Stereotactic radiotherapy (SRT) for brain tumours

Stereotactic radiotherapy (SRT) is a type of radiotherapy used to treat some brain tumours. It is sometimes called Gamma Knife or CyberKnife.

SRT uses many small beams of radiation that cross at the tumour. The tumour receives a high dose of radiation. Nearby areas are only affected by low doses.

Your treatment is planned using a brain CT scan (computerised tomography scan) or an MRI scan (magnetic resonance imaging scan). You may need a mask or head frame made. This helps to keep you in position during treatment. SRT is painless. Your radiotherapy team will not be in the room with you during treatment. But they can see, hear and talk to you if you need them at any time. They will tell you what to expect and how many sessions of treatment you will have.

You can usually go home after SRT. You will not be radioactive and it is safe for you to be with other people.

Side effects will depend on your exact treatment. Your doctor will tell you what is likely in your situation. They may give you steroids to prevent side effects. Tell them if you have any side effects so they can help.

What is stereotactic radiotherapy (SRT)?

Stereotactic radiotherapy (SRT) is a specialised type of radiotherapy. It can be used to treat several different types of tumour. This information is about SRT used to treat brain tumours.

Radiotherapy uses high-energy rays to treat cancer. It destroys tumour cells in the area being treated. Normal cells can also be damaged by radiotherapy. They can usually repair themselves, but the tumour cells can’t.

Standard radiotherapy is given using a machine called a linear accelerator (linac). This is similar to a large x-ray machine. It gives beams of radiation to the area that needs treatment. You usually have this type of radiotherapy as a series of short daily sessions over a few weeks.

SRT can be given using some linac machines, or by other radiotherapy systems such as Gamma Knife or CyberKnife. Many small, thin beams of radiation are directed from different angles and cross at the tumour. The tumour itself receives a high dose of radiation. But nearby areas are only affected by the individual low-dose beams. This lowers the risk of damage to normal cells and can sometimes reduce side effects.

SRT can be given as two to eight sessions or as a single treatment (this is called stereotactic radiosurgery). SRT is sometimes given over five to six weeks, like standard radiotherapy.


Other names for SRT

SRT for brain tumours is known by a number of different names and this can be confusing. These names include:

  • stereotactic radiosurgery (SRS)
  • brain or cranial stereotactic radiotherapy
  • stereotactic radiation therapy.

Sometimes SRT is called by the brand name of the system used:

  • Gamma Knife
  • CyberKnife.


When is SRT used for brain tumours?

SRT is used in certain situations to treat primary brain tumours and secondary brain tumours. This can depend on:

  • the type of tumour
  • the size and number of tumours in the brain
  • where the tumour is in the brain.

SRT is usually given to treat tumours that are hard to reach safely with surgery or other treatments. Your cancer doctor (clinical oncologist) can tell you if SRT is a possible treatment for your situation.


Planning SRT treatment for brain tumours

SRT is not available at every hospital. You may have to travel to another hospital to have this treatment.

Before you are given your treatment, it needs to be planned. This is an important part of SRT. Planning makes sure the radiotherapy is aimed precisely at the tumour and causes the least possible damage to nearby areas of the brain.

Your treatment may be planned on the same day as it is given or at an earlier appointment. This depends on the type of radiotherapy machine or system being used. Your radiotherapy team will tell you what to expect in your situation.

Masks and head frames

You may need a mask or head frame to help you stay still and in the right position during SRT for a brain tumour. Some people will have both.

A mask is made for you from plastic mesh or clear perspex. This may be done on the same day that your treatment is planned or at an earlier appointment.

During your treatment, you will lie on the radiotherapy treatment table. The mask is gently placed over your head and neck and fixed to the table. It will fit snugly but it should not be uncomfortable. You can breathe normally while you are wearing it. We have more information about how radiotherapy masks are made and used.

Sometimes a lightweight, metal head frame is needed. This is fitted and fixed around your head on the same day that you have treatment. A neurosurgeon will attach the frame to four points on your skull using local anaesthetic. This sounds scary and it may be a bit uncomfortable, but it should not be painful. During your treatment the head frame will be fixed to the radiotherapy treatment table. The radiotherapy system uses the frame to measure and position the machine accurately.

Wearing a mask or head frame can feel claustrophobic and some people feel nervous about wearing them. You may want to bring something to listen to during your treatment, such as calming music or a relaxation podcast. Your doctor may give you medication to take before the treatment to help you relax. Most people cope well with the support of the radiotherapy team. If you are worried or uncomfortable, let them know so they can help you.

