Background: 131I-metaiodobenzylguanidine (mIBG) offers an effectively targeted radionuclide therapy in pediatric patients. According to radiation protection authority in our country, the patient treated with high-dose (>1100 MBq) radioiodine is recommended to stay in the hospital. Hence, this study intends to measure the radiation exposure in nonlead-lined treatment room installing with portable lead shields located in general pediatric ward and surrounding areas. In addition, this study also aims to measure the radiation exposure to the family caregiver in pediatric patients received high dose 131I-mIBG.
Methods: Environmental OSL (optically stimulated luminescence) monitoring devices (InLight®, Al2O3:C) were prepared and calibrated by Thailand Institute of Nuclear Technology (TINT). Twenty-five set of OSLs were placed in and surrounded the treatment room. Dose to family caregiver was recorded by digital semiconductor dosimeter (ALOKA PDM-112) also calibrated by TINT. The measurement was carried for four pediatric patients treated with 131IMIBG (activity 3700 – 5500 MBq).
Results: The ambient doses equivalent and the dose rate were analyzed, the limit of 10 and 0.5 μSv/h are accepted for radiation worker and member of the public, respectively. The dose rate around the patient bed and toilet were high as expected. Dose rates at the wall of adjacent room and corridor were slightly greater than the public limit (range 1.82 to 4.48 μSv/h). Remarkably, the dose rates at caregiver chair (outside the shielding) were exceeded the limits (30.57 ± 5.69 μSv/h). Consequently, this was correlated with high personal dose equivalent to family caregivers which listed as 175, 1632, 6760 and 7433 μSv for the patient age of 15, 5, 1 and 1 year respectively.
Conclusion: These radiation monitoring data provided the important information to manage radiation protection and aware of radiation exposure when using non-lead-lined treatment room in general pediatric ward.
 Markelewicz Jr RJ, Lorenzen WA, Shusterman S, et al. Radiation exposure to family caregivers and nurses of pediatric neuroblastoma patients receiving 131i-metaiodobenzylguanidine (131i-mIBG) therapy. Clin Nucl Med. 2013;38(8):604-607.
 Tonnonchiang S, Sritongkul N, Chaudakshetrin P, Tuntawiroon M. Radiation exposure to relatives of patients treated with iodine-131 for thyroid cancer at Siriraj hospital. J Med Assoc Thai. 2016;99(2):220-224.
 Gains JE, Walker C, Sullivan T, et al. Radiation exposure to comforters and carers during paediatric molecular radiotherapy. Pediatr Blood Cancer. 2015;62(2):235-239.
 Cougnenc O, Defachelles A-S, Carpentier P, et al. High-dose 131i-mibg therapies in children: Feasibility, patient dosimetry and radiation exposure to workers and family caregivers. Radiat Prot Dosimetry. 2017;173(4):395-404.
 de la Guardia M, Mata S, McCammon S, et al. Physician and nursing personnel radiation exposure monitoring experience during the first year of performing i-131 metaiodobenzylguanidine (mIBG) therapy. Conference: Society of Nuclear Medicine and Molecular Imaging, Baltimore, MD. J Nucl Med. 2015;56(Supplement3):1251.
 Tuncel N, Karayalcin B, Koca G. The calibration process of OSL detectors used for staff and patient dosimetry in hospital environment. J Nuc Med Radiat Therapy. 2015;6(6):1000259.
 Dietze G, Menzel H-G. Dose quantities in radiation protection and their limitations. Radiat Prot Dosimetry. 2004;112(4):457-463.
 ICRP. The 2007 recommendations of the international commission on radiological protection: ICRP Publication 103. Ann ICRP. 2007;37(2-4).
 Bartlett DT. Personal dose equivalent, Hp(d), and reference point for calibration. Radiat Prot Dosimetry. 2006;121(3):209-210.
 Changmuang W, Chamroonrat W, Kositwattanarerk A, et al. Radiation from an admitted thyroid cancer patient with high dose I-131 treatment in related hospitalized area and exposure to associated personnel in Ramathibodi’s new inpatient unit. Asean J Radiol. 2012;18(2):118-122.
 Wrixon AD. New ICRP recommendations. J Radiol Prot. 2008;28(2):161-168.
 Chu BP, Horan C, Basu E, et al. Feasibility of administering high-dose 131I-MIBG therapy to children with high-risk neuroblastoma without lead-lined rooms. Pediatr Blood Cancer. 2016;63(5):801-807.
 Assessment of occupational exposure due to intakes of radionuclides. IAEA Safety Standards Series No. RS-G-1.2. Vienna: International Atomic Energy Agency; 1999.