放射生物學及防護課件VIP

OralandMaxillofacial

MedicalImaging

TrytoappearconfidentExplainwhat/whyAnswerquestionsNounnecessaryinformationAnteriorfilmsfirst

EmpathizeWorkquicklybutefficientlyComplimentpatientPatientManagement

GeneralGuidelinesSpecialSituationsPatientManagementGaggingreducedby:

Properpatientmanagement(filmorder,positivestatements)

DistractorsSaltontongueBreatherapidlythroughnoseFlavoringfilmsTopicalanesthetic

ChildrenKeepfilmstoaminimum(BW’s+Occl,PA’s,Pan)ExplainprocedureBefirmbutnon-threateningCompliment

AnatomyThirdmolarsMaxillarycuspidToriSpacelimitationsTongue-tiedThirdmolarsPanbestModifiedPAOKMaxillaryCuspidParalleling0Filmcan’tbeplacedfarenoughintothemouthdiagonalplacement(narrowarch)BisectingpalataltorusmandibulartorusTori

Placefilmontheoppositesideofpalataltorus(awayfromteethbeingradiographed)

Placefilmbetweentorusandtongue,makingsureitdoesn’trestontopoftorus

SpaceLimitationsShallowpalateShallowfloorofmouth

Usebisectingangletechnique

Tongue-tied(ankyloglossia)UsebisectingangletechniqueMayneedtousetongue-bladetosupportfilm(tapefilmtotongue-blade;placeontopoftongue)Usingthetonguebladetosupportthefilmforankyloglossialingualfrenum

portionoftonguesuperimposedoverroots

Trismus(prolongedspasmofjawmuscles;minimalopening)Pan(best)OcclusalPeriapical/hemostatUsingperiapicalfilmwithhemostatforpatientwithtrismusClaspingfilmwithhemostat,insertfilminmouthwithfilmparalleltofloor(horizontal)Oncethefilmhasclearedtheincisors,rotatethefilmtoaverticalpositioninmaxillaormandible.Edentulous

Pan(best)#4occlusal

HandicappedFilmholderAssistancefromrelative/friend;protectwithleadapron

HepatitisHIVUniversalprecautionsPregnancy

…thefetalexposureisonlyabout1microGrayforafull-mouthseries.Accordingly,theguidelinescanbeusedwithpregnantpatientsjustaswithotherpatients.Pregnancy

Theunbornchildisverysensitivetoionizingradiation.Limitradiographicexaminationduringpregnancytocaseswithaspecificdiagnosticindication.Postponeelectiveproceduresuntiltheterminationofthepregnancy.

DentalHistoryClinicalexamProfessionaljudgementSelectioncriteriaOrderingFilms0DentalHistorySymptomaticteeth,mostrecentfilms,frequencyofvisits,attitudeClinicalExamConditionofteeth(caries,restorations,displacement,mobility,etc.),#teethpresent/abutmentteeth,teethremovedfororthoProfessionalJudgementEducation,experience,finances

HistoricalFindingsPain,swelling,bleeding,mobilityTraumaEndoImplantsFamilyhistoryTMJpain

SelectionCriteriaLargecaries/restorationsPeriodontaldisease/mobility/bleedingEvidenceoftrauma/swelling/fistulaPotentialabutmentteethUnusualtoothappearance/positionThirdmolarsFacialasymmetrySelectionCriteriaClinicalFindingsFilmorder:4bitewings,Pan0Symptomatic:NoneFractured:NoneLargecaries:NoneLargerest.:#30Missing:#’s5,12,21,28(patientsays3rdshavenotbeenremoved)Gingiva:MildgingivitisLargerestorationFilmorder:2BW,1PA,Pan0Symptomatic:#8Fractured:#8Largecaries:NoneLargerest.:NoneMissing:#’s1,16,20,32Gingiva:HealthySmallrestorationFractureFilmorder:4BW,2PA,Pan0Symptomatic:#’s3,10Fractured:NoneLargecaries:#’s15,32Largerest.:#’s3,6,8,12,13,17,21,23,24,25,26,28,29,30Missing:#’s1,2,7,14,18Gingiva:Generalredness,inflammationbridgeSmallrestorationCrownsLargerestorationLargecariesbridgeFilmorder:4BW,15PA(AFM)00Filmorder:1PA,4BWFilmorder:3PA,2BW0Filmorder:4BW,15PA(AFM)0Filmorder:AFMorPan0

