External dose assessment from the patients treated by 177Lu-DOTATATE

Background: The present study was done to establish release criterion in the treated patients and to determine external radiation doses received by personnel and caregivers of patients with metastatic neuroendocrine tumors (NETs) during peptide receptor radionuclide therapy (PRRT) by means of Lutetium-177 (177Lu) DOTATATE. Materials and Methods: For this purpose, 30 patients were enrolled in the study who received 5.5±1.1 (in a range of: 3.7-7.4) GBq of 177Lu-DOTA-tyr3-octreotate. Dose rate was analyzed at distances 0, 0.25, 0.5, 1.0, and 2.0 m in different times after termination of infusion using an ionization chamber. Results: Mean dose rate at distance of 1 m from the patient, approximately 5 h after injection was considered as discharge limit. The maximum dose to caregivers in the first 48 h was equal to 340±29 μSv. Mean dose to the nurse was estimated as 6.3±0.4, and 7±0.5 μSv per patient with and without lead shield, respectively. Discussion: According to our findings, approximately a time delay of 5 h after injection is recommended as release criterion for patients treated by Lutetium-177 (177Lu) DOTATATE. For a total of 30 patients, external radiation dose to staff was found to be within permissible levels. Conclusion: The use of protective equipment is recommended at all stages of procedure for staff.