A day after outpatient surgery, Les Green of Layton is trying to decide what he wants to do with his day. He's home, he feels fine and he's tickled that no one had to cut his skin or remove pieces of skull.

He had brain surgery Wednesday to remove a nonmalignant but still dangerous tumor in his auditory canal.

His remarkable "surgery" is courtesy of the Leksell Gamma Knife Perfexion, recently installed at the Jon and Karen Huntsman Cancer Center at Intermountain Medical Center in Murray. Intermountain is the first medical center in the region to install the technology and among the first in the country.

The Gamma Knife is cutting edge, without actually cutting anything. During the stereotactic radiosurgery, it directs about 200 cobalt radiation beams directly at its target, with a high level of precision so that healthy tissue isn't damaged, according to Dr. Gordon Watson, radiation oncologist. Its accuracy level is "better than .3 mm," which is the thickness of a strand of hair. "It's an incredibly high dose of radiation ... that basically kills what it's aimed at."

It's also an outpatient surgery.

The device, first used by Intermountain early this week, was introduced to reporters during a news conference Thursday.

The Gamma Knife can be used in place of open-skull surgery and daily radiation treatments. It's a one-time procedure, as opposed to a regimen of daily radiation for several weeks. It also can be used as an adjunct to other cancer treatments, Watson said.

A frame is anchored on the surface of the patient's skull with four small prongs — uncomfortable while it's being put on, but not painful, Green said after experiencing it — to make sure the head does not move at all during the procedure. Then, for between 15 minutes and an hour, the radiation is delivered to the tumor. "They don't hear, see or smell anything," Watson said. "Then they go home and often are able to return to work the next day."

Besides tumors, it can be used on blood vessel abnormalities and particular lesions, according to Dr. Mark Reichman, neurosurgeon.

It's not for everyone. Treatment with the Gamma Knife is limited in part by size and location of a tumor. In some cases, a tumor is too large and surgeons reduce it in an open operation, then use the Gamma Knife as an adjunct. But for other people, it's the best option, for a variety of reasons, including for people who might be too frail to withstand the rigors of an open-brain surgery, Reichman said.

Watson said the radiation dose liquefies the tumor and the brain then absorbs and deals with it as it would other fluid.

Green was diagnosed with an acoustic neuroma last November after he noticed significant hearing loss in his left ear. An MRI showed a noncancerous, but nevertheless potentially dangerous, tumor. Although it's slow-growing, it grows in the auditory canal and blocks the nerve from the inner ear into the brain. If it grows enough, it can press on brain tissue, including the area that controls breathing, so it can be fatal, he was told.