Definitive radiation therapy is recommended for tumors that cannot be surgically removed without great risk or complications for the patient. Because the radiation passes through normal tissue surrounding the tumor, multiple small doses of radiation are given to maximize the damage to the abnormal cancerous tissue while minimizing the damage to the surrounding normal tissue. Conventional radiation therapy is mainly utilized for tumors that have tiny tendrils of cells extending from the tumor that are not possible to see with the human eye (microscopic disease) or with imaging. Cancers that are commonly treated with radiation alone include tumors inside the nasal passage, perineum and brain, and some soft tissue sarcomas. Depending on the location of the tumor, a CT or MRI and a computerized three-dimensional treatment plan may be used to plan the radiation treatment. Definitive radiation therapy is administered with the goal of achieving long-term control or cure of the disease. Treatment typically lasts three to four weeks and is often delivered on a Monday through Friday schedule.