Thefrequencyoftakingfilmsisbasedonthefollowingfactors:1.Patient’soralhygiene2.Cariesactivity3.Dentalhistory4.Reliabilityofpatient5.ADAGuidelines0ADAGuidelinesFull-mouthSeries1-5yearsBitewings6months-3yearsPanoramic1-5yearsRadiobiologyTheresponseoflivingsystemstoionizingradiationIonizationTheprocessofremovinganelectronfromanelectricallyneutralatomtoproduceanion.Anionisanatomorsubatomicparticlewithapositiveornegativecharge.Ionization0negativeionpositiveionIonizingRadiationElectromagneticX-rays,gammaraysParticulateAlphaparticles,electronsAttenuationReductionofx-raybeamintensity(thatreachesfilm)byinteractionwithmatter.1.Coherentscattering2.Comptonscattering3.Photoelectricabsorption

9%ofx-raysnotattenuatedCoherentScatteringLow-energyx-rayinteractswithouter-shellelectronandcausesittovibratebriefly.Scatteredx-rayofsameenergyasprimaryx-rayisthenemitted,goinginadifferentdirectionthanprimaryx-ray.Electronnotejectedfromatom.(Noionization).0CoherentScattering0

ComptonScatteringOutershellelectronejected(Ionization)ScatterradiationresultsOccurs62%ofthetime30%ofscatterexitshead

0recoilelectronscatteredx-rayComptonScattering0primaryx-rayTheprimaryx-raystrikesanouter-shellelectron,knockingitoutofitsorbit(ionization).Theprimaryx-raylosessomeofitsenergyandcontinuesinadifferentdirectionasascatteredx-ray.Inner-shellelectronejected(Ionization)CompleteabsorptionOccurs30%ofthetimePhotoelectricAbsorption0photoelectronprimaryx-rayPhotoelectricAbsorption0Theprimaryx-raystrikesaninner-shellelectron,knockingitoutofitsorbit(ionization).Thex-raylosesallofitsenergyanddisappears.Thereisnoscatter.Dose-ResponseCurvesthresholdlinearnon-linearnon-thresholdResponseDoseLinear:theresponseisdirectlyrelatedtothedose.Non-linear:theresponseisnotproportionatetothedose.Threshold:thedoseatwhicheffectsareproduced;belowthisdose,therearenoobviouseffects.Non-threshold:anydoseproducesaresponse.Stochasticeffect:occursbychance,usuallywithoutathresholdlevelofdose.Theprobabilityofastochasticeffectisincreasedwithincreasingdoses,buttheseverityoftheresponseisnotproportionaltothedose.Geneticmutationsandcancerarethetwomainstochasticeffects.Deterministiceffect:healtheffectsthatincreaseinseveritywithincreasingdoseaboveathresholdlevel.Usuallyassociatedwitharelativelyhighdosedeliveredoverashortperiodoftime.Skinerythema(reddening)andcataractformationfromradiationaretwoexamplesofdeterministiceffects.0CriticalMolecule(Target)DNA00

RadicalAtomormoleculethathasanunpairedelectroninthevalenceshell,makingithighlyreactive0MutationsCelldeathSublethalinjuryBiologicEffects0DNAaltered;cellfunctionalteredordevelopmentchanged.Itisunclearwhichcriticallesion/sinDNAmayleadtocancer.MutationNormalMutation0September25,2006LossofcapacityformitosisCellDeath0CellularRepairDamagetobiologicmolecules(single-strandbreakofDNA)2.Removalofdamagedsectionbycellenzymes3.Placementofnewmaterialbyothercellenzymes0

