Developing a simple method for determination of the activity absorbed by thyroid glands of nuclear medicine staff

The occupational safety of nuclear medicine staff working with radioactive iodine, I-131, has always been a great concern in nuclear medicine. As the radioiodine is a volatile substance it may enter the body during the respiration, and absorbed by the thyroid glands of the staff, and causing major problems for their health. This study aims to develop a simple method for determining the activity of the 131I absorbed in thyroid glands of nuclear medicine staff, using a home-made anthropomorphic neck-thyroid phantom. I-131 with the activity of 370kBq was injected inside the thyroid gland of the phantom. The dose rate was measured by putting a portable detector on the thyroid gland, at the surface of the neck phantom. The measurements were repeated for two months. Then a calibration curve was drawn, iodine activity inside the thyroid versus dose rate at the neck surface. Then the calibration curve was used to estimate the absorbed activity in the thyroids of the staff in one of the main hospitals of Shiraz city. Finally, new software was developed for assessing, and recording the activity concentration of 131I accumulated in the thyroid gland. Every day the dose rate was measured by putting the detector on the necks of the staff, and the dose rates were converted to the activity inside their thyroid using the above-mentioned calibration curve. The method used in this study can be used for estimation of the radioiodine concentration inside the thyroid glands of the staff; in normal working conditions and accidents.