A three-dimensional CT-based target definition for elective irradiation ofthe neck

Introduction: Elective treatment of the clinically node-negative neck by ra diation results in excellent control rates. However, radiation therapy with its organ-preserving properties is not without morbidity, Side effects of elective neck irradiation are mainly due to damage of the major and minor s alivary glands, resulting in the dry mouth syndrome. Given that RT is the p referred treatment modality in case of elective treatment of the neck in ma ny institutions, it is of utmost importance to try and reduce the associate d sequelae of RT, Material and Methods: With the introduction of CT-planning systems and the development of 3D conformal radiation therapy (3D CRT) techniques, it has b ecome feasible to deliver adequate doses of radiation to the target (neck) and at the same time saving (parts of) the salivary glands from doses beyon d tolerance. A prerequisite for these techniques is that they require a pre cise knowledge of the target (i.e., of the elective neck) on CT. To be able to correlate borders of the surgical levels in the neck (I-VI) with struct ures seen on CT, an anatomical study, using two fixed (phenol, formaldehyde ) human cadavers, was performed. Subsequently, the 6 potential lymph node r egions in the neck on CT were defined. Results and Discussion: The reference for the current 3D CT-based definitio n of the lymph node regions in the neck is the official report of the Ameri can Academy of Otolaryngology, describing, based on surgical anatomy, the l ymph node groups in the neck by Levels I-VI, The present investigation depi cts reproducible landmarks on transversal CT images, corresponding to anato mical reference structures known from surgical levels (I-VI) and, this way, CT-based lymph node regions (1-6) were constructed, (C) 1999 Elsevier Scie nce Inc.