-The workers performing different activities with radionuclides in nuclear medicine centers are at potential risk of external exposure and internal contamination. The IAEA Safety Guide N• RS-G-1.2 proposed criteria for determining the need for a routine monitoring program to assess internal contamination. For this purpose, an Excel template containing the IAEA criteria was applied in three nuclear medicine centers in Chile. The results show that it is necessary to carry out a routine monitoring program for five workers who handle 131 I and three for 99m Tc. We propose to implement this template at a national level in order to improve the conditions of radiation protection in the participating centers.

Anthropomorphic phantoms are used in nuclear medicine for imaging quality control, calibration of gamma spectrometry system for the study of internal contamination with radionuclides and for internal dosimetric studies. These are constructed of materials that have radiation attenuation coefficients similar to those of the different organs and tissues of the human body. The material usually used for the manufacture of phantoms is polymethyl methacrylate. Other materials used for this purpose are polyethylene, polystyrene and epoxy resin. This project presents the design and manufacture of an anthropomorphic thyroid-neck phantom that includes the cervical spine, trachea and oesophagus, using a polyester resin (ρ = 1.1 g cm(-3)). Its linear and mass attenuation coefficients were experimentally determined and simulated by means of XCOM software, finding that this material reproduces the soft tissue ICRU-44 in a range of energies between 80 keV and 11 MeV, with less than a 5 % difference.

Currently in Chile, there are about 42 nuclear medicine centres that mainly use 99mTc and 131I in diagnostic and therapeutic procedures. Therefore, staff performs various tasks that increase the risk of internal incorporation and the need to implement routine monitoring programmes. This article shows tools for self-monitoring of staff who exposed to 131I from measurements in thyroid and urine samples, using the gamma cameras of Nuclear Medicine Units. Then, the calibration factors of gamma cameras of participating units were determined, and a one-worker dose was calculated due to internal incorporation, using an Excel spreadsheet for self-monitoring. The worker who handles 131I in one of the studied units was monitored for 6 months. The goal of this study is to implement a routine self-monitoring programme for the estimation of committed effective dose of staff exposed to 131I using gamma cameras in Nuclear Medicine Units of clinical centres in Chile.

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