Motion Planning in Deformable Soft Tissue with Obstacles with Applications to Needle Steering

Abstract

In this chapter we introduce motion planning for steerable needles, a new class of needles that can follow curved paths around obstacles to reach clinical targets in soft tissue. Steerable needles are capable of reaching targets inaccessible by rigid needles.

We introduce a simulation and planner for steerable bevel-tip needle insertion that compensates for errors that occur due to tissue deformations. As in chapter 3, we begin with a simulation and planner in a 2-D imaging plane. Our interactive simulation approximates soft tissues as linearly elastic materials and uses a 2- D finite element model to compute tissue deformations due to tip and friction forces applied by the steerable needle. Polygonal obstacles represent tissues that cannot be cut by the needle, such as bone, or sensitive tissues that should not be damaged, such as nerves or arteries. The simulation enforces nonholonomic constraints on needle motion.