New Technology for Improved X-Ray Machine

Their cold-cathode device can generate sufficient x-ray flux to create images of extremities such as the human hand. The advantages of using carbon nanotubes is that machines incorporating them can work at room temperature rather than the 1,500o C or more required by conventional x-ray machines. A report on the research appeared in the July 8, 2002, issue of Applied Physics Letters.

The scientific team comprises researchers from the University of North Carolina at Chapel Hill (UNC, USA; www.unc.edu). The team notes that others have used carbon nanotubes in the past to produce electrons but until now, nobody could generate enough electrons to create distinct images, as conventional x-rays do. The nanotubes replace traditional metal filaments that must be heated to high temperatures before being subjected to an electric field. The tubes shed electrons easily because they are small and very sharp.

"We have already taken pictures of human hands and fish that are as good as standard x-rays,” said Dr. Otto Zhou, UNC associate professor of physics and materials sciences. "We think our images eventually will be clearer than conventional ones since we have a more pointed, tunable source of electrons.” Being able to miniaturize x-ray devices could have more major benefits, added Dr. Zhou, including allowing technicians to take x-rays inside or outside ambulances before leaving the scene of an accident. The scientists are now working with manufacturers to turn their discovery into working machines that they hope to have on the market within a year or two.