Planning radiotherapy

The radiotherapy team plans your radiotherapy before you start treatment. This means working out the dose of radiotherapy you need and exactly where you need it. Your planning appointment takes from 15 minutes to 2 hours.

For a brain tumour, you usually have a planning CT scan and a mask to keep your head still. 

The planning CT scan

You usually have a planning CT scan in the radiotherapy department. The scan shows the cancer and the area around it. You might have other types of scans to help your treatment team plan your radiotherapy. The plan they create is just for you.

Photo of a CT scanner

Your radiographers (sometimes called radiotherapists) tell you what is going to happen. They help you into position on the scan couch. You might have a type of firm cushion called a vacbag to help you keep still.

The CT scanner couch is the same type of bed that you lie on for your treatment sessions. You need to lie very still. Tell your radiographers if you aren't comfortable.

Injection of dye

You might need an injection of contrast into a vein in your hand. This is a dye that helps body tissues show up more clearly on the scan.

Before you have the contrast, your radiographer asks you about any medical conditions or allergies. Some people are allergic to the contrast.

Having the scan

Once you are in position your radiographers move the couch up and through the scanner. They then leave the room and the scan starts.

The scan takes about 5 minutes. You won't feel anything. Your radiographers can see and hear you from the CT control area where they operate the scanner. 

Keeping your head still

You need to keep your head still during radiotherapy. This is called immobilisation. You might have one of the following:

  • mask or mould
  • head frame 

Radiotherapy mask (mould)

A radiotherapy mask is also called a shell. It keeps your head still each time you have your radiotherapy. So your treatment is as accurate as possible.

You can see through most types of masks, as they usually have lots of small holes. The radiographers might make marks on them. They use the marks to accurately line up the radiotherapy machine for each treatment. 

You might have the mask made in the mould room of the radiotherapy department or during your CT planning session. It takes between 10 to 45 minutes depending on the type of mask. 

Before making the mask

The mask is normally made directly against your skin. It's helpful to wear clothing that you can easily take off from around your neck. You also need to take off any jewellery from that area.

Having a lot of facial hair can make it difficult to make a head mask. The radiotherapy staff will tell you about any hair issues at your planning session.

Making the mask

A mould technician or radiographer uses a special kind of plastic that they heat in warm water. This makes it soft and pliable. They put the plastic on to your face so that it moulds exactly. It feels a little like a warm flannel and is a mesh with holes in so you can breathe.

After a few minutes the mesh gets hard. The technician takes the mask off and it is ready to use.

The mask is kept in the radiotherapy department and you wear it for each treatment. Or you might have a mask made for a single treatment. 

The video below shows what happens when you have your mesh mask made. The video is about 1 and a half minutes long.

Head frame

You might have a head frame fitted if you are going to have treatment from a GammaKnife machine. You usually have the frame fitted on the same day of your radiotherapy treatment. 

The head frame is attached to your skull using 4 pins. Before it is attached, you have 4 injections of local anaesthetic at the points where the frame attaches to your head. This takes about 10 minutes. The head frame is then fixed into the radiotherapy machine while you are lying on the treatment couch. 

As the frame is fitted, you feel some pressure and tightness, but it usually feels better within a few minutes. You then have your radiotherapy treatment on the same day. 

Having radiosurgery treatment
Photograph showing woman having radiosurgery treatment

You usually have a head frame fitted for a single treatment or a small number of treatments. If you are going to have a number of treatments, you have the frame fitted and removed each time.

After your planning session

You might have to wait a few days or up to 3 weeks before you start treatment.

During this time the physicists and your radiographer doctor (clinical oncologist) decide the final details of your radiotherapy plan. They make sure that the area of the cancer will receive a high dose and nearby areas receive a low dose. This reduces the side effects you might get during and after treatment. 

Before you start your radiotherapy

You usually have your radiotherapy as an outpatient. This means that you go to hospital every day, but you don't stay overnight. These visits can disrupt your day. So it’s worth sorting out a few things before you start treatment. These might include:

  • work
  • care for children or other loved ones
  • care for your pets
Last reviewed: 
06 Aug 2019
  • Cancer Principles and Practice of Oncology (10th edition)
    VT Devita, TS Lawrence and SA Rosenberg
    Wolters Kluwer Health, 2015

  • External Beam Therapy (2nd edition) 
    Peter Hoskin
    Oxford University Press, 2012

  • Stereotactic Radiosurgery and Stereotactic Body Radiation Therapy (SBRT)
    D Heron, M Huq and J Herman
    Springer Publishing, 2019

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