Gamma Knife Radiotherapy

Gamma Knife® is a highly specialised form of stereotactic radiosurgery (SRS) used to treat conditions within the brain. Despite its name, Gamma Knife is not surgery — there are no incisions, no scalpel and no general anaesthetic.

Instead, Gamma Knife uses up to 192 finely focused beams of gamma radiation that converge precisely on a target within the brain. Each individual beam is too weak to damage healthy tissue significantly, but together they deliver a powerful dose of radiation to the tumour or abnormality.

Gamma Knife is one of the most accurate forms of radiation treatment available and has been used successfully to treat patients worldwide for more than 50 years. It is commonly used for:

• Brain metastases
• Meningiomas
• Vestibular schwannomas (acoustic neuromas)
• Pituitary adenomas
• Arteriovenous malformations (AVMs)
• Trigeminal neuralgia
• Selected other benign and malignant brain tumours

For many patients, Gamma Knife provides an effective alternative to open brain surgery.

No. Although the treatment is called Gamma Knife radiosurgery, it is not an operation. There are:

• No cuts or incisions
• No stitches
• No scalpels
• No removal of brain tissue
• Usually no overnight hospital stay

Instead, precisely focused radiation is delivered from outside the body while you remain awake throughout the procedure. Most patients return home on the same day.

Gamma Knife works by delivering hundreds of precisely focused beams of radiation to a carefully defined target within the brain. The radiation damages the DNA of abnormal cells, preventing them from growing and dividing. The effect depends on the condition being treated, for example:

• Brain tumours gradually shrink or stop growing.
• Brain metastases are destroyed over weeks to months.
• AVMs slowly close off over several years.
• Trigeminal neuralgia is relieved by interrupting pain transmission within the trigeminal nerve.

Because the radiation is focused so precisely, surrounding healthy brain tissue receives only a small dose.

Gamma Knife is used for a wide range of conditions affecting the brain, including:

• Brain metastases — Gamma Knife is widely used to treat one or more secondary cancers that have spread to the brain. It provides excellent local tumour control while avoiding many of the side effects associated with whole-brain radiotherapy.
• Meningiomas — many small or medium-sized meningiomas can be effectively controlled with Gamma Knife, particularly if surgery would be difficult or carries increased risk.
• Vestibular schwannomas (acoustic neuromas) — Gamma Knife is commonly used to stop tumour growth while preserving hearing and facial nerve function whenever possible.
• Pituitary adenomas — selected pituitary tumours can be treated after surgery or when surgery is not appropriate.
• Arteriovenous malformations (AVMs) — Gamma Knife causes the abnormal blood vessels to gradually close over several years, reducing the long-term risk of bleeding.
• Trigeminal neuralgia — Gamma Knife can relieve severe facial pain when medications are ineffective or surgery is not suitable.

Before treatment you will undergo several preparation steps. These usually include:

• Consultation with your treating specialist
• MRI brain scan
• Sometimes CT imaging
• Review by the multidisciplinary team
• Detailed treatment planning using specialised software

Depending on the type of Gamma Knife system being used, either a lightweight stereotactic frame or a custom-made mask will be used to keep your head still during treatment.

You lie on the treatment couch while your head is held securely using either the stereotactic frame or a custom mask. The treatment machine then delivers radiation automatically according to the personalised treatment plan.

Depending on the size and number of targets, treatment usually takes between 20 minutes and several hours. Once treatment is complete, most patients return home the same day.

No. You cannot feel the radiation during treatment. If a stereotactic frame is used, local anaesthetic is given before the frame is attached to the scalp, so discomfort is usually minimal. Mask-based treatments require no frame.

Gamma Knife is widely regarded as one of the most accurate forms of intracranial radiosurgery. Its design allows radiation to be focused with sub-millimetre precision, making it particularly well suited to treating very small targets within the brain.

However, modern linear accelerator (LINAC)-based radiosurgery systems also achieve excellent accuracy and clinical outcomes. The best treatment depends on the condition being treated, the available technology and the experience of the treating team.

Both Gamma Knife and CyberKnife deliver stereotactic radiation, but they are designed for different purposes.

Gamma Knife: treats the brain only, uses multiple cobalt radiation sources, is designed specifically for intracranial conditions, offers extremely high accuracy, and is often delivered in a single treatment.

CyberKnife: treats both brain and body, uses a robotic linear accelerator, can track moving tumours, and is commonly used for lung, prostate, liver, pancreas and spine tumours as well as some brain conditions.

Both systems provide excellent outcomes when used for the appropriate clinical indication.

Useful questions include:

• Is Gamma Knife the best treatment for my condition?
• Are surgery or observation reasonable alternatives?
• How many Gamma Knife procedures does your team perform each year?
• Will my case be discussed at a multidisciplinary meeting?
• What are the chances of controlling my condition?
• What side effects should I expect?
• Will I need steroids after treatment?
• How often will I need follow-up MRI scans?
• What symptoms should prompt me to seek urgent medical attention?

These questions can help you understand the potential benefits and risks of treatment and make an informed decision together with your specialist.