Presetting the target lesion. Click on to the image tags (within the blue frame), except for the main V1 tag, and preset the target lesion on the CT display. Select the “create polygonal shape” icon (within the red frame) to make an outline of the lesion. Adjust the “window level (WL)” tool bar (yellow arrow) to visualize the lesion. Click the visualized lesion using the “select and keep” icon (within the red frame) and choose a color (orange arrowhead) that you will use to indicate the target lesion. Select the “delete polygonal shape” icon (within the red frame) from the mask tools and delete the outline of adjacent chest wall and unnecessary blood vessels. After completion of presetting, click on the main V1 tag (within the red frame)

Presetting the route. On the CT display, click the “PATH” icon (within the red frame) under the path/measurement tab and a green dotted line will pop up (yellow arrow). The bronchus involved in the target lesion is defined as the end of the route. From this point, create connecting dots from the periphery to the carina by clicking on intermittent points or at bronchial bifurcations) along the center of the bronchial lumen. The line created by connecting these dots represents the bronchial route from the target lesion to the larger central airways. On the axial CT image, it is difficult to grasp the three-dimensional route of the bronchi. To create a route neatly and quickly, connect the dots using multi-planar reconstruction (MPR) images with intermittent arbitrary references to the axial image when a bronchial lumen becomes straight; this way, contact with the bronchial wall can be avoided. After creating the route, click the VE tab on the right upper corner (orange arrow) to switch to the virtual endoscopic image