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Dosimetry for Pediatric FDG Molecular Imaging Studies

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S O'Reilly

S O'Reilly1,4*, K Khamwan2 , D Plyku3 , J Brown4 , X Cao5 , Y Li3 , G Sgouros3 , F Fahey5 , S Treves6 , W Bolch4 , (1) University of Pennsylvania, Philadelphia, PA (2) Chulalongkorn University, Bangkok, Thailand (3) Johns Hopkins University, Baltimore, MD, (4) University of Florida, Gainesville, FL, (5) Boston Childrens Hospital, Boston, MA, (6) Harvard Medical School, Boston, MA


WE-F-201-11 (Wednesday, August 2, 2017) 1:45 PM - 3:45 PM Room: 201

Purpose: National campaigns to limit and standardize doses to pediatric patients have been established, such as “Go with the Guidelines” which provides North American consensus guidelines for administered activities (AA) for children. Radiation doses for pediatrics for ¹⁸F-FDG have been calculated and provided most recently in ICRP Publication 128. However, these calculations were completed using primarily adult-based biokinetic data, are not gender-specific and do not provide values for newborns.

Methods: New biokinetic models have been developed that are specific to pediatric ages 0 to 5 years for ¹⁸F-FDG using data from literature and imaging studies for thirty-five pediatric patients from Boston Children’s Hospital. These biokinetic models were used to determine S-values and effective doses for newborns, 1-yr-olds and 5-yr-olds using the UF/NCI family of hybrid computational phantoms. Radiation transport simulations were completed using MCNPXv2.7, directly sampling the ¹⁸F emission spectrum. The source organs/tissues were the brain, heart, lungs, liver, kidneys, urinary bladder contents, and rest of body. Target organs were those used in effective dose calculations.

Results: S-values, organ absorbed dose per AA, and effective doses were calculated for a newborn, 1-year-old, and 5-year-old male and female. The ICRP value for absorbed dose per AA for each organ is higher than the calculated value in this study, with the exception of the brain. This is expected as the brain residence time used in this study is age-specific and significantly higher than the ICRP value, 1.154 hours versus 0.21 hours. The ICRP value for effective dose per AA for the 1-year-old and 5-year-old are each about 2 times greater than the value calculated in this study.

Conclusion: These dosimetric differences are most likely due to the difference in biokinetic models, showing the importance of using age-specific models, and the refined phantom anatomy used in this study.

Funding Support, Disclosures, and Conflict of Interest: NIH grant R01 EB013558

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