Fig. 4

Dose Volume Histograms with and without the entire uterus included in the planning target volume. Dose Volume Histograms (DVHs) of 2 patients treated with a partial (yellow) or entire uterus (red) included in the planning target volume (PTV). a and c red contour = entire uterus included in the PTV; yellow contour = only the parts of the uterus closer than two cm of the gross tumor volume (GTV = red flooded contour) are included in the PTV. c and d DVHs of patient a and c respectively; the red DVHs correspond with the red contour (whole uterus); the yellow DVHs correspond with the yellow contour (selected parts of the uterus included in the CTV). The tail towards 62Gy in the DVH of the PTV corresponds with the SIB given to the GTV. In the first patient (a) the uterus lies in anteflexed position causing high doses to the bladder when irradiated entirely. A small reduction of PTV by reducing the amount of uterus included in the PTV causes a huge reduction in dose delivered to the bladder (b). A reduction of the PTV in case of a normal positioned uterus causes mainly a reduction in the irradiated volume of small bowel (d). Due to the large amounts of small bowel delineated, the reduction in terms of percentage seems small. However, in this case the amount of small bowel receiving 45Gy is reduced with 8%, which corresponds with 59 cc