Abstract
Radioiodine therapy is a treatment procedure in order to combat many diseases that affect the thyroid, being held from the oral administration of the I-131 and / or I-123 radioisotope. According to the Brazilian Norm of National Commission of Nuclear Energy the dose administration to the injected patient submitted of the treatment using I-131 with activity less than 1850 MBq is considered outpatient because the hospitalization is not necessary, however, he can only be released after being checked that the value of the dose rate is less than 0.03 mSv / h, measured at 2 meters of the patient. The objective of this study was to estimate the dose rate emitted by the patient measured in two meters away when subjected to outpatient treatment of radioiodine therapy. For this research, were evaluated patients submitted to the treatment in question in a nuclear medicine service located in Recife. As measurement instrument was used a counter digital Geiger-Muller type, and for dosimetry estimates, were made trendlines comparing them in order to choose the one that best represents the dosimetric estimate in relation to dose rate. The obtained results were presented in graphs showing the variation of the dose rates according to the radionuclide activity administered.