To minimize discomfort, the patient is first given a sedative, and then a metal frame is fitted securely around the patient's head. Because the headframe is rigid and fixed in place with a pin, the tumor or lesion can be plotted with exceptional precision using a CT or MRI scan. Three-dimensional planning software is then used to design a treatment that hits the exact contours of the tumor or lesion with an effective dosage of radiation.
A helmet-like device is fitted over the headframe in the treatment room, where the patient is gently moved into the gamma knife unit. Through the helmet, 201 beams of gamma radiation converge on a single point with an accuracy of within 0.3 millimeters – about the width of a human hair – destroying abnormal tissue without affecting surrounding healthy tissue.
After the procedure, the headframe is removed, and the patient usually can go home and resume normal activites the same day.
