Gamma knife

Your health expert: Josiah Rickman, Senior Gamma Knife Radiographer, Cromwell Hospital
Content editor review by Sarah Smith, March 2022
Next review due March 2025

Gamma knife is a type of treatment called stereotactic radiosurgery. It’s a type of radiotherapy that uses highly focused radiation. It’s usually used to treat brain conditions such as brain tumours.

About gamma knife

Gamma knife treatment gives you a really targeted, high dose of radiation. Several beams of radiation are focused onto a very small area of your brain using computers. This means the treatment is less likely to damage any healthy tissue around the area of concern,

You’ll usually have just one gamma knife treatment, although you can have more. Both adults and children can have it.

Gamma knife is a specialised treatment and it’s not available in every hospital. Your treatment may differ from what’s described here because it will be designed to meet your individual needs.

What is gamma knife used for?

Gamma knife can treat a number of different health conditions such as the following.

Brain tumours, including cancers and benign (non-cancerous) tumours such as acoustic neuroma.
Trigeminal neuralgia. This is intense stabbing pain in your face and is often caused when a nerve is under pressure.
Arteriovenous malformation (AVM). This is a complex tangle of blood vessels with abnormal connections. It’s something you’re usually born with and is often discovered during young adulthood.
Some types of epilepsy.

Gamma knife can sometimes be used to treat cancer that has spread to your brain (known as secondary brain tumours).You can have Gamma knife treatment just once or it can be used again to treat tumours that come back. It can also be used to treat conditions such as trigeminal neuralgia more than once.

What are the alternatives to gamma knife?

As well as gamma knife, there are other ways to deliver stereotactic radiosurgery. These include using a cyberknife machine and a machine called LINAC (linear accelerator).

Treatments other than stereotactic surgery depend on what condition you have. These might include:

medicines to help ease your symptom
open surgery
radiotherapy
chemotherapy
watchful waiting (when you don’t have treatment, but your doctor keeps a close eye on things)

Ask your doctor for more information about your options.

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Preparing for gamma knife

Gamma knife treatment needs to be carefully planned to make sure the radiation goes to exactly the right place. Planning may happen on the same day as your treatment or on another day beforehand. Here are some of the key steps your healthcare team will take to prepare you for treatment.

Imaging

Before your procedure, you’ll have an MRI scan, and sometimes a CT or PET scan as well. These will create pictures that help to direct the gamma knife to the exact place being treated

If you’re having gamma knife for a condition such as arteriovenous malformation, you may need to have a cerebral angiogram. This produces accurate images of your brain using X-rays and a special dye. During the procedure, the dye is put in through a thin tube in a blood vessel in your groin.

Depending on the type of scan you’re having, your doctor may ask you not to eat or drink for a few hours beforehand. Follow the advice of your healthcare team.

Fitting a mask

Depending on what condition you’re having the gamma knife for, you may need to have a face mask made to wear during treatment. These are usually made of a mesh with lots of small holes and help to keep your head still.

The face mask fits quite tightly. If you have a beard or moustache, you might be asked to shave. You won’t need to shave your head, but if you’re planning a haircut, have it before the mask is fitted. Wash your hair before you come in to have the mask fitted and don’t use any hair products you would usually use.

Fitting a head frame

Alternatively, you may have a lightweight frame fitted to your head to keep it still. This is usually done on the day you have your treatment. The frame is fitted around your head and secured in several places. Usually, a local anaesthetic will be injected into your skin at four places on your head - two at the back and two on your forehead. The frame will be fixed to your head with pins. It can feel uncomfortable while the frame is being fitted but it shouldn’t hurt.

Your doctor will discuss with you what will happen before your procedure, including any pain you might have. If you’re unsure about anything, ask. No question is too small. Being fully informed will help you feel more at ease and will allow you to give your consent for the procedure to go ahead. You may be asked to do this by signing a consent form.

Gamma knife surgery

If you’re taking any medicines, let your hospital know and bring them with you. If you usually take painkillers, take them before you come so that you’re as comfortable as possible during the procedure.

You’ll need to remove any make-up (including nail polish), as well as hair clips, contact lenses, glasses, dentures and any face or ear piercings before you have gamma knife.

You’ll lie down to have the gamma knife treatment. Your radiographer will fit your mask or head frame. This keeps your head still and in the right place for treatment, but it can feel a bit uncomfortable.

The bed you’re on will be moved into the machine and your treatment will begin. Computers help to guide the radiation beams to the right place, and you may also be moved into different positions during the treatment. You won’t feel anything, and the machine is usually quiet.

