Figure 3.

Case 1: Hypofractionated escalated-dose radiation therapy plan with isodose lines. Tumor coverage should be maximized for the PTV_Low, and for this patient, note the 3750 cGy isodose lines (yellow) encompass part of duodenum (white) and bowel structures (olive color wash). Given that the zPTV_High (red) provides no expansion from the tumor and consists of the gastrointestinal planning organ-at-risk volume subtracted from the internal gross tumor volume (black), planning may intentionally avoid part of the original tumor. In this patient, the 6750 cGy covers the central tumor but avoids the anterior lateral extent near the duodenum, whereas the near total extent of tumor is intentionally covered by an intermediate 4500 cGy (purple).