Patient-specific organ dose calculation using automatic segmentation and extension of CT scans

The primary objective of this study is to develop a fast and automated methodology for calculating personalized radiation organ dose from computed tomography (CT) scans using anatomical models derived from the CT images of the patient obtained during the imaging procedure. To validate this method, a comparison was conducted between experimentally measured dose values in a CT scan and those obtained through Monte Carlo simulation. Multiple point dose measurements were taken within a RANDO phantom during a Siemens Somatom Emotion CT scan, employing Metal Oxide Semiconductor Field Effect Transistor dosimeters. The software tools described in this work facilitate automatic Monte Carlo simulations using DICOM metadata and images from patient CT scans. A personalized patient-specific 3D voxelized model was created based on the DICOM images, and the radiation dose was estimated using the MC-GPU Monte Carlo code, which supports parallelization on a GPU. The required inputs for the simulations were automatically extracted from the DICOM data. Additionally, this study outlines the procedure for calculating the dose in actual patients (where the scans only cover a fraction of the body) and presents a comparison of the results with NCICT dose calculator, which uses a library of computational phantoms. A previously developed anatomical extension technique was applied to realistically extend the partially captured patient anatomy. Without this technique, the mean dose to organs that are only partially included in the CT scan is likely overestimated. Furthermore, a realistic case that uses a complete CT scan anatomy considering 134 anatomical structures or organs is presented. The results demonstrate a consistent trend when comparing simulated and experimental values, with a median difference of 5.7%. When comparing the simulated results with NCICT estimations, we observe similar magnitudes of values overall. However, significant dose differences up to 51% are noted for some organs, underscoring the importance of personalizing the dose calculation.