核技術(shù)醫(yī)療應(yīng)用的輻射安全和防護課件

1ContentsSourceAccidentProcessDoseCalculationClinicalManifestationSourceSource:Ir-192Usage:industricaldefectdetectionActivety:about0.94TBq(25.5Ci)2Process3

On7th,MayFourworkershaddoneindustrialdefectdetectionworkinaworkshopofafactorywhichlocatesinNanJing,abigcityinthesoutheastoftheChina.Theworkhadbeenfinished,thedetectioninstrumentsneededtobecollectedandtakenawayfromtheworkshop.4Process

7thMay,about3:00a.m.Whentheworkerscollectedtheinstruments,theyfoundthattheremotecontrolcablecan’tbeunloaded.Accordingtothemachine’sdesign,onlywhentheradiationsourcelocatesinthemachine,theremotecablecanbeunloaded.Otherwise,thecable’sunloadingisimpossible.

5So,theradiationsourcewassuspectedstillhadlocatedinthesourceguidetube,yet.Theworkersshooktheguidetubewantedtofindthesource,buttherewasn’tsourceinthetube.(Indeed,thesourcehadslidofftubewhentheyhadpickedthetubeup,beforetheyshookit.)ProcessGuideTube6ProcessOneworkertookadosimetertodetectthedosenearthesurfaceofthemachine.Thedoserateindicationwashigh,sohethoughtthesourcemustbelocatedinthemachine.(indeed,iftherehadbeenasourceinthemachine,thedoseratenearthemachinecan’tbesohigh.Themachine’sradiationshieldisthickenough.Theexposureactuallycamefromtheradiationsourcenearthemachine.)7ProcessBecausetheworkersbelievedthatthesourcehadlocatedinthemachine,theytookthemachinewiththeunloadedcableawayfromtheworkshop.

Aboutat7:00a.m.,7th,MayOtheremployeeswentintotheworkshopandbeguntheirwork.Oneworkerfoundthesource.Hepickeditup,lookeditcarefully.Hedidn’tknowwhatitwas,thenhethrownitoutoftheworkshop.

8ProcessAboutat8:00a.m.,7th,MayAnotherworker,namedWang(whoreceivedthemostradiationdoseinthisaccident),foundthesourceneartheworkshop’sdoor.Hethoughtitwasbeautifulandattractive,sohepickeditandputitintohispocket.

ThenWangtookarestwithsourceinhispocketinarestroomaboutonehour.TherewasaworkmateofWangintheroom,Theworkmatewasalsoirradiated.

9ProcessAboutat9:00a.m.,7th,MayWanghaddonehisnormalworktill11:30,somehisworkmatesnearhimhadbeenirradiated.Wanghadfinishedhisworkandwenthishomewiththesourceinhispocketatabout11:30.Thenheputthesourceinawarehouselocatesinhisbackyard.

10ProcessAtnight,8th,MayTheformalfourworkerstooktheinspectioninstrumentsintotheworkshopagain.Thefilmwasn’tphotosensitizedafterthe“exposure”.Sotheradiationsourcewasfoundlost!

11ProcessAt2:00,9th,MayTheradiationsourcelostaccidentwasreportedtoenvironmentprotectionbureauandpolicebureauofNanJingcity.At3:00,9th,MayEnvironmentprotectionbureau’semployeeswenttotheworkshopwherethesourcewaslost.At8:00,9th,MayThepolicemenwenttotheworkshopandaskedeveryoneworkedinthefactory.Theypromised20,000RMBYuantothepeoplewhoprovidedthecorrespondinginformation.Butthepolicemendidn’ttellthatthelostitemisharmful.12ProcessMr.Wangfeltfearful.Hehadnottheknowledgeaboutradiationsource,andhethoughttheitemhehadpickedupmustbeveryexpensive,otherwisethepolicemencan’tprovidesomuchmoneyforit’sinformation.Hethoughtpolicemenmayberegardhimasthiefwhostolenthe“veryexpensivetreasure”.Sohedidn’ttellpolicementhetruth,andhetelephonedhiswifetotransferthesourcetohisparents’home.Mr.Wangfearedandfearedatthatnight.Thenextmorning(10th,May),hewenttohisparents’home,wrappedthesourcewithadarkblueplasticbagandthrownittoagrass100metersawayfromhisparents’home.1314FindingthesourceTheapproximate

positionofthesourcewasfoundthroughgamma-raydetectioninstrumentsatmorning9:00a.m.on10thMay,afterWanghadthrownit3hourslate.Butthepreciseposition’sdeterminationwasdifficult,becausethesourcewastoosmallandtheradiationwastoostrongnearthesource.Finally,ametal-detectorwasusedtofindtheprecisepositionofthesource.15Process161718CalculationMr.Wang’sDoseLocalDose：

Thigh：D=157Gy(t=3.5h,r=5cm,D5cm=50Gy/h)Hands：

(pickedupandlookedupthesource,loadedthesource,tookthesource)

D=D1+D2+D3=14.33GyWholeBodyDose：2.55

Sv（Bladder,gonad,redmarrowandskinaremainlyconsidered.）19CalculationOtherPeople’sDoseWang’sWife：HandsDose(Carrying

source)：0.16Gy;WholeBodyDose(Carrying

sourceandclosecontactsourceathome）：270mSvThepersonwhofirstpickedupthesource：HandsDose：0.83Gy;WholeBodyDose：8.3mSv。20Otherpeopleworkinginworkshop：9person（3-5mfromsource），Dose：2.5-6.25mSv

4person（6mfromsource），Dose：1.74mSv

7person（15mfromsource)，Dose：0.28mSv20person

(20-40mfromsource)，AverageDose：0.07mSvTheroadconstructionworkersnearthewarehouse:

20person

(10-20mfromsource)

Dose：0.78~3.125mSv21CalculationOtherPeople’sDoseTheworkmaterestedalongwithWanginrestroom

Averagerangefromsource：3meters，Dose：13mSvWang’sfamilyandtenant:

Dose：25~37.5mSvWang’sparentsandsister:

Wang’sFather：0.09mSv;

Wang’sMother：1.22mSvWang’sSister：0.22mSv22CalculationOtherPeople’sDoseTwotenantslivedinsecondfloorupthesource’sroom

Dose：5.12-6.4mSv;Theconstructorsneartheplacewherethesourcewasfound

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constructors（30-80mfromthesource），

MaximumDose：0.42mSv23CalculationOtherPeople’sDoseConcludeofthecalculationNear100people(Morethan80)