Assessment of internal radiation exposure of nuclear medicine workers using whole body gamma counter

The use of unsealed sources in nuclear medicine may cause risks of internal exposure to the staffs. From the Basic Safety Radiation Protection Regulations (BSRP 2010) under ACT 304, the radiation workers should be assessed frequently for both internal and external exposures in order to ensure the compliance of dose limit of 20 mSv/y, averaged over defined periods of 5 years. The aim of this study was to evaluate the internal exposure of radiation workers from nuclear medicine centres who might be exposed to the unsealed sources such as Tc-99m and I-131. A total of 13 radiation workers from two nuclear medicine centres were invited to perform the whole-body counting in Malaysian Nuclear Agency. Each worker was scanned using ORTEC Whole Body Counter (WBC), bed type for 2400 s counting time. The internal exposure for each radionuclide of interest was then evaluated based on the ICRP Publication 68, IAEA's Safety Report Series No. 37 and BSRP 2010 in determining the committed effective dose. The results show that there is no internal exposure found for all monitored radiation workers, thus demonstrate that the radiation protection and safety were strictly implemented in these centres.