Precision-oriented Research On Key Technologies Of Robot-assisted Brachytherapy

Effective robot-assisted brachytherapy system can help to steer the instrument toreach the seed targets accurately. However, with the interaction between needle andtissue, the displacement of general flexible needle and creatual tissue can not beavoided.This study investigates a new tissue equivalent material used for application intargeting accuracy research on insertion procedures. We developed a transparent PVAhydrogel to mimic the creatural tissue deformation in lab environment. The effects ofchemical composition and synthesis technique on the equivalent material have beentested in detail. Furthermore, a physical model of human organs with PVA materialhas been developed by reverse engineering and rapid prototyping processing.As a part of on going efforts to improve the precision, a mechanics-based modelfor the bevel-tipped flexible needle has been proposed. Using the Galerkin method,the displacement response of geometry nonlinear Euler-Bernoulli needle resting on anonlinear Winkler foundation has been investigated. The Galerkin method was used todiscretize the governing equation and subsequently, its solution of the needle wasdetermined via the iterative method.Finally, we then presented a whole insertion process simulation in each time stepconstantly, which can be used to predict insertion error. A comprehensive parametricsensitivity analysis was carried out to investigate the effects of different parameters.Using this simplified model, the forward kinematics of the needle can be solvedanalytically, enabling dynamic trajectory planning in real time.