Fig. 1

a IGTV volume definition. IGTV-all consisted of GTV and GTVs across all respiratory phases. IGTV-gate consisted of GTV and all GTVs within the gating window around phase 50%. The latter was only used for patients whose tumor moved more than 10 mm in any direction. b Schema of the respiratory gating system. Beams turned on only when the monitored respiratory phase was within the predefined gating window. The gate level was defined for each patient by reference to the amplitude of tumor movement