Gamma Knife offers new hope for precision surgery $3 million device aids doctors in brain, neurological operations

July 09, 1992|By Jonathan Bor | Jonathan Bor,Staff Writer

A 20-ton capsule that looks suitable for carrying astronauts to the moon may be the latest hope for treating small brain tumors, blood vessel disorders and neurological diseases such as epilepsy.

The University of Maryland Medical Center yesterday unveiled its $3 million Gamma Knife, a machine that uses gamma radiation with knife-like precision to reach targets inside the brain.

The beauty of the device, said the physicians who use it, is that it works at such high intensity that it does its job in a 5-to-20-minute session. And because it pinpoints a diseased area as small as a pea, it doesn't burn off healthy tissue that should be left alone.

"This is the key," said Dr. Pradip Amin, assistant professor of radiation oncology. "We are delivering fairly high doses of radiation but sparing the surrounding tissue." Conventional low-dose radiation must be given in daily sessions spread across several weeks, and often scorches healthy tissue.

Since it was placed into service last month, the Gamma Knife has been used on three patients with blood-vessel disorders, two with cancerous brain tumors and two with benign tumors of the ear that threatened to cause deafness.

Dr. Aizik Wolfe, a neurosurgeon who has relieved epileptics of seizures by surgically removing culprit pieces of brain tissue, said the Gamma Knife may be able to do the same thing in one bloodless procedure. Other frontiers are the relief of intractable facial pain known as neuralgia and the tremors caused by Parkinson's disease.

The UM Medical Center is the 11th hospital in the United States and the only one in Maryland to purchase a Gamma Knife.

Physicians said yesterday that the high price -- $4 million when one includes construction of a sealed room -- has kept many hospitals from rushing to acquire the technology. A treatment, -- along with the customary one-night hospital stay, can cost $10,000 to $15,000.

The machine works by focusing 201 separate beams of radiation from evenly spaced points around the person's head. Individually, the rays are not strong enough to destroy anything. Together, they deliver a powerful dose at the point where the beams intersect.

To accomplish a precise hit, a metal frame is screwed into the skull after the patient is given a local anesthetic. As the patient lies on a flat "cradle," the head frame is bolted to a chrome helmet with 201 tiny holes that provide pathways for the %J radiologic beams.

Then the cradle slides the patient head-first into a hemispheric capsule containing cobalt-60, the source of the tissue-destroying radiation.

Dr. Amin said side effects are minimized because the radiation is delivered so precisely, and in one session. Some patients get mild headaches, but not the recurrent nausea that afflicts people undergoing conventional radiation therapy.

The radiation itself is delivered pain-free.

"I didn't feel a thing," said Marvin Myers, 55, a Brunswick man who said he spent one night in the hospital and went fishing the following week.

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