The 4th International Workshop on Computational Phantoms for Radiation Protection, Imaging and Radiotherapy, hosted by IT'IS/ETH on behalf of the Consortium of Computational Human Phantoms, was held May 20th to 22nd, 2013, at Technopark in Zurich, Switzerland. This 2.5-day workshop was attended by more than 50 scientists from around the world, who shared their latest findings on design and applications of computational phantoms towards development of a roadmap for future evolution of models and simulation platforms. The workshop combined plenary sessions and invited keynote papers with contributed oral sessions and posters that included reviews of national projects and descriptions of the various suites of available human models and their use in medicine and radiation safety. A highlight of the workshop was a site visit to IT’IS Tuesday evening for a tour through 4 presentation stations, followed by a superb and convivial meal at the nearby Accademia del Gusto.