Ambient Dose Equivalent measured atthe Instituto Nacional de CancerologiaDepartment of Nuclear Medicine

摘要

Ambient dose equivalent values were determined in several sites at the Instituto Nacional de Cancerologia, Departmento de Medicina Nuclear, using TLD-100 and TLD-900 thermoluminescent dosemeters. Additionally, ambient dose equivalent was measured at a corridor outside the hospitalization room for patients treated with ~(137)Csbrachytherapy. Dosemeter calibration was performed at the Instituto Nacional de Investigaciones Nucleares, Laboratorio de Metrologia, to known ~(137)Cs gamma radiation air kerma. Radionuclides considered for this study are ~(131)I, ~(18)F, ~(67)Ga, ~(99m)Tc, ~(111)In, ~(201)TI and ~(137)Cs, with main gamma energies between 93 and 662 keV. Dosemeters were placed during a five month period in the nuclear medicine rooms (containing gamma-cameras), injection corridor, patient waiting areas, PET/CT study room, hot lab, waste storage room and corridors next to the hospitalization rooms for patients treated with ~(131)I and ~(137)Cs. High dose values were found at the waste storage room, outside corridor of ~(137)Cs brachytherapy patients and PET/CT area. Ambient dose equivalent rate obtained for the ~(137)Cs brachytherapy corridor is equal to (18.51 ± 0.02) x 10~(-3) mSv/h. Sites with minimum doses are the gamma camera rooms, having ambient dose equivalent rates equal to (0.05 ± 0.03) x 10~(-3) mSv/h. Recommendations have been given to the Department authorities so that further actions are taken to reduce doses at high dose sites in order to comply with the ALARA principle (as low as reasonably achievable).