Stereotactic radiotherapy for brain tumours
'Stereotactic radiotherapy' means the use of computers and scanners to produce 3D images that very accurately locate a tumour within the brain and direct radiotherapy treatment towards it.
Many small beams of radiation are directed from different angles around the head towards the tumour. Where these beams meet and overlap at the site of the tumour, the doses of radiation add together and create a highly focussed, high dose of radiation to destroy the tumour cells.
To achieve this, it is extremely important to position the head in exactly the same place each time and keep it very still.
Though some types of conventional radiotherapy deliver radiotherapy beams from various angles around the head and work in a similar way to SRT, the difference with SRT is that it uses computers to pinpoint the tumour even more accurately. It is also stricter in keeping your head still during treatment.
As a result, a smaller area outside the tumour needs to be given radiotherapy to make sure the correct dose is given to the whole of the tumour. This means fewer healthy cells receive a high dose of radiation and people generally experience fewer side-effects.
The greater accuracy also means a higher dose can be safely given to the tumour, or fewer treatment sessions may be needed.
Often only one high dose of treatment is needed. This is called stereotactic radiosurgery (SRS). (Treatment given over several sessions is called fractionated stereotactic radiotherapy or FRST).
Can I have SRT/SRS?
Stereotactic radiotherapy and stereotactic radiosurgery are not suitable for all types of brain tumour. They are generally only used for small tumours (less than 3cm at the widest part). They are not used for larger tumours as the benefit is lost because it is not possible to get the same high dose of radiation across the whole of a large tumour.
Brain tumours that SRT/SRS are suitable for include:
- small low grade tumours with an obvious edge
- small gliomas that have come back (low and high grade)
- haemangioblastomas that couldn't be completely removed or which came back after surgery
- other small low grade tumours, such as:
- vestibular schwannomas (acoustic neuromas)
- meningiomas at the base of the skull
- pituitary adenomas
- secondary brain tumours (metastases)
SRT (and SRS) may NOT be suitable if the treatment area includes particular important nerves, as they may receive too much radiation and become damaged.
Similarly, not all brain tumours benefit from SRT or SRS - conventional radiotherapy is more appropriate in some cases.
The decision to treat with SRT/SRS is made on a case by case basis. Your oncologist will discuss your treatment options with you and the wider members of the multi-disciplinary team (MDT) to come up with the treatment plan that is best for you.
Additionally, SRT (and SRS) are not available in all hospitals as they require specialised equipment and staff. This issue is currently under review by the government and the NHS.
What does having SRT/SRS involve?
Much of the SRT/SRS procedure is similar to conventional radiotherapy and it uses the same type of radiation i.e. X-rays.
The positioning of your head in the same place is extremely important, particularly if you are having treatment over several sessions (fractionated SRT), to make sure that the beams are accurately hitting the same target each time.
There are two main ways of achieving this targeting:
This is similar to the mask used in conventional radiotherapy, but it is closer fitting to ensure your head remains still.
Making the stereotactic mask can take up to 45 minutes.
You only have to wear it when you go for treatment or have a planning scan.
This is more often used for SRS.
A frame is made to fit your head and attached, through your skin, to the surface of your skull, using four small pins. You will be given local anaesthetic at these points.
You may feel some tightness or pressure, and these areas may be sore afterwards. Wearing the frame can be quite tiring.
Scans will be taken with, and without, the mask or frame on, to allow your specialists to create a 3D image of your tumour, plan your treatment and set up the machine to target your tumour precisely.
This planning stage can take several hours.
Once planning is completed, you will receive your treatment.
As with conventional radiotherapy, you will wear your mask (or head frame) and be positioned on a treatment table. The medical staff will leave the room, but will be able to see and hear you, and you can hear them. You may be able to listen to music during treatment to help you relax.
The treatment is usually given by a machine similar to a large X-ray machine, which has an attachment that moves round your head delivering small beams of radiation from different angles. This does not hurt.
The length of the treatment session varies depending on the:
- size of your tumour
- dose of radiotherapy needed
- machine used
- LINAC machine (20 – 40 minutes)
- CyberKnife® (30 – 90 minutes)
- GammaKnife® - used for SRS (up to 4 hours).
None of the machines involve an actual knife and there is currently no identified advantage of one machine over another.
You will be at the hospital longer than these times, to allow for fitting the mask and positioning you correctly.
After treatment, your mask or head frame will be removed and you can usually go home – straightaway for FSRT, or after some monitoring, which may be overnight, for SRS. It is advisable to arrange transport, as you may feel very tired.
Typically, a course of FSRT is 5 -25 daily treatment sessions, but it will be tailored to your individual needs.
Before treatment begins (or shortly afterwards) your doctor may also give you steroids to reduce brain swelling. With SRS, you may also have anti-seizure drugs to help prevent a seizure (fit).
FSRT and SRS generally have fewer side-effects than conventional radiotherapy, but you may experience some. Most are short-lived.
If you work, it is likely that you will have to take some time off work during treatment and for a short time afterwards. Side-effects, such as tiredness and nausea, may mean you need a longer period of time off work.
Our employment resources provide help and information on how to approach your employer about your diagnosis and how they can support you through this time.
Stereotactic radiotherapy factsheet - PDF
Find out more about Stereotactic radiotherapy in the full fact sheet.
Stereotactic radiotherapy - Clear print factsheet - PDF
Find out more about Stereotactic radiotherapy in the full fact sheet - Clear Print version, designed to RNIB guidelines.
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