Radiation therapy



Radiation therapy (or radiotherapy) is the medical use of ionizing radiation
as part of cancer treatment to control malignant cells (not to be confused
with radiology, the use of radiation in medical imaging and diagnosis).
Although radiotherapy is often used as part of curative therapy, it is
occasionally used as a palliative treatment, where cure is not possible and
the aim is for symptomatic relief.

Radiotherapy is commonly used for the treatment of tumours. It may be used
as the primary therapy. It is also common to combine radiotherapy with
surgery and/or chemotherapy. The most common tumours treated with
radiotherapy are breast cancer, prostate cancer, rectal cancer, head & neck
cancers, gynaecological tumours, bladder cancer and lymphoma.

Radiation therapy is commonly applied just to the localised area involved
with the tumour. Often the radiation fields also include the draining lymph
nodes. It is possible but uncommon to give radiotherapy to the whole body,
or entire skin surface.

Although the actual treatment is painless, using radiation to tackle tumours
inevitably leads to side effects. The side effects can occur during
treatment (acute side effects such as soreness and redness over the affected
area; nausea and vomiting) or long after treatment has finished (late side
effects reflecting permanent organ damage).

Radiation therapy is usually given daily for up to 35-38 fractions (a daily
dose is a fraction). These small frequent doses allow healthy cells time to
grow back, repairing damage inflicted by the radiation. Tumours don't repair
the radiation damage as well.

Three main divisions of radiotherapy are external beam radiotherapy or
teletherapy, brachytherapy or sealed source radiotherapy and unsealed source
radiotherapy. The differences relate to the position of the radiation
source; external is outside the body, while sealed & unsealed source
radiotherapy has radioactive material delivered internally. Brachytherapy
sealed sources are usually extracted later, while unsealed sources are
injected into the body.

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