Radiation protection in radionuclide therapies with 90Y-conjugates: risks and safety

The widespread interest in 90Y internal radionuclide treatments has drawn attention to the issue of radiation protection for staff. Our aim in this study was to identify personnel at risk and to validate the protection devices used. 90Y-MoAb (Zevalin, 15 cases, 1.1 GBq/patient) and 90Y-peptide (90Y-DOTATOC) systemic (i.v., 50 cases, 3.0 GBq/patient) and locoregional (l.r., 50 cases, 0.4 GBq/patient) treatments were considered. Radiolabelling was carried out in a dedicated hot cell. Tele-tongs, shielded (PMMA: polymethylmethacrylate) syringes/vials and an automatic dose fractionating system were used. Operators wore anti-X-ray and anti-contamination gloves, with TLD dosimeters placed over the fingertips. For i.v. administration, activity was administered by a dedicated system; for l.r. administration, during activity infusion in the brain cavity, tongs were used and TLDs were placed over the fingertips. The air kerma-rate was measured around the patients. The use of devices provided a 75% dose reduction, with mean fingertip doses of 2.9 mGy (i.v. MoAbs), 0.6 mGy (i.v. peptides)/radiolabelling procedure and 0.5 mGy/l.r. administration. The mean effective dose to personnel was 5 μSv/patient. The air kerma-rate around the patients administered i.v. 90Y-peptides were 3.5 (1 h) and 1.0 (48 h) μGy/h at 1 m. Patient hospitalisation of 6 h (l.r.)/48 h (i.v.) guaranteed that the recommended limits of 3 mSv/year to family members and 0.3 mSv/year to the general population (Council Directive 97/43/Euratom) were respected. When specific procedures are adopted, a substantial improvement in 90Y manipulation is attainable, reducing doses and increasing safety. For the widespread clinical use of 90Y-conjugates, a completely automatic labelling procedure is desirable. (orig.)