ESTRO 2025 - Abstract Book

S3177

Physics - Inter-fraction motion management and offline adaptive radiotherapy

ESTRO 2025

Results: The DAPT UNC plan was on average 24% faster to deliver compared to plans with conventional beam arrangement, resulting in an average treatment delivery time of 14min. vs 18min. For NA PTV plan, 15% of fractions exhibited a target underdosage greater than 5%, particularly affecting the D 98% of CTV1 (average difference of -3.6% [-39.6%, 1.6%]). Both adaptive workflows showed improvements in daily target dose: in the DAPT CTV plan, no fractions exhibited differences exceeding 5% in target coverage; in the DAPT UNC plan, 9% of fractions showed target underdosage greater than 5%, specifically in D 98% for CTV 2 (-1.2% [-8.1%,4%]) and CTV 3 (-3.1% [-8.1%, 2.4%]). DAPT UNC outperformed NA PTV (Figure2) but had less conclusive results on OARs. In contrast, DAPT CTV reduced the normal tissue dose on average by 13%.