set: comparison of the dose distribution calculated for the “best case”, TP CT (left: a,b) and the “worst case” daily CT (right: c,d). The figure shows transversal (a,c) and saggital (b,d) views. CT studies are overlapped with the segmented contours and dose distributions. Contours of the target (PTV – blue, CTV - red) and the organs at risk (rectum – brown, bladder - yellow) are delineated with the thick lines on the transversal view and dots on the saggital view. In addition, the contour of the spacer gel is delineated in pink. Dose distributions (dose legend - e) are presented with thin isodose lines of 30%, 50%, 70%, 95%. Color field was used for the highest dose regions of 95-100% and 100-107%. The comparison of the subfigures described with the same letters on the Figures 1 and 2 allow seeing the differences resulting from application of spacer gel.