Release criteria and exposure of caregivers and public after discharge of patients undergoing 131 I-MIBG, 131 I-NaI and 177 Lu-DOTATATE therapies

The aim of this work is to investigate a protocol for discharging patients undergoing treatment with 131 I-NaI, 131 I-MIBG and 177 Lu-DOTATATE based on the patient-specific biokinetics. Release criteria and radiation protection recommendations have been determined according to the criteria established by European Commission Directive 2013/59/Euratom. The study analyzed dose rate at different distances of pediatric patients. Data have been used to establish radiation protection restrictions after discharge through a calculation model tailored on patients age and needs. Since younger patients need assistance even during hospitalization, caregivers exposure have been estimated through electronic dosimeters and these exposures were taken into account for the evaluation of prescriptions after patients discharge. Effective doses for caregivers of younger patients resulted up to 10 mSv during hospitalization for 131 I-MIBG administrations. The mean dose rate at 1 m at patient discharge was 10.3 µSv/h (ranging from 0.1 µSv/h to 82.5 µSv/h) for 131 I-NaI administrations, 45.4 µSv/h (ranging from 9.8 µSv/h to 103.5 µSv/h) for 131 I-MIBG administrations and 2.7 µSv/h (ranging from 0.6 µSv/h to 5.4 µSv/h) for 177 Lu-DOTATATE administrations. Radiation protection prescriptions have been evaluated considering the dose constraints for public and caregivers according to the Euratom Directive transposition in the Italian law. For public, obtained results showed that some days of abstention from every day activities are necessary especially for patients undergoing 131 I-MIBG therapies. Caregivers precautions have been evaluated stratifying patients in different age classes in order to consider that the younger is the patient, the more he need to receive contact assistance.