1183 / 1631
• CTV = stomach/perigastric nodes + involved nodes
• Sources of uncertainty
– Respiratory motion: 4DCT + ITV or DIBH
– Gastric contents: fasting, minimal oral contrast
– Residual movement + set-up variation: PTV expansion
• Constraints: kidneys, heart, liver
– 3DCRT, IMRT
Organ motion: Gastric Lymphoma