"I was not very interested in open surgery," says Alters, 53, of West Frankfort, IL.

She was told that''s what she would need after she fell off a horse last year. Persistent dizziness sent her to the doctor where an MRI found a menengioma (or benign tumor) on her brain.

Being a nurse at Herrin Hospital, Alters knew the details of having open brain surgery - an ear-to-ear cut of the scalp with general anesthesia given to the patient. After she began looking for alternatives, Alters found out about a machine in St. Louis called Gamma Knife.

"Gamma Knife was a miracle," says Alters. "I went home that day. With the other surgery, doctors were talking about ventilators and feeding tubes and I didn''t have to have any of that."

The name Gamma Knife is a bit of misnomer, as it doesn''t use a "knife" at all. It''s a machine that delivers 201 precisely focused beams of radiation to a targeted area of abnormal tissue within the patient''s head. The radiation is tightly focused and contoured to a tumor, AVM (malformed blood vessels) or for functional problems in the brain like trigeminal neuralgia. The surrounding areas of the brain get very little exposure to radiation.

"The Gamma Knife can be a very aggressive way to treat various problems in the brain, with low side effects," says Eric Filiput, RN, Gamma Knife operations manager at Barnes-Jewish Hospital.

The Gamma Knife of St. Louis at Barnes-Jewish Hospital is the only Gamma Knife in a 250-mile radius and one of about 90 nationwide. In addition, it''s something of a community resource as any physician credentialed to use the technology can take their patient to Barnes-Jewish for the procedure.

While Alters is still adjusting her medications post-op, she knows her chances of survival would have been diminished drastically were it not for the brain surgery instrument that doesn''t leave a mark.

"Being a nurse, I''m generally kind of paranoid about stuff like this," says Alters. "But I was impressed."