Investigation of Tissue Heterogeneities Effect on Dose Distribution from 192-Ir Source During Brachytherapy Treatments

[摘要] Backgroundandobjective:ThepossibledefectofrecommendedprotocolbytheAmericanAssociationofPhysicistsinMedicine(AAPM,TG43)fordosimetryinthefieldofbrachytherapyisthatthisprotocoldoesnotconsidertissueheterogeneities(suchasbone,lung,…)whenapplyingresulteddosimetryparametersintreatmentplanningsystems.Thepurposeofthisstudywastoevaluatedosedifferenceswithandwithoutheterogeneitiesinbrachytherapywithiridiumsource(Ir-192)SubjectsandMethods:DosedistributionfrommicroselectronHDRIr-192sourcelocatedincenterofthehomogeneouswaterphantomcalculatedbyMCNP-4Csimulationmethod.Indifferentsimulations,heterogeneitiesofbone,lung,airandsofttissuewereconsidered.Theeffectofsourcepositioninginphantomanddistancebetweensourceandheterogeneitiesondosedistributionwereevaluated.Results:Thecalculateddose,duetoheterogeneityofbone,wasreduced,whilethoseduetoairandlungwereincreased?Heterogeneityofsofttissueshasnomeaningfuleffectonthedosedistribution.Increasingdistancefromcenterofphantomdecreasesdoseduetodecreaseofscattering.Conclusion:Heterogeneitiesofbone,lung,andairespeciallyintheneardistancefromIr-192sourceimplantedpositioncanchangethedosecomparedtothewaterhomogeneityphantom.InfutureTreatmentPlanningSystem(TPS)TPS,foraccuratedoseestimation,theeffectofheterogeneitiesondosedistributionshouldbeconsidered.Furthermore,inordertoacquiretheexactdose,dueconsiderationsofcorrectamountofscattering,dosimetrymustbecarriedoutonalargeenoughphantoms.

[学科分类] 基础医学