The objective of this paper is to create networks of measuring and assessing internal dose due to intake iodine-131 using either thyroid uptake counter or gamma camera, which is currently mostly used in nuclear medicine facilities. There are thirteen nuclear medicine volunteers participated in the activity. Among the network, thyroid uptake counter technique was used by twelve representatives and gamma camera was used by one. All participants were trained to measure iodine-131 and assess internal dose base on IAEA safety series no.114 and ICRP 78. The efficiency calibrations with iodine-131 standard were performed for all participated instruments, in order to ensure that those systems are suitable for iodine-131 measurement of the interested samples, including thyroid, charcoal filter paper, contamination filter paper and a bottle of 5 ml urine. Then, internal doses were assessed. The efficiency of those iodine measurements were reported in the paper. After the evaluation, it is found that MDA values from all participants were lower than derived recording level (DRL), implying that their environments are suitable for measuring iodine-131. In some networks, however, MDA values were slightly higher than DRL. Therefore, decreasing background level to improve MDA to be lower than DRL is recommended to improve the efficiency of the measurement.
Keywords: internal dose, thyroid uptake, gamma camera, iodine-131, thyroid counting