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Abstract

In proton-beam therapy (PBT) and ion-beam therapy (IBT), treatment fields exhibit nonhomogeneous linear energy transfer (LET) distributions, which can cause variations in the relative biological effectiveness (RBE). Although these quantities are taken into account during treatment planning, there is currently no dedicated tool for the experimental assessment of LET and RBE in clinical practice. This lack of measurement tools poses a challenge to validating predictions from treatment planning systems, as is routinely done for absorbed dose. To address this gap, this thesis introduces novel methods for measuring LET and estimating RBE in PBT and IBT using aluminum oxide doped with carbon and magnesium (Al2O3:C,Mg) luminescent detectors. A method was developed to address variable sensitivity among individual fluorescent nuclear track detectors (FNTDs). Calibrations, enabling LET measurements in PBT and IBT, were established for both FNTDs and optically stimulated luminescence detectors (OSLDs). RBE models were integrated into the FNTDs workflow to predict RBE for protons and He-ions. Measurements to assess LET and RBE were conducted using proton and He-ion beams, and validated both in-vitro and in-silico. Finally, the developed techniques were applied during a measurement campaign aimed at identifying suitable detectors for LET measurements in PBT.