Needle Steering Modeling and Analysis using Unconstrained Modal Analysis

Precise needle placement is very important for a number of percutaneous interventions. Poor placement may cause tissue damage, misdiagnosis, poor dosimetry and tumor seeding. Yet precise needle placement is hard to achieve in real practice due to tissue heterogeneity and elastic stiffness, unfavorable anatomic structures, needle bending, inadequate sensing, tissue/organ deformation and movement, and poor maneuverability. To date, there are few effective physical-based needle steering systems exist that can correct the needle deflection in real time. In addition, many procedures are currently not amenable to needles because of obstacles, such as bone or sensitive tissues, which lie between feasible entry points and potential targets. Thus, there is a clear motivation for needle steering in order to provide accurate and dexterous targeting. In this paper, a spring-beam-damper system is proposed to model the system dynamics while applying steering force on the needle end. Instead of using the traditional finite element method, unconstrained model analysis is adopted to derive the system dynamic equations. The modeling procedure and analysis method are given in details. Experiment had also been carried out to verify the accuracy of the proposed model. Conclusions and future works are given in subsequent sections