Personnel Exposure in Labelling and Administration of (177)Lu-DOTA-D-Phe1-Tyr3-octreotide

Objective: The introduction of peptide receptor radionuclide therapy, mainly performed with (90)Y and (177)Lu-labelled somatostatin analogues, has widened the therapeutic horizon of nuclear medicine.The handling of (177)Lu-labelled pharmaceuticals implies an increase of the personnel exposure and this aspect is evaluated in this paper, in comparison with personal exposure in (90)Y manipulation.

Materials And Methods: Personal dose measurements were performed during 26 (177)Lu-DOTATOC preparations by using a series of thin active layer LiF: Mg,Cu,P thermoluminescence dosimeters fixed at the operator's fingertips to evaluate the skin equivalent dose and by means of direct reading dosimeters positioned at the chest to evaluate the personal effective dose. Individual protection devices, such as shielded aprons and anti-X gloves, were also used.

Results: The 95th percentile of the skin equivalent dose distribution for (177)Lu operations by using 0.20-mm anti-X gloves was 0.080 mSv/GBq for the chemist and 0.011 mSv/GBq for the physician, whereas the 75th percentile was 0.058 mSv/GBq for the chemist and 0.006 mSv/GBq for the physician. The use of the 0.25 mm Pb-equivalent anti-X apron halved the personal equivalent dose measured over the apron by a direct reading dosimeter. Skin doses were compared with (90)Y-DOTATOC procedures: no relevant exposure reduction is observed for chemists, whereas doses are considerably lower during administration procedures performed by physicians.

Conclusion: In this study, an evaluation of the skin equivalent doses during (177)Lu-DOTATOC labelling and administration is presented. These data can be useful to assess the risk for workers in centres that are starting to implement PRRT using (177)Lu. The use of appropriate protection devices and procedures allows the observance of International Commission for Radiological Protection dose limits for exposed workers.