Comparison of treatment plans involving intensity-modulated radiotherapy for nasopharyngeal carcinoma

Purpose: To compare intensity-modulated radiotherapy (IMRT) treatment plans with conventional treatment plans for a case of locally advanced nasopharyngeal carcinoma. Methods and Materials: The study case was planned using two types of IMRT techniques, as well as a three-dimensional conformal radiotherapy technique (3D-CRT), and a traditional treatment method using bilateral opposing fields. These four plans were compared with respect to dose conformality, dose-volume histogram (DVH), dose to the sensitive normal tissue structures, and ease of treatment delivery, Results: The planned dose distributions were more conformal to the tumor target volume in the IMRT plans than those in the conventional plans. With similar dose coverage of the clinical target volume (CTV), defined as delivery of minimum of 60 Gy to greater than or equal to 95% of CTV, the IMRT plans achieved better sensitive normal tissue structure sparing, while concomitantly delivering a minimum dose of 68 Gy to greater than or equal to 95% of the gross tumor volume (GTV) at a higher dose per fraction. Conclusions: Compared to conventional techniques, IMRT techniques provide improved tumor target coverage with significantly better sparing of sensitive normal tissue structures in the treatment of locally advanced nasopharyngeal carcinoma. With improvement of the delivery efficiency, IMRT should provide the optimal treatment for all nasopharyngeal carcinoma. Further studies are needed to establish the true clinical advantage of this new modality. (C) 2000 Elsevier Science Inc.