In accordance with at least some embodiments of the present disclosure, a process for calculating patient-specific organ dose is presented. The process may include constructing a computed tomography (CT) volume based on CT images generated by a CT scanner. The process may include segmenting the CT volume into a plurality of organ regions, generating a material density map for the CT volume based on Hounsfield Unit (HU) values, and generating a dose distribution map for the CT volume based on the material density map by simulating particles emitting from the CT scanner and flowing through the CT volume. The process may further generate a dose value delivered to a specific organ region of the plurality of organ regions based on the dose distribution map.