Carbon nanotubes are at the heart of a new x-ray machine that is slated for
clinical tests later this year at the University of North Carolina (UNC)
Hospitals. The machine could perform much better than those used today for x-ray
imaging and cancer therapy, say the UNC researchers who developed the
technology. They have shown that it speeds up organ imaging, takes sharper
images, and could increase the accuracy of radiotherapy so it doesn't harm
normal tissue.
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Capturing the heart: In a new scanner,
carbon nanotubes fire electrons instantly to generate x-rays. This gives sharp,
high-resolution pictures, such as this one of a fast-beating mouse heart.
Credit: Otto Zhou, University of North Carolina |
Conventional x-ray machines consist of a long tube with an electron emitter,
typically a tungsten filament, at one end and a metal electrode at the other.
The tungsten filament emits electrons when it is heated to 1,000 degrees
Celsius. The electrons are accelerated along the tube and strike the metal,
creating x-rays.
Instead of a single tungsten emitter, the UNC team uses an array of vertical
carbon nanotubes that serve as hundreds of tiny electron guns. While tungsten
requires time to warm up, the nanotubes emit electrons from their tips instantly
when a voltage is applied to them.
The researchers presented work on their nanotube scanner at the meeting last
week of the American Association of Physicists in Medicine.
Physics and materials science professor Otto Zhou
cofounded a company called Xintek in Research Triangle Park, NC, to commercialize the
technology. Xintek has teamed with Siemens Medical Solutions to form a joint-venture company, XinRay Systems, which has
developed the prototype system that will be clinically tested this year.
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