Radiation Therapy

Radiation Therapy is the medical use of ionizing radiation as part of treating cancer and to control malignant cells. Radiation therapy is also known as Radiotherapy. The use of radiation therapy on non-mailignant conditions is limited partly by worries about the risk of radiation-induced cancers. With treating cancer, radiation therapy also can be combined with surgery, chemotherapy, hormone therapy or a mixture. To spare normal tissues (skin or organs radiation must pass through to treat the tumor), the radiation beams are shaped and aimed from several angles to intersect the tumor and to provide a larger absorbed dose then in the surrounding, healthy tissue. Radiation therapy works by damaging the DNA of cells by free radicals and since cancer cells are stem-like they reproduce more and have a diminished ability to repair sub-lethal damage compared to healthy cells. The DNA damage is inherited through division and accumulates damage to the cancer cells causing them to die or reproduce more slowly. There are three types of radiation therapy. External beam radiotherapy, brachytherapy and unsealed source radiotherapy. The differences relate to the position of the radiation souce. External is outside the body, brachytherapy uses radioactive sources placed in the area under treatment and unsealed source radiotherapy is given by infustion or orally.