Time Trends in Nodal Volumes and Motion During Radiotherapy for Patients With Stage III Non-Small-Cell Lung Cancer

A large variability of changes in nodal volume between patients was observed. However, this had limited clinical impact because volumes and hence volume changes were small. The nodal motion did not change significantly during therapy. However, because of the large interpatient variability of nodal motion before treatment, internal margins for nodal areas should be calculated before radiotherapy using RCCT, such that the margins can be applied for individual patients. Repeated imaging of the nodes seems however to be of limited use because the observed individual changes in nodal volume and motion tend to fall within the commonly applied margins.