Dosimetric impact of interplay effect in lung IMRT and VMAT treatment using in-house dynamic thorax phantom

摘要

Tumormotionduetopatient'srespiratoryisasignificantprobleminradiotherapytreatmentoflungcancer.Thepurposeofthisprojectistostudytheinterplayeffectthroughdosimetryverificationbetweenthecalculatedanddelivereddose,aswellasthedosimetricimpactofleafinterplaywithbreathing-inducedtumormotioninIMRTandVMATtreatment.Inthisstudy,adynamicthoraxphantomwasdesignedandconstructedfordosimetrymeasurement.Thephantomhadalinearsinusoidaltumormotiontowardsuperior-inferiordirectionwithvariationofamplitudesandperiods.TLD-100LiF:Mg,TiandGafchromicEBT2filmwereusedtomeasuredoseinthemidpointtargetandthespinalcord.TheIMRTandVMATtreatmenthadprescriptiondoseof200cGyperfraction.ThedosimetricimpactduetointerplayeffectduringIMRTandVMATtreatmentwereresultedintherangeof0.5%to-6.6%and0.9%to-5.3%oftargetdosereduction,respectively.Meanwhile,meandosedeviationofspinalcordinIMRTandVMATtreatmentwerearound1.0%to-6.9%and0.9%to-6.3%,respectively.Theresultsshowedthatifrespiratorymanagementtechniquewerenotimplemented,thepresenceoflungtumormotionduringdosedeliveryinIMRTandVMATtreatmentcausesdosediscrepanciesinsidetumorvolume...