Marco Agus magus@crs4.it Andrea Giachetti giach@crs4.it Enrico Gobbetti gobbetti@crs4.it Gianluigi Zanetti zag@crs4.it Antonio Zorcolo zarco@crs4.it CRS4 VI Strada Ovest Z. I. Macchiareddu I-09010 Uta (CA), Italy www.crs4.it Presence, Vol. 12, No. 1, February 2003, 110–122 © 2003 by the Massachusetts Institute of Technology Real-Time Haptic and Visual Simulation of Bone Dissection Abstract Bone dissection is an important component of many surgical procedures. In this paper, we discuss a haptic and visual simulation of a bone-cutting burr that is being developed as a component of a training system for temporal bone surgery. We use a physically motivated model to describe the burr-bone interaction, which includes haptic forces evaluation, the bone erosion process, and the resulting debris. The current implementation, directly operating on a voxel discretization of patient-spe- cic 3D CT and MR imaging data, is efcient enough to provide real-time feedback on a low-end multiprocessing PC platform. 1 Introduction Bone dissection is an important component of many surgical procedures. In this paper, we discuss a real-time haptic and visual implementation of a bone-cutting burr that is being developed as a component of a training simula- tor for temporal bone surgery. The specic target of the simulator is mastoid- ectomy, a very common operative procedure that consists in the removal, by use of the burring tool, of the mastoid portion of the temporal bone. The im- portance of computerized tools to support surgical training for this kind of intervention has been recognized by a number of groups that are currently developing virtual reality simulators for temporal bone surgery (Wiet et al., 2000; Pesser, Petersik, Tiede, Hohne, & Leuwer, 2000). Our work is charac- terized by the use of patient-specic volumetric object models directly derived from 3D CT and MRI images, and by a design that provides realistic visual and haptic feedback, including secondary effects such as the obscuring of the operational site due to the accumulation of bone dust and other burring de- bris. The need to provide real-time feedback to users while simulating burring and related secondary effects imposes stringent performance constraints. Our solution is based on a volumetric representation of the scene, and it harnesses the locality of the physical system evolution to model the system as a collection of loosely coupled components running in parallel on a multiprocessor PC platform. Previous work has demonstrated the effectiveness of voxel-based rep- resentations for the generation of force feedback in the case of rigid body envi- ronments (McNeely, Puterbaugh, & Troy, 1999), virtual clay models (Avila & Sobierajski, 1996; Galyean & Hughes, 1991; Wang & Kaufman, 1995; He & Kaufman, 1997), or deformable bodies (Cotin, Delingette, & Ayache, 1996; Gibson et al., 1998; Frisken-Gibson, 1999; James & Pai, 2001). This article, an extended version of our IEEE Virtual Reality 2002 contribu- tion (Agus, Giachetti, Gobbetti, Zanetti, & Zorcolo, 2002a), focuses on the 110 PRESENCE: VOLUME 12, NUMBER 1