It is known that radiation damages lung tissue. New human studies at University of Iowa show that the radiation damage is not as expected. The purpose of this study is to document lung function using four-dimensional computed tomography (CT) and quantify changes three months after radiation therapy for malignant lung disease.

Inclusion Criteria:

• Histological diagnosis of small cell or non-small cell lung cancer or metastatic tumor to the lung being scheduled for localized radiation therapy (including radiosurgery)
• No prior or future planned surgery for the treatment of the lung cancer.
• Age ≥ 18 years
• Karnofsky 60%
• Not pregnant.
• Ability to understand and the willingness to sign a written informed consent document
• Ability and willingness to participate in breathing training and compliance wiht breathing apparatus so that radiation doses are optimally linked to 4D-CT images
• Ability to tolerate CT contrast

Exclusion Criteria:

• No prior thoracic radiotherapy will be permitted
• Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements
• Pregnant women
• Severe COPD that requires chronic prednisone or multiple inhalers
• Underlying collagen vascular disease or intrinsic lung disease that could complicate expected sequelae of radiation (idiopathic pulmonary fibrosis, Wegener's granulomatosis)
• Oxygen dependence at baseline
• Recent lung surgery or abdominal surgery (within 3 weeks) that would compromise respiratory pattern.

Cancer patients with lung disease requiring radiation therapy. Lung tumor may be lung cancer or metastasis to the lung. Radiation simulation method must be four-dimensional computer tomography (4D-CT)