ESTRO 2025 - Abstract Book

S2578

Physics - Detectors, dose measurement and phantoms

ESTRO 2025

1074

Digital Poster Impact of ultra-high dose and dose rate irradiations on common materials used in radiation therapy detectors and phantoms Marina Orts Sanz 1 , Yunus Can Gedik 2,3 , Alexandra Bourgouin 4,3 , Charbel Koumeir 5 , Severine Rossomme 6 , Kevin Souris 6 , Thomas Sounalet 5 , Edmond Sterpin 1,7,8 1 Institut de Recherche Expérimentale et Clinique, Université catholique de Louvain, Brussels, Belgium. 2 Nuclear Energy Research Institute (NÜKEN), Turkish Energy Nuclear and Mineral Research Agency (TENMAK), Ankara, Turkey. 3 PTB, Physikalisch-Technische Bundesanstalt, Braunschweig, Germany. 4 Metrology Research Center, National Research Council of Canada, Ottawa, Canada. 5 Subatech, Arronax, Nantes, France. 6 IBA, Ion Beam Applications, Louvain-La-Neuve, Belgium. 7 Department of Oncology, Laboratory of experimental radiotherapy, KULeuven, Leuven, Belgium. 8 PARTICLE, Particle Therapy Interuniversity Center Leuven, Leuven, Belgium Purpose/Objective: FLASH radiotherapy is being extensively studied as a promising technique for effectively controlling tumors while minimizing normal tissue toxicity. This treatment modality relies on ultra-high dose rates (UHDR). As with any radiotherapy technique, it requires robust quality assurance (QA) to ensure a safe delivery of the treatment. QA devices such as phantoms and ionization chambers are typically made out of polymeric materials to ensure water equivalence. However, radiation exposure, particularly at UHDR where delivering high doses is easier, may cause irreversible changes to the structure of these materials. These extreme conditions can compromise the integrity and reliability of QA devices, as illustrated in Figure 1. This study aims to characterize radiation damage in common materials used for QA devices and identify materials that can withstand these challenging conditions.

Material/Methods: A variety of materials commonly used in phantoms and ionization chambers, with diverse characteristics (transparent, opaque, conductive and non-conductive) were irradiated using 68 MeV proton and 20 MeV electron beams, reaching doses up to 1 MGy under UHDR conditions (average dose rates of 100 – 500 Gy/s). Material