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Planning radiotherapy

You have a planning session with your radiotherapy team a few days or weeks before you start treatment. Read about what happens.

What happens at your planning session

The radiotherapy team plan your external beam 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.

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 or x-rays to help your treatment team plan your radiotherapy. The plan they create is just for you.

Photo of a CT scanner

The radiographers make a treatment shell (mask) first. There is more detailed information about this below. They then put some markers on the mask when it is finished being made. You need to lie very still.

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

The scan takes about 5 minutes. You won't feel anything. The radiographers watch from the next room.

Before the planning appointment you might also have other scans, such as an MRI scan. Your treatment team puts all the scans together in a special computer to decide your radiotherapy plan.

Radiotherapy mould (shell)

Your treatment team might make a mould (shell) for you.

You wear it during the treatment sessions to keep you very still. The radiographers may also make marks on it. They use the marks to line up the radiotherapy machine for each treatment.

The process of making the shell can vary slightly between hospitals. It usually takes around 30 minutes.

Before making the shell

You need to wear clothes that you can easily take off from your neck and chest. You also need to take off any jewellery from that area.

Facial hair, long hair or dreadlocks can make it difficult to mould the shell. The radiotherapy staff will tell you if you need to shave or to tie your hair back.

Making the shell

A technician 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, neck and chest so that it moulds exactly. 

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

Radiotherapy mask

After your planning session

It can take a few days or up to 3 weeks before you start treatment.

Your radiographers and doctors create 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. 

Last reviewed: 
06 Mar 2018
  • External Beam Therapy
    P Hoskin
    Oxford University Press, 2012

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