Lung cancer is the second most common cancer and the leading cause of cancer-related deaths. 2-deoxy-2-((18)F)fluoro-D-glucose (FDG) positron emission tomography (PET) fused with computed tomography (CT) has become the standard of care in the initial staging of patients with non-small cell lung cancer and has been increasingly utilized for radiation treatment planning as disease extent and tumor volumes are better defined than CT alone. The biologic information from FDG-PET may be used for predicting outcome, assessing treatment response, and surveillance imaging. Addition of respiratory gating to PET reduces motion artifacts to improve tumor delineation. Novel radiotracers are being investigated to provide further biological information such as tumor hypoxia and cell proliferation.