Radiosurgery is a type of stereotactic radiotherapy, which aims radiotherapy beams very precisely at the tumour. Stereotactic radiotherapy is usually broken up into between 6 and 25 treatments.

What radiosurgery is

Radiosurgery is a type of stereotactic radiotherapy. Stereotactic radiotherapy aims the radiotherapy beams very precisely at the area of the brain tumour. It is usually split up into between 6 and 25 doses (fractions). Radiosurgery is usually a single dose of treatment. As with stereotactic radiotherapy, you have a head frame fixed to your head.

Sometimes radiosurgery is called gamma knife treatment after one of the machines used to give it. But this is only one way of giving radiosurgery. You can also have the treatment using the more common radiotherapy machine, the linear accelerator (also called LINAC).

Tumour types that radiosurgery can treat

Radiosurgery treatment gives a very high dose of radiation to a very small, precise area. It can work very well for some types of brain tumour. You are most likely to have it if you have an acoustic neuroma that is less than 3cm across. It can be used for other tumours, including

  • Small secondary brain tumours
  • Small pituitary adenomas, particularly for people who can't have surgery due to other medical conditions
  • Haemangioblastomas that couldn't be removed, were only partially removed, or came back after surgery

Doctors also use this type of treatment for non cancerous conditions, such as 'arteriovenous malformation' (AVM).

Specialists don't recommend radiosurgery for larger brain tumours. It isn't possible to get the same dose of radiotherapy throughout the treatment area with a large tumour.

Radiosurgery may also not be suitable if there are certain nerves running through the treatment area. The nerves could be given too much radiation. Then they would be damaged. This could cause problems such as hearing loss, depending on the role of the affected nerves.

Before your treatment

If you have the type of pituitary tumour that makes and releases hormones, you may be taking medicine to suppress these hormones. Your doctor may ask you to stop the medicine a couple of months before your radiosurgery. You will be able to restart your medicines a week after your radiosurgery.

Having radiosurgery treatment

To have radiosurgery, you have a head frame fitted. The head frame is fixed to your head under local anaesthetic. It stays in place while you have the treatment and is taken off afterwards. The treatment takes the best part of a day. You will be awake the whole time. Some hospitals let you eat and drink through the day; others don’t. If your hospital staff don't allow you to drink, you may have a drip (intravenous infusion) put up to give you fluids.

It takes about 10 minutes to fix the frame in place. This will be a bit uncomfortable because you will need about 4 local anaesthetic injections at the points where the frame is attached to your head. When the frame is fitted, you will feel some pressure and tightness and it may be sore.

Once the frame is in place, the doctors and radiographers check it to make sure everything has been done properly. Then you will have a CT scan or MRI scan with the frame in place. After that, there will be a wait while your treatment is planned. This can take a couple of hours. During the wait, you can have something to eat and drink unless there are medical reasons why you shouldn't.

When the planning is complete, you go to the treatment room. Your head frame is fixed into the machine while you are lying on the treatment couch. Once everything is in place, the couch slides into the machine and the treatment begins. The treatment takes an hour or two, depending on the amount of treatment and position of your tumour. When the treatment is over, the radiographers will help you out of the machine. They will take the frame off. Then you go back to the ward - usually for an overnight stay.

Side effects

There are not usually many immediate side effects from radiosurgery. Your doctor may give you a dose of steroids straight afterwards to help prevent side effects due to swelling of the brain.

When the staff take your frame off, you may have slight bleeding from the points where the frame was attached to your skull. You may feel sick or faint at first, or have a headache. You may also feel a bit weak and dizzy.

You may have tingling or itching where the frame was attached. This is a normal sign of healing. You may lose a patch of hair if your tumour was near the surface of your skull. But hair loss is not normally a side effect of radiosurgery. It is usual to feel very tired for some days after the treatment.

There are not usually any other symptoms. But tell your doctor or nurse if you have any new symptoms or your old symptoms seem to be getting worse.

Long term side effects

A small number of people have long term side effects from radiosurgery. This is because you have a very high dose of radiation delivered to a very small area. Over a period of time the treated area may develop a small area of dead cells. This is called radiation necrosis. Most people who develop this have no symptoms. The affected area is too small to make any difference to them. These days, these side effects are less likely because of the treatment doses used.

In people who develop radiation necrosis after radiosurgery, fewer than 1 in 10 have swelling that is large enough to cause symptoms. If you do develop this, your specialist will give you steroids to take. Some people need high doses of steroids for long periods of time. An even smaller proportion of people need surgery to remove the dead tissue. In people who develop radiation necrosis, fewer than 1 in 20 need surgery to have the area of dead tissue removed. 

References:

https://en.wikipedia.org/wiki/Radiosurgery

http://www.cancerresearchuk.org/about-cancer/type/brain-tumour/treatment/radiotherapy/radiosurgery-for-brain-tumours

http://www.irsa.org/radiosurgery.html

https://www.nlm.nih.gov/medlineplus/ency/article/007274.htm