High Sensitive¹²³I Thyroid Uptake Measurement Method Using an Imaging Plate

Abstract

A high sensitive ¹²³I thyroid uptake measurement method was devised by using an imaging plate and a bio imaginganalyzer system (IP system).The IP system gives an image reflecting thyroid outline.The IP system can detectthe thyroid activity of 600 Bq corresponding to 5% uptake 24 hr after administration of 42 kBq within an uncertaintyof 5%.The thyroid uptake study using IP system can be conducted by administrating the 1.1% activity of 3.7 MBqrequired for the NaI system in accordance with the guideline recommended by The Society of Nuclear Medicine.Thethyroid-absorbed dose for a normal adult administered 42 kBq was 0.13 mGy, that is comparable to the equivalentdose of the thyroid of 0.1 mGy due to the chest X-ray examination at the guidance level of 0.4 mGy recommended by IAEA.The PSL value-activity conversion coefficient was 6.0×10^-3±0.15×10^-3 PSL.sec^-1.Bq^-1.