Nanotubes for faster CT scans

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Scientists at the University of North Carolina at Chapel Hill are using carbon nanotube X-rays to create computed tomography (CT) images faster and with less power than traditional scanners.

The work is another step toward developing scanners for medical imaging and homeland security that are smaller, faster, and less expensive to operate, said Otto Zhou, Professor of Materials Science at UNC.

‘The current CT scanners take images sequentially, which is slow and inefficient. Using the nanotube X-ray technology, we show the feasibility of multiplexing, taking multiple images at the same time,’ Zhou said.

The UNC team uses carbon nanotubes in this work because they can emit electrons without high heat.

Traditional CT scanners use a single X-ray source that takes approximately 1,000 images from multiple angles by mechanically rotating either the X-ray source or the object being scanned at high speed.

In 2005, Zhou and colleagues created a scanner with multiple X-ray sources, called a multipixel scanner. The machine required no mechanical motion but switched rapidly between many X-ray sources, each taking an image of the object from a different angle in quick succession.

The team's latest innovation combines this multiple-X-ray-source innovation with a principle called multiplexing, in which all the X-ray sources are turned on simultaneously to capture images from multiple views at the same time.

‘With multiplexing, we can have all the X-ray pixels on at the same time for maybe 2 seconds. You still get all the images, only faster, and we need only about half of the original X-ray peak power,’ Zhou said.

‘What makes the multiplexing CT scanning possible is the novel multi-pixel X-ray source we developed and the ability to program each X-ray pixel electronically.’

In this study, Zhou and colleagues took images of a computer circuit board using a prototype multiplexing scanner, and then compared the images to those generated by a traditional X-ray scanner. The images showed little difference in resolution or clarity, but the prototype multiplexing scanner got the job done faster.