Gamma knife
Published by Bupa's health information team, June 2009.
This factsheet is for people who are planning to have gamma knife treatment, or who would like information about it.
Gamma knife uses highly focused beams of radiation to treat many conditions including brain tumours and trigeminal neuralgia. It's a non-surgical treatment and is usually given as a single dose.
Your care will be adapted to meet your individual needs and may differ from what is described here. So it's important that you follow your doctor's advice.
- About gamma knife
- What are the alternatives?
- Preparing for your procedure
- About the procedure
- What to expect afterwards
- Recovering from gamma knife
- What are the risks?
- Questions and answers
- Related topics
- Further information
- Sources
About gamma knife
Gamma knife is a non-invasive form of surgery. The aim of the treatment is to deliver a high dose of radiation to a very small area of the brain. This will prevent damage to normal brain tissue, nerves and blood vessels. It can be used as an alternative to open surgery.
Gamma knife can treat a number of different conditions including:
- malignant brain tumours
- benign brain tumours
- vascular malformations (abnormal arrangements of some of the blood vessels in your head)
- functional disorders such as trigeminal neuralgia
The procedure isn't suitable for tumours larger than four to five centimetres.
What are the alternatives?
Depending on your condition, it may be possible to have open surgery or radiotherapy. Your doctor will explain your options to you.
Preparing for your procedure
Gamma knife often requires one night in hospital and is usually done under local anaesthesia. Some gamma knife treatments are carried out as a day case or as a two night stay in hospital. Your doctor will let you know how long you will need to stay.
You may be asked to not eat or drink for four hours before the procedure. Your doctor will explain how to prepare for your procedure.
At the hospital, your nurse may check your heart rate, blood pressure, temperature and weight.
Your doctor will ask you to sign a consent form. This confirms that you understand the risks, benefits and possible alternatives to the procedure and have given your permission for it to go ahead.
There are a number of different steps involved in preparing for gamma knife treatment. These are explained here.
Frame fitting
You will be taken down to the gamma knife unit. You will need to have a light-weight frame fitted to your head. This is called a stereotactic frame and it's used to pinpoint the area to be treated by the gamma knife. A local anaesthetic will be injected at four sites on your head where the frame will be fixed with pins. This can be slightly painful but it shouldn't last long. The fitting can take between 15 and 20 minutes. The frame will stay attached to your head for the whole treatment.
Imaging
To find the exact position of the area that needs to be treated, you will have a magnetic resonance imaging (MRI) scan. An MRI scan uses magnets and radiowaves to produce images of the inside of the body. You may also have a cerebral angiogram (an X-ray image of the blood vessels in your head and neck) if the treatment is for a blood vessel malformation. Occasionally, your doctor will recommend a computerised tomography (CT) scan. The images will be transferred to a computer that will work out what dose of radiation you need.
Dose planning
Once the imaging stage is finished, you will either be taken back to your room (wearing the head frame) or stay in the gamma knife department. The images taken at CT, MRI or angiography will be fed into a computer that calculates the exact treatment time. A team of people including a neuroradiologist (a doctor who specialises in using imaging methods to diagnose medical conditions of the nervous system) will map out the target area to be treated and prescribe the exact dose. The planning of your treatment may take some time (possibly several hours).
About the procedure
You will lie on the treatment couch and the radiographers will position your head either into a docking device on the couch or a helmet, depending on the type of gamma knife unit. This is important because it will keep you 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 are able to see you at all times from the operators' room by cameras positioned in the treatment room.
When the treatment begins the door of the gamma knife unit will open and the couch will move you into the gamma knife unit to waist level. The beam will be given from hundreds of different angles that cross at the targeted area. The radiation treatment will be made up of a series of exposures (shots) and you will be either manually or automatically positioned, depending on the gamma knife unit, to the next shot position. The exposure of each shot may only be a few minutes but the entire procedure can last several hours. You won't feel any pain during the treatment.
Once the treatment has finished the head frame will be removed. You may notice slight bleeding around the area where the frame was placed and 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 nausea, the nurse can give you medication.
You may need to arrange for someone to drive you home depending on how you are feeling. You should 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 gamma knife treatment. Depending on your diagnosis, you may also have an MRI scan in the follow-up appointment.
Recovering from gamma knife
If your head is painful where the head frame was attached, you should talk to your doctor. He or she may recommend you take painkillers. Always read the patient information leaflet that comes with your medicine and if you have any questions, ask your pharmacist for advice.
If you notice pain, swelling or redness, or have any concerns following your treatment, you should contact your doctor.
The successful outcome of your treatment will depend on your condition. Some medical conditions require monitoring over many years.
What are the risks?
Gamma knife treatment is commonly performed and generally safe. However, in order to make an informed decision and give your consent, you need to be aware of the possible side-effects and the risk of complications of this procedure. The risks are specific to you and your condition and your doctor will discuss these with you.
Side-effects
These are the unwanted but mostly temporary effects of a successful treatment.
Gamma knife treatment usually has few side-effects because it only targets the affected area.
When the frame is taken off, you may have slight bleeding from the points where it was held in place. Rarely, you may feel sick or have a headache but this shouldn't last for more than four hours.
Complications
This is when problems occur during or after the procedure. Most people are not affected. Any complications which may arise are specific to you and your condition. Your doctor will have discussed these with you prior to the gamma knife treatment.
If the target area is large, or requires a high dose of radiation, you may experience temporary swelling of the surrounding areas. This can cause a small number of people to have abnormal feelings, sensations or fits. This is very rare and can be treated with steroids or surgery.
The exact risks are specific to you and differ for every person, so we have not included statistics here. Ask your doctor to explain how these risks apply to you.
Related topics
Further information
- Cancer Research UK
020 7121 6699
www.cancerresearchuk.org
Sources
- Gamma knife surgery. International RadioSurgery Association. www.irsa.org, accessed 15 April 2009
- Stereotactic radiotherapy for brain tumours. Cancer Research UK. www.cancerhelp.org.uk, accessed 26 March 2009
- Radiosurgery for brain tumours. Cancer Research UK. www.cancerhelp.org.uk, accessed 3 April 2009
- Frequently asked questions. International RadioSurgery Association. www.irsa.org, accessed 21 April 2009
This information was published by Bupa's health information team and is based on reputable sources of medical evidence. It has been peer reviewed by Bupa doctors. The content is intended for general information only and does not replace the need for personal advice from a qualified health professional.
Publication date: June 2009
Rate this page
