Fig. 2
Dmax values in CBW by the scheduled plans on CBCT1 or DeltaDmax values within CBW calculated on CBCT1 and CTplan using the scheduled plans are depicted for the 91 dose fractions from the 10 patients. As independent characteristics, density changes at the Dmax point in the CBW on CBCT1 between CBCT1 and CTplan (ΔHUCBCT2/CBCT@DmaxP_CBW_CBCT1_S1/S2) and a parameter for plan sensitivity to density changes in the CBALPTV CTplan with or withut water override (DeltaDmax_CBALPTV_CTplan ± WOR/CTplan_S1/S2) were used. Data from the scheduled plan according to method 1 are given with blue circles and according to method 2 with red triangles. a, Dmax values in CBW by the scheduled plans on CBCT1 are shown in dependence on the ΔHUCBCT1/CTplan@DmaxP_CBW_CBCT1_S1/S2 values from the same dose fraction and the plan sensitivity parameter DeltaDmax_CBALPTV_CTplan + WOR/CTplan_S1/S2. b, The dependence of the observed Dmax values in CBW on CBCT1 on the 5-fold cross validated predicted values according to the linear model build from the data shown in a. This model uses ΔHUCBCT1/CTplan@DmaxP_CBW_CBCT1_S1/S2 and DeltaDmax_CBALPTV_CTplan + WOR/CTplan_S1/S2 as main effects and a multiplicative interaction term of both factors to predict the Dmax values in CBW on CBCT1. c, Scatter plot of the DeltaDmax values within CBW calculated on CBCT1 and CTplan using the scheduled plans per dose fraction. d, 5-fold cross validated prediction of the DeltaDmax_CBW_CBCT1/CTplan_S1/S2 values. The linear model is built from the data shown in c