Figure 1.

Lung motion with and without abdominal compression. Axial (A,B) and coronal (C,D) CT images of a patient with a right lower lobe stage I non-small cell lung cancer planned for SBRT with contours after CT simulation of GTV (red), iGTV (blue) and PTV (green). (A,C) CT simulation without motion mitigation; (B,D) CT simulation with abdominal compression. SBRT, stereotactic body radiation therapy; GTV, gross tumor volume; iGTV, internal GTV; PTV, planning target volume; CT, computed tomography.