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External radiotherapy

In external radiotherapy high-energy x-rays are directed at the cancer from a machine outside the body. Different types of machines may be used, and they each vary slightly in how they look and how they work. The machine used will depend on the part of your body being treated and why radiotherapy is being given. Some are better at treating cancer near the skin; others are better for cancers deeper in the body.

Often external radiotherapy is given using a machine called a linear accelerator. Several specialised types of external radiotherapy may be used to treat certain cancers, such as three-dimensional conformal radiation therapy (3D-CRT), intensity modulated radiation therapy (IMRT) and image guided radiation therapy (IGRT). Many of these techniques allow the radiation beams to be delivered from several different directions. This reduces the amount of radiation to normal tissues.