inverse treatment planning with adaptively evolving voxel-dependent penalty scheme

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1、Inversetreatmentplanningwithadaptivelyevolvingvoxel-dependentpenaltyschemeYongYangandLeiXingDepartmentofRadiationOncology,StanfordUniversitySchoolofMedicine,Stanford,California94305-5847(Received26February2004;revised24May2004;acceptedforpublication9Augu

2、st2004;published21September2004)Incurrentinverseplanningalgorithmsitiscommontotreatallvoxelswithinatargetorsensitivestructureequallyandusestructurespeci®cprescriptionsandweightingfactorsassystemparam-eters.Inreality,thevoxelswithinastructurearenotidentic

3、alincomplyingwiththeirdosimetricgoalsandthereexistsstrongintrastructuralcompetition.Inverseplanningobjectivefunctionshouldnotonlybalancethecompetingobjectivesofdifferentstructuresbutalsothatoftheindividualvoxelsinvariousstructures.Inthisworkweproposetomo

4、deltheintrastructuraltradeoffthroughthemodulationofvoxel-dependentimportancefactorsanddealwiththechallengingproblemofhowtoobtainasensiblesetofimportancefactorswithamanageableamountofcomputing.Insteadoflettingthevaluesofvoxel-dependentimportancetovaryfree

5、lyduringthesearchprocess,anadaptivealgorithm,inwhichtheimportancefactorsweretiedtothelocalradiationdosesthroughaheuristicallyconstructedrelation,wasdeveloped.ItisshownthattheapproachisquitegeneralandtheEUD-basedoptimizationisaspecialcaseoftheproposedfram

6、ework.Thenewplanningtoolwasappliedtostudyahypotheticalphantomcaseandaprostatecase.Comparisonoftheresultswiththatobtainedusingconventionalinverseplanningtechniquewithstructurespeci®cimportancefactorsindicatedthatthedosedistributionsfromtheconventionalinve

7、rseplanningareatbestsuboptimalandcanbesigni®cantlyimprovedwiththehelpoftheproposednonuniformpenaltyscheme.©2004AmericanAssociationofPhysicistsinMedicine.[DOI:10.1118/1.1799311]Keywords:IMRT,inverseplanning,doseoptimization,objectivefunction,tradeoffINTRO

8、DUCTIONstructuresbutalsothatoftheindividualvoxelswithinanystructure.Computationally,thedeterminationofintrastruc-Inversetreatmentplanningisanindispensablestepintheturaltradeoffisanintensivetaskbecauseofthecouplingimplement