Radiotherapy is the use of high-energy x-rays (and other rays) to treat cancer. Radiotherapy has to be aimed very precisely to make sure that exactly the right area of the body is treated each time.
It's important to lie still while the treatment is in progress. This is because any movement could change the area that gets treated.
When you have radiotherapy to treat tumours in the head and neck area or brain tumours, it is even more important to be as still as possible. To help with this, you wear a radiotherapy mask during your treatment. This is sometimes called a mould, a head shell or a cast.
Once the mask is fitted, it is fixed to the radiotherapy treatment table. This holds your head and neck in exactly the right position for the treatment.
Wearing a mask reduces the possibility of any movement while you’re having radiotherapy. You only wear the mask during the planning procedures and during the treatment itself. Treatment usually takes about 10–20 minutes at a time each day. You’ll wear the same mask for planning and for treatment. You won’t have to wear the mask at any other time.