<qa>  What is the second goal of this study?The purpose of this study is first, to determine whether baseline perfusion characteristics of pancreatic cancer, as characterized by CT perfusion studies, can predict tumor response to treatment by stereotactic body radiotherapy SBRT. The second goal of this study is to determine whether baseline perfusion characteristics in those patients with resectable pancreatic cancer correlate with immunohistologic markers of angiogenesis such as microvessel density and vascular endothelial growth factor VEGF expression. 