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Planning volumes and risk structures. The tumor (GTV, white) and nearby vessels (TVI, red) are contoured. The sum of GTV and TVI forms CTV. A 5 mm expansion of the CTV makes planning target volume (PTV, blue). The main OARs are the duodenum (yellow), stomach (yellow), small bowel (light brown), and large bowel (dark brown). The evaluable PTV (PTV_EVAL, smaller blue volume) is PTV less GI structures with 3–5 mm margins. The fiducial marker is shown at the border of the GTV.
