Research Of Trajectory Planning Of Needle Insertion In Soft Tissue Based On Potential Field Method And Experiment Validation

With the aim of improving the precision of brachytherapy, this paper focuses on the process of needle insertion in soft tissue under assistance with robotic system. Artificial non-creatural material preparation and trajectory planning during needle insertion are main content in this research. The result can be concluded as following:Preparing method of polyvinyl alcohol hydrogel, which is an alternative material that substiture for soft tissue in seed implant brachytherapy simulation experiment, and its properties verification are introduced in detail. Based on a mass of experiments, the polyvinyl alcohol hydrogel with better transparence and force characteristic is prepared following the method of freeze and thaw cycles. Stress-strain curves of polyvinyl alcohol hydrogel have been received with groups of stretch tests. A reasonable proportion of ingredient is sought out by test and comparison with porcine liver.According to the characteristic of artificial potential field, the 3D potential function which combine the attract force and repulsion force is defined. The tissue model can be divided into elements, and the minimum of composition force can be calculated. Through static analysis the optimized position of needle tip can be obtained.In the experiment verification, an experiment setup is built to perform the needle insertion in soft tissue. A vision system, which can collect the three dimensional position data of target point, is contained. The reason of error is analyzed by comparing of simulation results and experiment results. Corresponding improving scheme is raised.