  This paper describes the use of the corotational cut Finite Element Method
(FEM) for real-time surgical simulation. Users only need to provide a
background mesh which is not necessarily conforming to the
boundaries/interfaces of the simulated object. The details of the surface,
which can be directly obtained from binary images, are taken into account by a
multilevel embedding algorithm applied to elements of the background mesh that
cut by the surface. Boundary conditions can be implicitly imposed on the
surface using Lagrange multipliers. The implementation is verified by
convergence studies with optimal rates. The algorithm is applied to various
needle insertion simulations (e.g. for biopsy or brachytherapy) into brain and
liver to verify the reliability of method, and numerical results show that the
present method can make the discretisation independent from geometric
description, and can avoid the complexity of mesh generation of complex
geometries while retaining the accuracy of the standard FEM. Using the proposed
approach is very suitable for real-time and patient specific simulations as it
improves the simulation accuracy by taking into account automatically and
properly the simulated geometry.
