An intestinal surgery simulator: real-time collision processing and visualization

This research work is aimed toward the development of a VR-based trainer for colon cancer removal. It enables the surgeons to interactively view and manipulate the concerned virtual organs as during a real surgery. First, we present a method for animating the small intestine and the mesentery (the tissue that connects it to the main vessels) in real-time, thus enabling user interaction through virtual surgical tools during the simulation. We present a stochastic approach for fast collision detection in highly deformable, self-colliding objects. A simple and efficient response to collisions is also introduced in order to reduce the overall animation complexity. Second, we describe a new method based on generalized cylinders for fast rendering of the intestine. An efficient curvature detection method, along with an adaptive sampling algorithm, is presented. This approach, while providing improved tessellation without the classical self-intersection problem, also allows for high-performance rendering thanks to the new 3D skinning feature available in recent GPUs. The rendering algorithm is also designed to ensure a guaranteed frame rate. Finally, we present the quantitative results of the simulations and describe the qualitative feedback obtained from the surgeons.

1. Introduction

Minimally invasive surgical (MIS) procedures are gaining popularity over open procedures among surgeons and patients. This is mainly due to less postoperative pain, fewer infections, and an overall faster recovery. The tremendous success of laparoscopic cholecystectomy (gall bladder removal) has prompted surgical practitioners and educators to apply such techniques to other gastrointestinal procedures. In this paper, we focus on laparoscopic colectomy (colon cancer removal). Studies show that many patients undergoing this procedure benefit from the advantages of the MIS procedures listed above while sharing the same risks of the corresponding open procedure [1]. Yet, as with most laparoscopic procedures, it is difficult to master, with a very flat learning curve [2]. As part of the current training procedure, surgeons practice on pigs to get a feel for the organ's behavior. However, this technique is prohibitively expensive and also raises numerous ethical issues. We believe that a VR-based simulator platform can significantly help nonspecialist surgeons and medical residents to acquire the necessary surgical skills in a cost-effective way. This may well result in popularizing the use of the laparoscopic technique for this procedure, thus benefiting more patients. Thus, our aim is to simulate the behavior of the intestine when the surgeon is practicing in the virtual environment. Note that the current scope of this research work does not include the simulation of the cancer removal itself. We focus on two important pedagogical problems: 1) camera positioning by allowing the trainee to visualize the relevant organs in 3D, 2) manual dexterity by letting them interactively manipulate these organs. For many surgeons who are trained primarily in open techniques, this may help to overcome the perceptual and motor challenges associated with MIS procedures.