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Information leaflet on Stereotactic Radiotherapy (SRT) to your Brain

This leaflet tells you about a type of radiotherapy treatment called stereotactic radiotherapy. The leaflet will explain how your treatment is planned and given. It will discuss side effects you may have and will tell you how to get more information and support. Contact telephone numbers are given at the end of the leaflet.

We hope this leaflet answers your questions.  Please ask us if you have other questions that we have not covered.

A glossary is provided at the front of this booklet to help you understand any words that you may find unfamiliar.  

Please bring a list of all the medication you are taking with the doses when you come for your radiotherapy treatment.

Smoking is not allowed within the grounds and inside Velindre Hospital. If you need help giving up please ask us.

This information is evidence based and reviewed annually

Glossary of terms

CT Scanner - a machine that uses X-Rays to take detailed scans of your body 

MRI Scanner - a machine that uses magnetism to take detailed pictures of your body

Treatment field -    Each area that the treatment machine points to on your mask is called a treatment field.

LA - This is the radiotherapy treatment machine where you will have your treatment (also called a linear accelerator or Linac).

Oncologist – a doctor who specialises in giving radiotherapy treatment.

Review Radiographer – a radiographer who has undergone extra training to help you cope with radiotherapy side effects and can prescribe medication for you.

What is stereotactic radiotherapy (SRT)?

It is a precise type of radiotherapy treatment which is given to a small area of the brain to destroy abnormal cells.  The course of treatment is given in equal doses known as fractions. We give it this way because it reduces the effect of the radiation on your normal brain tissue. It also helps to reduce the risk of late side effects. In some cases the full course of treatment will be given in a single fraction and this is sometimes called stereotactic radiosurgery or SRS.  Your Oncologist will talk to you about how many treatments you will need.

To make sure that you are in exactly the same position for each treatment, you will need to wear a special treatment mask (shell). Most patients find the treatment shell quite comfortable to wear during their treatment sessions. 

It is very important that you are not pregnant or become pregnant during your course of radiotherapy. 

Up to three planning visits may be needed before you start treatment.

The first planning visit - MRI scan

You may need to have an MRI scan. This will be done before you have your mask made. It will help us plan your treatment.  

The second planning visit - making your mask

The mask used for your treatment is made in the mould room. The mould room is part of the planning department for radiotherapy treatment. It is situated near out-patients, at the front of Velindre hospital.

It would be helpful if you could have your hair trimmed before coming to the mould room. This will help us get a good fit with the treatment mask.

What is a treatment mask?

The treatment mask is a plastic mask that you will wear each day when you have your radiotherapy treatment. It will cover your whole head down to your chin. 

Radiotherapy mask for head and neck treatment
Patient in a treatment mask

How is the mask made?

We will use warm plastic (not hot) to take an impression of the back of your head and then the front of your head, from your forehead to your chin. The plastic sheet is full of small holes, so you will be able to breathe normally through your nose and mouth. 

The plastic is warm as it goes on and it will be allowed to cool. This is not uncomfortable and most people find it quite soothing.

How long will it take?

It takes about 45 minutes to make the impression, but please allow an hour for your whole appointment.

The third planning visit – CT scan

At this appointment you try on your plastic mask. Then you will need a CT planning scan wearing your mask. 

On one of your visits to the mould room or planning, we will ask you to sign a treatment consent form. Your doctor will explain this to you. Please ask any questions or discuss any worries that you may have.

When will I start treatment?

Treatment normally starts about two weeks after these planning visits have been made.  If you have any questions before coming to see us, please phone the mould room on 029 2031 6213 and you will be able to speak to a member of the mould room staff.


Your treatment will be given on a machine called a linear accelerator or LA.

Each treatment will take between 30 and 45 minutes to give. If you are only having one treatment it may take a little longer.

At each treatment visit your radiographers will fit your treatment mask and they will make sure you are as comfortable as possible. They will move the machine so it is in exactly the right place for your treatment using the room lasers and lights.

Head and Neck patient on treatment couch
Patient on treatment couch

Your radiographers leave the room to switch the machine on. The treatment is given from several directions, known as ‘fields’ or ‘beams’. Your radiographers watch you carefully on television monitors. If you have any problems during the treatment, the machine can be switched off at any time.

You will not feel anything when you are having your treatment, though you may hear the machine buzzing or beeping.

Truebeam treatment machine
Treatment machine

Side effects

We do not expect you to have many side effects because the treatment beams and dose are so small. However, you may feel tired and possibly lose some hair in the treated area.
Occasionally some people feel sick or have a headache. You will be seen by one of the Review Radiographers at regular intervals, depending how many treatments you will be having. They will be able to advise you about coping with any side effects.

You may need a course of steroid tablets during your radiotherapy. Your Review Radiographer will advise you about this when you attend for the first treatment.

Follow up

We will give you an appointment to see your doctor at your last radiotherapy appointment. This will be a few weeks after you finish your radiotherapy. The Review Radiographer will also give you a follow up telephone call 1 week and 6 weeks after your radiotherapy is completed. We will continue to phone you approximately every 3-6 months for the following two years but we will inform you of these dates closer to the time.

Please contact the Review Radiographers if you have any concerns after your treatment is finished. 

Contact phone numbers

Velindre Hospital 02920 615888    

Mould Room Radiographers 029 2031 6213

Information, support & review Radiographers 029 2061 5888 ext 6421

Transport from Bridgend
 01656 743344

Transport from Merthyr
Cancer Aid Merthyr
 01685 379633

Transport from Rhondda Cynon Taff
Rowan Tree
01443 479369

Helplines and website

Tenovus cancer support line 0808 808 1010
A charity supporting people with cancer and their families

Macmillan cancer support 0808 808 0000        
A charity providing information about all aspects of cancer

Stop Smoking Wales 0808 250 6061

FS  37622

F.PI 14                                    Issue 8                      July 2019

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