Sci—Sat AM(2): Brachy — 09: Characterization of Al2O3:C Optically Stimulated Luminescence Dosimeters (OSLDs) to Therapeutic Proton Beams

In this work we present a characterization of the response of Al₂O₃:C optically stimulated luminescence dosimeters (OSLDs) to therapeutic proton beams. The following experiments were performed: dose response, proton energy response, percentage depth dose (PDD) profiles of un‐modulated and modulated proton beams and relative output factors (ROFs). The OSLDs were readout with optical filters that transmit both F‐center and UV emission bands from Al₂O₃:C. We observed that the proton dose response of OSLDs was linear in the interval of doses in which we had data (0.06 Gy to 3.5 Gy). Furthermore, the response of OSLDs showed to be independent of proton energy for in‐air irradiations in the energy interval from 100 MeV up to 250 MeV. However, the relative luminescence efficiency of OSLDs was lower than unity. Comparisons between un‐modulated and modulated PDD profiles measured using ionization chamber and OSLDs showed that OSLDs under‐responded in the distal edge region of the dose response curve for proton energies lower than 200‐MeV. An excellent agreement between ionization chamber and OSLD data was observed for un‐modulated and modulated 250 MeV proton beams. Finally, the agreement between OSLD and ionization chamber ROF data was within 1.6 %. We concluded that Al₂O₃:C OSLDs might be suitable for dose measurements in therapeutic proton beams. However, correction factors should be properly determined and applied to take into account the under‐response of the dosimeters when used for measurements in the distal edge region of the PDD profiles for proton beams with energies lower than about 200 MeV.