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At least 631 records · Page 35Linked to original sources

PubMed2004

Development and application of virtual reality technology to improve hand use and gait of individuals post-stroke.

Development and application of virtual reality (VR) systems for rehabilitation is an iterative process produced by collaboration of an inter-disciplinary team of engineers, neuroscientists and clinician-scientists. In this paper the use of virtual reality technology for the rehabilitation of individuals post-stroke is described. The development of the hardware is based on principles of motor control. Development of the software uses findings from the enrichment and motor plasticity and training literatures as well as principles of motor learning. Virtual environments are created to afford individuals post-stroke opportunities to practice tasks for which they require rehabilitation. These tasks, related to hand function and gait, are trained both at the impairment and functional level. The training engages users to allow for the repetitive intensive practice required for behavioral motor plasticity. Results from a series of upper and lower extremity studies indicate that use of VR technology to augment rehabilitation of individuals post-stroke merits further study.

Gait Disorders, Neurologic↗

PubMed2004

Realistic simulation of surgical cutting of soft tissues in real time with force feedback.

In this paper we present a geometrically efficient algorithm coupled with a physically based numerical scheme using a meshfree approach for the simulation of surgical procedures including surgical cutting in multimodal virtual environments. Progressive cutting, without the generation of new primitives, is achieved by snapping the nearest nodes to the interaction point between the cutting tool and the underlying polygon edge. The realism of the simulations is enhanced by employing a local subdivision algorithm in the vicinity of the tool-tissue interaction region and a cutting gutter to display the interior structure of the soft tissue as the cut opens up. A meshfree method is used to compute the deformation fields and interaction forces.

Algorithms↗

PubMed2004

Ensuring the usability of a knee arthroscopy simulator.

There is limited research considering the usability of medical virtual environments. Usability evaluation is an essential validation phase that considers the extent to which a product achieves its specific goals, with effectiveness, efficiency and satisfaction. A four-stage iterative approach is adopted to enhance usability in the development of a knee arthroscopy training system. This process has drawn attention to issues that may impede system usability for example non-conformity to platform conventions, and visibility of the system status. The process highlights features that computer scientists can overlook when working closely with a system but that are essential to user acceptance and effective application.

Arthroscopy↗

PubMed2004

A prototype virtual reality system for preoperative planning of neuro-endovascular interventions.

This paper describes our efforts at creating a system with real time acquisition and geometric processing of the patients vascular anatomy, supplemented by a framework to simulate catheter vasculature interaction. Our system uses biplane angiograms coupled with an algorithm for generation of 3D vascular trees for patient data acquisition. Surface reconstruction and processing of this data is performed to provide novel decision aids to the interventionalist. The processed data can be loaded in a virtual environment to simulate guidance of the catheter through the patient's vasculature. With our combination of techniques, a patient specific visualization and simulation environment can be prepared within the narrow time window available for this procedure.

Algorithms↗

PubMed2004

Haptic rendering of tissue cutting with scissors.

Current surgical simulations that involve cutting with scissors lack display of forces "between the fingers" of the operator. The objective of this work is to develop a fast, realistic haptic rendering technique for scissor cutting that can be easily integrated into soft tissue models commonly used in surgical simulators. A virtual environment was created for combined graphic and haptic display of cutting. Two 2-dimensional deformable mass-spring-damper models were developed: The first is a large mesh that is used to calculate translational forces. The second is a smaller, one-element-thick mesh that is used to calculate cutting (angular) forces. This technique was implemented on the haptic scissors, a haptic interface that allows motion and force feedback in translation and cutting.

Computer Graphics↗

PubMed2005

Dynamic generation of surgery specific simulators -- a feasibility study.

Most of the current surgical simulators rely on preset anatomical virtual environments (VE). The functionality of a simulator is typically fixed to anatomy-based specific tasks. This rigid design principle makes it difficult to reuse an existing simulator for different surgeries. It also makes it difficult to simulate procedures for specific patients, since their anatomical features or anomalies cannot be easily replaced in the VE. In this paper, we demonstrate the reusability of a modular skill-based simulator, LapSkills, which allows dynamic generation of surgery-specific simulations. Task and instrument modules are easily reused from LapSkills and the three-dimensional VE can be replaced with other anatomical models. We build a nephrectomy simulation by reusing the simulated vessels and the clipping and cutting task modules from LapSkills. The VE of the kidney is generated with our anatomical model generation tools and then inserted into the simulation (while preserving the established tasks and evaluation metrics). An important benefit for the created surgery and patient-specific simulations is that reused components remain validated. We plan to use this faster development process to generate a simulation library containing a wide variety of laparoscopic surgical simulations. Incorporating the simulations into surgical training programs will help collect data for validating them.

