Interstital lung access using nested cannulas

A cannula configuration method involves a generation of a discretized configuration space of a three dimensional image of an anatomical region, the discretized configuration space including a free-space for navigation of a nested cannula within the anatomical region and a forbidden space unreachable by the nested cannula. The method further involves a selection of a tube target location (24) within the free-space, the tube target location (24) being derived from a computation of contiguous tool trajectory nodes of the discretized configuration space representative of a trajectory of a surgical tool extending through the nested cannula from the tube target location (24) within the free-space to a tool target location (23) within the forbidden space. The method further involves a generation of a series of concatenated path shapes between the tube entry location (24) and the tube target location to form a cannula configuration pathway within the free-space.