A system and method are disclosed for computing a radiation dose delivered to a patient during a computed tomography (CT) scan of the patient. The CT image dataset generated during the scan of the patient, and one or more parameters relating to a x-ray source are used to calculate the radiation dose delivered to the patient as a function of the CT image data set and the one or more parameters of the x-ray source. The radiation dose is generally found by calculating a primary x-ray dose distribution and scattered x-ray dose distribution from the CT image dataset and taking the sum of the primary x-ray dose distribution and scattered x-ray dose distribution.