A fantastic voyage through the body is no longer a Hollywood dream. Roger Dobson examines the new technology which enables surgeons to practise skills without ever picking up a scalpel
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The Independent Culture
When a submarine carrying a medical team, which included Raquel Welch, was "shrunk" small enough to cruise through a patient's body, the special-effects technicians at Twentieth Century Fox had free reign. As the heroic medics in Fantastic Voyage fought evil antibodies and ran from ugly white cells, the only constraint on the imagery was the technicians' collective imagination.

Twenty-five years on from that epic voyage, science has caught up with - and exceeded - the dreams of Hollywood, producing remarkable images that lay bare the intimate workings of the body, from a single sperm to the sense organs deep inside the skin. Diagnostic skills have reached such a high level that there is no part of the body which cannot be inspected and observed by powerful imaging devices that can magnify something as normally invisible as a sweat gland into what looks like an erupting volcano.

The internal workings of the body have long held a fascination for physicians and anatomists but a not insignificant problem for students in the Middle Ages was that dissection of human cadavers was frowned on. Practitioners had to rely more on the stars than science for inspiration in visualising inner man. During the Renaissance, it was inquisitive artists and anatomists who first took to cutting up bodies. A pathfinder was anatomist Andreas Vesalius, whose text, De humani corporis fabrica, caused a stir because its pictorial guide was based on a systematic dissection of the body, layer by layer. His work, published in 1543, helped remove the taboos. Although this imagery was invaluable, it had one major disadvantage, it depended on the skills and interpretation of the artist and lacked precision.

The breakthrough came with photography, which gave physicians and surgeons accurate images of what the lens could see. The arrival of X-ray technology in the 1920s, allowed clinicians to see under the skin. Since then, medical imagery has not looked back. In the last 20 years, computer power, coupled with the physics of imaging, has led to a plethora of procedures.

The Computerized Axial Tomography (CAT) scan is almost the modern equivalent of the Vesalius text. While he peeled off layers of a corpse and drew each layer, the CAT scan gives cross-section, "bacon slicer", images of a living patient's body. Unlike conventional X-rays, CAT scans show up soft tissue including organs, blood clots and tumours. It involves a camera taking hundreds of X-rays as it revolves around the body with the results being fed into a computer, which converts them into an on-screen image.

Magnetic Resonance Imaging (MRI) gives a similar insight, but uses a magnetic field which is set up around the patient. When radio waves are targeted at the field, the hydrogen atoms in the patient's body bounce them back and a computer interprets the data and again displays a real- time image.

CAT and MRI scans, as well as conventional X-rays, endoscopy and ultrasound, are the main tools for the clinician wanting to see inside a patient's body, but photomicrography, goes beyond the wildest dreams of Renaissance anatomists. Here, powerful microscopes are linked with sensitive photography techniques to look at not just what is inside the body, but what lies inside organs. A new book, Inside Information, reveals what can be achieved.

Magnify a sperm 10,580 times and it looks like a javelin, while a white blood cell blown up to 9,000 times its real size can be seen consuming a yeast spore. Examine the windpipe when it has been magnified 9,600 times and the trachea's lining becomes a field of gently-swaying fibres, moving like underwater lilies to keep the throat moist and free of dust. The quality of these images makes them as much art the pictures of the Renaissance artists. Like those works, they are colour-enhanced, but do they have as much relative value?

Karl Radermacher of the Institute for Biomedical Engineering, Aachen, Germany, explains that these images provide a mental "walk-through" for surgeons: "Just as a golfer walks a course before a match, so the surgeon can walk through the operative area before the procedure begins."

New technology is also helping the study of medicine turn full circle. At the University of Wisconsin, medical students, like early physicians, do not use human cadavers for studying, but images. This time they are not drawings in books, but scans put into a computer to create the world's first digital cadaver. Students cruise through the body of a patient almost exactly as the Fantastic Voyage technicians imagined, but without Raquel Welch.

! Inside Information by William A Ewing, which includes the pictures featured on these pages, is published by Thames & Hudson on September 9. Price pounds 12.95.

Top left: a group red blood cells, magnified 1,800 times, move from a large vessel into a small capillary. Every day a red cell travels about nine miles around the body and there are 5,000 billion of them in every litre of blood. The cells transport oxygen from the lungs to the tissues. The carbon dioxide produced in the process is then returned to your lungs where it is exhaled

Above right: the duodenum, or small intestine, measures about six metres. The duodenal wall has numerous tiny folds called villi. These folds increase the absorptive and secretory surface on the mucous membrane that lines the small intestine. In this picture it is magnified times 25

Left: the stomach lining, or gastric mucosa, shown at 125 times its actual size. The gastric pits, shown here, contain glands which produce three litres of gastric juice every day. A thick coating of mucus stops the juices from digesting themselves

Right: a cultured white blood cell (blue in this picture) seizes a yeast spore, similar to the type which causes thrush. The cell will eventually swallow and digest the spore. White cells are vital to the immune response as they gather at infection sites where they consume or attack invaders