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. There was no imaging technology available in the 1940’s, and so brain atlases were used to 
determine the location of critical structures. Dr. Leksell theorized that his head frame could be used for patients with Parkinson’s disease to stabilize the head, locate the thalamus, and irradiate it, avoiding the risks of surgery.
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 non-invasive 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. His original plan for the technique was to treat functional
neurological disorders such as Parkinson’s disease.
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. The cancer treatments are based on the principle that radiation delivered precisely to the tumor will arrest its growth while minimizing 
injury to surrounding nerves and brain tissue. 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 Saint Joseph's Hospital of Atlanta 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 imm
ediate recovery time, its preservation of surrounding normal brain tissue, and its value as an alternative for patients unable or unwilling to undergo surgery. On the other hand, radiosurgery is limited to small or medium lesions. Where tumors are concerned, the patient should be aware that radiosurgical treatment is a means to seek to control the tumor’s growth without removing it.
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. The treatment team consists of a neurosurgeon, a radiation oncologist, a medical physicist, and a nurse. The physicians and physicists work together to develop a treatment plan based on the size and shape of the targeted lesion.
In radiosurgery patients, tumor cell growth is not arrested immediately. Some tumor cells die in a matter of weeks, but others do so more gradually, generally six to eighteen months after treatment. The treatment usually stops the growth of the tumor, and some tumors will shrink in size, but the tumor does not disappear. Tumor growth is controlled in a high percentage of cases, but some tumors continue to grow despite the treatment. It is not possible to determine which tumors will grow larger and which will not. Periodic MRI imaging is necessary to monitor this possibility.
Residual Problems Following Treatment
Radiosurgery, because it is an outpatient treatment performed under local anesthesia, is not associated with most of the complications of open surgery—such as infection, cerebrospinal fluid leak, stroke, or systemic problems. Although some side effects are possible, they are generally minimal, and most resolve in time.
The Gamma Knife Center of Saint Joseph's
The Gamma Knife team at Saint Joseph's Hospital consists of a neurosurgeon, a radiation oncologist, a medical physicist, and a registered nurse. This team of specialists has many years of training and experience in stereotactic radiosurgery and treatment of neurological and neurosurgical disorders. The healthcare professionals in the Gamma Knife Center at Saint Joseph’s are committed to the highest quality of care and the greatest potential outcomes for their patients. Anyone interested in obtaining more information about radiosurgery, Gamma Knife treatment options, or Saint Joseph’s Hospital in general are encouraged to call or visit the Center at any time.
For more information, please contact:
Rebecca O. Heitkam, RN, BSN, CCRN, coordinator
Gamma Knife Center
Saint Joseph's Hospital
404-851-5513
or toll free at 1-866-SJGAMMA
or email
rheitkam@sjha.org
