Pancreatic cancer is one of the most lethal malignant tumors, probably attributable to local recurrence deemed as a predominant factor influencing patients' prognosis and quality of life. Only 15%-20% patients are suitable for surgeries among those first diagnosed with pancreatic cancer and the 5-year survival rate of those patients with R0 resection is still less than 20%. Therefore, radiotherapy is becoming a promising method to improve survival. However, due to adjacent organs at risk, conventional external beam radiotherapy, besides long courses, sometimes results in severe radiation-induced toxicity, delaying the initial of thereafter treatment, such as chemotherapy, which reduces clinical benefits.