A computer based method of virtually generating an intra-lumen pathway to a target inside a body, comprising: imaging a patient to obtain a plurality of scans; creating a 3D image volume from the scans comprising a plurality of voxels; selecting a target in the 3D image volume; detecting an anatomical feature related to a network of lumens within the 3D image volume; identifying a seed point, wherein the seed point is a center of gravity of the detected anatomical feature; segmenting voxels that represent space inside the lumens of the network, wherein segmenting starts at a voxel represented by the seed point; generating a computerized three-dimensional model of the lumen network using the segmented voxels; marking an exit point on a pathway in the three-dimensional model of the lumen network; generating a pathway from the anatomical feature to the exit point on the three-dimensional model of the lumen network; and connecting the exit point and the target with a straight line; wherein segmenting voxels that represent space inside the lumens of the network comprises: a) defining a threshold value; b) marking all related voxels according to the threshold value beginning with the voxel represented by the seed point; c) recording a whole number of marked voxels; d) increasing the threshold value; e) repeating steps b) and c), thereby beginning a next iteration; f) comparing the number of marked voxels to the number determined in a previous iteration; g) setting a limit for the increase determined at f) over which the increase is attributed to leakage and the increased threshold value at d) is reset to that from the previous iteration, thereby establishing a selected threshold; h) segmenting the marked voxels using the selected threshold; i) adding the segmented voxels to the voxel represented by the seed point, thereby growing a pathway and resetting the seed point to a center of a distal end of the pathway; and j) repeating steps b) through i) until the pathway is complete. imaging a patient to obtain a plurality of scans; creating a 3D image volume from the scans comprising a plurality of voxels; selecting a target in the 3D image volume; detecting an anatomical feature related to a network of lumens within the 3D image volume; identifying a seed point, wherein the seed point is a center of gravity of the detected anatomical feature; segmenting voxels that represent space inside the lumens of the network, wherein segmenting starts at a voxel represented by the seed point; generating a computerized three-dimensional model of the lumen network using the segmented voxels; marking an exit point on a pathway in the three-dimensional model of the lumen network; generating a pathway from the anatomical feature to the exit point on the three-dimensional model of the lumen network; and connecting the exit point and the target with a straight line; wherein segmenting voxels that represent space inside the lumens of the network comprises: a) defining a threshold value; b) marking all related voxels according to the threshold value beginning with the voxel represented by the seed point; c) recording a whole number of marked voxels; d) increasing the threshold value; e) repeating steps b) and c), thereby beginning a next iteration; f) comparing the number of marked voxels to the number determined in a previous iteration; g) setting a limit for the increase determined at f) over which the increase is attributed to leakage and the increased threshold value at d) is reset to that from the previous iteration, thereby establishing a selected threshold; h) segmenting the marked voxels using the selected threshold; i) adding the segmented voxels to the voxel represented by the seed point, thereby growing a pathway and resetting the seed point to a center of a distal end of the pathway; and j) repeating steps b) through i) until the pathway is complete. a) defining a threshold value; b) marking all related voxels according to the threshold value beginning with the voxel represented by the seed point; c) recording a whole number of marked voxels; d) increasing the threshold value; e) repeating steps b) and c), thereby beginning a next iteration; f) comparing the number of marked voxels to the number determined in a previous iteration; g) setting a limit for the increase determined at f) over which the increase is attributed to leakage and the increased threshold value at d) is reset to that from the previous iteration, thereby establishing a selected threshold; h) segmenting the marked voxels using the selected threshold; i) adding the segmented voxels to the voxel represented by the seed point, thereby growing a pathway and resetting the seed point to a center of a distal end of the pathway; and j) repeating steps b) through i) until the pathway is complete.