Computer Simulation↗

PubMed2005

Desktop and conference room VR for physicians.

Virtual environments such as the CAVE and the ImmersaDesk, which are based on graphics supercomputers or workstations, are large and expensive. Most physicians have no access to such systems. The recent development of small Linux personal computers and high-performance graphics cards has afforded opportunities to implement applications formerly run on graphics supercomputers. Using PC hardware and other affordable devices, a VR system has been developed which can sit on a physician's desktop or be installed in a conference room. Affordable PC-based VR systems are comparable in performance with expensive VR systems formerly based on graphics supercomputers. Such VR systems can now be accessible to most physicians. The lower cost and smaller size of this system greatly expands the range of uses of VR technology in medicine.

Microcomputers↗

PubMed2005

BrainTrain: brain simulator for medical VR application.

The brain is known as the most complex organ in the human body. Due to its complexity, learning and understanding the anatomy and functions of the cerebral cortex without effective learning assistance is rather difficult for medical novices and students in health and biological sciences. In this paper, we present a new virtual reality (VR) simulator for neurological education and neurosurgery. The system is based on a new three-dimensional (3D) user-computer interface design with a tangible object and a force-torque sensor. The system is combined with highly interactive computer-generated graphics and acoustics to provide multi-modal interactions through the user's sensory channels (vision, tactile, haptic and auditory). The system allows the user to feel the simulated object from its physical model that formed the interface device, while exploring or interacting with the mimicked computer-generated object in the virtual environment (VE). Unlike other passive interface devices, our system can detect the position and orientation of the interacting force in real-time, based on the system's set-up and a force-torque data acquisition technique. As long as the user is touching the model, the positions of the user's fingertip in the VE can be determined and is synchronized with the finger's motion in the physical world without requirement of an additional six-degree-of-freedom tracking device. The prior works have shown the use of the system set-up in medical applications. We demonstrate the system for neurological education and neurosurgery as a recent application. The main functions of the simulator contribute to education in neuroanatomy and visualization for diagnostic and pre-surgery planning. Once the user has touched the model, the system will mark the associated anatomy region and will provide the information of the region in terms of text note and/or sound. The user can switch from anatomy to the brain's function module, which will give details of motor, sensory or other cortical functions associated to the touch areas. In addition, the user can generate and visualize arbitrary cross-sectional images from corresponding to the magnetic resonance imaging (MRI) datasets either for training or for diagnostic purpose. The user can manipulate the cross-section image interactively and intuitively by moving the finger on the interface device.

Brain↗

PubMed2005

A dynamic friction model for haptic simulation of needle insertion.

This paper describes a new friction model, termed the brush model, suitable for haptic simulations of needle insertion in virtual environments. A novel two-layer surface contact model is presented that provides real-time rendering of friction forces at haptic refresh rates. A significant modification to the brush model is also presented, leading to a new friction model, termed the fixed bristle brush model. Simulation results show that the two models can accurately reflect the experimentally observed friction characteristics. This paper presents a simulation of friction during needle insertion; results agree with the experimental observations.

Computer Simulation↗

PubMed2005

Preflight virtual reality training as a countermeasure for space motion sickness and disorientation.

INTRODUCTION: Research suggests that preflight training in virtual reality devices can simulate certain aspects of microgravity and may prove to be an effective countermeasure for space motion sickness (SMS) and spatial disorientation (SD). It is hypothesized that exposing subjects preflight to variable virtual orientations, similar to those encountered during spaceflight, will reduce the incidence and/or severity of SMS and SD. METHODS: Subjects were assigned to either a variable training (VT) or nonvariable training (NVT) condition to perform a simple navigation and switch activation task in a virtual space station. VT subjects performed the task starting in several different orientations, whereas NVT subjects always performed the task starting in the same orientation. On a separate day, all subjects then performed the same task in a transfer of training session starting from a novel orientation. RESULTS: When exposed to the novel test orientation, VT subjects performed the tasks more quickly (12%) and with fewer nausea symptoms (53%) than during the training session, compared with NVT subjects who performed more slowly (6%) and with more nausea symptoms (28%). Both VT and NVT conditions were effective in reducing the number of wall hits in the novel orientation (39% and 34%, respectively). DISCUSSION: These results demonstrate the effectiveness of using variable training in a virtual environment for reducing nausea and improving task performance in potentially disorienting surroundings, and suggest that such training may be developed into an effective countermeasure for SMS, SD, and associated performance decrements that occur in spaceflight.

