Michael C. Joiner, PhD, is a founding teacher and previous Course Director of the Basic Clinical Radiobiology Course at ESTRO, and Advisor and Teacher of Clinical Radiobiology at Wayne State University, Detroit, Michigan, USA. Albert J. van der Kogel, PhD, is a founding teacher and previous Course Director of the Basic Clinical Radiobiology Course at ESTRO, and Advisor and Teacher of Clinical Radiobiology at the University of Wisconsin, Madison, Wisconsin, USA.