Pediatric 131I-MIBG Therapy for Neuroblastoma: Whole-Body 131I-MIBG Clearance, Radiation Doses to Patients, Family Caregivers, Medical Staff, and Radiation Safety Measures

Abstract

Purpose I-131-metaiodobenzylguanidine (I-131-MIBG) has been used in the diagnosis and therapy of neuroblastoma in adult and pediatric patients for many years. In this study, we evaluated whole-body I-131-MIBG clearance and radiation doses received by patients, family caregivers, and medical staff to establish appropriate radiation safety measures to be used in therapy applications. Methods Research was focused on 23 children and adolescents with metastatic neuroblastoma, with ages ranging from 1.8 to 13 years, being treated with I-131-MIBG. Based on measured external dose rates from patients, dosimetric data to patients, family members, and others were calculated. Results The mean SD I-131-MIBG activity administered was 8.55 +/- 1.69 GBq. Percent whole-body retention rates of I-131-MIBG at 24, 48, and 72 hours after administration were 48% +/- 7%, 23% +/- 7%, and 12% +/- 6%, with a whole-body I-131-MIBG effective half-life of 23 +/- 5 hours for all patients. The mean doses for patients were 0.234 +/- 0.096 mGyMBq(-1) to red-marrow and 0.251 +/- 0.101 mGyMBq(-1) to whole body. The maximum potential radiation doses transmitted by patients to others at 1.0 m was estimated to be 11.9 +/- 3.4 mSv, with 97% of this dose occurring over 120 hours after therapy administration. Measured mean dose received by the 22 family caregivers was 1.88 +/- 1.85 mSv, and that received by the 19 pediatric physicians was 43 +/- 51 Sv. Conclusion In this study, we evaluated the whole-body clearance of I-131-MIBG in 23 pediatric patients, and the radiation doses received by family caregivers and medical staff during these therapy procedures, thus facilitating the establishment of radiation safety measures to be applied in pediatric therapy.