Clinical application of a sub-fractionation workflow 105 Supplementary B Next to the analysis of residual 3D displacements per fraction, a classical margin analysis was performed using the data from the 15 included patients (73 fractions included) considering the remaining intrafraction motion with the applied sub-fractionation workflow. Using the standard van Herk recipe, the required margins were calculated. The following equation was used: Margin = 2.5å + 1.64Ö(s2 + s2 penumbra) – 1.64spenumbra With: å = standard deviation (SD) of the systematic errors s = SD of the random errors spenumbra = 3.2 mm Table S3 shows the input parameters and the calculated margins. For each patient, the mean intrafraction CTV displacement and its SD was calculated. The error resulting from rotational motion were extracted from De Muinck Keizer et al.17 These rotational errors (converted to translational components) depend on the shape of the CTV and the numbers used here are on the ‘safe’ side (i.e. for most patients, smaller numbers will be applicable). Furthermore, although very small, machine uncertainties (position of the isocentre of the accelerator in the MRI coordinate system and geometrical uncertainties of the MR scanner) were taken into account, as estimated previously by van Lier et al.27 and Bernchou et al.28 Component LR (mm) CC (mm) AP (mm) Mean of means 0.09 -0.18 0.08 åtranslations 0.3 0.4 0.5 stranslations 0.8 1.3 1.4 årotations 0.0 0.6 0.6 srotations 0.0 0.6 0.6 åmachine uncertainty (isoc linac in MRI coordinate system) 0.2 0.2 0.2 åmachine uncertainty (geometrical uncertainty MR scanner) 0.2 0.2 0.2 Margin 1.2 2.4 2.6 Table S3 – Input parameters for margin calculation. Legend: LR = Left-Right. CC = Cranial-Caudal. AP = Anterior-Posterior. å = Standard deviation of the systematic errors. s = Standard deviation of the random errors. 5
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