Determination of intake and internal radiation dose for occupationally exposed workers to iodine 131

Workers who prepare and inject radioactive Iodine I131 doses at the medical centers in Syria are potentially exposed to the radioactive intake by ingestion or inhalation during preparation or injection processes. The received amount of the radioactive intake differs according to the amount of the I131 that released during the preparation or injection processes, and to the work conditions and the applying ways of the radiation protection principles. Because of this radioactive intake, the thyroid gland may expose to amounts of I131 which may negatively affect the health of the workers, so it is necessary to make routine monitoring for all workers who receive an intake of more than 10% of the annual intake limit which is (2x106 Bq/y) for I131. To make this monitoring process, it is necessary to use either the thyroid gland counter in order to know the concentrated amount of the radioactivity in the gland, or the analysis of a 24 hours urine sample of the exposed workers to determine the eliminated amount of the radioactivity using gamma spectrometry, also the two processes can be applied at the same time. Since the thyroid gland counter is not available, the analysis of urine sample was done to determine the concentrated amount of the radioactivity in urine, then to estimate the radioactive intake and the internal radioactive dose. The results of applying this method dictated that some workers work in safe conditions according to the radiation protection and there is no need for them to make routine monitoring . But the other workers receive a radioactive intake of about 10% yearly of the annual intake limit and that requires a routine periodical monitoring for those workers in addition to the necessity of applying the principles of the radiation protection during the work with I131. These principles and systems should indicate the basic requirement of radiation protection that must be available in the laboratory that deal with I131 either for therapy or for diagnosis. (Authors)