Dosimetric comparison of stereotactic body radiotherapy using 4D CT and multiphase CT images for treatment planning of lung cancer: Evaluation of the impact on daily dose coverage

Compared to the conventional approach using helical images for target definition, 4D CT and multiphase 3D CT have the advantage to provide patient-specific tumor motion information, based on which such designed PTVs could ensure daily target coverage. 4D CT-based treatment planning further reduces the amount of normal lung being irradiated while still providing a good target coverage when image guidance is used.