Evaluation of external radiation exposure in patients treated with 177Lu-PSMA and radiation safety assessment of the patient caregivers.

This study evaluates dose rates at various distances and time intervals after 177Lu-PSMA treatment and assesses caregivers' effective doses. Dose rates were measured in 47 patients at 0.5 and 1 m up to 168 h post-injection. Initial dose rates were 34.6 ± 9 μSv (0.5 m) and 24.6 ± 5 μSv (1 m) at 5 min, peaking at 48.5 ± 15 and 31.6 ± 8 μSv at 1 h, then declining significantly over time. Caregivers' effective doses ranged from 20 to 1170 μSv, remaining below international safety limits. This study demonstrates that patient dose rates at a distance of 1-m decline to below 30 μSv/h within 2-3 h post-injection and fall further to under 20 μSv/h after 6 h. Patients may be considered radiologically safe approximately four days post-procedure, depending on individual factors. While 177Lu-PSMA is a safe and effective PRRT modality, strict safety measures are essential to minimize exposure risks.