The Gamma Knife
In 1949, the Swedish neurosurgeon Lars Leksell, along with radiobiologist Borje Larsson, developed the first stereotactic instrument for human functional neurosurgery. Dr. Leksell believed that very precise doses of radiation could be focused on a target in the brain and be as effective as the use of a scalpel in the hands of a neurosurgeon. To accomplish this, Dr. Leksell developed a head frame to hold a patient’s head securely during the procedure and to provide a frame of reference for locating a specific site in the brain.
The frame that Dr. Leksell developed was a rigid metal frame that was attached to the patient’s skull. In 1951, Leksell and Larsson first employed proton beams coming from several directions into a small area into the brain during experiments in animals and in the first treatments of human patients. With this development, Dr. Leksell achieved a new noninvasive method of destroying small anatomical targets within the brain while minimizing the effect on the surrounding tissues. Dr. Leksell coined the term “radiosurgery” to describe his concept of converging beams, because the technique differed greatly from conventional radiation therapy.
In 1967, Dr. Leksell developed the prototype for the Gamma Knife machine which was installed in the Karolinska Hospital in Stockholm, Sweden in 1969. The machine was later manufactured by the Elekta company, founded by Dr. Leksell in 1972. When advanced imaging technology became available in the 1980’s, neurosurgeons were able to precisely locate brain tumors, and Dr. Leksell’s radiosurgery concept gained a foothold as a viable cancer treatment. In 1987, the international launch of the Gamma Knife was begun, and the first unit was installed in the United States in Pittsburgh.
Gamma Knife technology has evolved over the years as have the Gamma Knife machines. The Gamma Knife Center at Monmouth Medical Center utilizes the Gamma Knife C® Unit, the latest technology employing an automatic positioning system. During the treatment, 201 small beams of gamma radiation from a cobalt-60 source are aimed at a target in the brain. A high dose of radiation is delivered to the targeted area, but very little radiation is delivered to the surrounding normal brain structures. Radiosurgery is delivered as a one-time, outpatient treatment, and patients generally are discharged within a few hours. Gamma Knife patients have benefited from treatment with high success rates and little risk of complications.
There are obvious advantages to radiosurgery including its non-invasive nature, its shortened immediate recovery time, its preservation of surrounding normal brain tissue, and its value as an alternative for patients unable or unwilling to undergo surgery. The source of radiation used in radiosurgery with the Gamma Knife is radioactive cobalt. The radiation is called a gamma ray when it comes from a cobalt source.