It is generally accepted that the presence of chronically hypoxic cells, or tumor cells which do not receive enough oxygen as a result of tumor growth, may be an important cause of resistance to radiation therapy (RT) and resultant tumor recurrence, particularly in large tumors such as advanced non-small-cell lung cancer (NSCLC). Therefore, delivering a higher RT dose, as is done with hypofractionated RT, to the tumor may result in higher success rate.