Mechanics-based modeling of needle insertion into soft tissue

Insertion of bevel-tip steerable needles to reach target positions inside the tissue is an important step in modern minimally invasive surgery (MIS). When the needle is inserted into soft tissue, it bends naturally due to the asymmetric forces. In this paper, mechanics-based modeling of needle insertion is developed, based on which the needle deflection during insertion can be predicted. Utilizing the beam theory and Rayleigh-Ritz method, the shape function of the needle deflection can be formulated mathematically. An online evaluation method for load distribution is further proposed to determine the distributed load when the needle is inserted into non-homogenous tissue. Experiments are finally performed to verify the correctness of the proposed approach.