COMPARATIVE STUDY OF THERMOLUMINESCENT RESPONSE OF Α-AL2O3 AND LIF-MTS CERAMIC DETECTORS IN HIGH ENERGY BEAMS

Radiotherapy is an area that is primarily dealt with using clinical protocols as well as delivering high doses of radiation for therapy. To check the dose that the patient actually receives in radiotherapy treatments, in vivo dosimetric techniques are used to evaluate the doses being delivered using specific dosimeters for this use, such as thermoluminescent (TL) dosimeters, radiochromic films, gel dosimeters, semiconductor dosimeters, etc. The aluminum oxide ceramic dosimeters (α-Al2O3) developed at the CDTN by the solgel process were characterized for their morphology and dosimetric properties at energies up to 662 keV (137Cs). The use of these ceramic detectors in radiotherapy applications opens a new perspective for their practical use. The aim of this paper is to carry out a preliminary study of characterization of these ceramic detectors in high energy beams commonly used in radiotherapy treatments, aiming to determine the technical feasibility of their use in this application. For this, the integrals of the thermoluminescent response curves as a function of the absorbed dose in solid water were obtained for the α-Al2O3 ceramic detectors and lithium fluoride detectors (LiF-MTS) for comparison purposes. For this purpose, homogeneous lots of these detectors were selected and both lots were irradiated with doses between 0.5- 2.5 Gy, in 6 MV photon and 6 MeV electron beams with 10 x 10 cm dimension fields. Elekta Synergy Linear Accelerator, installed at Radiocare Centro Especializado em Radioterapia, located at Felício Rocho Hospital. For LiF-MTS detectors, the TL response was linear over the entire dose range studied in both beams used. For LiFMTS detectors, the TL response was linear over the entire dose range studied in both beams used. For the alumina ceramic detectors, the TL response obtained showed linear behavior up to a dose of 1.0 Gy, for both beams, and above this dose value, the response increased, following a nonlinear behavior, typical of the saturation regime. The results obtained with this study indicate that LiF-MTS has technical feasibility in radiotherapy, in all studied dose range, without the need to use correction actors, as well as for α-Al2O3 detectors, in doses up to 1.0 Gy. However, for higher doses, α-Al2O3 detectors need more careful studies to characterize them.