Novel method for calculating the effective dose using size-specific dose estimates conversion factors in abdomen-pelvis computed tomography

We propose a novel method for calculating the effective dose that closely reflects the individual attenuation, utilizing two conversion coefficients. A total of 180 adult patients who underwent abdomen-pelvis computed tomography were categorized into six groups based on sex and body type. The effective dose was calculated by multiplying the dose-length product with the effective dose conversion coefficient and the size-specific dose estimate conversion factor. The effective dose calculated using a simulation-based dose calculator (WAZA-ARI) was employed as the reference value. The following values, obtained through both methods, were compared within each category: distribution of the effective dose, median effective dose, and relative difference in median effective dose across additional body mass index (BMI) categories. For male patients, no significant disparity was observed in the median effective doses calculated using the two methods. The relative differences in median effective doses across additional BMI categories ranged from - 5 to 6%. Conversely, among female patients, the median effective dose calculated using our method slightly undercut that calculated using WAZA-ARI, with relative differences ranging from - 16 to - 9%. Additionally, relative differences in median effective dose across additional BMI categories ranged from - 18 to - 7%. The median effective dose differed slightly depending on the calculation method because of the different reference phantoms applied in dose calculations. Our proposed method is sensitive to individual size and helps compute a size-specific effective dose.