Positron Emission Tomography Scan and CT Scan in Planning Radiation Therapy for Patients With Stage II or Stage III Non-Small Cell Lung Cancer

OBJECTIVES: Primary * Determine the impact of positron emission tomography (PET)/CT fusion scan and CT scan alone, by comparing gross tumor volume (GTV) contours and three-dimensional conformal radiotherapy treatment plans using 2 separate data sets (PET/CT fusion scan and CT scan only), in patients with stage II or III non-small cell lung cancer who are planning to undergo radiotherapy. * Determine the impact of PET on GTV (cm\^3), number of involved nodes, location of involved nodes, and dosimetric measures of normal tissue toxicity (mean lung dose, V20, and mean esophageal dose). Secondary * Determine the rate of elective nodal failures (nodal failures in regions that are not intentionally irradiated to definitive doses \[i.e., ipsilateral hilum, mediastinum, or ipsilateral supraclavicular fossa\]). OUTLINE: This is a multicenter study. Patients are stratified according to neoadjuvant chemotherapy (yes vs no). Patients undergo a combined positron emission tomography (PET)/CT scan. Patients also undergo a CT scan alone. A single three-dimensional conformal radiotherapy (3DCRT) plan is generated from the combined PET/CT scan results. A single 3DCRT plan using the planning target volume is derived from the CT scan only. Patients are followed every 3 months for 1 year, every 6 months for 2 years, and then annually thereafter. PROJECTED ACCRUAL: A total of 48 patients will be accrued for this study.