In this book special emphasis is placed on the lymph node areas at risk for microscopic infiltration, addressing the question of which of these areas should be included in the target volumes. Each chapter comprehensively reviews all available data from clinical, radiological and pathological examination as well as the pattern of locoregional relapse, and offers recommendations for the selection of the clinical target volumes. Then based on a three-dimensional description of the anatomical regions where the areas at risk are located, guidelines for the delineation of the clincal target volumes are proposed. To help the reader, two chapters on descriptive anatomy and anatomical radiology on CT/MRI slices have been included. The data presented should enable the reader to make appropriate decisions regarding the selection and delineation of the target volumes when confronted with the most frequent tumor types and sites.