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It's a scary diagnosis. Of the 70,000 new brain tumors expected to be diagnosed in the American population next year, more than one-third will be malignant, meaning they're cancerous. And those tumors are difficult to remove because to a surgeon's naked eye, cancerous brain tissue looks like normal brain tissue. It's hard to differentiate and it's critical that doctors not harm healthy tissue during surgery...

PhD candidate Kolbein Kolste

...When you compare a portion of the brain under white light with no obvious signs of cancer to the same portion using fluorescence, the cancer shows as hot pink. The technique is improving accuracy tenfold, but it doesn't show smaller, low-grade brain tumors. And that's where a new probe comes in.

"Touch the brain, push a button and it glows through," said Kolbein Kolste of Thayer School of Engineering at Dartmouth.

Developed by doctors at Dartmouth and biomedical experts at its engineering school, the probe is now being studied at just a handful of research facilities nationwide.

"There are certain parts of the brain or tumors that don't glow as strongly and so we use this fiber optic probe to be able to detect the lower levels of light," Kolste said.

It's allowed doctors to use fluorescence technology on a much larger patient population—those with high-grade, low-grade and deep-tissue tumors.