Stereotactic radiosurgery (SRS) allows high doses of radiation to be delivered to intracranial lesions with limited radiation to surrounding structures. SRS has been shown to be beneficial in the treatment of disorders such as selected brain tumors, acoustic neuromas, and meningiomas as well as trigeminal neuralgia and functional disorders of the brain and cranial nerves. While various techniques for delivering this type of radiation are available, one of the more popular techniques is Gammma Knife (GK) Radiosurgery.
SRS is usually performed as an outpatient procedure. A special device, the stereotactic frame, is fixated to the patient’s head. An MRI is then performed which allows the neurosurgeon, radiation oncologist, and radiation physicist to precisely localize the lesion and to formulate a treatment plan at a computer work station. The patient is then positioned in the Gamma Knife unit where the radiation dosing is administered. 201 beams of radiation delivered by the decay of radioactive cobalt are focused on a single point whose size can be customized using special collimation helmets placed around the head and attached to the stereotactic frame. By moving the patient relative to the helmet the precise contour of the lesion can be irradiated. This takes an hour or so, depending on the size lesion and what exactly is being treated. After the radiation is given the stereotactic frame is removed from the head and the patient can be sent home.
As with other forms of radiation therapy, stereotactic radiation leads to rare complications. These may include radiation injury to adjacent brain tissue or nerves (eg loss of vision from radiation effects on the optic nerve), headache, hormonal abnormalities from radiation injury to the pituitary or hypothalamus, hair loss, radiation injury to the skin and scalp, and radiation induced tumors.