The Gamma Knife


       We have learned more about the human brain during the past decade than
     in all previous history. First, the CAT scanner revealed details of the
     cranium. The MRI scanner showed us the gray and white sections of the
     brain. Then the PET scanner revealed the electronic activity in the
     brain. Quantified Signal Imaging (QSI) moved us onto new ground, adapting
     an older technique, the Electroencephalogram (EEG), to produce a map of
     our thinking processes.

       Now the gamma knife performs neurological surgery without the scapel.
     Credit for developing the first prototype twelve years ago in Sweden goes
     to Borje Larsson of the Gustaf Werner Institute at the University of
     Uppsala and to Lars Leksell at the Karolinska Institute in Stockholm. The
     gamma knife showed that a directed energy source could be an effective
     treatment for brain tumors. The Presbyterian-University Hospital in
     Pittsburgh is home to this latest bit of medical-science technology. The
     only two other units outside Sweden are in Buenos Aires, Argentina, and
     Sheffield, England.

       This unit converts cobalt-60 in a new technique called stereotactic
     radio surgery. In effect, it sends an electronic knife into the brain to
     dissolve dangerous tumors. Length of treatment can be as short as fifteen
     or twenty minutes. Most treatments do not require general anesthesia and
     cause no immediate side effects.

       The gamma knife, which has met the exacting standards of the U.S.
     Nuclear Regulatory Commission, is safer than many existing procedures. It
     eliminates risky, open-skull operations. Television monitoring is used
     during the procedure and two-way voice contact between the physician and
     patient is maintained at all times. Patients usually leave the hospital
     the day after the operation.

       Because more than fifteen hundred patients have already received
     treatment at the Karolinska Institute with no deaths, the gamma knife is
     not considered experimental. Of five hundred patients at the Karolinska
     Institute who were suffering from arteriovenous malformations (AVM), 87
     percent had their AVM completely obliterated by this treatment. Another
     11 percent had theirs partially altered. Tumor growth was prevented in 90
     percent of other cases. A wide range of brain problems can now be treated
     with this procedure.

       At the Presbyterian-University Hospital, the patient's head is placed
     within a large helmet-like device. The attending physician adjusts the
     radiation through small openings called collimator ports. This allows a
     great deal of energy to be directed to the intended target inside the
     brain. Every ten years or so a robot reloads the unit with the
     radioactive cobalt-60 material.