The purpose of this study is to compare the results of two CT scans of the chest performed within minutes of each other. We will compare several different measurements of lung cancer tumors. This study will help show whether we can get accurate results when we compare measurements on different CT scans. This information is important for patients with cancer, who often have more than one CT scan during their treatment.

Standard criteria for tumor response assessment have used uni-dimensional or bi-dimensional measurements as a surrogate for volume determination. Modern CT scan techniques, in combination with algorithms developed at MSKCC, allow the calculation of tumor volume. This protocol is designed to evaluate the reproducibility of the calculated volume of pulmonary masses on separate CT scans obtained on the same day in patients with non-small cell lung cancer (NSCLC). Patients with NSCLC undergoing non-contrast CT scan of the chest will have a second, non-contrast CT scan of the chest performed. Uni-dimensional, bi-dimensional, and volume measurements for the primary NSCLC lesion will be determined on both scans and the values compared.

Inclusion Criteria:

• Have pathologically confirmed non-small cell lung cancer
• Have measurable primary pulmonary tumors ≥ 1cm
• Have plans for a clinically indicated non-contrast CT scan of the chest
• All patients must be ≥ 18 years old

Exclusion Criteria:

• Pregnant or lactating women

Thoracic Oncology Service at MSKCC clinic.