( Nanowerk Spotlight ) A little trivia you might not know about: The Beatles are responsible for computer tomography (CT). No, John, George, Ringo, and Paul weren't moonlighting scientists, but you could argue that their musical success was directly responsible for the invention of CT. The technology, which produces cross-sectional images, or slices, of internal body structures has become an extremely important diagnostic tool in the field of medicine.

British engineer Godfrey Hounsfield conceived and developed the idea at Thorn EMI Central Research Laboratories in England in 1967. He was able to spend four years developing the scanner into a practical clinical tool with funding made possible by the huge profits EMI earned from the sale of the Beatles' records. The first clinical CT scanners, which were installed in the mid 1970s, were dedicated to head imaging only, but whole body systems became available in 1976.

By 1980, CT became widely available. There are now about 30,000 CT scanners installed worldwide. The first CT scanner developed by Hounsfield took several hours to acquire the raw data for a single scan and took days to reconstruct a single image from this raw data.

The latest multi-slice CT systems can collect up to four slices of data in about 350 ms and reconstruct a 512 x 512-matrix image from millions of data points in less than a second. An entire chest (forty 8 mm slices) can be scanned in five to ten seconds using the most advanced multi-slice CT system. Over the past three decades, CT has made significant improvements in speed, patient comfort, and resolution.

Today, CT scans are used to image bone as well as soft tissues. Because the digital image is sharp, focused, and three-dimensional, many structures can be better differentiated than with standard X-rays. CT has also been widely used for non-medical purposes, such as archaeology, soil science, biology, aviation security and non-destructive materials testing.

However, other fields, such as chemistry, have not yet taken advantage of tomographic techniques. But, say chemists, the advent of nanotomography is beginning to change that. With recent advances in tomography, it has become possible to achieve experimental resolution at the nanoscale, which has enabled scientists to determine the three- dimensional (3D) distribution of materials.