Research On Geometric Model And Insertion Force Of Biopsy Needle

With the development of modern medical technology, Minimally Invasice Surgery(MIS) has been widely used in clinical practice. As the indispensable tool of MIS, biopsy needles play an important part in tissue biopsy sampling, local radiation therapy and robot-assisted percutaneous surgery. However, in the process of biopsy needles’ purcture, because of lacking the analysis of cutting tip shape and modeling of insertion force, the target tissue’s positioning is not accurate, which results the rate of operation is greatly reduced.Consequently, both the analysis of cutting tip shape and modeling of insertion force has been a hot topic.In the paper, to start with, the research sets up the geometric model of the biopsy needles’ shape and deduces the mathematical expression of needle tip’s cutting parameters.The research aims to get the influence rule of different biopsy needles. The normal rake angle and inclination angle’s distribution characteristics are studied. Then, the puncturing process is divided into contact phase and fracture phase through the analysis of the insertion mechanism between percutaneous biopsy needle and tissue. In order to get the characteristic of biopsy needle’s force at the contact phase, the contact model is set up and the mathematic expression of biopsy needle’s contact force 一 s deduced. It reveals that the contact force changes with the shear modulus, inclination angle and the number of needle’s plane, and makes the optimization of the needle’s cutting parameters after the comprehensive consideration. In order to obtain the force along the puncturing direction, the biopsy needle’s force is divided into frictional force, cutting force and extrusion force, which is analyzed by theoretical model respectively; based on the law of conservation of energy, biopsy needle’s cutting efficiency is studied. Finally, slicone tissue is punctured by test platform to get the test data and the contact model is validated by force data of contact phase. According to the comparsion between experiment and theory, The mathematical expression of unit area’s tissue mode is derived by the experimental data and the insertion force of fracture phase is accurate and effective.The paper aims to investigate the geometric characterstic of biopsy needle, and builds the model of insertion force during the puncturing process. It provides the analysis basis for the accurate positioning and tissue puncture of the clinical diagnosis. Meanwhile, the analysis of multi-plane needle’s contact force extends the contact theory. The method also has a reference value for the puncture mechanism between soft tissue and biopsy needle.