Interobserver variability in the definition of the primary lung cancer and lymph nodes on different 4DCT reconstructions

Abstract

Background: Delineation variability is a major uncertainty in radiotherapy for lung cancer. As respiratory motion is an important part of this uncertainty, respiratory correlated computed tomography (4DCT) imaging is widely used. Several image reconstruction techniques are available to generate 3D data for delineation, such as the Maximum Intensity Projection (MIP) and the mid-ventilation (MidV) technique. The latter selects data at the time weighted mean tumor position. Both techniques are prone to motion artefacts. The new Mid-position (MidP) technique averages CT data after motion compensation to the mean position reducing such artefacts. The aim of this study is to evaluate interobserver variation for tumor delineation for these three image reconstruction techniques.