The use of the TL and OSL phenomena for determination of absorbed dose rates of 90Sr + 90Y sources by a postal method

• A postal dosimetric system was developed to calibrate clinical applicators.
• Al2O3:C samples were characterized in relation to their TL and OSL response.
• The clinical applicators from UFS were calibrated.
• The absorbed dose rates were compared with those provided on the certificates.

International recommendations establish that 90Sr + 90Y clinical applicators have to be calibrated in order to determine the absorbed dose rates in the case of the sources that do not have original calibration certificates, or to update the absorbed dose rates presented in the source certificates. Following these recommendations, a postal dosimetric system was developed to calibrate clinical applicators using two luminescent techniques: thermoluminescence (TL) and optically stimulated luminescence (OSL). In this work, Al2O3:C commercial detectors were characterized and their TL and OSL responses were analyzed. The results showed the efficiency and the optimal behavior of this material in beta radiation beams. After characterization, the system was sent to the Federal University of Sergipe (UFS), Brazil, for calibration of five 90Sr + 90Y clinical applicators, where the detectors were irradiated and returned to IPEN, for their evaluation and determination of the absorbed dose rates. A comparison between these absorbed dose rates and those adopted by the UFS as original was made; the differences obtained were within those of other studies, and they demonstrated the usefulness of the system.