CellCycleMoredamageresultswhencellirradiatedduringtheG1/earlySportionofcellcycle0ManymitosesUndifferentiatedLymphocytes,germcells,basalcellsofskinandmucosa,erythroblastsRadiosensitiveCells0FewmitosesWelldifferentiatedNerve,muscle,boneRadioresistantCells0RadiationEffectsInfluencedby:

TotaldoseDoserateTotalareacoveredTypeoftissueAge0

LinearEnergyTransfer(LET)Therateoflossofenergyfromradiationasitmovesthroughtissue.ParticulateradiationhashigherLETthanx-rays.0Oxygenhelpsproduceperoxylfreeradical,themostdamagingOxygenEffectSurvivalDose0SomaticCellDamage

(affectsindividual)

vs.GeneticCellDamage

(affectsoffspring)0

HORMESISLowdosesofradiationarebeneficialStimulatesourantimutagenicDNAdamagecontrolsystem(oxidativefreeradicalscausemutations;theseareminimizedbypreventiveantioxidants,repairingenzymes,celldeathandimmunesystem)Dr.MyronPollycove,U.S.NuclearReg.Comm.010-MINUTEBREAK0DOSIMETRY0Whole-bodyRadiation

vs.Specific-areaRadiation0UnitsofRadiationMeasurementRoentgen(R)CoulombsperkilogramradGrayrem

Sievert0

Roentgen(R)RadiationExposure(inair)SIunit=coulomb/kg0

rad

radiationabsorbeddose(intissue)SIunit=Gray(Gy)=100rads1cGy=1rad0

remroentgenequivalentmanradxQF=remcompareseffectsofdifferenttypesofradiationSIunit=Sievert(Sv)=100rems1cSv=1rem01R=1rad=1rem1Gray=1Sievert1000mrem=1remAnnualRadiationExposure

360mrem(3.6mSv)/yearRadon200mrem(55%)Cosmic27mrem(8%)Rocks/soil28mrem(8%)Internal40mrem(11%)Medicalx-rays39mrem(11%)Nuclearmedicine14mrem(4%)Consumerproducts10mrem(3%)Othersources<1mrem(1%)Natural(Background)

Radiation

3000

μSv

External(16%)

CosmicTerrestrialInternal(Food-11%)Radon(55%)CertainblacksandbeachesinBrazilproduceradiationlevelsashighas5mrem/hour.Thiswouldbeequivalenttogettingafullseriesofx-rayfilmseveryhour.SomeplantsinanotherareaofBrazilhaveabsorbedsomuchradiumthattheywillproduceanautoradiographwhenplacedonphotographicpaper.Medical

(11%)

(Dental-0.1%)NuclearMedicine(4%)ConsumerProducts

(3%)Artificial(Man-made)

Radiation

600

μSv

SurfaceExposurePeriapical/BW:100mrem(F-speed)250mrem(D-speed)Panoramic:500mremAFM:2rem(F-speed)LateralCeph:150mremChestFilm:20mrem1mrem=.001remor1000mrem=1remEffectiveDoseEquivalentAFM(round,F)60μSvAFM(rect.,F)27μSvPanoramic7μSvCeph220μSvChest80μSvNaturalRadiation3000μSvEquivalentBackgroundExposureAFM(round,F)5daysbkgrAFM(rect.,F)2daysbkgrPanorex(rare)10hoursbkgrAdult:50mSv/yrNCRP&OhioMinor:5mSv/yrPregnant:5mSv/yr5mSv/yr(0.5rem)NCRP1mSv/yr(0.1rem)(Ohio)RadiationWorkers(Over18)GeneralPublic

MPDMaximum

PermissibleDoseOne-in-onemillionchanceofdying:

AFMSmoking1cigaretteDrinking30cansofdietsodaRidingabicycle10milesDrivingacar300milesFlying1000milesProfessionalJudgmentSelectionCriteriaEquipmentReliabilityLeakageradiationTimeraccuracyX-rayproductionStateinspectionSta