ESTRO 2024 - Abstract Book

S3179

Physics - Detectors, dose measurement and phantoms

ESTRO 2024

Marjorie Grandvillain 1 , Franck Mady 1 , Petter Hofverberg 2 , Fiammetta Fricano 3 , Mourad Benabdesselam 1 , Joël Herault 2 , Marie Vidal 2 1 Université Côte d’Azur, Institut de Physique de Nice, CNRS UMR 7010, Fédération de recherche Claude Lalanne, Nice, France. 2 Centre Antoine Lacassagne, Fédération de recherche Claude Lalanne, Nice, France. 3 Université Jean Monnet Saint-Etienne, CNRS, Institut d Optique Graduate School, Laboratoire Hubert Curien UMR 5516, Saint-Étienne, France

Purpose/Objective:

New radiotherapy techniques, such as those using flash irradiations, require developing innovative dosimeters capable of measuring high dose rates. However quality assurance conventional dosimeters such as ionization chambers are affected by electron-ion recombination. This work aims at characterizing miniaturized silica fiber-based radioluminescence dosimeters, optimized for a recombination free response [1] in proton beams, and almost water equivalent.

Material/Methods:

We studied the luminescence of Gd3+, Ce3+ and N-doped silica fibers. The probes, 1 cm long and 120 or 220 µm in diameter, were spliced to radiation-hard silica fibers capable of transmitting the radiation-induced luminescence to the detector. They were irradiated with 65 MeV clinical proton beam in order to measure the depth dose deposit in a water phantom. The signal produced during irradiation was collected with a photomultiplier tube associated with a counting unit. The depth dose distributions obtained with the different fibers were compared with the reference Bragg peak that was measured with the diode BAS21 from Philips Semiconductors and Monte-Carlo simulations run with Geant4 based code GATE v9.3. Regarding the physics parameters used for MC simulations, QBBC_EMY for the beam and em_standard_opt4 with FTFP_BERT_HP for fibers were used. We also investigated in further detail the common effect of scintillation quenching. For these measurements, the 1cm doped fibers were exposed to air and irradiated with a homogenous beam with dose rate from 0.1 to 4.8 Gy/s and for energies ranking from 15 MeV to 61 MeV.

Results: