RESUMO
(90)Sr+(90)Y clinical applicators are used for brachytherapy in Brazilian clinics even though they are not manufactured anymore. Such sources must be calibrated periodically, and one of the calibration methods in use is ionometry with extrapolation ionization chambers. (90)Sr+(90)Y clinical applicators were calibrated using an extrapolation minichamber developed at the Calibration Laboratory at IPEN. The obtained results agree satisfactorily with the data provided in calibration certificates of the sources.
Assuntos
Braquiterapia/instrumentação , Braquiterapia/normas , Radiometria/instrumentação , Radiometria/normas , Radioisótopos de Estrôncio/administração & dosagem , Radioisótopos de Ítrio/administração & dosagem , Partículas beta/uso terapêutico , Brasil , Calibragem/normas , Oftalmopatias/radioterapia , Humanos , Dosagem Radioterapêutica , Dermatopatias/radioterapia , Radioisótopos de Estrôncio/normas , Radioisótopos de Estrôncio/uso terapêutico , Radioisótopos de Ítrio/normas , Radioisótopos de Ítrio/uso terapêuticoRESUMO
Two secondary standard systems of beta radiation were used to calibrate a PTW extrapolation chamber Model 23391. Three (90)Sr+(90)Y sources of different activities were used in this calibration procedure. Medium-term stability of the response of the chamber was also studied. The calibration was performed with and without field-flattening filters. The relative standard deviation of the obtained calibration factors was 8.3% for the aluminum collecting electrode and 4.1% for the graphite collecting electrode.