An evaluation of the variability of tumor-shape definition derived by experienced observers from CT images of supraglottic carcinomas (ACRIN protocol 6658).

Purpose: Accurate target definition is considered essential for sophisticated, image-guided radiation therapy; however, relatively little information has been reported that measures our ability to identify the precise shape of targets accurately. We decided to assess the manner in which eight "experts" interpreted the size and shape of tumors based on "real-life" contrast-enhanced computed tomographic (CT) scans.

Methods And Materials: Four neuroradiologists and four radiation oncologists (the authors) with considerable experience and presumed expertise in treating head-and-neck tumors independently contoured, slice-by-slice, his/her interpretation of the precise gross tumor volume (GTV) on each of 20 sets of CT scans taken from 20 patients who previously were enrolled in Radiation Therapy Oncology Group protocol 91-11.

Interobserver reliability of computed tomography-derived primary tumor volume measurement in patients with supraglottic carcinoma.

Background: Prior studies have determined that macroscopic ("gross") tumor volume (GTV), as calculated from pretreatment computer tomography (CT), was capable of predicting local control in squamous cell carcinoma arising in different subsites in the head and neck in patients who were treated with nonsurgical organ-preservation therapy. The majority of these studies were single-institution, retrospective investigations. Consequently, there has been concern that GTV measurements may not be reproducible by different readers at different institutions.