Feasibility of pancreatectomy following high-dose proton therapy for unresectable pancreatic cancer

Figure 3 Typical proton dose distributions used to treat pancreatic cancers. Shown in the axial (A), coronal (B), and sagittal (C) projections. A heavily weighted (75% of the target dose) posterior or posterior oblique field is combined with a more lightly weighted (25% of the target dose) right lateral oblique field. Because protons are associated with a low entry dose and no exit dose compared with X-rays, there is significant sparing of small bowel and stomach tissue, which are highly sensitive to radiation damage. This normal-tissue sparing explains the low incidence of gastrointestinal toxicity when protons are used to deliver upper abdominal radiotherapy.