Gamma Knife Treatment and Radiosurgery

1. What Is Gamma Knife Radiosurgery?

Despite the word “knife” in its name, Gamma Knife is not conventional surgery. The skull is not opened, and no surgical incision or sutures are required. Numerous fine gamma-ray beams approach from different directions and converge at the intended target. This makes it possible to deliver an effective radiation dose to the target while preserving surrounding healthy brain tissue as far as possible.

The aim depends on the condition: to stop tumor growth or achieve shrinkage, help an arteriovenous malformation (AVM) close over time, or modulate the relevant neural circuit in functional conditions such as trigeminal neuralgia or tremor.

How is treatment delivered?

• Consultation and imaging: The patient’s clinical condition, MRI/CT images and previous treatments are reviewed.
• Individual planning: The neurosurgeon, radiation oncologist and medical physicist define the target and safe dose limits.
• Radiation delivery: The patient is awake. Radiation itself does not cause pain, burning or a sensation of heat.
• Discharge and follow-up: Most patients leave hospital on the same day after a short observation period. Because the effect develops over time, regular clinical and MRI follow-up is required.

Frame-based and mask-based Gamma Knife

Two methods can be used to keep the head still during treatment:

Stereotactic frame: The frame is fixed to the head under local anesthesia and is most often used for single-session treatment. It is removed on the same day after treatment is completed.

Custom thermoplastic mask: The mask allows treatment without attaching a frame to the head. It can permit treatment to be divided into several sessions, especially for larger targets or lesions close to sensitive structures such as the optic nerves or brainstem.

With mask-based treatment, the patient’s position is verified by the imaging system at every session. Head movement is continuously monitored during treatment; radiation delivery stops automatically if movement exceeds the safety threshold.

The choice between a frame and a mask is not based on patient preference alone. The condition, target size, location and required precision are considered together.

Key advantages

• No surgical incision or general anesthesia is required.
• Deep targets or targets that are risky to reach surgically may be treated.
• Hospital stay and return to daily life are usually brief.
• For suitable patients, it may be an alternative to surgery or complement surgery.

Gamma Knife does not replace surgery in every situation. Open surgery may be more appropriate for large masses causing pressure, urgent surgical situations, or when tissue diagnosis is required.

2. Conditions That May Be Treated With Gamma Knife

Gamma Knife is not selected based on a diagnosis alone. The size and location of the lesion, surrounding swelling, the patient’s age and general health, and previous treatments are considered together.