Epidemiologic studies that include patients who underwent radiation therapy for the treatment of cancer aim to quantify the relationship between radiotherapy and the risk of subsequent late effects. Because of the long follow-up period required to observe late effects, these studies are conducted retrospectively. The studies routinely include patients treated across numerous institutions using a wide range of technologies and represent treatments over several decades. As a result, determining the dose throughout the patient's body is uniquely challenging. Therefore, estimating doses throughout the patient's body for epidemiologic studies requires special methodologies that are generally applied to a wide range of radiotherapy techniques. Over ten years ago, the MD Anderson Late Effects Group described various dose reconstruction methods for therapeutic and diagnostic radiation exposure for epidemiologic studies. Here we provide an update to the most widely used dose reconstruction methodology for epidemiologic studies, analytical model calculations combined with a 3D age-specific computational phantom. In particular, we describe the various adaptations (and enhancements) of that methodology, as well as how they have been used in radiation epidemiology studies and may be used in future studies.