Margin-Intense Combo Therapy in Pts w/Potentially Resectable Pancreatic Cancer

RATIONALE: Stereotactic body radiation therapy may be able to send x-rays directly to the tumor and cause less damage to normal tissue. Drugs used in chemotherapy, such as gemcitabine hydrochloride, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. Giving stereotactic body radiation therapy together with gemcitabine hydrochloride may kill more tumor cells. PURPOSE: This phase I trial is studying the side effects of stereotactic body radiation therapy when given with or without gemcitabine hydrochloride in treating patients with pancreatic cancer that can be removed by surgery.