Figure 2.

(a) Effect of increasing the weight of the edge penalty on the dose-related cost function penalty, total plan MUs, and the edge metric. The dotted line shows the value of the dose-related cost function, the dashed line shows the total plan MUs, and the solid line shows the edge metric (i.e., the aperture complexity). (b) Example aperture shapes from three different plans with penalty weights of 0%, 3.1%, and 15.3% of the total cost function after optimization [these points are circled in part (a)]. The contours of the cord and PTV are shown. (c) DVHs for the cord and PTV for three example plans with penalty weights of 0%, 3.1%, and 15.3% of the total cost function after optimization. (d) Example slices showing the 36, 24, 15, and 10 Gy isodose lines for a plan without the edge penalty (top) and a plan with a penalty weight of 3.1% (bottom). Contours of the PTV and cord are shown.