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Radiotherapy treatment for thyroid eye disease

Radiotherapy treatment for thyroid eye disease at Velindre hospital

This booklet will help you understand what will happen when you come to Velindre hospital for radiotherapy treatment for thyroid eye disease.

The booklet 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. Your treatment may vary slightly from what’s in this booklet. Your doctor will explain your treatment to you in detail before treatment starts.

If you have any language, communication or other personal difficulties please let us know.

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

Contact telephone numbers are given at the end of the booklet.

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

Please bring a list of all the medication you are taking every time you come to Velindre.

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.


Consent form - Before we give you any treatment we will ask you to sign a form saying you agree to the treatment and understand what is involved. 

CT scanner - a machine that uses X-rays to take detailed pictures of your brain.

Mould Room - This is where your treatment mask is made. 

Radiographers - The staff that make treatment masks and work the radiotherapy machines. They wear white tops with blue collars.

Treatment couch - A hard bed that you lie on during treatment.

Treatment mask - A plastic mask that fits over your head and keeps you still during your treatment. 

Treatment plan - This describes how the machines will be positioned to give your treatment.

Treatment planning -     This process involves all the preparations for your radiotherapy and includes making a treatment mask in the mould room and a CT scan.

What is thyroid eye disease?

Thyroid eye disease usually happens to people who have an overactive thyroid. However it can develop before the thyroid becomes overactive or after the thyroid has been successfully treated. 

Thyroid eye disease is caused by swelling and inflammation of the fat and muscles behind the eye.

In severe cases, the eye is pushed forward making it difficult for the eye to close properly and sometimes causing double vision. 

In the very worst cases, your eyesight may be affected. This is caused by drying out of the front of the eye (cornea) or pressure on the optic nerve which carries messages from the eye to the brain.

What is radiotherapy?

This type of treatment uses powerful x-ray. The x-ray beams are directed at the eye sockets and will also treat half the eye itself.

Why is radiotherapy used to treat thyroid eye disease?

Radiotherapy can reduce the cells which cause the inflammation and so reduce the swelling behind the eye.

How is radiotherapy given?

Radiotherapy is given by a radiotherapy machine in the radiotherapy department of Velindre hospital. The powerful x-rays needed for treatment are produced by machines called linear accelerators. These are sometimes called Lin. Accs. or LA and are numbered. Velindre hospital is the only hospital in South East Wales with these machines. That is why you will be treated in Cardiff, even if you have a hospital closer to home.

To have your treatment, you will lie on a treatment couch wearing a treatment mask. 

Before you can start your treatment, it must be planned carefully. This will mean you will need to have a treatment mask made. You will need to wear this mask whilst having your treatment. Your mask will be made in the mould room.

Treatment planning

It is very important when having radiotherapy that you are lying still and in the same position each day that you are treated. Because of this, the planning of your treatment starts with a visit to the mould room.

What will happen in the mould room?

Here your radiographers will make a treatment mask that fits the shape of your head and keeps you in the same position for your treatments.

What is a treatment mask?

The treatment mask is a plastic mask that you will wear for a few minutes each day when you have your radiotherapy. It will cover the front of your face and head. The plastic sheet is full of holes so you will always be able to breathe normally through your nose and mouth. 

How are the masks made?

To make a treatment mask we need to position you on a special couch for you to lie as straight as possible. You will have handles to hold on to and small pads that rest comfortably but firmly onto your shoulders. This will keep you in the correct treatment position.

Having the mask made

We will use a piece of warm plastic (not hot) to take an impression of your head, from your chin or upper neck over your face to the top of your head. 

How long will it take?

It takes about 20 minutes to make the impression, but please allow one hour for your whole appointment. This is because you may then have a CT scan wearing your mask.

What will I feel?

The plastic is warm as it goes on. This is not uncomfortable and some people find it quite soothing. You will feel it being stretched over your face and fitted into position. You will feel the mask being moulded over the bridge of your nose, your chin and over your ears. The mask will be left on for 10 minutes to completely cool, then it will be removed. 

Wearing the mask

What do I have to do?

To get a good fit with the treatment mask it will be useful if you:

  • shave or closely trim your beard 
  • do not use hair spray when you come for this appointment.
  • wear loose clothing that can be removed easily.

What happens when I have the CT scan?

Once your treatment mask has been made, you will need a CT planning scan wearing your mask. This can’t always be done on the same day. We may give you another appointment to have your CT scan wearing your mask.

For the CT scan you will lie on the couch in the same position as when your mask was made.

When will I see my doctor?

Your consultant, or one of his/her team, will meet you before you have any radiotherapy. They will explain the treatment, answer any questions you have and ask you to sign a consent form.  If you change your mind after signing the consent form, please let us know and we will not go ahead with the treatment.

How will I know when to come for my treatment appointment?

We will give you a letter with your first treatment appointment when you come to the mould room. This will tell you the date and time of your first appointment and which radiotherapy machine that you will be treated on. This will be a few weeks after your planning appointments. 

