The primary objective of this study is to assess the safety and feasibility of personalized radiotherapy with four-dimensional (4D) computed tomography (CT)-based pulmonary ventilation imaging, which selectively avoids irradiating highly-functional lung regions.

In this clinical trial, the investigators will assess the safety and feasibility of 4D CT ventilation image-guided personalized radiotherapy. The investigators will deliver personalized radiotherapy treatments that selectively avoid irradiating highly-functional lung regions for lung cancer patients, and follow up patients to assess the safety and feasibility. The primary hypothesis to be tested is: 4D CT ventilation image-guided personalized radiotherapy can be delivered safely for lung cancer.

Inclusion Criteria:

• Primary lung cancer or metastatic disease to the lungs to be treated with either conventionally-fractionated radiotherapy (CFRT) or hypo-fractionated stereotactic ablative radiotherapy (SABR).
• Age restriction and/or gender/ethnic restrictions: Patients must be ≥18 years of age. There are no gender or ethnic restrictions.
• Concurrent chemotherapy is allowed, but not required.
• Life expectancy with treatment should be ≥6 months in the estimation of the treating physicians.
• Zubrod performance status ≤2
• Adequate marrow and hepatic function defined as Hgb ≥8; platelets ≥100k; ANC≥1500; LFTs ≤2x upper limit of normal and creatinine ≤1.3 or creatinine clearance of ≥50
• Patient must be able to provide study specific informed consent prior to study entry.

Exclusion Criteria:

• Prior radiotherapy for thoracic cancer or other malignancy leading to any overlap of planned radiotherapy fields.
• For patients undergoing definitive CFRT, patients with distant metastatic disease are not eligible.
• For patients undergoing SABR, both early stage primary lung cancer patients and those with limited metastatic disease to the lungs are eligible; however, patients with oligometastatic disease should have a controlled primary and no more than one other involved organ system.
• Children (<18 years of age), pregnant women, University of California employees or students, or prisoners will be excluded from this study.

Serious and other adverse events assessed for up to 12 months after treatment is completed, an average of 2 years. All cause mortality assessed for up to about 2.5 year after treatment complete.