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Gamma knife

Key points

  • Gamma knife is a type of radiotherapy that uses highly focused beams of radiation to treat a small area of your brain. It’s used to treat brain tumours and other conditions, such as trigeminal neuralgia.
  • Before your treatment you will have a light-weight frame fitted to your head. This keeps your head still and allows your doctor to pinpoint the area for treatment very accurately.
  • You may feel very tired for a few days after your treatment. You may also have a headache or feel sick and dizzy immediately after the procedure.

Gamma knife uses highly focused beams of radiation to treat conditions, such as brain tumours and trigeminal neuralgia. It's a non-surgical treatment and usually given as a single dose.

You will meet the doctor carrying out your procedure to discuss your care. It may differ from what is described here as it will be designed to meet your individual needs.

About gamma knife

Gamma knife is a non-invasive procedure. This means that no cut is made to your skin and all of the treatment takes place outside your body. It’s a specialised treatment which is only carried out at a few hospitals.

Gamma knife treatment gives a high dose of radiation. It’s targeted precisely to reach a very small area of your brain. Hundreds of energy beams are directed from different angles into your brain. Where they all cross is the area where you need treatment. All of the energy beams together are very powerful. However, each beam on its own is weak. You’ll have just one treatment session. You can have gamma knife treatment as an alternative to open surgery.

Gamma knife can be used to treat a number of different conditions including:

  • brain tumours, both benign (non-cancerous) and malignant (cancerous) – gamma knife can treat tumours smaller than 4cm in size
  • vascular malformations – this is when some of the arteries and veins in your brain aren’t connected properly
  • other conditions, such as trigeminal neuralgia and some types of epilepsy

What are the alternatives to gamma knife?

Depending on your condition, there are a number of alternative treatments. If you have a brain tumour, you may be offered open surgery, radiotherapy or chemotherapy. If you have trigeminal neuralgia you may be offered medicines or surgery to treat your condition. Talk to your doctor for more information about your options.

Preparing for gamma knife

You will probably need to stay overnight in hospital after gamma knife treatment. You will stay awake during the procedure.

During your procedure, you will need to have a frame attached to your head. This keeps your head still during treatment. You will be given a local anaesthetic to completely block any pain from the areas where the head frame is attached.

You may have gamma knife to treat a pituitary tumour. If so, your doctor may ask you to stop taking some of your medicines two months before the procedure.

At some hospitals you may be able to eat and drink throughout the day while you have the procedure. At other hospitals you will be asked not to eat or drink. In these hospitals you will be given a drip instead (fluids which go into your vein) to make sure you don’t get dehydrated.
You will be asked to remove all make-up (including nail polish), hairpieces, contact lenses, glasses and dentures.

Your nurse may check your heart rate, blood pressure, temperature and weight.

Your doctor will discuss with you what will happen before, during and after your procedure, and any pain you might have. You can help yourself by preparing questions to ask about the risks, benefits and any alternatives to the procedure. This will help you to be informed, so you can give your consent for the procedure to go ahead. You may be asked to do this by signing a consent form.

There are a number of different steps involved in preparing for gamma knife treatment. These are explained here.

Frame fitting

You will need to have a light-weight frame fitted to your head. Your doctor will inject local anaesthetic into the skin at four places on your head. This is where the frame will be fixed with pins. Having the frame fixed in place can be uncomfortable and it may be sore, but the pain shouldn't last long. The fitting usually takes about 10 minutes. The frame will stay attached to your head during the treatment and will be taken off afterwards.


You will have an MRI scan or a CT scan to find the exact position of the area that needs to be treated. An MRI scan uses magnets and radiowaves to produce images of the inside of your body..

You may have a cerebral angiogram (an X-ray image of the blood vessels in your head and neck) if you’re having gamma knife treatment for a vascular malformation.

Treatment planning

The images taken by CT, MRI or angiography will be fed into a computer. This will help to calculate the exact treatment you need. A team of people including a neuroradiologist will plan your treatment, deciding the exact area to be treated. This may take several hours.

What happens during gamma knife

You will lie on the treatment couch. The radiographers will position the frame attached to your head either into a docking device on the couch or a helmet. This will depend on the type of gamma knife unit. It’s important because it will keep your head still during the procedure.

Once your head has been positioned and the relevant checks have been completed, the radiographers will leave the treatment room. You can speak to the radiographers at any time during the procedure via a microphone. They can see you from the control room by cameras positioned in the treatment room.

A radiographer preparing a man for gamma knife treatment, with the man lying on the treatment table.

                                                         Gamma knife

A radiographer operating the gamma knife machine from the control room.

                                                    Gamma knife control room

When your treatment begins, the couch will move you into the gamma knife unit. The radiation treatment will be made up of a series of exposures to radiation in different places. After each exposure you will be moved by the staff or the machine into a new position for the next stage of treatment. The exposure of each shot may only take a few minutes but the entire procedure can last more than an hour. You won't feel any pain during the treatment.

Once the treatment has finished your head frame will be taken off. You may notice slight bleeding around the area where the frame was. It may feel sensitive for several days.

What to expect afterwards

After your treatment you will be taken back to your room where you can rest. If you have a headache or feel sick, you can have medicines to ease your symptoms.

Your doctor may prescribe you steroids to take after the procedure. This can help to prevent any swelling or inflammation around the area that was treated with radiation.

You may need to arrange for someone to drive you home depending on how you’re feeling. Try to have a friend or relative stay with you for the first 24 hours.

After your treatment, your doctor will arrange a follow-up appointment to check how you're recovering and what your response has been to the treatment. You may also have an MRI scan in the follow-up appointment.

Some people find that the symptoms of a brain tumour get worse after this kind of treatment. This is a reaction to the treatment itself and doesn’t mean the tumour has got any worse.

Recovering from gamma knife

If you have a headache, or if your head is painful, you can take painkillers such as paracetamol and ibuprofen. Always read the patient information leaflet that comes with your medicine. If you have any questions, ask your pharmacist for advice.

If you notice pain, swelling or redness, or have any concerns following your treatment, contact your doctor.

What are the risks?

As with every procedure, there are some risks associated with gamma knife. We have not included the chance of these happening as they are specific to you and differ for every person. Ask your doctor to explain how these risks apply to you.


These are the unwanted but mostly temporary affects you may get after having your treatment.
Gamma knife treatment usually has few side-effects because it only targets the affected area.

However, possible side-effects include:

  • tiredness
  • headaches
  • feeling sick and dizzy
  • losing some hair if your tumour is close to the surface of your skull
  • bleeding from the places where the head frame was fixed


This is when problems occur during or after the procedure. Any complications that may arise are specific to you and your condition. Your doctor will have discussed these with you prior to the gamma knife treatment.

Because a high dose of radiation is used on a small area in your brain, some of the healthy cells can die. This is called radiation necrosis. For a small number of people this can cause the brain to swell. This doesn’t usually cause any symptoms. However, if you do develop symptoms your doctor will prescribe steroids to treat the problem.

You can have seizures (fits) 24 to 72 hours after gamma knife treatment. For this reason you should not drive until your doctor says it’s safe to.

Reviewed by Dylan Merkett, Bupa Health Information Team, March 2014.

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  • This information was published by Bupa's Health Information Team and is based on reputable sources of medical evidence. It has been reviewed by appropriate medical or clinical professionals. Photos are only for illustrative purposes and do not reflect every presentation of a condition. The content is intended only for general information and does not replace the need for personal advice from a qualified health professional. For more details on how we produce our content and its sources, visit the about our health information page.

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