Lung isolation techniques are commonly used to facilitate surgical exposure and to provide single-lung ventilation for patients. We have developed an automatic comparison software for 3D reconstruction based on CT data (3DRACS). It reconstructs the trachea and bronchus and compares them with the DLT, predicting the most suitable size and depth of the DLT for lung isolation.The aim of this study was to compare whether the use of 3DRACS to select a DLT size compared to conventional empirical selection methods could improve incidence of DLT intubation success and reduce airway injury.