Physically-based virtual environments (VEs) provide realistic interactions and behaviors for computer-based medical simulations. Limited CPU resources have traditionally forced VEs to be simplified for real-time performance. Multi-core processors greatly increase the computational capacity of computers and are quickly becoming standard. However, developing non-application specific methods to fully utilize all available CPU cores for processing VEs is difficult. The paper describes a pipeline VE architecture designed for multi-core CPU systems. The architecture enables development of VEs that leverage the computational resources of all CPU cores for VE simulation. A VE's workload is dynamically distributed across the available CPU cores. A VE can be developed once and scale efficiently with the number of cores. The described pipeline architecture makes it possible to develop complex physically-based VEs for medical simulations. Initial results for a craniotomy simulator being developed have shown super-linear and near-linear speedups when tested with up to four cores.

Virtual Reality-based surgical simulators can utilize Collaborative Virtual Environments (C-VEs) to provide team-based training. To support real-time interactions, C-VEs are typically replicated on each user's local computer and a synchronization method helps keep all local copies consistent. This approach does not work well for voxel-based C-VEs since large and frequent volumetric updates make synchronization difficult. This paper describes a method that allows multiple users to interact within a voxel-based C-VE for a craniotomy simulator being developed. Our C-VE method requires smaller update sizes and provides faster synchronization update rates than volumetric-based methods. Additionally, we address network bandwidth/latency issues to simulate networked haptic and bone drilling tool interactions with a voxel-based skull C-VE.

Many computer based medical simulators focus on individual skills training. However, medical care is frequently rendered by teams. In addition, the conditions under which care is provided can be a crucial factor in training. For example, mass-casualty events can involve the management and triage of large numbers of victims under austere environments. Learning to care for the injured warfighter during combat requires realistic simulation of battlefield conditions. Current simulation systems do not adequately address team training requirements within lifelike environments. This paper describes our work toward the development of an immersive virtual environment that meets these needs.

Traumatic head injuries can cause internal bleeding within the brain. The resulting hematoma can elevate intracranial pressure, leading to complications and death if left untreated. A craniotomy may be required when conservative measures are ineffective. To augment conventional surgical training, a Virtual Reality-based intracranial hematoma simulator is being developed. A critical step in performing a craniotomy involves cutting burrholes in the skull. This paper describes volumetric-based haptic and visual algorithms developed to simulate burrhole creation for the simulator. The described algorithms make it possible to simulate several surgical tools typically used for a craniotomy.

Aims: Open cricothyroidotomy is an essential skill in emergency airway management. It is the procedure of choice when ventilation cannot be achieved by less invasive methods. This skill has relevance to both military and civilian medical services. For example, cricothyroidotomy is the recommended approach for the management of certain thermal or toxic gas injuries during tactical field care. As another example, cricothyroidotomy may be necessary to secure the airway in gunshot wounds to the face, a situation that can be encountered both during combat and in the civilian emergency room. Current training models are inadequate from a physiological and anatomical perspective. We have developed a VR-based simulator that addresses these shortcomings. To date, no comparable computer-based simulator for cricothyroidotomy has been developed. Methods: Our system is based on the Haptic Workbench. Using this paradigm, users can feel virtual objects in the same location as their visual sense reports. Hand-eye coordination is preserved. Our simulator teaches students the dexterous skills necessary for cricothyroidotomy. Students can palpate a virtual neck to locate the cricothyroid membrane. The thyroid model encodes the properties of various tissue types. The system uses a novel combination of texture-mapped visuals and haptic feedback to simulate cutting. This approach creates the appearance of incisions on the skin surface, but does not change the model’s topology. Surgical effects, such as bleeding are generated. The system can also simulate endotracheal tube insertion. Results: Fig. 1 is a screenshot of the simulator in use. Preliminary assessment by surgeons familiar with the procedure has been favorable. The evaluators commented favorably on the accuracy of tactile response during palpation, incision, and intubation, as well as the visual effects of bleeding.FigureConclusions: A prototype cricothyroidotomy simulator has been developed. Initial evaluation by subject matter experts is favorable. Our next focus is to incorporate self- and cognitive-training capabilities in the simulator. Conflict of Interest: Authors indicated they have nothing to disclose.

Training professionals for real-world application of required knowledge and skills and assessing their competence are major challenges. Simulations are being used in education and training to enhance understanding, improve performance, and assess competence. Validated virtual reality (VR) simulations provide a means of making experiential learning reproducible and reusable. Advanced communication networks, such as Internet2 Access Grid, allow dissemination of these simulations and collaborative learning independent of distance. The prior experiences of our three universities led to an interdisciplinary collaboration to further develop and evaluate an integrated, fully immersive, interactive VR based system. This environment employs simulations that are visually three-dimensional and are driven dynamically by a rules-based artificial intelligence engine within Flatland, a virtual environments development software tool, and associated commodity hardware. Studies include usability and validation, deployment for distributed testing over Internet2, and evaluation of impact on training and performance using concept mapping and knowledge structure methods. Subject matter experts found face and content validity in our closed head injury simulation. Seven pairs of medical students participated collaboratively in problem solving and managing of the simulated patient in VR. Students stated that opportunities to make mistakes and repeat actions in VR were extremely helpful in learning specific principles and they felt more engaged than in standard text-based scenarios. 48 students participated in knowledge structure experiments pre and post simulation experiences. Knowledge structure relatedness ratings were significantly improved in those students with lower pre-VR relatedness ratings indicating a potential value of VR simulation in learning. This research cuts across the integration of computing, networking, human-computer interfaces, learning, and knowledge acquisition. VR creates a safe environment to make mistakes and could allow rapid deployment for just-in-time training or performance assessment.