Evaluation of the influence of breathing on the movement and modeling of lung tumors

Abstract

Purpose/Objective: Breathing causes movement and potential shape change in lung tumors that is not fully appreciated using conventional (free-breathing) CT models for radiotherapy planning. While target expansion may be performed to allow for the potential error in delineation and motion on a free breathing CT scan, large variations in individual patients’ tumor movement directions and distances may make such expansions difficult to define, and further may involve unnecessary inclusion of excess normal lung in the treated volume. This study has been designed to evaluate the influence of breathing movement on tumors and to assess the validity of the free-breathing CT scan for target delineation in the lung.