In vitro validation of viscoelastic and nonlinear physical model of liver for needle insertion simulation

Needle insertion treatments require accurate placement of the needle tip into the target cancer. However, it is difficult to insert the needle into the cancer because of cancer displacement due to the organ deformation. Then, a path planning using numerical simulation to analyze the deformation of the organ is important for the accurate needle insertion. The objective of our work is to develop and validate a viscoelastic and nonlinear physical liver model. First, an overview is given of the development of the physical liver model. Second, the experimental method to validate the model is explained. In-vitro experiments that made use of a pig's liver were conducted for comparison with the simulation using the model. Results of the in-vitro experiment showed that the liver model reproduces 1) the relationship between needle displacement and force during needle insertion, 2) velocity dependence of needle displacement and force when a puncture occurs, and 3) nonlinear and viscoelastic response of displacement at an internally located point displacement, with high accuracy.