Biomedical subjects

Venkat Devarajan

Publications and source records attributed to Venkat Devarajan.

9 recordsLinked to original sources

PubMed2006

Selective tessellation algorithm for modeling interactions between surgical instruments and tissues.

We present a selective spatial tessellation algorithm that is specifically optimized for instrument-to-tissue and instrument-to-instrument collision detection cases, which are the essential part of interaction modeling in surgery simulation with haptic feedback. Virtual surgeries demand haptic rate collision solutions only when instruments are involved in collisions. Other collision cases can be processed at slower rates. The proposed selective tessellation algorithm is capable of differentiating among various collision cases and assigning different priorities to their processing. Without making assumptions about any object movement, the algorithm derives clipping volume as collision detection regions which tightly enclose the objects of interest. Results of implementation of the algorithm in a surgical simulation are provided.

Algorithms↗

PubMed2006

Physically accurate mesh simulation in a laparoscopic hernia surgery simulator.

In this paper we use the 2D angular spring based mass-spring-damper (AMSD) model to simulate the plastic mesh in a laparoscopic hernia surgery simulator. We propose a physically based method to systematically derive the optimal parameters of the 2D AMSD model. While the traditional 2D MSD model lacks resistance against bending, the 2D AMSD model with optimized parameters can provide correct bending resistance as well as stretching resistance. The simulated mesh is demonstrated to be much more realistic.

Algorithms↗

PubMed2005

Haptic herniorrhaphy simulation with robust and fast collision detection algorithm.

Collision detection and soft tissue deformation are two major research challenges in real time VR based simulation, especially when haptic feedback is required. We have developed a real time collision detection algorithm for a prototype laparoscopic surgery trainer. However, this algorithm makes no assumptions about its applications and thus can be a generic solution to complicated collision detection problems. For soft tissue modeling, we use the mass-spring model enhanced with volume constraint and, stability control methods. We use both the new collision detection and tissue modeling algorithms in a bimanual hernia repair simulator which performs a mesh prosthesis stapling operation in real time.

Algorithms↗

PubMed2004

StapSim: a virtual reality-based stapling simulator for laparoscopic hemiorrhaphy.

The growing interest in laparoscopic hernia surgery and in surgical simulators has motivated our current research. In this paper, we present our work in simulating the process of stapling used in laparoscopic herniorrhaphy. By connecting two separate deformable preperitoneal meshes together, our model has simulated the repair process for a bilateral hernia correction. The task of mesh placement and stapling of corners was simulated, to allow surgeons to practice their hand-eye coordination. Various deformable models and numerical methods were researched to comply with the real time requirements. The stapling simulator can either be independently used as a part-task (sub-task) trainer or be integrated as a module of a complete VR-based simulator. A phantom device was used to provide haptic-based force feedback during task rehearsals.

Computer Simulation↗

PubMed2004

Realistic anatomical texture for laparoscopic surgery simulation.

Visual realism in laparoscopic surgery simulation is very desirable. Previously, much work has been done to extract the organs and textures from the visible human data (VHD) using various rendering techniques. We present here a technique to extract the true texture from visible human data for the laparoscopic herniorrhaphy simulation. A VHD slice provides texture only in the direction in which it was visualized whereas the surgeons visualize the facet of an organ during a laparoscopic surgery. Our paper describes an approach for the extraction and mapping facet texture from the VHD.

Algorithms↗

PubMed2003

Special visual effects for surgical simulation: cauterization, irrigation and suction.

Simulation of cauterization and irrigation forms an important part of a virtual laparoscopic trainer. Typically, they are carried out to stop the intragastric bleeding due to an accidental cut by the surgeon. In this paper, we present a method to simulate these special visual effects in an integrated fashion in real-time. We have simulated cauterization and irrigation using a particle-based system. A physics-based model is used to simulate accumulation and removal of fluids. The integrated special effects were implemented and tested in a prototype environment.

Cautery↗

PubMed2003

Simulation of a preperitoneal mesh in laparoscopic herniorrhaphy.

During a laparoscopic hernia surgery, a preperitoneal mesh is tacked or stapled to the defect on the inside in order to close the fissure created by the hernia. Here we have proposed and implemented a novel technique for simulating the movement and stapling of the mesh for use in a virtual reality based laparoscopic trainer. The use of particle based system and Mass-Spring model in simulating the movement of the mesh is also discussed.

Computer Simulation↗

PubMed2002

Simulation of bleeding during laparoscopic herniorrhaphy.

Simulation of intragastric bleeding due to an accidental cut by the surgeon is an important component of a virtual laparoscopic herniorrhaphy trainer. We present a method for simulating bleeding during laparoscopic hemiorrhaphy here. The various approaches used in previous research work are reviewed and our present approach is justified. Physically based fluid models used in computer graphics are used to simulate bleeding.

Algorithms↗

PubMed2002

Adaptive hybrid interpolation techniques for direct Haptic rendering of isosurfaces.

Direct Haptic rendering of voxels from an anatomical dataset provides patient specific haptic feedback vital for diagnosis and surgical planning. Our algorithm uses zero sets of scalar trivariate function for polynomial interpolation with sixty-four neighborhood points to generate isosurfaces on the fly for haptic rendering. This approach gives continuity in surfaces as well as better capture of isosurface features of the medical dataset. The detailed algorithm is presented along with the description of results from haptically rendering medical datasets.

Algorithms↗