The patient's head is then placed into the Gamma Knife, a large helmet-like device with 201 openings that focus the narrowbeams of radiation onto the target in the brain. The dose of radiation each patient receives is selected by the neurosurgeon and radiation oncologist depending on the type and location of each lesion. The radiation treatment session usually lasts 30 to 60 minutes, and up to several hours for very complex cases. Following the completion of radiosurgery, the head frame is removed and the patient is sent home with only two bandaids on the forehead to show for the entire procedure. Gamma Knife treatment causes few of the immediate side effects that are associated with conventional external beam radiation.
Patients usually return home the same day and return to their normal schedule within a day or so.
While results are not as immediate as with surgery, the prognosis is promising. With AVMS, the expectation is complete obliteration of 80 percent of the treated lesions within two years. Certain tumors, like acoustic neuromas and meningiomas stop growing over 95 percent of the time. People with lesions that were considered inoperable or with health issues which made them poor candidates for surgery are good candidates for this procedure. The Gamma Knife is also an alternative to conventional open surgery.