How much do ⁶⁸Ga-, ¹⁷⁷Lu- and ¹³¹I-based radiopharmaceuticals contribute to the global radiation exposure of nuclear medicine staff?

Background: The radiation exposure of nuclear medicine personnel, especially concerning extremity doses, has been a significant focus over the past two decades. This study addresses the evolving practice of NM, particularly with the rise of radionuclide therapy and theranostic procedures, which involve a variety of radionuclides such as ⁶⁸Ga, ¹⁷⁷Lu, and ¹³¹I. Traditional studies have concentrated on common radioisotopes like ^99mTc, ¹⁸F, and ⁹⁰Y, but there is limited data on these radionuclides, which are more and more frequently used. This study, part of the European SINFONIA project, aims to fill this gap by providing new dosimetry data through a multicenter approach. The research monitors extremity doses to hands, eye lens doses, and whole-body doses in nuclear medicine staff handling ⁶⁸Ga, ¹⁷⁷Lu, and ¹³¹I. It examines the type of activities performed and the protective measures used. The study extrapolates measured doses to annual doses, comparing them with annual dose limits, and assesses the contribution of these specific procedures to the overall occupational dose of nuclear medicine personnel.

Results: Measurements were conducted from November 2020 to August 2023 across nine hospitals. The highest whole-body, eye lens and extremity doses were observed for ⁶⁸Ga. Average maximum extremity doses, normalized per manipulated activity, were found of 6200 µSv/GBq, 30 µSv/GBq and 260 µSV/GBq for ⁶⁸Ga, ¹⁷⁷Lu and ¹³¹I, respectively. Average whole-body doses stayed below 60 µSv/GBq for all 3 isotopes and below 200 µSv/GBq for the eye lens dose. The variation in doses also depends on the task performed. For ⁶⁸Ga there is a risk of reaching the annual dose limit for skin dose during synthesis and dispensing.

Conclusions: This study's measurement campaigns across various European countries have provided new and extensive occupational dosimetry data for nuclear medicine staff handling ⁶⁸Ga, ¹⁷⁷Lu and ¹³¹I radiopharmaceuticals. The results indicate that ⁶⁸Ga contributes significantly to the global occupational dose, despite its relatively low usage compared to other isotopes. Staff working in radiopharmacy hot labs, labeling and dispensing ¹⁷⁷Lu contribute less to the finger dose compared to other isotopes.