4-Dimensional CT Derived Ventilation Versus SPECT Aerosol Ventilation in Patients With Thoracic Malignancies

Inclusion Criteria: 1. Patients with pathologic diagnosis of esophagus or lung cancer (Stage I through IV). 2. Patients must be able to lie flat for the duration of the treatment planning sessions. 3. Patients must sign informed consent. 4. Patients who are scheduled to receive radiation therapy. 5. A cohort of 6 lung cancer patients whose primary tumors move greater than 1 cm will be recruited (CPAP cohort). Exclusion Criteria: 1. Significant pleural effusion as evaluated by the attending Radiation Oncologist is excluded. 2. Women of childbearing potential (A woman of child-bearing potential is a sexually mature woman who has not undergone a hysterectomy or who has not been naturally postmenopausal for at least 24 consecutive months \[i.e., who has had menses at any time in the preceding 24 consecutive months\]) and male participants must practice effective contraception (oral, injectable, or implantable hormonal contraceptive; tubal ligation; intra-uterine device; barrier contraceptive with spermicide; or vasectomized partner) throughout the study. 3. Patients with severe COPD or asthma will be excluded from the CPAP cohort.