28/08/2023
Happy Birthday Godfrey Hounsfield - he would have been 104 today.
Godfrey Hounsfield was almost 50 when, in 1967, he invented the computed tomography (CT) X-ray scanner that won acclaim as one of the twentieth century's most important advances in medical diagnostics.
Godfrey Newbold Hounsfield was born in Newark, Nottinghamshire, in 1919. The youngest of five children, he grew up on a farm in Sutton on Trent. An introverted, diffident youngster, his keenest interest was experimenting in electronics and other scientific principles, such as flight - from haystacks with a home-made hang-glider - and propulsion, using acetylene and water-filled steel barrels. Less hazardously, he designed and constructed his own audio recording system.
Apart from his aptitude for physics and mathematics, he did not shine at Magnus Grammar School, Newark. After leaving school he worked in a local builder's drawing office and, with the outbreak of war in September 1939, joined the RAF. His wide knowledge of radio communications enabled him to pass the RAF's radio mechanics' entry examination without taking the course. After specialist radar training, he was posted as an instructor to RAF Cranwell, and gained promotion to corporal. While there he took the City and Guilds of London radio communications examination. He left the RAF in 1946 to study electrical and mechanical engineering at Faraday House in London.
He was already in his 30s when he graduated in 1951 and joined Electric & Musical Industries Ltd (later renamed EMI Limited) at Hayes, Middlesex
, where the recorded music company also had several engineering operations and its renowned Central Research Laboratories (CRL).
After working initially on radar, Hounsfield headed the design team for the EMIDEC 1100, the first British solid-state business computer. Then, at CRL, he went on to make notable advances in computer memory design. In 1967, when this programme ended, it was agreed that he should focus on automatic pattern recognition, whereby machines could automatically identify and interpret complex shapes, such as alphanumeric characters.
His work led him to realise that the main drawback in pattern recognition was that much of the information one could reveal on a shape's composition was squandered by inefficient data retrieval methods.
Although work was his main preoccupation, he enjoyed country walks; it was during a walk that the idea for the scanner came to him. It struck him that - theoretically - readings from a large quantity of measurements taken randomly at all angles through a closed box, when processed would reveal the shape of objects contained in the box.
X-rays could provide the means for gaining such readings, but he realised (and later demonstrated) that a conventional X-ray is highly inefficient. A vast amount of information in the photon beam that creates the 'shadow' picture of the intervening object on the film is unused. He calculated that all but one percent of the available data was wasted by beam-scatter, dense tissue obscuring 'soft' tissue, and the inadequacies of film recording.
His answer was to use multi-angle scanning and greatly improved beam measurement. To achieve this, he saw that one feature of conventional X-ray tomography, where pictures are taken of a series of sections or 'slices' through the patient, would be particularly helpful. It would confine beam-transmission readings to a single plane, simplifying the prodigious data-handling problem, while pictures from contiguous slices would together give a three-dimensional representation of tissue structure.
Hounsfield reasoned that readings from a tightly profiled pencil-beam of photons passing through the body, recorded using highly sensitive detectors instead of film, would provide much higher levels of information. By rotating the beam and detectors around the plane of the body, to scan readings from many angles, information at the intersections of the beam-paths could be reconstructed as a matrix in which each point would have a calculable density value. Sophisticated computer analysis would be essential to interpret the mass of data, but the system's much greater sensitivity would use all of the information in the beam. For the first time it should be possible to 'map' the structure of dense and soft tissues, non-invasively.
The most important application would be in medical diagnosis
, a market largely unknown to EMI. However, the company allocated some money to his project and Hounsfield was authorised to consult the Department of Health and Social Security (DHSS) on the scanner's potential. Following a favourable report by an eminent radiologist, the DHSS suggested its use for brain examinations: the brain is contained in a dense bone 'box', and existing examination methods afforded very limited information, sometimes with discomfort and risk for the patient. The DHSS provided modest financial support for the project.
Hounsfield developed an experimental machine that produced convincing results. He and his small team then made a prototype scanner that was installed at Atkinson Morley's Hospital, Wimbledon, in September 1971 for use in clinical trials. These were conducted by radiologist Dr James Ambrose. The first patient to be examined showed symptoms of a cerebral cyst, the location of which was indeterminate. Dr Ambrose recalled that the pictures from the scanner gave a clear indication of its position in the brain, and that he and Hounsfield felt like footballers who had just scored the winning goal. A comprehensive programme of clinical evaluation showed the scanner to be an outstanding diagnostic advance. The DHSS underwrote EMI's production of the first five machines.
The EMI brain scanner, and its technique of computed tomography (CT) scanning, as it became known, was launched in April 1972, to an amazed reaction from radiologists. In November 1972 it was displayed before 2,000 doctors and radiologists at the RSNA annual meeting in Chicago. Dr Ambrose's lecture on the clinical trials received a standing ovation.
Hounsfield had given radiologists the means to see subtle variations and anomalies in brain tissue. On a worldwide surge of demand for the scanner, EMI established a flourishing medical electronics business (from which it withdrew when it merged with Thorn Electrical Industries in 1979).
In 1972, Hounsfield won the MacRobert Award, the UK's highest accolade for innovation. A stream of honours and distinctions followed from around the world. Often, only colleagues' heavy persuasion would prevent him declining awards, which he found an irksome distraction from his dedication to continued development of CT scanning. This bore fruit in 1975 with the launch of a machine able to scan the whole body, not just the head, marking a huge extension of the diagnostic applications for Hounsfield's invention.
In 1975 he was made a Fellow of the Royal Society and received the USA's prestigious Lasker Award. He was appointed CBE in 1976 and was awarded a Nobel Prize in 1979. He was knighted in 1981. He was elected a Honarary Fellow of the Royal Academy of Engineering in 1994. He received six honorary degrees and over 40 awards by scientific institutions around the world. Hounsfield remained unaffected by the fame that resulted from his work (although he would privately admit that the benefit it had brought to countless thousands of people around the world gave him great satisfaction). He continued at CRL as a senior researcher and after his retirement in 1984, aged 65, became a consultant to the laboratories. He carried on in this role after Scipher plc acquired CRL in 1996, until prevented by illness approximately two years before his death. He lived in Whitton, Middlesex, and was unmarried.
nSir Godfrey Hounsfield was born on 28 August 1919. He died on 12 August 2004, aged 84, following a long illness.
