The Varian 6 EX is a state of the art 6 MV Linear Accelerator with multi-leaf collimators (MLCs). It is capable of delivering 2D treatments, 3D treatments, and intensity modulated radiation therapy (IMRT) treatments. It is equipped with an electronic portal imaging system (Theraview) to better position the patient for the accurate delivery of radiation to the tumor. Many patients will be receiving image guided radiation therapy (IGRT) on this machine.