Non-small cell lung cancer (NSCLC) is a disease that often cannot be surgically operated on. As a result, treating the tumor with radiation has become the main standard of treatment. Radiation therapy though, is limited by various factors, including the difficulty in properly imaging the lung tumor since the lung can move up to 4 cm between breathing in and out. Consequently, a radiation oncologist must consider a larger area of the lung to treat with radiation - increasing the amount of normal tissue exposed to harmful rays and therefore leading to increased side-effects. Two techniques being explored into improving tumor management while minimizing the side effects in NSCLC are breath-held gating and tomotherapy. Breath-held gating is a technique for consistently imaging the tumor at the right moment in a patient's breathing cycle - decreasing the normal tissue exposed to harmful radiation. Tomotherapy, a new technique in delivering radiation, will further allow the investigators to focus treatment on the tumor and exclude more normal tissues. Therefore, they hope that these methods will prove to be a better way in treating people with NSCLC.