Radiotherapy uses controlled doses of high-energy X-rays to destroy the cancer cells while doing as little harm as possible to the normal cells.

When is radiotherapy used as a treatment?

Not everyone with cancer will need radiotherapy. Whether or not it is part of your child's treatment plan will depend on the type of cancer they have and where it is in their body.

Radiotherapy is sometimes given in combination with other treatments, such as chemotherapy. It is also sometimes given before or alongside surgery to remove a tumour.

How is radiotherapy given?

There are two types of radiotherapy: external radiotherapy and internal radiotherapy. A member of your medical team will help explain the procedure and help your child prepare for it; for younger children, this may be a play specialist.

External radiotherapy

External radiotherapy is done from outside the body. Having external radiotherapy is a bit like having an X-ray. It’s not painful and will only last a few minutes. The longest part is setting up the machine for the treatment.

It is important for your child to stay very still during the treatment, so specialists may give younger children a sedative or general anaesthetic to help them relax or sleep.

Your child may also need a plastic mould called an ‘immobilisation device’ to help prevent movement in the part of the body that is being treated.

Radiotherapy is usually given Monday to Friday with breaks at the weekends and bank holidays. Each day’s dose is called a fraction. Giving the treatment in fractions means that less damage is done to the normal cells. A course of radiotherapy may last anything between one day and seven weeks.

Internal radiotherapy

Internal radiotherapy works from inside the body. It’s based on the idea that cancer cells take up some radioactive substances faster than normal cells do, so it can target cancer cells while having less effect on normal cells.

To have this treatment, your child might be given a radioactive drink or tablet, or it might be given as an injection in the vein or inserted into the body as radioactive wires or pellets.

If your child has had internal radiotherapy, they will need to stay in the hospital until the radioactivity has left their body. During this time your child may need to be kept isolated from other people. How long they are in hospital will depend on their treatment, and it could be just a few hours or up to a few days.

Where next?

Updated November 2017, next review due 2019.