JAMIE AMBROSE occupies an important niche in the history of medicine as the radiologist who, with the physicist Godfrey Hounsfield, was responsible for the development of the CT scanner, one of the 20th century’s chief advances in medical diagnostics.

When he performed the first CT scan, on October 1, 1971, medical imaging was changed forever.

James Ambrose was born in Pretoria, South Africa, in 1923. At Pretoria Boys High School he excelled academically and became a King’s Scout. On the outbreak of war he was refused for military service on grounds of age, so he studied engineering in Johannesburg until his 18th birthday when he was accepted for flying training with the South African Air Force. He was posted to the Mediterranean war zone as a fighter pilot. He was attached to the RAF and served from 1941 to 1945, flying Spitfires in the Middle East, Italy and southern France.

After demobilisation he returned to South Africa and his studies, switching to medicine at the University of Cape Town. He graduated in 1952 and two years later he moved to England and began his radiological training at the Middlesex Hospital, then moving on to become a senior registrar at Guy’s Hospital.

He obtained his Diploma in Medical Radiological Diagnosis in 1956, and the fellowship of the Faculty of Radiologists in 1959, and was appointed a senior registrar in diagnostic radiology at Atkinson Morley’s Hospital, Wimbledon, becoming a consultant in 1962. He had originally gone to Atkinson Morley’s to train as a neuroradiologist under Dr James Bull, who had worked with Dr Erik Lindgren in Sweden developing percutaneous angiography and pneumoencephalography.

Ambrose’s mastery of these specialised invasive radiological procedures in the diagnosis of neurological disease made him much in demand. By the early 1960s the department was performing more than 1,000 carotid angiographic studies a year, and he was undertaking most of them. However, his ambition was to find noninvasive diagnostic methods. He began to develop the use of ultrasound and radioisotope scanning for the diagnosis of brain and spinal disease and injury and reported his results to the BMA in 1969.

In the same year the Department of Health asked him, as an eminent figure in radiology, to meet an electronics engineer, Godfrey Hounsfield, who was working for EMI and whose ideas for a new imaging technique had been falling on stony ground — years later, Ambrose discovered that Hounsfield had been dismissed by another eminent radiologist as a crank. Hounsfield received a much more sympathetic, and perceptive, reception from Ambrose who saw the marvellous potential in Hounsfield’ s idea and lobbied the Department of Health on his behalf.

Funding followed, and the development of the first CT scanner began. This work was carried out at Atkinson Morley’s by Ambrose, Hounsfield and a team of physicists and engineers. By August 1970 they had produced the design and specification of the prototype scanner and, just over a year later, the first working model was ready. On October 1, 1971, Ambrose carried out the first CT scan on a live patient, revealing a detailed image of a brain tumour.

It was a moment when medical science abandoned incremental advance and took a giant step forward. Clinical trials followed, conducted by Ambrose at Atkinson Morley’s, and in April 1972 he and Hounsfield presented the first papers on CT scanning to the annual congress of the British Institute of Radiology. In November 1972 the scanner was displayed to 2,000 doctors at the Radiological Society of North America’s annual meeting in Chicago, and Ambrose’s lecture on the clinical trials received a standing ovation.

Although neither he nor Hounsfield relished the role of spokesman, it fell to Ambrose to spread the word internationally and he became an ambassador for the new technique. He performed this role as a scientist rather than as a salesman, and gained respect for doing so, though fewer honours came his way for his self-effacing conduct.

Hounsfield was knighted and was jointly awarded, with Allan Cormack, the Nobel Prize in Medicine in 1979. Ambrose received the Barclay Prize of the British Institute of Radiology in 1974, the annual prize of the European Society of Radiologists in 1977, was elected a Fellow of the Royal College of Physicians in 1977, was made an Honorary Fellow of the Royal Australian College of Radiologists in 1986, was awarded the Gold Medal of the Royal College of Radiologists in 1992 and honorary membership of the British Institute of Radiology in 1993. Yet there was a consensus among his colleagues that he did not receive the recognition he so richly deserved for his pioneering work. He was a towering figure in neurology, and changed it for the better — imaging made life easier for clinicians, and safer and more comfortable for patients.

He retired in 1988 and moved to Argyll, where he was able to pursue his love of plants and wildlife. If he had not found medicine, he might well have become a professional horticulturalist.

He is survived by his wife, Sheena, whom he married in 1965, and by their son and daughter.

Dr James Ambrose, neuroradiologist, was born on April 5, 1923. He died on March 12, 2006, aged 82.