 Radiation therapy or radiotherapy, often abbreviated root, party-X, or XRT, is therapy using bionizing radiation, generally as part of cancer treatment to control or kill malignant cells and normally delivered by a linear accelerator. Radiation therapy may be curative in a number of types of cancer if they are localized to one area of the body. It may also be used as part of adjuvant therapy, to prevent tumor recurrence after surgery to remove a primary malignant tumor. For example, early stages of breast cancer. Radiation therapy is synergistic with chemotherapy, and has been used before, during, and after chemotherapy in susceptible cancers. The subspecialty of oncology concerned with radiotherapy is called radiation oncology. Radiation therapy is commonly applied to the cancerous tumor because of its ability to control cell growth. Ionizing radiation works by damaging the DNA of cancerous tissue leading to cellular death. To spare normal tissues such as skin or organs which radiation must pass through to treat the tumor-shaped radiation beams are aimed from several angles of exposure to intercept at the tumor, providing a much larger absorbed dose there than in the surrounding, healthy tissue. Besides the tumor itself, the radiation fields may also include the draining lymph nodes if they are clinically or radiologically involved with tumor, or if there is thought to be a risk of subclinical malignant spread. It is necessary to include the margin of normal tissue around the tumor to allow for uncertainties in daily setup and internal tumor motion. These uncertainties can be caused by internal movement for example, respiration and bladder filling and movement of external skin marks relative to the tumor position. Radiation oncology is the medical specialty concerned with prescribing radiation, and is distinct from radiology, the use of radiation in medical imaging and diagnosis. Radiation may be prescribed by a radiation oncologist with intent to cure a curative or for adjuvant therapy. It may also be used as palliative treatment where cure is not possible and the aim is for local disease control or symptomatic relief for a therapeutic treatment where the therapy is survival benefit and it can be curative. It is also common to combine radiation therapy with surgery, chemotherapy, or bone therapy, immunotherapy or some mixture of the four. Most common cancer types can be treated with radiation therapy in some way. The precise treatment intent curative, adjuvant, neal adjuvant therapeutic, or palliative will depend on the tumor type, location, and stage, as well as the general health of the patient. Total body irradiation TBI is a radiation therapy technique used to prepare the body to receive a bone marrow transplant. Broccy therapy, in which radioactive sources placed inside or next to the area requiring treatment, is another form of radiation therapy that minimizes exposure to healthy tissue during procedures to treat cancers of the breast, prostate and other organs. Radiation therapy is several applications in non-malignant conditions, such as the treatment of trigeminal neuralgia, acoustic neuromas, severe thyroid disease, teridium, pigmented villanage alert synavitis, and prevention of keloid scar growth, vascular restenosis, and heterotopic ossification. The use of radiation therapy in non-malignant conditions is limited partly by worries about the risk of radiation-induced cancers.