Summary This is a study for patients who have cancer of the lung and will be receiving radiation therapy. The treatment that will be given is called stereotactic body radiation therapy and is investigational. This involves a technique that uses precise patient positioning and multiple radiation beams to deliver fewer but much higher and more precise doses of radiation to a lung tumor. Previous studies using this technique have suggested that the higher more focused radiation dose may work better to kill the cancer cells while limiting damage to normal surrounding structures.