Radiation protection considerations in outpatient treatment using 131-I radioiodine

Abstract

Thyrotoxic patients treated with radioiodine 131-I on outpatient basis create radiation hazard to the public especially their family members. These patients need to be restricted for certain number of days before they can resume their normal activities to ensure others will not be exposed to radiation. In this study the period of restrictions were determined based on the 24hr uptake and effective half-life of 131-I in the thyroid gland. The amount of radioiodine retained in the thyroid gland was measured over the period of 1-20 days after therapeutic administration of the radionuclide using scintillation uptake probe. The mean activity in the gland at day 1 was 74.7%, SD 8.5% of the administered activity and thereafter retention followed a single exponential effective half-life of 5.8 days, SE 0.5 day. From these results the restriction periods for administered activities of 200-1000 MBq were estimated. Information could be used to advise patients before they leave the hospital since no local guidelines are available at the moment.