The basic premise of this pilot study is to enroll 40 patients over 1.5 years who have Stage III or IV non-small cell lung cancer and are planned for definitive treatment with concurrent chemoradiation when a contrast-enhanced 4DCT is planned. The primary goal is to quantify the reproducibility of lung perfusion and ventilation imaging and evaluate changes seen in imaging following radiation therapy. Using the perfusion and ventilation images from Scans 1 and 2, we will perform the following analysis to quantify image reproducibility Inclusion criteria: - Patients have histologic diagnosis of non-small cell lung cancer - Patients have AJCC stage III or IV disease were the plan is to receive definitive concurrent chemoradiation to 60 Gy or higher - Age 18 years of age - Patients are able to provide informed consent - No additional lung radiation is planned until after the 3rd CT on this study (i.e. patient does not have a solitary pulmonary nodule or second primary that the plan is to undergo SBRT) - Patient must have adequate kidney function to receive IV contrast (following institutional policy supplied by radiology) Exclusion criteria: - Allergy to IV iodine contrast - Inadequate kidney function - Further thoracic radiation therapy is planned. This study aims to quantify the reproducibility of DECT/4DCT lung V/Q data that is now available from radiation treatment planning CT data. This will be accomplished by a series of IV contrast CT scans at multiple time points.

You may be eligible for this study if you meet the following criteria:

• Conditions: Medical Research
• Age: 99 years or below
• Gender: All