Scans and planning

Once the mask or head frame is ready, you will have a brain CT or MRI scan. Your radiotherapy team use information from the scans to plan how the machine will give your treatment.

For the scans, the radiotherapy team will help you get into the right position. You will be lying on a table that is similar to the one used for treatment. If needed, the mask or head frame will be gently fixed to the table so your head and neck do not move during the scan. If you are uncomfortable, tell the staff so that they can try to adjust it.

Sometimes during the scans you may be alone in the room. But the radiographers can see you at all times. They can also hear and talk to you through microphones and speakers in the room.


Having SRT treatment for brain tumours

It is important to tell your radiotherapy team about any medications and allergies you have. If you take painkillers, they may suggest you take them before your treatment so that you are comfortable.

SRT can cause some swelling of the area being treated. This can cause side effects (see possible side effects listed below) or make any symptoms of the brain tumour worse. Your cancer doctor may give you steroids to take before treatment to stop this. You will usually keep taking them for a time after treatment. Follow your doctor’s instructions carefully and do not stop taking the steroids without their advice.

When you have the SRT treatment, you lie in the same position as you did for the planning scans. The radiotherapy team will help you and will attach the mask or head frame to the treatment table.

The treatment room may look similar to the one you had your planning scans in. Depending on the type of radiotherapy machine, there may be equipment that moves around you during the treatment. The table you lie on may change position slightly during treatment.

The treatment itself is painless. You may hear a slight buzzing noise from the radiotherapy machine during treatment. In some treatment rooms you can listen to music to help you relax. If you would like to listen to your own music, ask your radiographer if this is possible.

You may only need one session of treatment. Or it may be broken up with short breaks or spread over several days. A session of treatment can take from about 15 minutes to four hours, depending on the type of machine. Your radiotherapy team will tell you what to expect.

The staff will not be in the same room with you when you have the treatment. But they can see, hear and talk to you, and will be close by if you need them at any time. You can usually go home when the treatment is finished. SRT does not make you radioactive. It is safe for you to be with other people, including children, after your treatment.


Possible side effects of SRT for brain tumours

Side effects can depend on which area of the brain has been treated and the amount of radiotherapy given. Your cancer doctor will explain what is likely in your situation. Some side effects are mild and easy to cope with. Others may be managed with drugs or other treatments.

You may develop some of the side effects we mention here. But you are unlikely to have them all. Side effects usually get better gradually after your treatment. Sometimes side effects or symptoms of the brain tumour get worse for a while after treatment has finished. If this happens you may feel low or worry that treatment isn’t working. But this is usually a normal reaction to the radiotherapy. It may also happen because your steroids have been reduced or stopped.

Tell your radiotherapy team about any side effects. They can prescribe drugs to help control them and give you advice about managing them.

  • Feeling sick – some people feel sick for a time after treatment. This is usually mild. Your doctor can give you anti-sickness drugs (anti-emetics) to control this.
  • Dizziness and vertigo – if you feel dizzy or unsteady, let your doctor know.
  • Seizures – this is rare, but sometimes after SRT there is a slight risk of a seizure. It is more common in people who have had seizures before. Let your doctor know if this happens.
  • Headaches – ask your doctor for advice about painkillers. If you are not already taking them, your doctor may prescribe steroids to help.
  • Soreness – if you had a head frame for treatment, you may have some sore spots where it was fixed to the skull.
  • Tiredness – you are likely to feel tired for a few weeks after treatment. Allow yourself plenty of rest. Balance this with some physical activity – even going for short walks will help you to feel less tired.
  • Itchy skin – your skin may get red, dry or itchy in the treated area. Your radiotherapy team can give you advice about skin care.
  • Hair loss – you may lose your hair in the treatment area. If this happens it usually grows back. Sometimes hair loss is permanent. Your cancer doctor can tell you what is likely to happen with your treatment.
  • Second cancer – with any radiotherapy treatment there is a very small risk of developing another cancer in the treated area years later. This is rare and the benefit of having radiotherapy usually far outweighs the risk.

SRT does not make you radioactive, and it’s perfectly safe for you to be with other people, including children, during and after your treatment.


After SRT treatment for brain tumours

After treatment, you will have regular check-ups with your cancer doctor and nurse. Sometimes SRT causes side effects that develop months or even years later. Let them know about any symptoms or side effects so they can help.

Back to Radiotherapy explained

Who might I meet?

You will meet many different specialists before, during and after radiotherapy treatment.