GeRTiSS: a generic multi-model surgery simulator. Carlos Monserrat, Oscar López, Ullrich Meier, Mariano Alcañiz, Carmen Juan, Vicente Grau Medical Image Computing Laboratory (MedICLab), Universidad Politécnica de Valencia, (Spain) cmonserr@dsic.upv.es Abstract. The construction of surgery simulators will be a key tool in the development and diffusion of minimally invasive surgery. Nowadays, most simulators are oriented to training surgeons in only one surgery technique. Most of them only permit the modelling of tissues with only one kind of deformable model. In this paper, we present our generic surgery simulator for minimally invasive surgery. In this surgery simulator, surgeons can construct any surgery scenario that they want to practice. Our surgery simulator permits the surgeons to select the deformable model that best adjusts to the biomechanical properties of each organ. Once the surgeon has finished the training, our surgery simulator can generate a report that contains an assessment evaluation of that training. 1.- Introduction. One of main challenges in new technologies applied to medicine is the construction of virtual environments for surgical training. Environments of this kind are called surgery simulators. These simulators require [6][3]: • the internal organs of a patient, to be visualised as realistically as possible; • the organs to react realistically in real time to user interactions and to the established environmental restrictions; • these virtual organs to react, to typical surgeon gestures (like cauterisation, cutting or clipping) through realistic geometric and topologic modifications,. While 3D visualisation techniques are sufficiently developed to accomplish the first requirement, the last two are very difficult to complish. This limitation is due to the fact that current computer power is too slow with respect to the computational requirements of surgery simulators to simulate the biomechanical behaviour of internal organs of virtual patients. Surgery simulators can be grouped into three technologically sequential generations [1][21]: • first generation: these surgery simulators only consider the geometric nature of human anatomy [8][9];