Definition of the supraclavicular and infraclavicular nodes: Implications for three-dimensional CT-based conformal radiation therapy

PURPOSE: To delineate with computed tomography (CT) the anatomic regions co ntaining the supraclavicular (SCV) and infraclavicular (IFV) nodal groups, to define the course of the brachial plexus, to estimate the actual radiati on dose received by these regions in a series of patients treated in the tr aditional manner, and to compare these doses to those received with an opti mized dosimetric technique. MATERIALS AND METHODS: Twenty patients underwent contrast material-enhanced CT for the purpose of radiation therapy planning. CT scans were used to st udy the location of the SCV and IFV nodal regions by using outlining of rea dily identifiable anatomic structures that define the nodal groups. The bra chial plexus was also outlined by using similar methods. Radiation therapy doses to the SCV and IFV were then estimated by using traditional dose calc ulations and optimized planning. A repeated measures analysis of covariance was used to compare the SCV and IFV depths and to compare the doses achiev ed with the traditional and optimized methods. RESULTS: Coverage by the 90% isodose surface was significantly decreased wi th traditional planning versus conformal planning as the depth to the SCV n odes increased (P <.001). Significantly decreased coverage by using the 90% isodose surface was demonstrated for traditional planning versus conformal planning with increasing IFV depth (P =.015). A linear correlation was fou nd between brachial plexus depth and SCV depth up to 7 cm. CONCLUSION: Conformal optimized planning provided improved dosimetric cover age compared with standard techniques.