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Brachytherapy is a type of radiation therapy used to treat certain kinds of cancer. Also known as seed implantation, this treatment involves implanting a small, radioactive pellet into a tumor, allowing radiation to kill cancer cells over time. Brachytherapy is considered an extremely effective way of treating several types of cancer, including prostate, lung, rectum, breast and cervical cancers. This treatment has the added advantage of causing fewer side effects than conventional radiation therapy.
In conventional radiation therapy, known as external beam radiation therapy, a patient lies on a surface while a beam of radiation is directed at the location of the tumor. The radiation is emitted by a piece of equipment called a linear accelerator, which uses microwave technology to generate ionizing X-rays. These rays are toxic to cells, and the beam is concentrated and directed in order to specifically target cancer cells. Despite the efforts made to target only the tumor, side effects occur in almost all cases because of the effects of radiation on surrounding tissues.
Brachytherapy is different from external beam therapy in several ways. First, the radiation is delivered from inside the body, rather than from outside the body. This is achieved by implanting a microscopic pellet, or seed, inside the tumor itself, using a catheter or needle. After the seed has been implanted, its location is confirmed with an MRI, CT or other imaging scan, and the location is adjusted as needed. The seed is enclosed in a metal capsule, which itself is not radioactive but allows radiation to pass through to surrounding tissues.
Another difference between brachytherapy and external beam therapy is that the radiation emitted by the seed travels only a short distance. The seed emits radiation in a radius around itself, and when implanted correctly, tumor cells are affected while healthy tissue is left unharmed. As a result, this type of cancer therapy causes fewer side effects, which generally are less severe. Often, side effects are limited to some tenderness and swelling in the location where the seed has been implanted. In addition, treatment tends to be more effective because the use of a sealed, radioactive seed allows for the use of a higher dose of radiation than would be possible with external beam therapy.
There are two main types of brachytherapy: temporary and permanent. When the therapy is temporary, a higher dose of radiation is delivered in seeds that are left in place for only a short time. Often, the patient receiving the therapy remains in a hospital while the seeds are in place. If the therapy is permanent, a lower dose of radiation is used, and the patient can return home a short time after the seed has been implanted. Although the danger is minimal, the patient must take care to limit close contact with women who are pregnant and with children.
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