Joao Seco graduated with a PhD from the University of London, at the Institute of Cancer Research (ICR) and Royal Marsden Hospital in London, UK. He then went on to become an Assistant Professor of Radiation Oncology at Harvard Medical School in Boston, working at the Massachusetts General Hospital (MGH). He then returned to Europe to work at the German Cancer Research Center, DKFZ in Heidelberg, heading up a new group dedicated to ion beam research and with the focus on 1) novel imaging technologies to reduce Bragg peak positioning errors in patients and 2) on investigating the mechanism of radiation triggered DNA damage via reactive oxygen species. He is also presently the Chair of Medical Physics at the Department of Physics and Astronomy, Heidelberg University and is a member of the EFOMP Scientific Committee, representing the DGMP, German Society for Medical Physics. Frank Verhaegen is Head of Clinical Physics Research at the MAASTRO Clinic in Maastricht, the Netherlands. He holds a professorship from the University of Maastricht. Formerly, he held an Associate Professorship at McGill University in Montreal, Canada. He earned his PhD from the University of Ghent in Belgium in 1996. He held research positions at the Royal Marsden Hospital and the National Physical Laboratory (UK) for several years. Dr Verhaegen is a Fellow of the Institute of Physics and Engineering in Medicine and the Institute of Physics. His group has published about 250 research papers, a significant fraction of them about Monte Carlo modelling. His interests range broadly in imaging and dosimetry for photon, proton and electron therapy, brachytherapy and small animal radiotherapy. He also founded a company that offers Monte Carlo-based treatment planning for preclinical precision radiation research. Dr Verhaegen has been passionate about Monte Carlo simulations since the days of his Masters thesis in the late eighties.