Calibration of a gamma camera for the routine monitoring of personnel exposed to I-131 in Carlos Andrade Marin hospital

The objective of this work was to calibrate a detection system that allows to implement the monitoring of workers occupationally exposed to I-131 in the Nuclear Medicine center of the Carlos Andrade Marín Hospital, in order to guarantee that the radiological conditions are satisfactory and that the levels of security are acceptable [1]. This will allow the estimation of the effective doses committed due to the incorporation of this radionuclide. During calibration, a Millennium brand Gamma camera model ASM 1301, a neck phantom, a thyroid simulator with a certified Ba-133 activity and also a certified point source of Ba-133 were used. The calibration factor, detection efficiency and the minimum detectable activity (AMD) for different geometries were determined. The measurements were made without collimator, with a counting time of 15min, distance between the detector and the phantom of 20 and 25 cm and an energy window (15% - +) centered on the peak main of I-131 (364keV); In addition, a background level was established by taking measurements with a inert simulator and with individuals not exposed [3]. The results obtained show that the method is feasible for the routine monitoring of personnel exposed to I-131 for the established measurement geometries. (author)