ESTRO 2025 - Abstract Book

S3569

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

ESTRO 2025

Conclusion: Both arc modalities provided lower OAR-doses, but both higher and lower OAR LET-values. LET optimization evened out the differences in LET values in the CTV, however, more patients are needed to see clear differences between the modalities.

Keywords: Proton Arc Therapy, LET, dose

4453

Digital Poster Linear energy transfer and dirty dose distributions for clinical planning approaches in proton radiotherapy Aleksandr Vanchugov 1 , Anna M Flejmer 2 , Erik Traneus 3 , Iuliana Toma-Dasu 4 , Alexandru Dasu 1,5 1 ----, The Skandion Clinic, Uppsala, Sweden. 2 Department of Radiation Oncology, Uppsala University Hospital, Uppsala, Sweden. 3 ----, RaySearch Laboratories, Stockholm, Sweden. 4 Medical Radiation Physics, Stockholm University and Karolinska Institutet, Stockholm, Sweden. 5 Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden Purpose/Objective: An increasing number of patients benefit from proton therapy that can limit the dose delivered to critical structures. However, concerns have been raised in light of the evidence supporting an increased proton biological effectiveness with increased ionisation density as found towards the end of the proton ranges. This study presents a systematic investigation of distributions of dose-averaged linear energy transfer (LET d ) and dirty dose (DD) for clinical planning approaches for cranial treatments. These quantities offer different information on the ionisation density in and around the target (Figure 1).