  Virtual models are important for training and teaching tools used in medical
imaging research. We introduce a workflow that can be used to convert
volumetric medical imaging data (as generated by Computer Tomography (CT)) to
computer-based models where we can perform interaction of tool with the tissue.
This process is broken up into two steps: image segmentation and tool-tissue
interaction. We demonstrate the utility of this streamlined workflow by
creating models of a liver. A FE model for probe insertion has been developed
using cohesive elements to simulate the tissue rupture phenomena. FE based
simulations are performed and the results are compared with that of various
published papers. An analytical model that governs the reaction forces on the
needle tip has also been developed. Expressions for reaction forces acting in
both axial and transverse directions on a symmetric tip needle and a bevel tip
needle are developed. These models consider local tissue deformation by the
needle and the frictional forces generated due to the inclusion of the needle
in the tissue, but do not consider the role of tissue rupture toughness
parameter Gc due to which some differences are visible in FE based simulations
and these analytical results.
