James Paterson was born in Edinburgh on 21 May 1897. After education at George Heriot's School, Edinburgh, he served from 1915 to 1918 as an officer with the Argyll and Sutherland Highlanders and was awarded the Military Cross. Graduating with honours from Edinburgh University in 1923, he shortly went into radiology and held training appointments in Chicago, Toronto, South Africa, and a Fellowship at the Mayo Clinic. He returned to Edinburgh in 1930 in acting director of the department of radiology at the Edinburgh Royal Infirmary. He then decided to specialise in the newly emerging specialty of radiotherapy. In 1932 he was appointed director of the Manchester and District Radium Institute which became the amalgamated Christie Hospital and Holt Radium Institute in the following year. The most formative years of the Manchester department were in its first decade when Paterson built up a centralised well-equipped radiotherapy centre with a network of peripheral clinics extending to a population of four and a half millions. The Paterson Parker rules, a system for ensuring precise and reproducible dosimetry in radium therapy is still in regular use to-day all over the world, though now very largely applied to radium's successors. With a carefully picked staff his department developed the Manchester method of treatment for cancer of the cervix uteri, the technique of precise and balanced beam directed X-ray therapy, and the concept of optimum dose, all of which were fundamental to the development of modern radiotherapy. Paterson was a pioneer in public education about cancer and set up what is now the Manchester Regional Committee on Cancer Education. This centre was unique in devising methods of measuring the effectiveness of this public education. Aware of the need for fundamental research, he developed what is today the very large multi-disciplinary Paterson Research Laboratories, with a staff exceeding 200, and where his wife, Dr Edith Paterson, was the first radiotherapist elucidating clinical problems in the laboratory. His bold organisational skill led to many invitations from overseas to visit and advise governments and related organisations. He was President of the British Society of Radiotherapists, 1938-1939, a founder member of the Faculty of Radiologists (now the Royal College of Radiologists) and its President from 1943 to 1946. He was elected to the FRCS in 1948 and appointed CBE in 1950, during which year he was President of the first post war International Congress of Radiology in London. He was awarded the Gold Medal of the Society of Apothecaries in 1961 and of the Faculty of Radiologists in 1966, having been appointed Professor of Radiotherapeutics in the University of Manchester just two years before his retirement. He and his wife then turned their energies to developing a first-class sheep and cattle farm near Moffat, in Scotland. They both retained their lifelong interest in the affairs of the Christie Hospital and made their old friends warmly welcome at their new home. Paterson died there on 29 August 1981 and was survived by his wife, two sons and one daughter.