The purpose is to destroy cells such as cancer cells that grow abnormally rapidly and in abnormal sites. The doctor who carries out the treatment is called a radiotherapist. Radiotherapy is almost always used to treat various forms of cancer. In the past it was used to treat the fungal infection ringworm and some inflammatory conditions of the bones, but this is not the case now.
Different cancers respond differently to radiotherapy.
The more common cancers, such as breast cancer, cervical cancer and lung cancer, lie somewhere in between these two extremes and their response to radiotherapy is very variable, even for the same type of cancer. Often, the initial response of a cancer to radiotherapy is a good indication of how successful the treatment will be. The type of procedure that is performed depends on the type of cancer and where it is in the body. Different machines are used to produce narrow beams of X-rays, gamma rays and particles such as electrons. These beams have different energies and properties which determine the depth that the beam penetrates into the body.