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Gamma knife


Expert reviewer, Sara Shergill, Senior Gamma Knife Radiographer, Bupa Cromwell Hospital
Next review due July 2022

Gamma knife is a type of treatment called stereotactic radiosurgery that uses highly focused radiation to treat brain conditions such as brain tumours. Gamma knife is a specialised treatment that’s only available in certain hospitals.

An image showing a doctor talking to a patient

About gamma knife

Gamma knife treatment gives you a high dose of radiation. Your healthcare team will target this precisely to reach a very small area of your brain so that it doesn't damage surrounding, healthy tissues. The area to be treated usually has to meet certain criteria, including size.

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

Gamma knife treatment can treat various health conditions, which include:

  • brain tumours
  • trigeminal neuralgia – pain in your face, usually on one side, when a nerve is under pressure (compressed)
  • arteriovenous malformation (AVM), a tangle of blood vessels with abnormal connections between arteries and veins, which you’re usually born with
  • cavernoma, a cluster of abnormal blood vessels, usually in your brain and spinal cord
  • some types of epilepsy

You’ll meet the team who are going to do your procedure to discuss your care. This team might include:

  • a neuro-oncologist – a doctor who specialises in diagnosing and treating brain tumours and other tumours of the nervous system
  • a neurosurgeon – a doctor who specialises in surgery on the brain, spine, and other parts of the nervous system
  • medical physicists – scientists who will help plan how treatment is given
  • a radiographer – a health professional trained to perform imaging procedures
  • a neuro-radiologist – a doctor who specialises in interpreting diagnostic images to identify what treatment is needed

Your treatment may differ from what’s described here as it will be designed to meet your individual needs.

Preparing for gamma knife

Your hospital might give you a special shampoo to use before you come in to have gamma knife. This will make sure your head is properly prepared for the procedure. If you’re taking any medicines, let your hospital know and bring them with you.

You might be able to have something to eat and drink after you have been through the imaging part of the procedure (see our section: The procedure – Imaging).

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

You’ll usually have gamma knife treatment and go home the same day, but it’s possible you’ll need to stay overnight – check with your hospital. You’ll have a local anaesthetic to completely block any pain from your head, and you’ll stay awake during the procedure.

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.

What are the alternatives to gamma knife?

Other ways to deliver stereotactic radiosurgery include a Cyberknife machine and a linear accelerator machine called LINAC. Other alternative treatments to gamma knife depend on what condition you have and might include:


Ask your doctor for more information about your options.

Gamma knife surgery

Gamma knife uses multiple beams of radiation that meet to focus precisely on a small area such as a tumour. Advanced systems and robotic technology are used to move you by tiny amounts during your treatment to focus the radiation accurately.

Before the treatment starts, there are some necessary preparation steps.

Frame fitting

Your radiographer will fit a lightweight frame to your head to keep your head still during treatment. You might worry about having this frame on your head. But it’s really important because it will make sure the therapy is delivered to exactly the right place.

Your healthcare team will inject a local anaesthetic into your skin at four places on your head – two in your forehead and two in the back of your head. They’ll then fix the frame to your head with pins, which usually takes about 10 minutes. It can feel uncomfortable and tight while the frame is being fitted but it shouldn’t be painful.

Imaging

After the frame is fitted, you’ll have a magnetic resonance imaging (MRI) or computed tomography (CT) scan. This helps to find the position of the tumour in relation to the head frame so the team can plan exactly where to deliver the therapy.

If you’re having gamma knife treatment for a vascular malformation, you may need to have a cerebral angiogram. In this procedure, a doctor will put a catheter (thin tube) into a blood vessel in your groin. They’ll direct the catheter to your brain and then pass a dye through it. They’ll then take some X-ray images of the blood vessels in your brain.

Treatment planning

The images from your scans will be fed into a computer. This will help your team at the hospital to calculate the exact treatment you need. You can rest while they plan your treatment, and decide the exact area to be treated. It may take an hour or two. You can have something to eat and drink while you’re waiting.

The treatment

When you’re ready to start gamma knife treatment, a radiographer will ask you to lie on a treatment bed. Your radiographer will then fix the head frame into the gamma knife unit or into a helmet that narrows the radiation beams.

Once they’ve positioned your head and completed some checks, your radiographer will leave the treatment room. You can speak to them at any time during the procedure through a microphone. And there are cameras in the treatment room so they can see you from the control room.

Your radiographer will then remotely operate the bed to move you into the gamma knife unit and deliver the radiation treatment. You won’t feel the treatment, and the machine is quiet.

