Calibration methodology and selection of TLD – 100

Abstract

In Brazil, it is estimated that for the biennium 2018 2019, that occurred 600 thousand of new cases of cancer for each year and lung cancer is the most common of all malignant tumors. Radiotherapy acts as a form of treatment from which come two basic modalities for the treatment of cancer: teletherapy and brachytherapy. In teletherapy is used a linear accelerator to make the application and before starting the treatment is carried out a planning that makes the acquisition of all anatomical information of the patient and then the classification of areas of interest in the patient. All planning prior to initiation undergoes a quality control dosimetry, which ensures that the dose prescribed in the planning will be delivered accurately in the treatment of the patient. In radiotherapy the dosimetry is applied as an independent measurement and this work has the objective of comparing the dosimetric plan of lung cancer in adjacent organs in this case the organ of risk is the heart with dose values calculated in the planning system (TPS) using an anthropomorphic phanton. All dosimetry was performed with thermo luminescent dosimeters (Lif: Mg,Ti TLD 100). We selected 50 TLDs that underwent a calibration process with thermal treatment, irradiation and reading. All the dosimeters passed through the reader in order to quantify its reading. The TLDs chosen were those that obtained coefficients of variation of less than 5% for three cycles of irradiation, in order to prove the methodology used for the thermal treatment, reading and calibration of dosimeters.