Analytical Method for Determination of Wedge Factors Dependency of Field Size and Depth for 6mv & 18mv Photon Beams In Siemens Primius Plus Accelerator

[摘要] BackgroundandObjectives:Shieldswithvariablethickness(physicalwedge)isusedinradiotherapyforeliminatinghotspotsandcreateauniformdosedistributionbeam.Inthisregard,determiningafactorforcalculatingtheattenuationofbeambyusingthewedgeisimportantinordertocompensateforthedoseofthetreatment.Thisstudyaimstouseasemi-experimentalmethodandconvertittocomputersoftwarefordeterminingthewedgefactorandenlargingtreatmentplanningsystem(TPS)inradiotherapydepartment.SubjectsandMethods:RelativedosimetryofacceleratorPrimusplusofAhvazGolestanhospitalradiotherapydepartmentwasperformedforwithwedgeandwithoutwedgefieldsatthereferencedepth(10cm),byionizationchambers(CC13/SN-61866187)thatwascalibratedinatomicenergyorganizationofIran(SSDLcenter).Thewedgefactorswerecalculatedforsquarefieldswithwedgeangles15,30,45and60.Finally,ananalyticalequationforwedgefactorisdefined.Bythisequationtheattenuationcoefficientofwedgecanbeobtained.Withtheseresultsthewedgefactorinalldepths¬ofphantom,therapeuticfieldsandphotonenergy(6and18MV)isdetermined.Therefore,usingTBLCurvever5andMATLABtheywereconvertedintoacomputersoftware.Results:ByusingTBLCurvever5softwareananalyticalequationfordifferentdepthsofwedgedfieldsinphotonenergies6and18MVwithaccuracy(r2›0/995)isobtained,thatcandeterminethewedgefactorwithaccuracylessthan5%comparedtomeasurement.Conclusion:Basedonthisresearchdeterminationofwedgefactorforallfieldsizeatanydepth,energyandforeachphysicalwedgeisavailableevenforanycasewhichthemeasuringofwedgefactorisnotpossible.

[学科分类] 基础医学