title: Evaluation of radiation dose to anthropomorphic paediatric models from positron-emitting labelled tracers.
abstract: PET uses specific molecules labelled with positron-emitting radionuclides to provide valuable biochemical and physiological information. However, the administration of radiotracers to patients exposes them to low-dose ionizing radiation, which is a concern in the paediatric population since children are at a higher cancer risk from radiation exposure than adults. Therefore, radiation dosimety calculations for commonly used positron-emitting radiotracers in the paediatric population are highly desired. We evaluate the absorbed dose and effective dose for 19 positron-emitting labelled radiotracers in anthropomorphic paediatric models including the newborn, 1-, 5-, 10- and 15-year-old male and female. This is achieved using pre-calculated S-values of positron-emitting radionuclides of UF-NCI paediatric phantoms and published biokinetic data for various radiotracers. The influence of the type of anthropomorphic model, tissue weight factors and direct human- versus mouse-derived biokinetic data on the effective dose for paediatric phantoms was also evaluated. In the case of (18)F-FDG, dosimetry calculations of reference paediatric patients from various dose regimens were also calculated. Among the considered radiotracers, (18)F-FBPA and (15)O-water resulted in the highest and lowest effective dose in the paediatric phantoms, respectively. The ICRP 103 updated tissue-weighting factors decrease the effective dose in most cases. Substantial differences of radiation dose were observed between direct human- versus mouse-derived biokinetic data. Moreover, the effect of using voxel- versus MIRD-type models on the calculation of the effective dose was also studied. The generated database of absorbed organ dose and effective dose for various positron-emitting labelled radiotracers using new generation computational models and the new ICRP tissue-weighting factors can be used for the assessment of radiation risks to paediatric patients in clinical practice. This work also contributes to a better understanding of the factors influencing patient-specific radiation dose calculation.
authors.affiliation: Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, CH-1211 Geneva 4, Switzerland.
authors.forename: Tianwu
authors.initials: T
authors.lastname: Xie
authors.forename: Habib
authors.initials: H
authors.lastname: Zaidi
mesh_terms: D000293:Adolescent; D000375:Aging / Q000502:physiology*; D040761:Biomimetic Materials; D002648:Child; D002675:Child, Preschool; D003198:Computer Simulation; D004583:Electrons; D005260:Female; D006801:Humans; D007223:Infant; D007553:Isotope Labeling; D008297:Male; D008954:Models, Biological; D009928:Organ Specificity; D019047:Phantoms, Imaging; D049268:Positron-Emission Tomography / Q000295:instrumentation / Q000379:methods*; D011829:Radiation Dosage; D011849:Radioactive Tracers; D011868:Radioisotopes / Q000032:analysis*; D014915:Whole-Body Counting / Q000379:methods*
chemical_list: D011849:Radioactive Tracers; D011868:Radioisotopes