#$%^&*AU2016210734A120170316.pdf#####ABSTRACT A method, consisting of receiving a computerized tomography scan of at least a part of a body of a patient, and identifying voxels of the scan that 5 correspond to regions in the body that are traversable by a probe inserted therein. The method also includes displaying the scan on a screen and marking thereon selected start and termination points for the probe. A processor finds a path from the start point to the 10 termination point consisting of a connected set of the identified voxels. The processor also uses the scan to generate a representation of an external surface of the body and displays the representation on the screen. The processor then renders an area of the external surface 15 surrounding the path locally transparent in the displayed representation, so as to make visible on the screen an internal structure of the body in a vicinity of the path. 2839253vl2/7 PERFORM CT SCAN OF PATIENT 10 NASAL SINUSES f0 GENERATE VOXEL DATA, INCLUDING HOUNSFIELD UNITS, FROM SCAN. DISPLAY 102 3D IMAGE FROM VOXEL DATA PHYSICIAN MARKS STARTAND END POINTS 104 ON IMAGE DEFINE HOUNSFIELD UNITS / GRAY SCALES / 106 SPECIES NAMES OF IMAGE THAT ARE TO BE TREATED AS PERMISSIBLE FOR PATH 1 08 OPERATE PATH FINDING ALGORITHM OVERLAY SHORTEST PATH FOUND ON 3D 110 IMAGE OPTIONALLY ADVISE OF NON-AIR f112 SECTIONS OF PATH GEND FIG. 2
