This study assesses computed tomography (CT) perfusion imaging in predicting treatment response in patients with non-small cell lung cancer or tumors that have spread from the primary site (place where it started) to the lungs (metastases) treated with stereotactic ablative radiation therapy. CT perfusion imaging is a special type of CT that uses an injected dye in order to see how blood flow through tissues, including lung tissue. CT perfusion imaging of the lungs may help doctors learn whether perfusion characteristics of lung tumors may be predictive of response to treatment and whether lung perfusion characteristics can be used to follow response to treatment.

PRIMARY OBJECTIVES:

I. To assess the feasibility of performing computed tomography (CT) perfusion imaging (CT perfusion imaging) at baseline, within 48 hours post-stereotactic ablative radiation therapy (SABR), and at 2-4 months SABR in patients undergoing SABR for treatment of a lung tumor per standard of care.

SECONDARY OBJECTIVES:

1. To determine the range (variability) of perfusion parameters at baseline, within 48 hours post-SABR, and at 2-4 months post-SABR
2. To assess the change in perfusion parameters at baseline, within 48 hours post-SABR, and at 2-4 months post-SABR
3. To correlate any change in perfusion parameters with circulating-tumor deoxyribonucleic acid (DNA) levels at baseline, within 48 hours post-SABR, and at 2-4 months post-SABR
4. To correlate perfusion parameters with tumor response 1 year post-SABR

OUTLINE:

Patients receive an infusion of Isovue-200 and undergo CT perfusion imaging of the lungs at baseline, within 48 hours of first SABR, and at 2-4 months after completion of SABR. Cancer Personalized Profiling by Deep Sequencing (CAPP-Seq) will be conducted evaluate circulating-tumor DNA levels.

Perfusion parameters will be correlated with tumor control at 1 year post-SABR, with tumor control defined as no evidence of disease seen at the site of SABR by surveillance imaging at 1 year post-SABR.

After completion of treatment, patients are followed up at 2-4 months and then at 1 year.

Inclusion Criteria:

• Patients undergoing SABR for the treatment of a lung tumor, inclusive of non-small cell lung cancer or lung metastases

Exclusion Criteria:

• Patients who are pregnant or are trying to become pregnant are excluded from this study
• Patients with renal failure, defined as glomerular filtration rate (GFR) < 60 at the time of the radiation treatment-planning (RTP) scan, will be excluded