Targeted alpha therapy in the clinical practice: radiation protection considerations

Abstract Targeted alpha particles therapy (TAT) has been introduced in the clinical practice in the last decade and is rapidly growing mainly due to higher therapeutic effect of alpha particles than beta emitters. According to the European Directive Euratom 59/13 the member states shall require licensing for administration of radioactive substances to patients and should provide a risk assessment for workers and members of the public. This work presents expected dose contributions in clinical scenarios where Th-227, Ac-225, Ra-223, Bi-213, Pb-212 and At-211 are handled. Three exposure scenarios are considered: single dose preparation and injection, and patient care. Both the external and internal exposures are evaluated. Using appropriate dose conversion factors, the whole body effective dose and the equivalent dose to the extremities are estimated. In addition, the committed dose was assessed. In the incident scenario, the liquid spills contaminating the floor and the workers; the doses to the personnel involved in the decontamination are estimated. A deterministic model has been used to estimate the dose to third parties. The whole body effective dose is negligible. In the injection phase workers receive larger doses to the extremities than in the other scenarios. The internal exposure in normal workload does not pose a significant risk. The spillage scenario deserves attention for the skin dose to workers involved in the clean-up. The dose to third parties for single administration is at least one order of magnitude lower than the dose constraints. The scenarios are intentionally conservative in order to provide an overestimate. The approach is general and can be refined according to the national legislation.