Fig. 1

Pairwise comparisons of PTV dose. Each data point was derived from subtracting the value achieved with one plan from the one achieved with another plan. Horizontal bars indicate median values. PTV = planning target volume; Dmax = maximum dose; Dmin = minimum dose; DV = absorbed dose that covers a specified fractional volume V; HO, MHE, and HE plans = homogeneous, moderate heterogeneous, and heterogeneous plans