Past Event: Oden Institute Seminar

Real-time error controlled surgical simulation: Towards personalised medicines

Satyendra Tomar, Head, Centre for Information Technologies & Applied Mathematics, U. Nova Gorica; Senior Researcher, Institute of Comp. Engin., U. Luxembourg

Abstract

In this talk, the first a posteriori error-driven adaptive finite element approach for real-time simulation will be presented, and the method will be demonstrated on needle insertion problems. The used model is based on corotational elasticity and a frictional needle/tissue interaction. For simulating soft tissue deformation, the refinement strategy relies upon a hexahedron-based finite element method, combined with a posteriori error estimation driven local h-refinement. The local and global error levels in the mechanical fields (e.g., displacement or stresses) are controlled during the simulation. After showing the convergence of the algorithm on academic examples, its practical usability will be demonstrated on a percutaneous procedure involving needle insertion in a liver and brain. The brain shift phenomena is taken in to account which occurs when a craniotomy is performed. It is observed that the error in the computation of the displacement and stress fields is localised around the needle tip and the needle shaft during needle insertion simulation. By suitably and adaptively refining the mesh in this region, our approach enables to control, and thus to reduce, the error whilst maintaining a coarser mesh in other parts of the domain. Through academic and practical examples it will be demonstrated that our adaptive approach, as compared with a uniform coarse mesh, increases the accuracy of the displacement and stress fields around the needle shaft and, for a given accuracy, saves computational time with respect to a uniform finer mesh. This facilitates real-time simulations. Moreover, this work provides a first step to discriminate between discretization error and modeling error by providing a robust quantification of discretization error during simulations. The proposed methodology has direct implications in increasing the accuracy, and controlling the computational expense of the simulation of percutaneous procedures such as biopsy, brachytherapy, regional anaesthesia, or cryotherapy. Moreover, the proposed approach can be helpful in the development of robotic surgeries because the simulation taking place in the control loop of a robot needs to be accurate, and to occur in real time. The talk will conclude with some discussion on future outlook towards personalised medicines. Bio After completing his Ph.D. from IIT Kanpur (on parallel h-p spectral element methods), he worked as a postdoctoral researcher on numerical simulation of water waves using discontinuous Galerkin method at University of Twente, Netherlands. Thereafter, from 2005 to 2014, he worked as a research scientist at RICAM, Austria, and developed optimal order iterative solvers, and reliable and sharp a posteriori estimates for non-conforming approximations. Since 2015, as a senior researcher at University of Luxembourg, he is working on real-time surgical simulations and some meshless/meshfree methods. Moreover, since October 2018, he is also leading the Centre of Information Technologies and Applied Mathematics at University of Nova Gorica, Slovenia.