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. This area to be treated usually has to be less than about 3cm.
You’ll usually have just one gamma knife treatment, although you can have more. Both adults and children can have the treatment.
Gamma knife can treat various health conditions, which include:
- brain tumours, both non-cancerous (benign) and cancerous
- trigeminal neuralgia – pain in your face due to compression on a nerve
- 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 and tremor
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 radiotherapy
- a neurosurgeon – a doctor who specialises in brain surgery
- medical physicists – scientists who will help plan how the treatment is given
- therapeutic radiographers – health professionals who are specially trained to operate radiotherapy machines
- a radiographer – a health professional trained to perform imaging procedures
Your treatment may differ from what’s described here as it will be designed to meet your individual needs.
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 hospital might give you a type of shampoo to use before you come in to have gamma knife. This will make sure your head is clean 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 throughout the day while you have the procedure. But it’s possible that you’ll need to wait until after your treatment.
You’ll need to remove any make-up (including nail polish), hairpieces, contact lenses, glasses and dentures before you have gamma knife.
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 gamma knife to go ahead. You may be asked to do this by signing a consent form.
As well as gamma knife, there are other ways to deliver stereotactic radiosurgery, such as using a linear accelerator machine called cyberknife. Other alternative treatments to gamma knife will depend on what condition you have and might include:
Ask your doctor for more information about your options.
Before the treatment starts, there are some steps to prepare.
Your radiographer will need to fit a lightweight box-shaped frame to your head. This will keep your head still during treatment. You might feel worried about having this frame on your head. But it’s really important as 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 with pins, which usually takes about 15 minutes. This can feel uncomfortable and feel tight but you shouldn’t have any pain.
You’ll need to have a computed tomography (CT) scan before gamma knife treatment. This will help to find the exact position of the tumour in relation to the head frame and where to deliver the therapy. If you’re having gamma knife treatment for a vascular malformation, you may also 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.
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. They’ll plan your treatment, and decide the exact area to be treated. This may take an hour or two.
You’ll need to lie on a treatment bed. Your radiographer will then position the head frame either into a docking device on the couch or into a helmet.
Once they have positioned your head and completed some checks, they’ll leave the treatment room. You can speak to your radiographer at any time during the procedure via 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. They’ll then deliver the radiation treatment. You won’t feel the treatment, and the machine is quiet. You might see flashes of light even if you have your eyes closed.
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 will usually last about 30 to 90 minutes but it can take longer.
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 might be a bit of bleeding from where the pins were so you might need to wear a bandage for a bit.
After your treatment, you’ll be taken to a room where you can rest. If you have a headache or feel sick, a doctor can give you medicines to help ease this. Your doctor might prescribe you a steroid medicine to take after the procedure too. 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. And ask someone to stay with you for a day or so while you recover.
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.
You may get a bit of 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.
If you have any pain, swelling or redness, or have any concerns after having your treatment, contact your hospital.
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:
- feeling tired
- a headache
- feeling sick and dizzy
- losing some hair if your tumour is close to the surface of your skull
- bleeding from where the head frame was fixed
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 of the healthy cells can die. This is called radiation necrosis. 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 have discussed these with you before your gamma knife treatment.
Yes, you may be able to have gamma knife again if you have more than one tumour or if the tumour spreads to another area. You can also have gamma knife treatment again to re-treat a tumour if it comes back after your first treatment. Gamma knife treatment can also be done if you’ve already had another form of radiotherapy but it hasn’t worked. This is because gamma knife treatment is very precise and does little damage to healthy nerves and tissues.
No, the pins only go through your skin to the outer part of your skull. You’ll be given four injections of local anaesthetic to numb the area where the pins are attached. This can feel slightly uncomfortable. You might get a feeling of increased pressure or tightness in your head when the frame goes on but this shouldn’t last long.
The pins on the head frame will keep the frame rigid. It’s really important that your head is kept very still during the procedure.
It 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.
This will depend on whether you have any side-effects and how you feel after the treatment.
Gamma knife treatment usually has few side-effects. You can return to your usual routine as soon as you feel well enough.
You may find you feel very tired for a few days after treatment. But as the treatment is non-invasive (it’s all done from outside your body) you should get back to normal quickly. 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.
Most people who have gamma knife treatment don't lose their hair because the radiation is directed to a specific area and doesn't usually damage healthy tissue. You may lose a patch of hair if the area targeted is near the surface of your skull. If you do lose some hair, it will usually grow back within a few months but it may grow back lighter and finer. You’ll never lose all your hair.
- Cancer Research UK
0808 800 4040
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Reviewed by Rachael Mayfield-Blake, Freelance Health Editor, February 2017
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