Biodistribution and radiation dosimetry of 82Rb at rest and under adenosine stress in the paediatric population.

Background: We aimed to estimate ⁸²Rb paediatric dosimetry based on adult biokinetic and prospectively acquired paediatric biokinetic data. Organ absorbed doses (OAD) and effective doses (E) were estimated using ICRP-103 based OLINDA/EXM.2.1 software. We extrapolated paediatric OAD and E from existing adult biokinetic data (OAD_{p, Ab} and E_{p, Ab} respectively). ⁸²Rb EANM paediatric dosage card (PDC) cluster and the recommended administered activity were determined. Ten paediatric participants (M: F 7:3; mean age 8.8 ± 6.6y) underwent prospectively 3D-SiPM ⁸²Rb PET/CT. Using PMOD software, source organs volumes were delineated to obtain source organ time activity curves and participant specific organ masses based on PET/CT data. Subject specific OAD (OAD_p and E_p respectively) were derived from original paediatric data.

Results: ⁸²Rb was assigned to the EANM PDC B-Cluster. Estimated ranges for E_{p, Ab} resp. E_p were 2.19E-02 ̶ 1.15E-03 resp. 9.62E-03 ̶ 1.04E-03 mSv/MBq. E_{p, Ab} resp. E_p with 10 MBq/kg and 5MBq/kg after a single ⁸²Rb infusion was between 0.5 and 0.7 mSv resp. 0.4-0.8 mSv and 0.2-0.4 mSv. The most irradiated organs were the kidneys and the heart wall in infant and newborn group, followed by heart wall in the other age groups, hence, the small intestine, pancreas, lungs, adrenals, and rest of the gastrointestinal tract. ⁸²Rb PET/CT was safe and well-tolerated by all participants.

Conclusions: We firstly provide original dosimetry data for the use of ⁸²Rb PET/CT in the paediatric population, showing reasonably low radiation exposure, and confirming safety and tolerability of ⁸²Rb PET/CT in this population.