Development of surgical simulator based on FEM and deformable volume-rendering

In this paper, we describe our novel surgical simulation system, which provides FEM-based real-time deformation, interaction by using haptic device, and high-quality visualization of the liver and inner blood vessel structures based on 3D texture-based deformable volume-rendering. Our software system consists of mainly four components of independent processes and threads; (1) 3D texture based volume rendering, (2) haptic device input/output, (3) FEM computation, and (4) inter-process communication management. Tetrahedral meshes for FEM computation and volume-rendering are updated for every frame of image display and deformation. For faster FEM computation, we employed the central-difference method for forced displacement calculation. We implemented our system with dual Pentium Xeon 3GHz PC workstation with 1G byte RAM, a video card with nVIDIA Quadro4 900XGL GPU, and Windows XP Professional OS. As a haptic device, PHANToM desktop was employed. We used liver data of 128x128x128 matrix size as 3D-texture data, which was segmented in abdominal X-ray CT Angiography data set and colored in grayscale and dual-indexed coloring based on radial basis function interpolation. By using window size of 480, we obtained refresh rate of 67 frames/sec for image display and 16 msec for haptic device output. Our preliminary study shows feasibility of surgical simulators with FEM and deformable volume-rendering.