You might have the treatment all in one go, or it may be broken up into smaller parts. After each exposure, you’ll be moved by the staff or the machine into a new position for the next stage of treatment. In total, the treatment can last anything from less than an hour to up to five hours.

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 your healthcare team will take the head frame off. 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 taken to a room where you can rest. If you have a headache or feel sick, tell your hospital team so 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 might be able to go home the same day that you have gamma knife, or you may need to stay overnight. 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 you have responded to the treatment. You might need to have another scan in the follow-up appointment, depending on what your treatment was for.

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.

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Recovering from gamma knife

You can return to your usual routine after gamma knife treatment as soon as you feel well enough, maybe 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 and, if you have any questions, ask your pharmacist for advice.

You may find you feel really tired for a few days after treatment. You can go back to work the next day, although most people find that they need a few days rest before they return to work.

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

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

Side-effects of gamma knife

As with every procedure, there are some risks associated with gamma knife. 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.

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

  • tenderness around where the pins were
  • feeling tired
  • a headache
  • feeling sick and dizzy
  • losing some hair if your tumour is close to the surface of your skull but hair loss after gamma knife is rare
  • bleeding from where the head frame was fixed

Complications of gamma knife

Complications are when problems happen during or after the procedure. 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 is one of the reasons that can cause their brain to swell. This doesn’t usually cause any symptoms but if you get this, your doctor can prescribe steroids to treat it.
  • Seizures. You can have seizures (fits) 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 it might affect your hearing.

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.

Frequently asked questions


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Related information

    • Gamma knife and other stereotactic radiotherapies for acoustic neuroma. Medscape. emedicine.medscape.com, updated 13 July 2017
    • Stereotactic radiosurgery for trigeminal neuralgia using the gamma knife. National Institute for Health and Care Excellence (NICE), August 2004. www.nice.org.uk
    • Stereotactic radiotherapy. Cancer Research UK. www.cancerresearchuk.org, last reviewed 20 October 2015
    • Gamma knife. Radiological Society of North America. www.radiologyinfo.org, reviewed 20 January 2018
    • AlignRT for intracranial stereotactic radiosurgery. National Institute for Health and Care Excellence (NICE), May 2018. www.nice.org.uk
    • Stereotactic radiotherapy (SRT). The Brain Tumour Charity. thebraintumourcharity.org, published April 2016
    • NCI dictionary of cancer terms. National Cancer Institute. www.cancer.gov, accessed 1 May 2019
    • Stereotactic radiotherapy (SRT) for brain tumours. Macmillan. www.macmillan.org.uk, reviewed 31 August 2016
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    • Cerebral arteriovenous malformation. BMJ Best Practice. bestpractice.bmj.com, last reviewed April 2019
    • Stereotactic radiosurgery. Medscape. emedicine.medscape.com, updated 19 December 2008
    • What is a cavernoma? Cavernoma Alliance UK. www.cavernoma.org.uk/about-cavernoma, accessed 1 May 2019
    • A typical treatment day. International Radiosurgery Association. www.irsa.org, accessed 1 May 2019
    • Radiosurgery for brain tumours. Cancer Research UK. www.cancerresearchuk.org, last reviewed 3 December 2015
    • Gamma knife surgery. International Radiosurgery Association. www.irsa.org, accessed 1 May 2019
    • Stereotactic radiosurgery overview. International Radiosurgery Association. www.irsa.org, accessed 1 May 2019
    • Brain tumours in adults. Patient. patient.info, last checked 29 June 2015
    • Stereotactic radiosurgery (SRS) and stereotactic body radiotherapy (SBRT). Radiological Society of North America. www.radiologyinfo.org, reviewed 17 February 2017
    • Neurological disorders: assessing fitness to drive. Driver and Vehicle Licensing Agency (DVLA). www.gov.uk, last updated 14 February 2019
    • Koiso T, Yamamoto M, Kawabe T, et al. Follow-up results of brain metastasis patients undergoing repeat gamma knife radiosurgery. J Neurosurg 2016; 125(Suppl 1):2–10. doi:10.3171/2016.6.GKS161404
    • Frequently asked questions. International Radiosurgery Association. www.irsa.org, accessed 2 May 2019
    • Personal communication, Sara Shergill, Senior Gamma Knife Radiographer, Bupa Cromwell Hospital, 21 June 2019
  • Reviewed by Rachael Mayfield-Blake, Freelance Health Editor, July 2019
    Expert reviewer, Sara Shergill, Senior Gamma Knife Radiographer, Bupa Cromwell Hospital
    Next review due July 2022



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