Haptic simulation of needle and probe interaction with tissue for prostate brachytherapy training

This paper presents a haptic simulator for prostate brachytherapy. Both needle insertion and the manipulation of the transrectal ultrasound (TRUS) probe are controlled via haptic devices. These are used to render tissue interaction forces computed using a deformable tissue model based on the finite element method (FEM). Needle flexibility and lateral needle bevel forces are also simulated. The TRUS-tissue simulation allows a trainee to practice the 3D intra-operative placement of the TRUS probe for registration with the pre-operative volume study. The needle-tissue simulation allows a trainee to practice needle insertion and targeting. The TRUS probe and the needle can be maneuvered simultaneously. Approaches to computational acceleration for real-time haptic performance are presented. Trade-offs between accuracy and speed are discussed. A graphics-card implementation of the numerically intensive mesh-adaptation operation is also presented.