Figure 1

Gross tumor volumes (GTVs) on CT scans obtained before and after induction chemotherapy in a representative case. The pretreatment GTV was first contoured on a diagnostic CT scan obtained before chemotherapy (A) and overlaid on the simulation CT (B), and a radiation therapy plan was generated based on normal tissue contours on the simulation scan. After chemotherapy, the GTV was outlined on the simulation CT by the treating physician (C) and the subsequent radiation treatment was planned according to institutional standards as described in the text (D).