Radiation-Induced Toxicity and Related Management Strategies in Urological Malignancies

Abstract

The lower abdomen and pelvis encompass several organs at risk (OAR), some of which are vital and are inevitably affected during radiotherapy (RT). In this chapter, the contouring recommendations and dose-volume constraints of the rectum, bowel bag (i.e., the whole small and large bowel together with their meso), urinary bladder, penile bulb, proximal femurs, and sacral plexus will be discussed in order to spare these OARs as much as possible during the RT of urological malignancies. Among these OARs, the bowel bag, penile bulb, and sacral plexus are serial organs in which the maximum point dose affects the function of the whole organ. On the other hand, the rectum, bladder, and femurs are in a parallel structure for which the mean dose to a specific volume is more important than the maximum dose. In order to interpret the dose-volume histograms (DVH) precisely, the accurate delineation of OARs is crucial.