Dixon pursued medicine in Nottingham, obtaining his MRCP in 1974 (proceeding FRCP 1991), before specialising in radiology. After periods in paediatric radiology at Great Ormond Street Hospital and in computed tomography (CT) at St Bartholomew's Hospital, he became a lecturer at the University of Cambridge's Department of Radiology in 1979. He was elected as a Fellow of Peterhouse in 1986. In 1994 he became a professor of radiology at the university, and remains Emeritus Professor and an Honorary Consultant Radiologist. He was appointed editor-in-chief of European Radiology in 2007, completing a 6-year term in 2013.