Nanotubes used to generate X-rays

Basic X-ray technology has remained essentially the same for a century, but now researchers at the University of North Carolina and Applied Nanotechnologies Inc. say they should be able to improve it significantly.

Basic X-ray technology has remained essentially the same for a century, but now scientists and physicians at the University of North Carolina at Chapel Hill and Applied Nanotechnologies Inc. say they should be able to improve it significantly.

Experiments conducted by the team have shown they can cause carbon nanotubes to generate intense electron beams that bombard a metal ‘target’ to produce X-rays. Researchers say they have demonstrated that their cold-cathode device can generate sufficient X-ray flux to create images of extremities such as the human hand.

The advantage of using carbon nanotubes is that machines incorporating them can work at room temperature rather than the 1500 or so degrees Celsius that conventional X-ray machines currently require.

‘If this works as well as we think it will, we can make such machines a lot smaller and cooler and be able to turn them on and off much faster,’ said Dr. Otto Z. Zhou, associate professor of physics and materials sciences. ‘Other advantages are that they should be cheaper, be safer in terms of the lower heat generated, last longer, use less electricity and produce higher resolution images.

In the past, UNC scientists and others have used carbon nanotubes to produce electrons. Until now, no one could generate enough electrons to create distinct images like conventional X-rays do. 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, being so small, they are extremely sharp.

‘We already have taken pictures of human hands and fish that are as good as standard X-rays,’ Zhou said. ‘We think our images eventually will be clearer than conventional ones since we have a more pointed, tuneable source of electrons. That would help doctors, for example, get more useful information from pictures of broken bones, for example.’

The physicists are working with manufacturers to turn their discovery into working machines and expect to have them on the market within a year or two, he said.

Being able to miniaturise X-ray devices could have more major benefits, Zhou said, including allowing technicians to take X-rays inside or outside ambulances before ever leaving the scenes of accidents. No major technical obstacles remain in their way.

In addition, the new X-ray technology will allow manufacturing of large-scale X-ray scanning machines for industrial inspections, airport security screening and customs inspections.