If you have a problem with the appointment time (for example, child care arrangements or your work), then please ring the booking clerk and let us know. We will do our best to help you. The booking clerk’s phone number is at the end of this booklet.

How will I get to Velindre hospital?

Most people come with their own transport. Some local support groups can also arrange transport. Contact numbers are at the back of this booklet. 

If you need an ambulance, please tell the radiotherapy staff and they can arrange this for you. The ambulance transport may be a car. We need two days notice to arrange ambulance transport for you. 

Space is limited on the ambulance transport service. If you are not able to manage on your own, please tell us so we can try and arrange for you to bring someone with you on the ambulance transport. 

Why am I asked my name, address and date of birth so often?

We will ask your name, address and date of birth every time you come to the radiotherapy department. This is because our staff are trained to constantly double check your personal details to avoid any confusion.

When will I have my treatment?

Your radiotherapy is given once a day, Monday to Friday (but not bank holidays). Your treatment may start on any day of the week.

You will have ten days of radiotherapy treatments (two weeks).

What should I do on my first day of treatment?

When you come for your first treatment, please come to the radiotherapy entrance which is around the back of Velindre hospital. Give your name and hand your letter to the receptionist in the radiotherapy waiting room. She / he will let the treatment machine radiographers know that you have arrived. She / he will tell you where to sit and wait or direct you straight to your treatment machine. 

Your radiographers will explain the treatment and the possible side effects. We may ask you to sign the consent form again. We will also check all your other appointments have been made for you. If you are female and under 55 years old, we will also ask you if you are pregnant.

Most people feel anxious at this time so please ask any questions you have. We will do our best to put your mind at rest.

What will happen in the treatment room?

In the treatment room, we will ask you to lie on the couch wearing your mask. This is the same position you were in for your CT scan. The radiographers will position you carefully and move the machine so it is in exactly the right place for your treatment. 

The couch is moved closer to the machine and the room lights are dimmed. A light beam shines out of the machine to indicate the X-rays. This helps your radiographer’s line up the treatment beam in exactly the right place for your treatment. Once you are in the correct position, we will ask you to lie still and breathe normally.

Your treatment is given in two x-ray beams, one to either side of your head. Each of these beams is known as a treatment field. The fields are marked on your treatment mask and treatment plan. 

When you are in the right position, the radiographers leave the room to switch the machine on. They watch you carefully on television monitors. You will not feel anything when you are having your treatment, though you may hear the machine buzzing.

After the first field, the treatment machine is moved to the second treatment field position. When your treatment is finished, the couch is lowered, your mask is taken off and you can leave the treatment room.

What if I need to move?

If you need the radiographers to come in to you while the machine is on, you can wave your hand. The radiographers will switch the machine off then come in to you. The treatment can be restarted when you are comfortable again.  

What are the side effects of my radiotherapy?

  • You may feel tired.
  • Your skin may become slightly dry and pink in the area being treated. It often looks like mild sunburn. It usually returns to normal within two weeks.
  • You may lose patches of hair in areas receiving treatment, for example, the tip of the eyebrows or the edge of the scalp. Hair loss is not common and usually grows back after the treatment finishes.

Some side effects do not show whilst you are having your radiotherapy but may develop months or even years later. These are not common.

  • Although we plan your treatment carefully to avoid treating the lenses of the eyes, there is a very small risk of cataracts developing in later years. These are easily treated.
  • There is an extremely small increased risk of cancer developing in the area treated. This is due to the radiation received by the normal tissues. This extremely small risk should be compared with the likely benefits of the treatment.
  • There is a very small risk of changes in the back of the eye (retina). This is more likely if you are diabetic.

What happens after my radiotherapy has finished?

When your treatment has finished, we will give you contact phone numbers so that you can speak to someone if you have any questions before your next appointment.

You will see your ophthalmologist (eye doctor) in clinic to be examined and assess the effects of the treatment. This clinic will not be in Velindre. Your ophthalmologist will see you regularly to monitor your eyes.

Contact phone numbers

Velindre Hospital 029 2061 5888

Review Radiographers 029 2061 5888 ext 6421 

Mould Room 029 2031 6213

Information and Support radiographers 029 2061 5888 ext 6428 
Radiotherapy booking clerks 02920 196836

Transport from Aberdare
Cancer Support Cynon Valley
01443 479369

Transport from Bridgend
 01656 743344

Transport from Merthyr
Cancer Aid Merthyr
 01685 379633

Transport from Upper Rhymney Valley
CLURV, Bargoed
 01443 839326

Transport from Rhondda Cynon Taff
Community Cancer Services
 01443 421999

Support organisations

British Thyroid Association

Thyroid Eye Disease Charitable Trust
PO BOX 1928
BS37 0AX
National Help Line: 0844 800 8133 

F PI 36                    Issue 3                June 2010