[P049] Moving forward to personalized pediatric dosimetry on computed tomography applications

Purpose Personalized dosimetry is of high interest in pediatric applications where exposure to ionizing radiation is widely debated. This study intends to create an organ dose database for pediatric reference individuals undergoing 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 [1] was used for modeling a multislice helical CT system. The energy spectrum was calculated using Spektr software, and consequently imported in GATE as a gamma-particle point source with an almost continuous helical movement. To validate our results, simulations were performed with the standard CTDI head/body phantoms. A thin-walled ionization chamber was simulated according to the manufacturer specifications at 1 center, and 4 peripheral positions. Five pediatric computational models in the 5–15 y age-range [2] , [3] , were used to simulate realistic helical chest protocols and compare the variations on absorbed dose/organ. Results The CT scanner model was validated against experimental CTDI measurements with differences being lower than ∼18%. The simulated dose variations for the different pediatric phantoms are presented. Indicatively, normalized absorbed doses for selected organs inside the scan coverage varied between 25–35%, and 43–51% for 5 vs. 8, and 8 vs. 11 years-old girls respectively. Conclusions 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 characteristics such as weight, height, age, gender) to provide more accurate and patient-specific organ doses.