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Editorial |
Since the death last year of Sir Godfrey Hounsfield there have been many tributes to him. Mostly in the form of obituaries, these have concentrated on the man and his lifetime's work. The British Journal of Radiology wishes to pay its own tribute by reminding readers of the extraordinary impact X-ray CT has had, and continues to have, on the diagnosis, treatment and management of disease.
Janet Husband, immediate Past President of the British Institute of Radiology and President of the Royal College of Radiologists writes of the clinical impact:
The advent of computed tomography (CT) in the early 1970s changed the practice of medicine forever. It was like switching on a light in a darkened room, a light which burns ever more brightly as advances in technology have taken us from early generation CT scanners, to single slice and then to multislice machines.
The first clinical results were presented at the Annual Meeting of the British Institute of Radiology in 1972 by Dr Jamie Ambrose, who showed images from the prototype of the very first EMI brain scanner. The atmosphere in the lecture theatre was electric, there was standing room only and I was there as a very junior trainee in radiology. The ability to demonstrate lesions in the brain, tumours, abscesses and haemorrhage directly for the first time caught the imagination of radiologists around the World. It was clear even in those early days that the invention of CT had launched a new era in the detection and evaluation of disease. Professor Isherwood undertook pioneering work at Manchester University on the first commercial EMI scanner and the radiology literature began to reveal the potential impact of CT on the management of patients.
Then, in 1975 Sir Godfrey took the World by storm once more with the announcement of body CT at an international conference in Bermuda. The feverish activity which followed again took radiology to the forefront of medical advance.
I was fortunate to work with Dr Louis Kreel on the prototype of the World's first body scanner, the EMI 5000 in 1976. The UK, together with a few centres in the USA led the World in exploring and evaluating the clinical potential of body CT. Within 5 years most of the major centres throughout the World had installed CT systems and CT had already made a major impact as a first line investigation for staging and follow up of malignant disease. This, of course, has been one of its major applications throughout the decades, but in the early 1980s clinical investigation and further technological development led to much wider applications of CT such as the evaluation of lung disease, musculoskeletal disorders and the assessment of trauma. During the last 20 years major development in CT technology has focused on reduction in scan times and reconstruction times and improvements in image quality. Today it is hard to believe that we began reporting CT from images stored on magnetic tape, and a scan of the chest, abdomen and pelvis took about 45 minutes to review. We scanned a maximum of eight patients a day and now we can perform over 35 whole body examinations a day.
By 1980 the number of CT installations had expanded so rapidly that there was an urgent need to share knowledge, educate each other and train the CT specialists of the future. Teaching courses sprang up in the USA and in other parts of the World and together with Dr Ian Kelsey Fry and other young CT enthusiasts, I set up The Annual London CT Course, which was first held at the Selsdon Park Hotel in Surrey with a total of 50 delegates. We moved to the Gleneagles Hotel in 1985 and here Tiba Seear and I have continued to run and develop the course so that today the programme incorporates multislice CT, MRI and PET scanning. In 2001 we were very proud that Sir Godfrey agreed to give his name to our annual prestigious honorary lecture. This year we are looking forward to celebrating our 25th Anniversary of "The Gleneagles Course". It is astonishing to reflect that, over the years, well over 3500 radiologists from all over the World have participated in the programme. We hope this educational forum in cross-sectional imaging will continue for many years to come.
CT remains the workhorse of cancer imaging and is the investigation of choice in a wide range of other areas. There are literally millions of people throughout the World who have benefited from Sir Godfrey Hounsfield's extraordinary achievement.
Today imaging is at the dawn of another new era, the era of molecular medicine in which we will use imaging to identify early disease, to profile disease more precisely and to observe the effects of specific therapies. I am sure the next 30 years will be just as exciting as the last, but it has been a great privilege to work in radiology at a time of astonishing technological and clinical development.
Günter Dombrowe, President of the British Institute of Radiology, adds a technical dimension:
When rumours of a cross-sectional X-ray imaging technique first emerged during the early 1970s, research and development departments in the traditional X-ray companies were highly sceptical. Most of the technological innovation effort at that time was aimed at improving spatial resolution (typically down to 0.2 mm) and exposure time. A technique that promised an image comprising 80 by 80 pixels which took minutes to acquire and hours to compute seemed decidedly unattractive.
All this changed overnight with the first public demonstration of clinical images by Dr Ambrose, which impressively demonstrated the huge potential of improved contrast resolution, and within weeks all major established companies as well as a number of newcomers had started crash programmes to replicate and improve on the results.
Soon afterwards, there were almost 20 different commercial scanner designs and a fierce debate was raging about the merits of different "generations" of scanning geometry, which in some quarters did not subside until the mid 1990s, although all the basics had been proposed by 1977. Hounsfield and his team initially seemed slow in adopting the more adventurous approaches and continued to rely on the original translate-rotate mechanical scanning principle, until they once again appeared to set the pace with their prototype of a much faster body scanner which was to combine the advantages of "third" and "fourth" generation designs with its unique "nutating" detector ring. Unfortunately it was a step too far for the time and EMI decided to leave the field soon after.
In the meantime, the more traditional X-ray vendors had invested heavily in dedicated CT component design and computing know-how, and with their superior understanding of clinical requirements rapidly achieved great improvements in examination speed, post-processing and user friendliness, thereby turning CT from an esoteric scientific instrument to the workhorse of the modern imaging department. As a secondary effect of Sir Godfrey's work, once these fundamental skills and capabilities, created in the pursuit of CT excellence, existed, they could be utilized as the basis for equally rapid development of later technologies, such as MRI and digital radiography, thereby completely changing the World of medical imaging as we knew it.
25 years later CT is thriving, its R&D and manufacturing is dominated by the "big four" diagnostic imaging companies with an annual segment turnover of several billion pounds. CT technology and clinical application has shown enormous resilience against alternative diagnostic methods and at the moment is stronger than ever. There have been important enhancements of the basic design principles on the way, perhaps most notably the introduction of spiral CT, followed more recently by multislice systems. It is humbling to note how even these recent developments owe something to the genius to Sir Godfrey. The manuscript of the original project proposal written by him in 1967 (!) contains a drawing of a multirow detector which could come straight off one of today's commercial brochures.
X-ray CT has not only stood the test of time, its obvious relevance to cutting edge research such as molecular imaging, its increasing use in radiotherapy treatment planning and the substantial commercial investment in combined imaging modalities such as CT/PET show that it has much more to offer.
We owe Sir Godfrey a deep debt of gratitude.
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