Frequently Asked Questions
1. What is stereotactic radiosurgery (SRS)?
Stereotactic radiosurgery is a medical procedure that allows physicians to treat brain disorders non-invasively, by delivering a high dose of radiation to a targeted area of the brain. This highly effective single session treatment may require an overnight hospital stay, but it is commonly performed as an outpatient surgical procedure with regularly scheduled follow-up.
2. When was the first Leksell Gamma Knife® installed?
The Leksell Gamma Knife is a Swedish invention. In 1968, the first Leksell Gamma Knife was installed at a private hospital, Sophiahemmet, in Stockholm, Sweden. In the United States, the first Gamma Knife unit was installed in 1987 in Pittsburgh. To date, more than 350,000 patients world-wide have been successfully treated with the Gamma Knife.
3. Why is it called surgery?
Radiosurgery (one-session treatment) has such a dramatic and precise effect in the target zone that the changes are considered surgical. Through the use of three-dimensional, computer-aided planning and the high degree of immobilization of the patient, the treatment minimizes the amount of radiation to surrounding healthy brain tissue, while successfully pinpointing radiation to the diseased area. Stereotactic radiosurgery is routinely used to treat brain tumors and lesions. It may be the primary treatment, utilized where a tumor is inaccessible by surgical means, or as a boost or adjunct to other treatments with a recurring or malignant tumor.
4. How does SRS work?
Stereotactic radiosurgery (SRS) works in the same way as other forms of radiation treatment. SRS does not remove the tumor or lesion, but it distorts the DNA of the targeted cells. The cells then lose their ability to reproduce and retain fluids. In lesions such as arteriovenous malformations (AVMs, a tangle of blood vessels in the brain), radiosurgery causes the blood vessels to thicken and close off.
The shrinking of a tumor or closing off of a vessel occurs during a period of time, at the same rate as the normal growth rate for that specific tumor cell. For benign tumors and vessels, this process typically takes 18 months to two years. For malignant and metastatic tumors, results may be seen within a couple of months, as these cells are very fast-growing.
The Leksell Gamma Knife delivers ionizing radiation from a total of 201 cobalt-60 sources arranged in a hemispherical pattern. The beams of gamma radiation converge at a fixed focal point within the radiation unit. Each beam contributes a small dose, and has minimal impact on healthy brain tissue on its way to the target. At the focal point, where all 201 beams meet, the cumulative dose of radiation will deliver the desired therapeutic effect. The dose is delivered with pinpoint accuracy, making it possible to treat targets which are very close to sensitive structures, deep within the brain or complex shaped areas. The built-in robotic movements of the Automatic Positioning System™ automatically set the coordinates directly from the treatment plan, giving improved performance and speed.
5. Are there any side effects after Gamma Knife surgery?
Patients may experience side effects, but they are often very mild. Immediately after the procedure, some patients have headaches, dizziness, seizures or nausea, but these effects disappear shortly thereafter.
6. What is the radiation risk with Gamma Knife surgery?
Although Gamma Knife uses radiation to treat the medical condition, the great advantage of this technology is that it focuses the radiation with submillimeter precision on the diseased tissue. Surrounding healthy brain tissue receives little to no radiation.
7. Who determines if radiosurgery is appropriate?
Upon thorough evaluation of a prospective patient’s medical condition, a neurosurgeon, radiation oncologist or other specialist will determine the appropriateness of this treatment option. Our physicians will answer questions and review treatment options with patients and their families. Before making a decision, patients and their families are encouraged to review all treatment options.