How is Gamma Knife Surgery performed?

At the beginning of the treatment, the stereotactic frame is attached to the patient’s head. The fixation points are infiltrated with local anesthesia. There is no need to shave any hair. This frame defines the spatial reference system for the rest of the treatment. Next, the head is imaged using a MRI or CT scanner and in case of vascular malformations an angiogram is obtained as well.

The dose planning is then carried out on the treatment planning computer defining the Gamma Knife set-up and treatment parameters to be calculated. The aim of the treatment plan is to cover the diseased area with an exactly shaped radiation dose and ensuring at the same time that the healthy brain tissue in close proximity of the lesion is not damaged.

This is done with an extremely high precision of a target deviation of less than one millimeter. The dose planning takes between one and three hours depending on the complexity and position of the diseased area. During the planning procedure, the patient stays in our waitingroom. Once the dose plan is completed the patient is brought into the treatment room. The Gamma Knife unit itself and the stereotactic frame are set up according to the computed dose plan. When all the parameters have been set and double checked, the medical team leaves the Gamma Knife treatment room and the irradiation process is started. The Gamma Knife shielding doors open and the patient is moved into the correct position with the lesion in the focus point.

When the predefined treatment time for the irradiation position has elapsed (usually a few minutes), the patient is moved out of the Gamma Knife unit and the shielding doors close automatically. Usually a several different irradiation positions (isocenters) are needed to optimally cover the whole lesion. The procedure is repeated for each so called isocenter position according to the treatment plan. During the irradiation the patient and the treatment team are in contact over a video link and an intercom system.

When the irradiation process is finished, the stereotactic frame is removed. Often, the patient is able to return home the same day. The whole procedure from the initial fixing of the stereotactic frame to its final removal takes between 5 to10 hours.