Acute radiation lung injury RTOG grading criteria: Grade 0: no change. Grade 1: Mild dry cough or dyspnea on exertion. Grade 2: Persistent cough requiring narcotic cough suppressants/ dyspnea with slight activity, but no dyspnea at rest. Grade 3: Severe cough, ineffective to narcotic cough suppressants, or dyspnea at rest/clinical or imaging evidence of acute radiation pneumonia/intermittent oxygen or possible need for steroid therapy. Grade 4: Severe respiratory insufficiency/continuous oxygen or assisted ventilation therapy. Grade 5: Fatal.