Fig. 3

Guidance screen of the VBN. The red line represents all bronchial pathways and the blue line is the automatically searched-for route with the closest access to the virtual target. The navigation direction accuracy was defined as the concordance in the progression of the blue line between the VBN using low dose CT and that using standard dose CT. The number of branching’s was defined as the number of red lines that directly branched from the blue line, and the accuracy of the number of branching’s was defined according to the concordance of this number between the VBNs using low dose and standard dose CT. VBN = virtual bronchoscopy navigation