by Ron Alterovitz

Abstract:
Medical procedures such as biopsies, anesthesia injections, and brachytherapy cancer treatment require inserting a needle to a specific target location inside the human body. This is difficult because (1) needle insertion causes surrounding soft tissues to displace and deform, and (2) it is often difficult or impossible to obtain precise imaging data during insertion. To facilitate physician training and pre-operative planning for these procedures, we are developing an interactive simulation of the insertion of needles into soft tissue. The simulator is based on a 2D finite element model where the tissue mesh is updated to maintain element boundaries along the needle shaft and the tissue is deformed due to cutting and frictional forces. The motion planner combines the simulation with numerical optimization to compensate for predicted tissue deformations caused by needle insertion.
We consider both traditional stiff needles and a new class of highly flexible bevel-tip needles that follow curved paths and can be steered around obstacles to reach a target.