斜尖针穿刺软组织建模及针尖轨迹预测

Modeling of bevel-tipped needle inserting into soft tissue and estimation of needle tip trajectory

在经皮穿刺过程中,当带斜尖的针穿刺软组织时,针与其周围组织相互作用,导致针体产生弯曲变形,针尖偏离预定方向,进而直接影响穿刺手术的定位精度。将针穿刺软组织的过程视为准静态过程,并进行离散化,建立针-组织相互作用模型。在该模型中,考虑到软组织的非线性与各向异性,将针视为由一系列非线性弹簧支撑的悬臂梁,且各点的弹簧刚度彼此不同。建立针-组织相互作用中的摩擦力及切割力模型,借助于穿刺实验,将穿刺力分解为摩擦力和切割力,进而获得力模型中的各个参数。基于虚拟非线性弹簧模型和穿刺力模型,根据最小势能原理,采用瑞利-里兹法预测针的偏转,进而获得进针过程中针尖的轨迹。仿真及实验结果表明,该模型能够精确地预测针尖位置,为穿刺路径规划提供理论依据。

In percutaneous puncture process, when a bevel-tipped needle is inserted into soft tissue, the needle will bend and its tip will deviate from the predetermined direction due to the interaction between the needle and soft tissue, which directly affects the positioning accuracy of the puncture operation. This paper assumes that the process of the needle inserting into soft tissue is a qua- si-static process and the process is discretized, and a needle-tissue interaction model is established. In this model, taking into account the nonlinearity and inbomogeneity of the soft tissue, the needle is considered as a cantilever beam supported by a series of nonlinear springs, and the stiffness value of each spring is different. From the needle insertion experiment, the insertion force is decomposed into the friction force and cutting force, the friction force model and cutting force model for the needle-tissue interaction are established, and then the parameters of the two force models are obtained. Based on the virtual nonlinear spring model and insertion force models, according to the minimum potential energy principle, the Rayleigh-Ritz method is used to predict the deflec- tion of the needle, and then the trajectory of the needle tip in the needle insertion process is obtained. The simulation and experi- ment results show that the proposed model can accurately predict the position of the needle tip, which provides a theoretical basis for further puncture path planning.