Radiation therapy is the treatment of cancer with high-energy radiation. Radiation therapy works by using special equipment to deliver high doses of radiation to cancerous tumors to keep them from growing, multiplying, or spreading. Radiation therapy is effective in treating many kinds of cancer in almost any part of the body. Radiation therapy can be used before surgery to shrink a tumor, or after surgery to stop the growth of any cancer cells that remain. It can also be used along with anticancer drugs to destroy the cancer, or to relieve symptoms caused by cancer.
Radiation therapy is given either externally or internally.
Internal radiation therapy involves the placement of radioactive material inside the body as close as possible to the cancer. The radiation oncologist will plan the treatment with an x-ray procedure called simulation. This allows the doctor, physicists, and radiation therapists to target cancer tissue and protect normal organs. The radiation therapist will often mark the skin with special ink to outline the treatment area where the radiation therapy will be aimed. The doctor will then decide on how much radiation is needed and how many treatments should be given.