Feasibility of Administering High-Dose (131) I-MIBG Therapy to Children with High-Risk Neuroblastoma Without Lead-Lined Rooms

Background: Although (131) I-metaiodobenzylguanidine ((131) I-MIBG) therapy is increasingly used for children with high-risk neuroblastoma, a paucity of lead-lined rooms limits its wider use. We implemented radiation safety procedures to comply with New York City Department of Health and Mental Hygiene regulations for therapeutic radioisotopes and administered (131) I-MIBG using rolling lead shields.

Procedure: Patients received 0.67 GBq (18 mCi)/kg/dose (131) I-MIBG on an IRB-approved protocol (NCT00107289). Radiation safety procedures included private room with installation of rolling lead shields to maintain area dose rates ≤0.02 mSv/hr outside the room, patient isolation until dose rate <0.07 mSv/hr at 1 m, and retention of a urinary catheter with collection of urine in lead boxes. Parents were permitted in the patient's room behind lead shields, trained in radiation safety principles, and given real-time radiation monitors.

Results: Records on 16 (131) I-MIBG infusions among 10 patients (age 2-11 years) were reviewed. Mean ± standard deviation (131) I-MIBG administered was 17.67 ± 11.14 (range: 6.11-40.59) GBq. Mean maximum dose rates outside treatment rooms were 0.013 ± 0.008 mSv/hr. Median time-to-discharge was 3 days post-(131) I-MIBG. Exposure of medical staff and parents was below regulatory limits. Cumulative whole-body dose received by the physician, nurse, and radiation safety officer during treatment was 0.098 ± 0.058, 0.056 ± 0.045, 0.055 ± 0.050 mSv, respectively. Cumulative exposure to parents was 0.978 ± 0.579 mSv. Estimated annual radiation exposure for inpatient nurses was 0.096 ± 0.034 mSv/nurse. Thyroid bioassay scans on all medical personnel showed less than detectable activity. Contamination surveys were <200 dpm/100 cm(2) .

Conclusions: The use of rolling lead shields and implementation of specific radiation safety procedures allows administration of high-dose (131) I-MIBG and may broaden its use without dedicated lead-lined rooms.