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'Solar' surgery much cheaper than lasers

By
CHARLES CHOI, UPI Science News

NEW YORK, July 30 (UPI) -- Israeli scientists say concentrated sunlight could be used to burn away tumors and other dangerous growths, much as laser surgery does now, but at only a fraction of the cost.

"Solar surgery offers an alternative that could be 10 to 100 times less expensive," researcher Jeffrey Gordon, a physicist at Ben-Gurion University of the Negev in Sede Boqer, Israel, told United Press International.

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"We have just completed clinical trials of solar surgery on live healthy rats, with gratifying success," Gordon said. "The next experiments we are planning will target malignant tumors with solar surgery."

Conventional laser surgery pumps laser beams through optical fibers to zap diseased cells. The method is both highly effective and minimally invasive, but it is unavailable to many patients worldwide because of its prohibitive cost, Gordon said. "Current laser fiber-optic surgical systems commonly cost upward of $100,000," he explained.

Gordon and his partner Daniel Feuerman have worked with solar energy for years. They began thinking about harnessing sunlight for surgery after hearing about laser surgery's exorbitant prices keeping their university's medical center and many others around the world from employing the potentially life-saving technology.

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Instead of using lasers, the duo began attempting to concentrate light from commonplace sources. "Conventional light sources were not bright enough. But the surface of the sun is adequate," Gordon commented.

Their prototype employs a highly reflective, eight-inch-wide concave dish, which collects and focuses sunbeams and funnels them down a flexible optical fiber. The sunlight emerges in an operating theater, a narrow beam of light rays deployed from the one-millimeter-wide tip of a surgeon's tool.

Each square yard of the Earth's surface receives about 950 watts of solar energy during the day. "Our solar surgery prototype concentrates sunlight to about 12,000 times its ambient level," Gordon said.

So far, Gordon and Feuerman have focused the device on soft tissue, but they also want to be able to use the solar technology on bone and other hard targets, so they have developed sculpted optical fiber tips for even higher sunlight concentrations. At the opposite end of the power curve, they have developed a means to modulate the

device's energy.

"A simple iris on the solar concentrator controlled from within the operating theater can reduce the solar power delivered to the patient as required," Gordon noted.

The obvious limitation of solar surgery is its dependence on sunlight. Clearly, nighttime is precluded and solar surgery must be restricted to days and locations with clear skies, leaving out perennially rainy cities such as Seattle.

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Still, Gordon noted, even laser surgery often is planned well in advance and is not considered an emergency procedure. In Sun Belt climes, he estimated, there should be operating windows of seven to 10 hours a day for 250 days or more each year.

"A great deal of the planet would qualify," he said, including parts of Africa, the Middle East, South America, India, the southwest United States and Australia.

Gordon's team began experiments on livers and chicken breasts last year. Now, in findings appearing in the July 31 issue of the British journal Nature, the scientists report the very first clinical trials of solar surgery on live animals. They used the method on liver tissue in anesthetized rats with much of the success expected with laser therapy.

"It's an exciting area of research that has a lot of potential," ear, nose and throat surgeon Jim Smith of Oregon Health & Science University in Portland told UPI. "I've been doing laser surgery for 25 years, and lasers are all very expensive ... This certainly could have application to developing countries."

After they complete experiments with cancerous mice, Gordon said his team plans similar work on pigs.

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"As for clinical trials on humans, it's too far into the future to project," Gordon said. "Our current first-generation prototypes provide the basic tool we needed for our experiments, but they are not especially surgeon-friendly. In the near future, we hope to redesign solar surgery prototypes that are more amenable to the surgeon's special needs."

When Smith met Gordon in Singapore in February, Smith said the Singapore government wanted to help develop solar surgery against liver tumors -- their surgical collaborator, Solly Mizrahi, is a liver specialist -- due to the high frequency of liver cancer in Singapore.

"They're hoping to do animal experiments over the next year-and-a-half to two years, potentially using it on humans within three years," Smith recalled. "A lot of it will depend on animal studies. They've got to calibrate it, so as a surgeon, you know how much power you're using ... then they'll have to look at the killed cells under the microscope, to find the right dosage that kills all the tumor cells and leaves the viable liver cells behind."

The researchers said they also hope use highly concentrated sunlight to power the synthesis of potentially lucrative molecules, such as buckyballs and carbon nanotubes, which scientists hope to fabricate as cogs in future micro-devices.

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