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Pediatric Chest, Abdomen and Head Computed Tomography Exams for Personalized Dosimetry, Using GATE Monte Carlo Simulations

T Kostou1 , P Papadimitroulas2 , D Mihailidis3 , G Loudos4 , G Kagadis5*, (1) University of Patras, Rion, Ahaia, Greece (2) BET Solutions, Athens, Attiki, Greece (3) University of Pennsylvania, Philadelphia, PA, (4) Technological Educational Institute of Athens, Egaleo, Attiki, Greece (5) university Patras, Rion - Patras, Greece


(Tuesday, 7/31/2018) 4:30 PM - 5:30 PM

Room: Exhibit Hall | Forum 1

Purpose: This study intends to create an organ dose reference database for pediatric individuals undergoing chest, abdomen and head computed tomography (CT) examinations. The data will permit quick estimates of organ effective doses for patients of different age, gender, and examination procedure.

Methods: The GATE MC toolkit was used for modeling a multislice helical CT system. The simulated scanner model was validated with the standard CTDI head/body phantoms. A thin-walled ionization chamber was simulated according to the manufacturer specifications at the center, and 4 peripheral positions. Six pediatric computational models in the 5 - 14 y age range were used to simulate realistic helical chest, abdomen and head protocols, to calculate the absolute absorbed dose/organ and the dose variations with varying organ mass.

Results: The CT scanner model was validated against experimental CTDI measurements with statistical differences being lower than ~18%. The absorbed doses/organ for selected organs were estimated for each protocol and the dose variations for the different pediatric phantoms are presented. Indicatively, for chest protocol, absorbed doses for selected organs inside the scan coverage varied between 25-35%, and 43-51% for 5 vs. 8, and 8 vs. 11 y old girls respectively. For the abdomen protocol, absorbed doses for selected age varied between 18-31%, and 3-19% for 5 vs. 8, and 8 vs. 11 y old girls respectively.

Conclusion: This is an ongoing study for the creation of a CT dosimetry pediatric database and for the quantification of the differences on the absorbed doses in tissue/organ level, using several models with variations in anatomical features. Every patient could be matched to the best anatomical model of this database according to the characteristics of its internal organs, resulting to more accurate organ dose calculation.

Funding Support, Disclosures, and Conflict of Interest: This study is part of a project that has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 691203.


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