Abstract
The PSL value-radioactivity conversion factor and the detection limit of a thyroid 131I in vivo monitoring system using an imaging plate (IP) were investigated by using thyroid-neck phantom loaded aqueous 131I solution. The conversion factor of the IP system was approximately constant for the thyroid volume between 7.7 and 20.5ml and neck diameter between 10cm and 14cm. The conversion factor linearly decreased with increasing the tissue thickness. The detection limits ranged from 311 to 506 Bq depending on the combinations of neck diameter, thyroid volume and prethyroid tissue thickness. The detection limit of the IP system was less than 1/60 of the screening level of 30 kBq in cases of public emergencies. The IP system is a new option for thyroid 131I monitoring method.
