Sensorless planning for medical needle insertion procedures

− Medical procedures such as seed implants, biopsies, and treatment injections require inserting a needle tip to a specific target location inside the human body. This is difficult because (1) insertion causes soft tissues to displace and deform, and (2) it is often difficult or impossible to obtain imaging data during insertion. We are developing a sensorless planning system for needle insertion that incorporates numerical optimization and a soft tissue simulation based on finite element methods. The simulation, based on a dynamic FEM formulation, models the effects of needle tip and frictional forces on soft tissues defined by a 2D mesh. In this paper we describe a sensorless planning algorithm for radioactive seed implantation that computes needle offsets to minimize seed placement error. The resulting needle offsets compensate for predicted tissue deformations without real-time imaging.