The purpose of the study is to assess the time, dose dependence, and fraction-size dependence of radiation (RT)-induced changes in regional lung and heart perfusion/function/structure following thoracic RT delivered using newer IMRT/conformal/radiosurgery techniques. The PI hopes to develop models to better relate and predict RT-induced changes in regional lung and heart perfusion/function/structure with changes in global cardiopulmonary function. Patients will undergo pre- and serial post-RT lung and heart assessments to better understand RT-induced regional heart/lung changes.