ESTRO 2025 - Abstract Book

S3465

Physics - Optimisation, algorithms and applications for ion beam treatment planning

ESTRO 2025

between nominal and re-calculated plans, of (-0.7 ± 1.2)% and (0.0 ± 0.9)%, for plan-D, and (-1.0 ± 1.1)% and (0.3 ± 0.8)%, for plan-DL. No toxicity, higher than expected, was observed for this patient cohort.

Conclusion: This study confirmed the feasibility and initial safety of a new optimization strategy for CIRT for large radioresistant sacral chordoma patients, based on the synergistic effect of maximizing dose, RBE and LETd in the target volume, with the aim of increasing tumor control.

Keywords: clinical dose-averaged LET, sacral chordoma

References: [1] T. Inaniwa et al. , “Reformulation of a clinical-dose system for carbon-ion radiotherapy treatment planning at the National Institute of Radiological Sciences, Japan,” Phys. Med. Biol. , vol. 60, no. 8, pp. 3271–3286, 2015, doi: 10.1088/0031-9155/60/8/3271.