Estimating the dose variation in a volume of interest with explicit consideration of patient geometric variation

A method to measure the effects of internal organ motion and deformation and patient setup error on cumulative dose variation in a volume of interest is proposed. The method uses multiple CT scans and electronic portal images of a single patient to numerically simulate dose-volume effects over the entire course of the patient’s external beam treatment. The results are expressed in the form of a novel dose-volume histogram, called an expected dose-volume histogram (EDVH).