Although the ultimate intention was to evaluate VMAT planning, we originally attempted to use fixed‐gantry IMRT with nine beams to develop the set of AP dosimetric goals, as IMRT takes far less planning time. However preliminary trials indicated that it was not feasible to achieve plans of acceptable quality by the institutional standards, which was consistent with our previous manual planning experience. Therefore the AP techniques were developed with VMAT. To minimize the influence of delivery mechanical constraints on plan quality, all AP plans involved three full arcs with maximum delivery time of 140 s per beam and MLC motion constrained to 0.46 cm per 1° of gantry rotation. (16) Allowing this ample delivery time during optimization provides the necessary freedom to the optimization algorithm, while the linac software usually finds a faster way to deliver the resulting plan. (16) Full convolution calculation was performed after the 10th optimization iteration and the total number of iterations was limited to 100. The collimator was typically rotated ±15∘, except when a different angle was dictated by the target size. All plans were calculated on a 3×3×3 mm3 grid with the Adaptive version of Pinnacle Collapsed Cone Convolution algorithm. (17) Following the recommendations by Yartsev et al. (18) for planning studies, the starting technique is presented in full detail in Table 1. This technique was used for the first series of autoplans (AP1) and was developed with vendor's assistance. The advanced tuning settings used for all APs are shown in Fig. 2.