With the advent of highly conformal and adaptive radiotherapy techniques, the significance of accurate delineation of organs at risk (OARs) is becoming more and more important. Techniques such as Intensity modulated radiotherapy (IMRT) and intensity/volumetric modulated arc therapy (VMAT) has allowed for improved dose conformation within the target. It has also allowed for steep dose gradients around the target for better normal tissue sparing. The accurate contouring and delineation of the OARs are thus warranted as variation in delineation has been systematically reported in studies. All these facts have led to the development of contouring guidelines for OARs in various sites. Head and neck cancers (HNC) are a perfect example where outcome and quality of life (QOL) balance remains a therapeutic challenge. There are several OARs and thus the accurate delineation following a standard guideline becomes more important. This chapter looks into the published guidelines for the delineation of such structures.
Part of the book: Cancer Survivorship