Figure 1) Panoramic Image of Abdominal Cavity, made from composited Endoscopic Images
Figure 2) Simulation of Cauterization of Gallbladder Border.
The objective of this project is to continue development of the HIT Labs laparoscopic surgical simulator and to evaluate its effectiveness as a training tool for teaching port site placement. The choice of entry point locations in laparoscopic procedures is critical to a successful surgery. Improper placement results in approach angles and relative angles between instruments that are awkward for the surgeon, making the procedure difficult or impossible. Through the use of an interactive simulation of laparoscopic port placement and subsequent surgical tasks we hope to
Additional educational objectives are:
The current virtual laparoscopic port-site simulator as developed in the HIT lab consists of a virtual model of an abdominal cavity with retracted liver and gallbladder, two virtual instruments, and a virtual scope that provides the variable angle and magnification of an endoscope being moved into and out of the environment. What is seen on the screen depends on the position and attitude of the virtual scope. This model is implemented in Iris Inventor in C++ on an SGI O2 hardware platform running IRIX.
The virtual abdominal model consists of a photographic texture made from composited frames taken from actual video footage of a laparoscopic cholecystectomy. The texture is mapped onto a simplified geometry
The position and orientation of the virtual instruments and scope is determined by those of actual endoscopic instruments and a physical scope mock-up which are tracked by a Polhemus 6 degree of freedom input device. These physical instruments are inserted into a mockup patient abdomen model
We have developed two prototype physical abdomen models. One consists of nylon mesh stretched over a plastic dome wire frame. The second is a half cylinder of Plexiglas with a grid of holes. We are considering purchasing a latex mannequin model from Simulates for additional realism. The holes in the various abdomen models represent possible port sites for the instruments.
In a previous version of the simulator the surgeon's hands are tracked rather then the instruments themselves. The resulting virtual hand grabbed the virtual instruments. The use of tracked instruments in the current version results in a simulation that is closer to the actual surgical tasks.
The modeling and graphics software have been configured to provide:
Figure 1) Panoramic Image of Abdominal Cavity, made from composited Endoscopic Images |
Figure 2) Simulation of Cauterization of Gallbladder Border. |
We plan to perform two studies in which we run medical students from the UW through a training program using the simulator. Human Subjects Approval will be sought for this study. The preliminary study will have the following objectives.
Based on results from this first study, we will make possible modifications to the software, the trial protocols, the anatomical models and the surgical task. The follow on study will have the following additional objectives.
In the second study we will create a non-simulator tube cannulation task as a control evaluator to determine the usefulness of the simulator for transfer of training. The study participants will be partitioned into subgroups that perform different numbers of simulator trials (including 0 trials) prior to performing the non-simulator task. The non-simulator task will be either a surgical task using abstract or realistic physical models, or an actual surgical task using lab animals. The correlation between number of simulator trials and performance on the non-simulator task will provide an indication of the effectiveness of the simulator as a training tool.