Parameter identification for a needle-tissue interaction model.

In this work, needle-tissue interaction forces are modeled by a three parameter force distribution composed of two step functions with variable amplitudes and spacing. A finite element based simulation is used to adjust the parameters and fit the simulation results to the experimental data. In experiments, needle displacements and needle base forces were measured along with tissue displacements. A real-time version of the time-domain cross-correlation method was employed in this study to estimate the tissue displacements from ultrasound radio-frequency data, as done in elastography. In addition to the force model parameters, the elastic parameters of the tissue were adjusted to match the simulated and measured displacements.