Employing a technique that uses highly focused beams of high-energy radiation, neurosurgeons are having success in battling deep-seated and previously inoperable benign brain tumors.

Dr. Michael Dogali, a neurosurgeon at New York University Medical Center, said the new technique, known as stereotactic radiosurgery, also aids in the treatment of certain kinds of swollen blood-vessel malformations that are prone to sudden bleeding with strokelike effects.Stereotactic radiosurgery utilizes a high dose of radiation to attack the small tumor area in the brain without damaging surrounding tissue, unlike traditional radiation therapy which uses a low dose of radiation to treat a larger area.

In applying radiosurgery, neurosurgeons combine a number of technologies - X-rays or CT scans, highly advanced computer programs and a linear accelerator which creates the ionizing radiation, Dogali said.

These technologies are used in conjunction with a special head-frame fitted for the patient that displays a series of computer-generated coordinates on film to pinpoint the precise location of the target area.

The computer is fed all the data from which it calculates the exact size and location of the tumor or malformation, the number of radiation beams necessary, and at what angles the radiation beams should be positioned.

"For radiosurgery to be successful, the target lesion must be less than 3 centimeters in diameter - about the size of a walnut - and the goal is to deliver an effective dose of radiation to that area," explained Dogali.

It takes very little time to recover from radiosurgery; patients usually go home the next day.

"If a patient has several small tumors in different parts of the brain, radiosurgery is the only effective method we have available," asserted Dogali.

There are some disadvantages to radiosurgery, however.

Dogali said the technique cannot be used for large diseased areas.

And unlike conventional surgery, when the surgeons know immediately that the entire or most of a tumor has been removed, the effectiveness of radiosurgery cannot be determined in less than six to 24 months because the lesion shrinks very gradually after being irradiated.

Looking toward the future, Dogali said, there are some exciting future applications being developed for radio-surgery.

"Once we know which area of the brain controls such functional disorders as Parkinson's disease, epilepsy and intractable pain disorders, we may be able to employ the technique to ease or even eliminate the problem," Dogali added.