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What radiotherapy is

Nurse and patients talking about cancer

This page tells you about radiotherapy treatment. There is information about



Radiotherapy means the use of radiation, usually X-rays, to treat illness. X-rays were discovered in 1895 and since then radiation has been used in medicine for diagnosis and investigation (X-rays) and treatment (radiotherapy).

Doctors have a lot of experience using radiotherapy in medicine. About 4 out of 10 people with cancer (40%) have radiotherapy as part of their treatment. It can be given in various ways

  • From outside the body as external radiotherapy, using X-rays from linear accelerator machines, electrons, and more rarely other particles such as protons
  • From within the body as internal radiotherapy, by drinking a liquid that is taken up by cancer cells or by putting radioactive material in, or close to, the tumour

How radiotherapy works

Radiotherapy destroys the cancer cells in the treated area by damaging the DNA within these cells. Although normal cells are also affected by radiation, they are better at repairing themselves than the cancer cells.


Having radiotherapy

You usually have radiotherapy as a series of treatments over a number of days or weeks. Each treatment is known as a fraction. Fractions are usually given once a day from Monday to Friday with a rest at the weekend to help normal cells recover. Healthy cells that are damaged are often replaced as part of the bodies' repair systems. This depends on the type of cell and the dose of radiotherapy. But if cells can't be replaced, side effects can sometimes be permanent.


Worries about treatment

You may feel anxious about radiotherapy and this is perfectly normal. It can help to talk through any worries you have with your doctor, nurse or radiographer. There is detailed information about feelings, emotions and radiotherapy in the general radiotherapy side effects section.

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Updated: 15 April 2014