Figure 6.

Dose distributions in the transverse plane for the BOS cancer case illustrating that the robustly optimized 3-beam IMPT-3D plan was relatively insensitive to setup uncertainty compared with the conventional PTV-based optimized 3-beam IMPT-3D plan. Left panels: PTV-based plans. Right panels: robustly optimized plans. Top row: nominal position. Bottom row: with patient moved to the right by 3 mm. CTV: orange color wash (middle filled area); brainstem: magenta color (bottom enclosed area); red solid arrows: beam directions.