Figure 6. Comparison of the steepness of dose gradient outside the GTV boundary.

The images show BWPs along with the results of FT, SPHT, and WSRT (A, B); and the spillage volumes (cc) of the IIVs with 75% (A) and 50% (B) of the GTV D_{V-0.01 cc} outside the GTV to demonstrate the steepness of dose gradient outside the GTV.

GTV: gross tumor volume; IIV: irradiated isodose volume; WSRT: Wilcoxon signed-rank test; CA: coplanar arcs; NCA_L: non-coplanar arcs with limited rotations; NCA_F: non-coplanar arcs with full rotations; BWPs: box-and-whisker plots; FT: Friedman’s test; SPHT: Scheffe’s post hoc test; D_{V-0.01 cc}: a minimum dose to cover a target volume (TV) minus 0.01 cc.