Radiation protection in 90Y-labelled DOTA-D-Phe1-Tyr3-octreotide preparations

Beta-emitting radionuclides are being increasingly used in targeted radionuclide therapy in nuclear medicine. In particular, the pure high-energy beta-emitter 90Y (Emax=2.27 MeV) has a physical half-life compatible with the pharmacokinetics of peptides. The use of this isotope implies an increase in the radiation dose received by the nuclear medicine staff. The aim of this study is thus the evaluation of the personal beta-dosimetry data related to therapeutic 90Y-labelled DOTA-D-Phe1-Tyr3-octreotide preparation and administration in a nuclear medicine department.

Personal dose measurements were carried out with a series of thin active layer ultrasensitive MCP-Ns (LiF: Mg, Cu, P) dosimeters fixed at the operator's fingertips and by means of some direct reading dosimeters; other individual protection devices, such as shielded aprons and anti-X gloves, were also used.

The 95th percentile of the chemist's skin equivalent dose distribution was 1.759 mSv/GBq by using 0.10-mm anti-X gloves and 0.265 mSv/GBq by using 0.20-mm anti-X gloves. The 95th percentile of the physician's skin equivalent dose distribution was 1.198 mSv/GBq by using 0.10-mm anti-X gloves. The use of an anti-X apron during administration permits saving absorbed doses by a factor over 97% for both Hp(10) and Hp(0.07).

Because of the physical properties of beta-emitters, an increased number of therapeutic sessions is to be expected. The dose values measured till now, resulting from a high radioprotection level modus operandi, have always respected the threshold limits reported by the European Directive EURATOM 96/29 05/13/1996 for exposed workers, even in addition to other clinical practices in the department.