CHARACTERIZATION OF BEO DETECTORS USING OPTICALLY STIMULATED LUMINESCENCE TECHNIQUE FOR RADIOTHERAPY APPLICATIONS

The Optically Stimulated Luminescence (OSL) technique is widely applied in various areas for ionizing radiation dosimetry such as dating and health. Its main advantage over the thermoluminescence (TL) technique is the optical nature of the process; For dose-associated luminescent emission, optical rather than thermal stimulation is employed, leading to rapid and simple reading. Beryllium oxide (BeO) detectors have several intrinsic characteristics for clinical dosimetry such as tissue equivalence, linear dose response range, low energy dependence and angular in radiodiagnostic range. Considering the advantages of the OSL technique and the properties of BeO, the objective of this study was to characterize the detectors using the OSL technique for radiotherapy using photon beam and electrons. BeO detector (Thermalox 995 - Materion Co) readings were taken on an automated Risø TL / OSL reader (DTU). To evaluate the dose response and energy response of the BeO detectors, 6 and 15 MV photon beams and 6, 9, 12 MeV electrons (2100SC Varian linear accelerator) were used. Angular dependence was verified for photon incidence of 6 MV at 45º. The energy response was obtained by sensing the detectors for the different photon and electron energies by making a linear adjustment of type y = bx of OSL intensity as a function of dose. The detectors presented linear response dose up to 3.5 Gy and saturation for doses above this value, low energy dependence for photons and electrons and showed no significant variations in response considering the incidence of the beam at 45º. Thus, we conclude that BeO, together with the OSL technique, is adequate for radiotherapy dosimetry considering the linear dose response range and can be used for both photons and electrons.