Masks for radiotherapy

When you have radiotherapy, it’s important to be still so that the treatment is given to exactly the right area. Wearing a radiotherapy mask during sessions of radiotherapy to the brain, head or neck helps keep your head still.

The mask is made to fit you snugly, but shouldn’t be uncomfortable. It doesn’t affect your breathing. If you need any dental work, it needs to be done before your mask is made. Some people are given a dental guard to wear while the mask is being made and during radiotherapy. If you have a beard, you need to trim it or shave before the mask is made.

The mask is made in the radiotherapy department. This usually takes about 30 minutes. You only wear it during radiotherapy planning and during treatment.

During treatment you will be asked to lie on a treatment table. The mask is then gently placed over your head and neck and fixed to the table. If you are worried about the mask, let your radiotherapy team know so they can help. Treatment takes 10–20 minutes and is not painful.

What is a radiotherapy mask?

You might find it helpful to read this with our other information on radiotherapy. We have information about radiotherapy for head and neck cancers and for brain tumours.

Radiotherapy uses high-energy rays to treat cancer. It has to be aimed precisely to make sure exactly the right area of the body is treated each time. So when you have radiotherapy it’s important to be as still as possible.

If you have radiotherapy to the brain, head or neck area, you wear a radiotherapy mask to help you keep still. This is sometimes also called a mould, head shell or cast.

Once you are wearing the mask, it’s fixed to the radiotherapy treatment table. The mask holds your head and neck in exactly the right position. It will fit snugly but it should not be uncomfortable. You can breathe normally while you are wearing it. You only wear the mask while radiotherapy is being planned and during the treatment itself. You won’t have to wear the mask at any other time.

Before the radiotherapy mask is made

There are some things you need to do before your mask is made to make sure it fits well. After the mask is made, it can only be adjusted slightly.

Dental work

Before the radiotherapy mask is made, you need to see a dentist to have your mouth and teeth checked. If some of your teeth are unhealthy, you may need them removed or repaired. Dental work can change the shape of your mouth and face slightly. So it’s important this is done before the mask is made.

Mouth guards

Some people are given a special mouth guard to wear inside their mouth during radiotherapy. A mouth guard holds your mouth and face in position so the right area is treated. This can also help reduce side effects.

Your radiotherapy team will tell you if you need a mouth guard. If you do, you’ll need to wear it while your mask is made and during treatment.


If you have a beard, you need to trim it, or shave it off, before the mask is made. Sometimes radiotherapy can cause a skin reaction on the face. Shaving can make skin reactions worse. Your radiotherapy team can tell you if this side effect is likely with your treatment.

You don’t usually need to have your hair cut before the mask is made. But after it’s made, don’t make big changes to your hairstyle or facial hair as this can affect how well the mask fits.

How a radiotherapy mask is made

A technologist or radiographer will usually make the mask in the radiotherapy department. The process of making the mask can be different depending on the hospital, but it usually takes about 30 minutes. You may need to take off some of your clothes and wear a hospital gown while it’s being made.

Masks are made using a type of mesh plastic, which is heated and moulded to fit the shape of your head and neck. Or sometimes wet plaster bandages are used to make a mould, which is then used to make a clear plastic (perspex) mask.

Mesh plastic mask

Your mask may be made using a type of plastic mesh that becomes soft when heated in hot water (thermoplastic).

The technologist or radiologist heats the plastic mesh and puts it onto your face so it gently moulds to fit your head and neck exactly. This feels a bit like a hot flannel, but it won’t burn you and it cools down very quickly. The plastic mesh has lots of holes in it so you can breathe easily.

You lie still for up to 15 minutes while the plastic mesh cools down and hardens. The mask is then taken off and is ready to be used.

Mesh plastic mask
Mesh plastic mask

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Perspex mask

A perspex mask is made in two stages. First the technologist or radiologist makes a plaster mould of your head and neck. Then they use the mould to make the clear plastic (perspex) mask for your treatment.

You will be given a swimming cap or other covering to protect your hair from the plaster mould mixture.

Strips of plaster of Paris being applied to the face to make a mould
Strips of plaster of Paris being applied to the face to make a mould

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The technologist or radiologist spreads a cool cream or gel on your face. They then put wet strips of plaster of Paris bandage on top. They will leave holes around your nose and mouth, so you can breathe easily.

Plaster of Paris gets warm as it sets. This is normal and won’t burn you, but it may feel uncomfortable. It takes about five minutes to set and then the mould is taken off. They then make a perspex mask from the mould.

Radiotherapy masks and treatment

Once the mask is ready, your treatment can be planned. This could be straight after the mask is made or you may need to come back for another appointment.

Treatment planning makes sure the radiotherapy is aimed precisely at the cancer. You may need to take off some clothes and wear a hospital gown. 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. The mask is gently placed over your face and fixed to the table so your head and neck don’t move. The mask should be tight but not uncomfortable. If it’s uncomfortable, tell the staff so that they can try to adjust it.

When you’re in position, you usually have a CT (computerised tomography) scan taken of the area to be treated. This helps your team plan the precise area for your radiotherapy. Sometimes you will be alone in the room. But the radiographers can see you at all times on a screen. They can also hear and talk to you through microphones and speakers in the treatment room.

Some people are very nervous about wearing the mask or feel claustrophobic. You may want to bring some calming music or a relaxation podcast to listen to during your appointments. 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.

During treatment planning, the doctor or radiographer may make a few ink marks on the mask. You may also have a permanent mark (tattoo) made on your chest. This involves making a small scratch in the skin with a needle and some ink. These marks make it easier to get you into the same position each time you come in for treatment. 

Treatment planning usually takes 30–60 minutes. You won’t need to wear the mask for the whole time.

When you have the radiotherapy treatment, you lie in exactly the same position on a table below a radiotherapy machine. The mask is then gently placed over your head and neck, and fixed to the table. Treatment can take 10–20 minutes and is not painful. Again, the staff can see, hear and talk to you and will be close by if you need them at any time.

Back to Radiotherapy explained

Planning your treatment

Your specialist will plan your radiotherapy carefully to make sure it’s as effective as possible.

Possible side effects

If you are having radiotherapy for cancer of the larynx, you may have some side effects during treatment and afterwards.

Before your radiotherapy

Before you start radiotherapy, your team will explain what your treatment involves and how it may affect you.

Your radiotherapy team

You will meet many different specialists from your radiotherapy team. You may see them before, during and after radiotherapy treatment.

After treatment

It can take time to recover from radiotherapy. Support is there if you have any problems.