Fig. 2.

Daily CT image guidance allows monitoring of the stomach and small bowel. Daily CT image guidance is an essential component of the safe delivery of ablative doses of radiation to a tumor surrounded by gastrointestional luminal structures. An inspiration breath-hold technique is used to control respiratory motion. The intravenous contrast-enhanced simulation scan on the right is registered with the daily CT scan on the left for verification of luminal organ position. The daily CT can be used for adaptive planning if internal organ position is consistently different from that in the simulation CT.