Pilot Study of Regional Lung Ventilation

Inclusion Criteria: * Patients that have early stage non-small cell lung cancer or clinical suspicion of the same in cases where the lesion is not amenable to biopsy but is enlarging and PET-positive. All patients are to be treated with stereotactic body radiation therapy as a monotherapy. * Eligible patients must have appropriate staging studies identifying them as specific subsets of AJCC 7th edition stage I or II based on only one of the following combinations of TNM staging: * T1a-b, N0, M0 * T2a, N0, M0 * T3 (invading the chest wall, \<5 cm in diameter) N0 M0 * Must be at least 18 years of age * Eastern Cooperative Oncology Group (ECOG) performance status of 0-2 * Women of childbearing potential and male participants must use an effective contraceptive method such as condom/diaphragm and spermicidal foam, intrauterine device, or prescription birth control pills. Exclusion Criteria: * Patients with T2b tumors or T3 tumors \>5 cm or patients with tumors involving the central chest/structures of the mediastinum; * Primary tumor of any T-stage within or touching the zone of the proximal bronchial tree, defined as a volume 2 cm in all directions around the proximal bronchial tree (carina, right and left main bronchi, right and left upper lobe bronchi, bronchus intermedius, right middle lobe bronchus, lingular bronchus, right and left lower lobe bronchi. * Direct evidence of regional or distant metastases after appropriate staging studies * Patients with active systemic, pulmonary, or pericardial infection; * Pregnant or lactating women, as treatment involves unforeseeable risks to the embryo or fetus. * Patients that receive chemotherapy (induction or sequential) * Psychiatric or addictive disorders that impair subject's voluntary ability to participate in informed consent or protocol procedures