Upon fitting the patient with the stereotactic frame, which serves as a measuring guide, the frame's external axis are used to determine coordinates for targeting the abnormality. State-of-science computer technology enables the neurosurgeon, radiation oncologist, radiation physicist, and technicians to tailor radiation dose distribution to conform specifically to the lesion volume.

A collimator helmet containing 201 evenly distributed portals is attached to the frame and the patient is introduced headfirst into the heavily shielded, 18-ton Gamma Knife cavity, where the 201 sources of cobalt-60 are positioned to converge on a single target with pinpoint accuracy. The single high dose of precisely focused radiation targets the lesion, sparing the surrounding healthy tissue.