Impact of a fiducial marker based ART strategy on margins in postoperative IMRT of gynecological tumors

PurposeTo investigate the potential of an offline Adaptive Radiotherapy (ART) strategy, based on interfractional vagina motion (IVM) measured using fiducial markers (FM) during initial number fractions, CTV to PTV margins in post-operative gynecological patients.Materials and methodsIn 18 patients, treated post-operatively for tumors, systematic residual IVM was quantified after simulating ART procedure, utilizing average with FM a varying numbers fractions find optimal moment adapt treatment plan threshold selecting patients replanning. Clinical zero, 2 5 mm strategy were calculated assess possible margin reduction.ResultsApplying reduces significantly (P < 0.025), allowing reduction clinical 3 (20%) CC direction (13%) AP direction. A replanning shows no difference margin, but workload 12%.ConclusionAn adapting provides opportunity reduce postoperative tumors. To keep balance best achievable reduction, adaptation is recommended.