Figure 1.

Inner outline (pink) is contour of proximal bronchial tree (PBT). Outer line (light green) is a 2-cm expansion on PBT. Central lesions are defined as those which abut this 2 cm expansion and touching heart and great vessels. Ultracentral lesions lie within 1 cm of the PBT and include lesions that abut esophagus and trachea. In this illustration, the ultracentral lesions about the proximal bronchial tree and lie within the expansion of the PBT and the 2 cm expansion outlined in light green. Peripheral lesions lie well outside of the outer line (light green).