ESTRO 2025 - Abstract Book

S4340

RTT - Treatment planning, OAR and target definitions

ESTRO 2025

Results: There were 56 re-CTs and 15 underwent adaptive replanning. Results of the adaptive replanning contributing factors and its time of occurrence are shown in Figure 1 . Most of the replans were triggered midway of treatment. It was observed 53% of replanning were due to tumour regression while 20% were because of setup challenges. The remaining replans were for weight loss and internal anatomical changes. All 15 adaptive plans have significant dose difference for the CTV coverage (D99%, D98% and D95%) ( p <0.05) ( Figure 2) . Dmax was noticeably higher for replan likely due to increase of hotpots detected in re-CT dose evaluation.