Although your radiographer won’t be in the room with you, you’ll be able to speak to them and hear them and they can see you too. They will be close by if you need them.

You might have the treatment all in one go or it may be broken up into smaller parts. In most cases, gamma knife treatment lasts between 30 minutes and three hours. This will vary depending on your individual circumstances. Your healthcare team will let you know how long your treatment is expected to take.

A chime may sound when your treatment is finished, and the bed will move back to its original position. You can then sit up and have your mask or head frame taken off. If you had a head frame, there may be a little bleeding from where the pins were, so you might need to wear a bandage for a while.

What to expect afterwards

After your treatment, you’ll be monitored for a while to make sure you’re feeling well. If you have a headache or feel sick after the treatment session, tell your hospital team. They can give you medicines to help ease this. Your doctor might prescribe you a steroid medicine to take after the procedure. These can help to prevent swelling around the area treated with radiation.

You should be able to go home the same day that you have gamma knife. When you’re ready to go home, make sure someone can take you.

Gamma knife doesn’t make you radioactive so it’s safe for you to be with other people, including children, after your treatment.

Your doctor will arrange a follow-up appointment to check how you're recovering and how well the treatment worked. You might need to have another scan in the follow-up appointment, depending on what your treatment was for.

Recovering from gamma knife

You can go back to your usual routine after treatment as soon as you feel well enough, which is usually on the following day.

You may get a little bleeding around the area where the frame was, and it may feel sensitive for several days. If you have a headache, you can take over-the-counter 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.

Sometimes, you may feel really tired and drained of energy after the treatment. For some people, this can last for days or weeks. If this happens, get plenty of rest, eat healthily and ask someone to help you with day-to-day tasks if you need it.

Some people find that the symptoms of a brain tumour get worse after gamma knife treatment. This is a reaction to the treatment itself and doesn’t mean your tumour has got any worse – talk to your doctor if you’re worried.

When you can drive again depends on what you had gamma knife treatment for. You might have to stop driving if there’s a risk of you having a seizure, for example. Ask your doctor for advice and check the website of the Driver and Vehicle Licensing Agency (DVLA) for more information.

If you have any pain, swelling or redness or have any concerns after having your treatment, contact your hospital.

Side-effects of gamma knife

Side-effects are the unwanted but mostly temporary effects that you may get after having your treatment. Possible side-effects after gamma knife treatment include:

swelling and pain around where the pins were
feeling very tired
a headache
feeling sick and being sick
losing a patch of hair
bleeding from where the head frame was fixed
red, sore and irritated skin on your head

Complications of gamma knife

As with every procedure, gamma knife does have some risks. We haven’t 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.

Complications are when problems happen during or after the procedure. The complications you might get will usually depend on what condition you’re being treated for. Your doctor will discuss these with you before you have gamma knife treatment.

Possible complications of gamma knife include the following.

Radiation necrosis. Because a high dose of radiation is used on a small area in your brain, some healthy cells may die. For a small number of people, this can cause swelling. Your doctor can prescribe steroids to treat it.
Seizures (fits). You can have these one to three days after gamma knife treatment. For this reason, you shouldn’t drive until your doctor says it’s safe to.
Cranial nerve injury. Your face may feel numb or your hearing might be affected. This is usually temporary.

Sometimes, complications may develop months or years after your treatment. This will depend on the part of your brain that was treated, but could include:

problems with your memory and thinking
changes to your vision such as a developing a cataract
changes in your hormone levels

Gamma knife is used to treat a very small and specific area in the body. It gives a really targeted high dose of radiation, focused onto the target area using computers. That means the treatment is less likely to damage any healthy tissue around the area of concern.

For more information, see our sections: About and Uses above.

Gamma knife can be used to treat brain tumours, but it can also treat other health conditions. These include:

trigeminal neuralgia, which is an intense stabbing pain in your face
arteriovenous malformation, which is a complex tangle of blood vessels with abnormal connections
some types of epilepsy

For more information, see our Uses section above.

Yes, you may be able to have gamma knife again if a tumour comes back, spreads to another area or a new tumour appears. You can also have more than one gamma knife treatment if you’re having it to treat trigeminal neuralgia.

Find out more in our Uses section above.

Gamma knife can be used to treat a range of conditions. These include small cancers, such as brain tumours, and some types of epilepsy. It can also be used to treat trigeminal neuralgia, which is a condition where you have stabbing pains in your face.

Find out more in our Uses section above.

Most people who have gamma knife treatment don't lose their hair. You may lose a patch of hair if the area of your brain being treated is near the surface of your skull. If you do lose some hair, it will usually grow back within a few months but it can sometimes grow back thinner or a slightly different colour.

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