טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentKabesa Lior
SubjectGuide Wire Catheterization: Simulation and Actuation
DepartmentDepartment of Mechanical Engineering
Supervisors Professor Moshe Shoham
Dr. Nir Shvalb
Full Thesis textFull thesis text - English Version


Abstract

Minimally invasive techniques such as guide wire insertion for catheterization and stent insertion have become important cardiac procedures.  Nevertheless, there are risks of causing harm by forceful use of the guide wire and catheter during these procedures.  We introduce a novel catheterization technique using an external manipulator that controls the guide wire using fluoroscopic imaging and simulation.  In order to enable accurate and continuous navigation of the guide wire, we examine all the relevant factors for the system's model, e.g., boundary conditions and mechanical properties of the guide wire and the tissue.  This thesis deals with establishing a physical model for the guide wire geometry and with devising an overall system for guide wire navigation.  We introduce a method to use the guide wire simulation together with the electro-mechanical system in order to provide automatic or semi-automatic treatment.

In the first chapter, we provide a short medical background review that clarifies the need to reduce vascular complications during catheterization process, and we survey some common techniques for computing the guide wire deformation such as: Cosserat, FEM, Dynamic Spline, Mass-spring and Rigid links. The second chapter is dedicated to the physical model; we model the guide wire using concatenated rigid links attached to each other via a torsion spring.  The external boundaries determine the deformation of the guide wire inside the artery, assuming small quasi-static movements towards the target.  For that purpose we incorporate external normal forces acting on the guide wire during the collision with the body tissue and internal forces from the torsional stiffness of the guide wire. We define energy terms for those forces and solve the energy equation to find the local minimal energy.  We first review the rigid links energy model that is the basis of this work, then, knowing the limitations of the model, we introduce our modification, which allows enhanced dexterity of the guide-wire.  In order to accomplish this, we analyze the forces exerted on the tissue wall, which in turn may be used to reduce the vascular complications risks while manipulating the guide wire.  To enable a large set of controlled experiments, we fabricated a robot that can manipulate the guide wire from its base point.  We introduce the robot design and the overall system in the third chapter.  Experimental methods and results are given in the last chapters and show our simulation results and our improvement.