Pulse-low-dose Rate (PLDR) Radiation in Pancreatic Cancer

Inclusion Criteria: * Patients must have histologically or cytologically-confirmed pancreatic adenocarcinoma. * Patients must have non-metastatic pancreatic cancer not appropriate for immediate surgical resection. This includes the following: * Any involvement (defined as loss of fat plane on contrast CT) of any of the following vessels\*: * Common hepatic artery * Superior mesenteric artery * Celiac axis * Superior mesenteric vein * Portal vein * Aorta * These criteria will be judged by the operating surgeon in conjunction with a radiologist prior to enrollment. * Poor performance status not immediately conducive to radical surgery * Other clinical reasoning by the treating physicians that supports pre-operative chemoradiation * Patients must have evaluable disease as measured by RECIST 1.1 criteria. * Planned surgical resection at the time of enrollment (may be initially staged as resectable, borderline resectable, or locally-advanced/unresectable). * Eastern Cooperative Oncology Group, or ECOG, performance status 0-2. * Adequate bone marrow, hepatic, renal function. * ANC ³ 1,500/ml and PLT ³ 100,000/ml * Bilirubin less than 1.5 ULN * AST and ALT \< 3X ULN * Serum Creatinine \<1.5X ULN * Prior chemotherapy allowed, but not mandatory. Patients who have undergone chemotherapy prior to participating in this study must have had a 2 week washout period at the time of signing the consent form. * Women of childbearing potential must be non-pregnant (negative pregnancy test within 72 hours prior to registration. Postmenopausal woman must have been amenorrheic and nonlactating for at least 12 months to be considered of non-childbearing potential. Men and women of child bearing potential must be willing to exercise an effective form of birth control (abstinence/contraception) while on study and for 3 months after therapy is completed. Please refer to section 6.4 for additional detail. * Age \> 18 years * Participants must sign a written informed consent and HIPAA consent prior to performance of study-specific procedures or assessments and must be willing to comply with treatment and follow up. Exclusion Criteria: * Radiological or cytologically confirmed metastatic disease * Patients who have had any prior therapy for pancreatic cancer, except chemotherapy (see 6.1.7) * Concurrent non-study chemotherapy or biologic therapy * A history of ataxia telangiectasia or other documented history of radiation hypersensitivity * Scleroderma or active connective tissue disease * Active inflammatory bowel disease * Serious, active infections requiring treatment with IV antibiotics * Uncontrolled intercurrent illness including, but not limited to, psychiatric illness/social situations that would limit compliance with study requirements.