Some great inventions are birthed at a bar, their futures scribbled on cocktail napkins. Multi-pixel X-ray technology, the first substantial technological change in X-rays in more than a century, was born over a greasy Philly cheesesteak sandwich.
It was 2000. Otto Zhou was the principal investigator on a $6 million grant from the Office of Naval Research to find applications for carbon nanotubes. Zhou and Jianping Lu, both physics professors at the University of North Carolina at Chapel Hill, often brainstormed ideas over lunch. Other scientists across the country were applying the material to flat-panel displays.
“We were at Miami Subs when we thought, ‘what about X-ray?’” said Zhou, the Lyle Jones Distinguished Professor of Physics and Materials Sciences in UNC’s College of Arts and Sciences.
“We thought, basically, TV is no different from X-rays, and X-rays are one of the most commonly used devises,” Lu said. “We started drawing around on a napkin. We have limited medical knowledge but we understand the basic physics of X-rays.”
Zhou, Lu and other collaborators grew their napkin diagram and the grant-funded research into Xintek, a small nanotechnology start-up company that licensed technology from UNC and Duke University. Two years ago the company established formal collaborations with Siemens Medical Solutions in Erlangen, Germany.
Siemens and Xintek announced on Sept. 18, 2007, a new joint venture company, XinRay Systems, with headquarters in North Carolina’s Research Triangle Park, to further develop the technology.
“This agreement with Siemens is a major step for us,” said Zhou. “We can be as confident as we want, but it’s nice to be confirmed by others willing to take the next steps. That’s gratifying.
“As engineers we like to see ideas become something useful, more than just a stack of papers,” Zhou said. “We like to see the papers, but we want our work to translate into something useful to society.”
Zhou originally thought their technology would first be used in manufacturing settings, inspecting parts for tiny defects. Sept. 11, 2001, changed that. Now, with grants from the U.S. Department of Homeland Security, he said he expected their first products to be airport security screeners. They could enter the field of medical diagnostics within a few years.
X-ray technology has many limitations: it requires heating a filament to 1,000 degrees in order to produce the electrons that make an X-ray image; it requires large and bulky equipment; and it’s slow.
Early CT scanners use one x-ray source that rotates around an object. They have limited imaging acquisition speed. Siemens’ technology has addressed some of these issues, and the new nanotechnology enabled x-ray sources may improve future generations of CT scanners.
In 2005, UNC and Xintek announced a major advance by placing multiple carbon nanotube sources in an array. In this multi-pixel configuration all the energy sources – the carbon nanotubes – can fire at once from different angles, and they can fire repeatedly, in one-millionth of a second, Lu said. Fast enough to clearly capture a beating heart.
Carbon nanotubes are sheets of carbon rolled into a seamless tube about 300 times smaller than the diameter of human hair. They require much less energy to produce electrons which means they can be turned on and off very quickly at low energy. And, unlike conventional filaments, they’re microscopic.
In today’s digital imaging technology, only the detector, the medium, is digital. Multi-pixel X-rays digitize the source. “This,” say Zhou and Lu, “is truly digital.”
College campuses are increasingly becoming the site of such discoveries and developments. Zhou, who worked at Bell Labs before coming to UNC in 1996, said industry is taking fewer risks in research and development than it did 20 years ago. “Universities have to take up some of those risks with private funding, venture capital.”
At UNC, Zhou has brought to bear on his research expertise from a wide palette of specialties, including biomedical engineers, radiation oncologists, radiologist, chemists and physicists. His students have also pursued interdisciplinary studies and they’ve found jobs in his lab and with Xintek.
Zhou and Lu also have appointments in UNC’s Lineberger Comprehensive Cancer Center. They were instrumental in the center’s receiving major National Cancer Institute funding that created the Carolina Center for Cancer Nanotechnology Excellence. That Center, in turn, dovetails with the UNC Roadmap Office, which brings together researchers from a variety of disciplines under a National Institutes of Health program.
UNC’s Office of Technology Development, which helps place UNC among the top 10 U.S. universities in patent strength, also assisted Zhou, Lu and other collaborators to obtain patents, create Xintek and license the technology.
“It’s not so often,” Zhou said, “that you can find a technology that will help so many people – cancer screening, security – you can talk with your mom about without getting too technical.”
Zhou and Lu can bask, at least momentarily, in their current success. But if history is in the making, curators years from now will bemoan the loss of one key artifact; they didn’t save the napkin.