Radiotherapy Health Dictionary

Treatment of cancer and, occasionally, some noncancerous tumours, by X-rays or other radiation. Radioactive sources produce ionizing radiation, which destroys or slows down the development of abnormal cells. Normal cells suffer little or no longterm damage, but short-term damage is a side effect.Radiotherapy may be used on its own in an attempt to destroy all the abnormal cells in various types of cancer, such as squamous cell carcinoma and Hodgkin’s disease. It may also be used with other cancer treatments. Surgical excision of a cancerous tumour is often followed by radiotherapy to destroy any remaining tumour cells. Radiotherapy may also be used to relieve the symptoms of a cancer that is too advanced to be cured.

If benefits outweigh risks, radiotherapy may be used to treat noncancerous diseases; for example, part of an overactive thyroid gland (see thyrotoxicosis) may be destroyed using radioactive iodine.

Radiotherapy is usually performed on an outpatient basis. X-rays (or sometimes electrons) produced by a machine called a linear accelerator are aimed at the tumour from many directions. This produces a large enough dose of radiation to destroy the tumour. Alternatively, a source of radiation, in the form of tiny pellets, is inserted into the tumour through a hollow needle (see interstitial radiotherapy) or into a body cavity (see intracavitary therapy). Radioactive iodine used to treat thyrotoxicosis is given in liquid form and drunk through a straw.

There may be unpleasant side effects, including fatigue, nausea and vomiting, and loss of hair from irradiated areas. Rarely, there may be reddening and blistering of the skin.

The treatment of disease (mainly CANCER) with penetrating RADIATION. For many years RADIUM and X-RAYS were the only sources available, but developments in knowledge led to the use of powerful X-rays, beta rays or gamma rays, either produced by linear accelerator machines or given o? by radioactive isotopes (see ISOTOPE). The latter is rarely used now.

Beams of radiation may be directed at the tumour from a distance, or radioactive material

– in the form of needles, wires or pellets – may be implanted in the body. Sometimes germ-cell tumours (see SEMINOMA; TERATOMA) and lymphomas (see LYMPHOMA) are particularly sensitive to irradiation which therefore forms a major part of management, particularly for localised disease. Many head and neck tumours, gynaecological cancers, and localised prostate and bladder cancers are curable with radiotherapy. Radiotherapy is also valuable in PALLIATIVE CARE, chie?y the reduction of pain from bone metastases (see METASTASIS). Side-effects are potentially hazardous and these have to be balanced against the substantial potential bene?ts. Depending upon the type of therapy and doses used, generalised effects include lethargy and loss of appetite, while localised effects – depending on the area treated – include dry, itchy skin; oral infection (e.g. thrush – see CANDIDA); bowel problems; and DYSURIA.

A treatment which uses atomic particles and high energy rays to destroy cancerous cells.

n. therapeutic radiology: the treatment of disease with penetrating radiation, such as X-rays, beta rays, or gamma rays, which may be produced by machines or given off by radioactive isotopes. Beams of radiation may be directed at a diseased part from a distance (see teletherapy), or radioactive material, in the form of needles, wires, or pellets, may be implanted in the body (see brachytherapy). Many forms of cancer are destroyed by radiotherapy.