Fig. 3

Output factors for open fields at d_max reported by IROC–H, and calculated with PRIMO using the DPM algorithm. The maximum differences between simulations and IROC–H data are − 1.6% for Clinac 2100, and 0.4% for TrueBeam. Uncertainty bars show (with k=2) the standard deviation of the IROC–H data, and the statistical uncertainty of the simulations. Data points are artificially separated along the horizontal axis for clarity