofatissuedoserate(in y.Gy/s)andacorrectedcurrent(inpA) .Thereportedresultsarelisted belowinGy/nC: CalibrationFactor absolute rat... Open at page → 70 Page 70 Appendix 4.PredictingBeta-ParticleResponseofInstrumentsfromtheir ResponsetoNearlyMonoenergetic Electrons(Seesec.7.1.) KadialionHroteciiimOosimclry Vol14No2pp 1IA-I15(I'«6) NuclearTechnologyPublishing PREDICTINGBETAPARTIC... Open at page → 71 Page 71 Appendix 4,continued ( .aSi internalalgorithmsforderivingabsorbeddosefrom themeasuredpulse-heightspectra. DISCUSSIONOFEXPERIMENTSAND RESULTS Accelerator-produced, nearly monoenergetic electronbeamswereusedtomeasuretheres... Open at page → 72 Page 72 Appendix4,continued I'RIDHTINdlihIAI'ARIICl.HHISI'ONSi: REKERENCTS 1.Ehrlich,M.,Pruill, J.S.andSoares,C.G.StandardBeta-ParticleandMonoenergelic F.lectronSourcesforihi- Calihraiionoflieia-Radiation Protection Instrumentat... Open at page → 73 Page 73 Appendix 5.RoleofNearlyMonoenergetic ElectronSourcesintheDevelopment ofaNewGenerationofSurveyMeters: ExcerptsfromtwoPublications NUREG/CP-0050 Proceedingsofthe InternationalBetaDosimetry Symposium HeldatWashington,D.C. F... Open at page → 74 Page 74 Appendix 5,continued LOSALAMOSPORTABLEBETA-RAYSPECTROMETER B.H.Erkkila, R.J.Brake,andD.A.Waechter LosAlamosNationalLaboratory, LobAlamos,NM87545 *ThisworkwasperformedundertheauspicesoftheU.S.DepartmentofEnergy Abstract:... Open at page → 75 Page 75 Appendix 5,continued NUREQ/CR-4a« EOG-244* OtotributtonCatagonr:AN FIELDTESTSOFAPORTABLETISSUEEQUIVALENT SURVEYMETERFORMONITORINGMIXED BETA/GAMMARADIATIONFIELDS D.E.Martz B.L.Rich L.O.Johnson S.H.Daniel. Ill PublishedMay... Open at page → 76 Page 76 11.ListofPertinentTablesandReportsonFileintheOfficeoftheDosimetry Group 11.1PertainingtotheCorrectionsLeadingfromIonizationMeasurementswith TheExtrapolation IonizationChambertoAbsorbedDoseRatetoWater Berger,M,J.andSeltze... Open at page → 77 Page 77 NBS-IMA(REV.2-ao) U.S.DEPT.OFCOMM. mmmi^DADLIIORATA BIBLIOGRAPHICDATA SHEET(Seeinstructions) 1.PUBLICATIONOR REPORTNO. NBS/SP-250/21 2.PerformingOrgan.ReportNo.3.PublicationDate April 1988 4.TITLEANDSUBTITLE NBSMeasureme... Open at page → 79 Page 79 .1 Open at page → 80 Page 80 U.S.DepartmentofCommerce NationalBureauofStandards Gaithersburg,MD20899 OfficialBusiness PenaltyforPrivateUse$300 StimulatingAmerica'sProgress 1913-1988 Open at page →