Fig. 2

Example of an upper larynx contained in the RapidPlan model that was identified as a dosimetric outlier in the model configuration window. Screenshots taken from the RapidPlan model configuration window. The discrepancy between the predicted and achieved dose-volume histogram (DVH) lines (a) was solved by replanning the corresponding patient (indicated by solid blue line) using the RapidPlan model (b). The shaded region indicates the DVH prediction range for the selected plan. RapidPlan uses principal component analysis to decompose the shape of the achieved and predicted DVHs in the model library, allowing for a more consistent way to compare the estimated and obtained dosimetry. The residual plot (c) shows the correlation between the obtained (DVH principal component score 1) and predicted dosimetry (estimated DVH principal component score 1) after replanning (d), indicating that the predicted OAR DVH closely corresponds to the OAR DVH included in the model library. Since more than one upper larynx was identified as an outlier in the two iterations of outlier replanning, more DVHs are noted to change