 The purpose of this study is to find out whether a new device can help obtain more accurate CT and PET scans of the lungs and chest tumors and the liver and liver tumors to help in delivering radiation therapy. When we breathe, the amount of air in the lung changes. Lung tumors may also move during breathing. Liver tumors may also move with breathing; as the lungs inflate, the liver can be pushed down. A CT scan a special type of X-ray is routinely obtained as part of planning for lung or liver radiation therapy. Since patients breathe during this CT scan and their lung or liver tumors move, these CT scans can sometimes be inaccurate. We are now testing a device to only obtain the CT and an additional PET scan while patients are breathing in or out. This will hopefully allow us to deliver radiation with more accuracy. 