Procedures using iodine-131 represent more than 90% of all therapies in nuclear medicine in Algeria. It is important to evaluate the long-term biological effects of iodine treatment on non-target organs to improve patient radiation protection. This experimental radiotoxicology study aims to determine the biokinetic models of iodine contamination. For this purpose, two Wistar rat models, with and without a thyroid, have been used to evaluate the biological half-life of iodine and then to perform a biodistribution study of iodine activity in 15 organs and tissues. For the most relevant organs, the respective absorbed doses have been calculated using RODES software.