ESTRO 2025 - Abstract Book

S2720

Physics - Dose prediction, optimisation and applications of photon and electron planning

ESTRO 2025

RayStation 12A (research version) and compared against standard-of-care clinical plans across various treatment sites, including glioblastoma, pancreas, and liver. Additionally, the advantages of HUC treatment strategies combining hypofractionated UHDR electron boosts with sequential normofractionated CDR VMAT treatments were assessed under two scenarios for FLASH sparing utilizing the sudden effect transition model tuned to mammalian experimental data [1]. Results: HUC treatment plans demonstrated comparable dosimetric quality to standard-of-care RT, with similar PTV coverage (V 95% within 0.5%), homogeneity, and DVHs for critical OAR while delivering the bulk dose to the PTV (D median >50%) and adjacent tissues at UHDR ( Figure 1 a-d ) . For a 15-Gy-UHDR-electron-boost to a glioblastoma, FLASH sparing Scenario A resulted only in a moderate sparing magnitude (10% for D 2%,PTV ) while Scenario B led to a more pronounced sparing of healthy brain tissues inside and outside the PTV (32% for D 2%,PTV , 31% for D 2%,Brain ) ( Figure 1 e-g ).