Respiratory Motion-Corrected Cone-Beam CT and Intratreatment Gating Based on Electromagnetic Transponders to Reduce Target Position Uncertainty in Radiation Treatment of Lung Malignancies

The first purpose of this study is to test a new computer program that reduces the blurring in the cone-beam CT scan and helps the doctor to better locate the tumor. The investigators want to find out what effects, good and/or bad, that this has on the patient and the way we treat the cancer in the lungs. The second purpose of this study is to test how well this computer program tracks markers in the images, compared to using radio signals to follow the markers.