Automatic feathering algorithm for VMAT craniospinal irradiation: A comprehensive comparison with other VMAT planning strategies

In craniospinal irradiation, field matching is very sensitive to intrafraction positional uncertainties in cranio-caudal direction, which could lead severe overdoses/underdoses inside the planning target volume. During last decade, significant efforts were made develop volumetric-modulated arc therapy strategies, less setup uncertainties. this study, a treatment system-integrated method, named automatic feathering (AF) algorithm, was compared against other strategies. Three patients retrospectively included. Five different techniques compared, including overlap (O), staggered (SO), gradient optimization (GO), with AF algorithm turned on (O-AF), and (SO-AF). overlapping lengths considered (5 cm, 7.5 10 cm). The middle isocenter shifted of ±1 mm, ±3 ±5 mm simulate Plan robustness simulated evaluated by calculating near maximum minimum dose differences between nonshifted plans (?D2%, ?D98%). Dose among combinations junction tested using Wilcoxon signed-rank test. Higher ?D2% ?D98% obtained technique (?D2% = 15.4%, 15.0%). O-AF SO-AF provided comparable plan GO technique. Their performance improved significantly for grater length. For 10-cm 5-mm shift, GO, O-AF, yielded better (5.7% < 6.0%, 6.1% 7.6%). SO an intermediate (9.8% 10.8%, 8.9% 10.3%). addition improves especially if larger are used. Using become as robust optimized more sophisticated time-consuming approaches (like GO).