Expert reviewer, Caroline Fadipe, Senior Radiographer
Next review due May 2021

Radiotherapy is a treatment for cancer, and some other health conditions. Over half of people who are treated for cancer have radiotherapy, often in combination with other types of treatment such as chemotherapy and surgery.

An image of radiotherapy equipment

About radiotherapy

Radiotherapy usually uses high-energy X-rays to destroy unwanted cells such as cancer cells. The aim of radiotherapy is to target the unwanted cells while avoiding damaging your healthy cells as much as possible.

Your doctor may recommend radiotherapy to help cure your cancer. Or they may offer radiotherapy to help control your symptoms and improve your quality of life. Your radiotherapy will be designed for your particular circumstances and will be tailored to you. As well as support from your doctor, you can get information about treatment for cancer from the organisations listed below under ‘Other helpful websites'.

Types of radiotherapy

There are two main types of radiotherapy.

  • External beam radiotherapy is the most common type of radiotherapy. Radiation is directed into the affected area of your body from outside your body, usually from a machine called a linear accelerator (linac).
  • Internal radiation is directed from inside your body. A small source of radiation is placed near to or inside the affected area in your body. This may be put there temporarily or permanently. Or your doctor may inject you with a radioactive medicine or ask you to drink a radioactive liquid that’s taken up by cancer cells.

What will happen before I have radiotherapy?

You’ll usually start by seeing a radiation oncologist – a specialist cancer doctor who’ll oversee your treatment. They’ll carefully plan your course of treatment. You may need to have an X-ray, CT scan or MRI scan to help find the size and position of your cancer to help with this planning.

Not all hospitals have a radiotherapy department, so you may need to go to a specialist cancer hospital or a large regional hospital.

If you're having external radiotherapy, your radiotherapy team will ask you to come to the radiotherapy department for a CT planning scan to help plan your treatment.

You might need to stop eating and drinking for a while before you have radiotherapy, but this depends on your individual circumstances. Your radiotherapy team will let you know if you need to do this.

Your radiotherapy team may also tattoo a few tiny dots on your skin to show where the radiotherapy will be directed and to make sure you’re in the right position for each session. They’ll discuss this with you before they do it.

If you’re going to have radiotherapy to your head or neck, you might need to wear a special plastic mask. This will hold your head in the right position while you’re having radiotherapy.

A member of your radiotherapy team will explain what’s going to happen and what you need to do.

What happens during radiotherapy?

Having radiotherapy doesn’t hurt, but you might find it uncomfortable staying in position while you’re having it. Your radiotherapy team will make every effort to make you as comfortable as possible.

If you’re having external beam radiotherapy, you’ll usually have this in small amounts (called fractions) over a number of days or weeks. You’ll probably be able to have treatment as an outpatient, rather than stay in hospital.

You’ll have radiotherapy in a special treatment room with a large machine called a linear accelerator (linac). Your radiotherapy team will explain what you’ll see and hear during your treatment, which may take up to 20 minutes each time. Radiotherapy is usually given on weekdays, so you should get weekends off.

If you’re having internal radiotherapy, you may need to stay in hospital for a few days. The type of internal radiotherapy you have will depend on what type of cancer you have. Your doctor will explain what will happen and give you time to ask questions if you’re unsure about anything.

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What are the side-effects of radiotherapy?

Not everybody gets side-effects from radiotherapy. Your radiotherapy team will do all they can to minimise your chance of getting side-effects, and to help you cope with them if you do get them. Side-effects can vary depending on what part of your body is being treated, the type and dose of radiotherapy, and your own health.

Soon after starting treatment you may:

  • get problems with your skin (for example, dryness, itching, blistering or peeling)
  • feel tired and weak – but it’s important to try and keep as active as you can
  • lose your hair in the area that’s being treated (you won’t lose any hair on other parts of your body)

Some side-effects may be specific to the part of your body that’s being treated. You may get:

  • dry mouth, difficulty swallowing and a sore mouth if you have radiotherapy to your head and neck
  • shortness of breath or an inflammation of the lung called pneumonitis if you have radiotherapy to your chest
  • nausea, vomiting and diarrhoea if you have radiotherapy to your tummy (abdomen)
  • changes to your periods if you’re a woman having radiotherapy to your pelvis (you might stop having them)

For many people, the side-effects do wear off but this can take several weeks. Sometimes, radiotherapy can leave you with long-term side-effects. These might happen weeks or even years after you finish treatment, and there’s also a risk that the radiotherapy itself can cause another cancer. Your doctor will give you more information about how long-term side-effects may affect you.

Is there any follow-up after radiotherapy?

After you have finished radiotherapy, you’ll usually have a number of follow-up appointments with your specialist radiation oncologist. This can vary from a week to four weeks after radiotherapy. Your doctor may need to take some X-rays and do some diagnostic tests to check how the treatment went, and they’ll go through these with you.

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Related information

    • Radiotherapy. PatientPlus., last checked 23 December 2015
    • Radiotherapy. British Institute of Radiology., accessed 4 May 2018
    • Principles of radiation oncology. Oxford handbook of oncology (online). Oxford Medicine Online., published September 2015
    • Planning your external radiotherapy. Cancer Research UK., last reviewed 15 February 2016
    • Where will I have radiotherapy? Macmillan., reviewed 31 December 2015
    • Where you have radiotherapy. Cancer Research UK., last reviewed 10 February 2016
    • Side effects of radiation therapy. Cancer.Net., approved December 2016
    • Personal communication, Caroline Fadipe, Senior Radiographer, Bupa Cromwell Hospital, 4 June 2018
  • Reviewed by Rachael Mayfield-Blake, Freelance Health Editor, May 2018
    Expert reviewer, Caroline Fadipe, Senior Radiographer
    Next review due May 2021