Assessment of organ dose for adult undergoing CT examinations: Comparison of three software applications using Monte Carlo simulation

Understanding organ dose during CT scans is crucial due to cancer risks from low-level radiation exposure. This study aims to analyze and compare different methods for estimating CT organ doses in adult male and female patients, assessing the compatibility of NCICT with standard phantoms and NCICT with body size adjustment with GEANT4 simulations. It also evaluates the impact of different CT manufacturers on organ dose calculations. Previous research used various phantoms to represent organ doses across age groups. This study utilizes DICOM images from real adult patients undergoing CT scans to evaluate organ dose using the GEANT4 simulation toolkit. A retrospective analysis of 240 CT scans (head, chest, and abdomen-pelvis) compared GEANT4 dose estimates to the software tool NCICT. Data from Siemens and Philips CT scanners were included. Organ doses for 34 organs were calculated using Siemens patient DICOM data, while Philips estimates made using only NCICT with body size adjustment. Statistical analysis assessed differences in organ doses by gender and scanner type. Organ doses for the brain, spinal cord, and liver were higher in females (48.1, 4.9, and 6.7 mGy) compared to males (42.5, 4.4, and 6.3 mGy). NCICT with body size adjustment estimates were more consistent with GEANT4 (differences up to 18%) compared to NCICT with standard phantoms (differences up to 46%). Notable variations were found between Siemens and Philips scanners, despite identical detector rows. Accurate models and scanner-specific differences are critical for reliable radiation dose assessments, emphasizing the need for tailored dosimetry to enhance patient safety.