Adult↗

PubMedDate not supplied

Web-based courses. More than curriculum.

Online program development depends on an educationally and technologically sound curriculum supported by a solid infrastructure. Creation of a virtual environment through design of online registration and records, financial aid, orientation, advisement, resources, and evaluation and assessment provides students with access and program integrity.The planning of an academic support system as an electronic environment provides challenges and institutional issues requiring systematic analysis.

Curriculum↗

PubMedDate not supplied

[Neurodarvinism: models of selection of neuronal groups].

Concept of neurodarvinism is regarded in the context of simulation of the "natural" and "artificial" selection of neurons, synapses and neuronal groups. "Natural" selection of neurons is based on mobile devices built of neuron-like elements. These devices should be capable for adaptation to real surrounding. "Artificial" selection of neurons is performed using computerized "neurointelligence" model operating in a virtual environment. Comparison of the models suggests the advantage of the integration of these approaches.

Artificial Intelligence↗

PubMedDate not supplied

Medical education for rural areas: opportunities and challenges for information and communications technologies.

Resources in medical education are not evenly distributed and access to education can be more problematic in rural areas. Similar to telemedicine's positive influence on health care access, advances in information and communications technologies (ICTs) increase opportunities for medical education. This paper provides a descriptive overview of the use of ICTs in medical education and suggests a conceptual model for reviewing ICT use in medical education, describes specific ICTs and educational interventions, and discusses opportunities and challenges of ICT use, especially in rural areas. The literature review included technology and medical education, 1996-2005. Using an educational model as a framework, the uses of ICTs in medical education are, very generally, to link learners, instructors, specific course materials and/or information resources in various ways. ICTs range from the simple (telephone, audio-conferencing) to the sophisticated (virtual environments, learning repositories) and can increase access to medical education and enhance learning and collaboration for learners at all levels and for institutions. While ICTs are being used and offer further potential for medical education enhancement, challenges exist, especially for rural areas. These are technological (e.g., overcoming barriers like cost, maintenance, access to telecommunications infrastructure), educational (using ICTs to best meet learners' educational priorities, integrating ICTs into educational programs) and social (sensitivity to remote needs, resources, cultures). Finally, there is need for more rigorous research to more clearly identify advantages and disadvantages of specific uses of ICTs in medical education.

Computer-Assisted Instruction↗

PubMed2006

Evaluation methods of a middleware for networked surgical simulations.

Distributed surgical virtual environments are desirable since they substantially extend the accessibility of computational resources by network communication. However, network conditions critically affects the quality of a networked surgical simulation in terms of bandwidth limit, delays, and packet losses, etc. A solution to this problem is to introduce a middleware between the simulation application and the network so that it can take actions to enhance the user-perceived simulation performance. To comprehensively assess the effectiveness of such a middleware, we propose several evaluation methods in this paper, i.e., semi-automatic evaluation, middleware overhead measurement, and usability test.

Computer Simulation↗

PubMed2006

A biomechanical analysis of surgeon's gesture in a laparoscopic virtual scenario.

Minimally invasive surgery (MIS) has become very common in recent years thanks to many advantages that patients can get. However, due to the difficulties surgeons encounter to learn and manage this technique, several training methods and metrics have been proposed in order to, respectively, improve surgeon's abilities and assess his/her surgical skills. In this context, this paper presents a biomechanical analysis method of the surgeon's movements, during exercise involving instrument tip positioning and depth perception in a laparoscopic virtual environment. Estimation of some biomechanical parameters enables us to assess the abilities of surgeons and to distinguish an expert surgeon from a novice. A segmentation algorithm has been defined to deeply investigate the surgeon's movements and to divide them into many sub-movements.

Algorithms↗

PubMed2006

PelvicSim--a computational-experimental system for biomechanical evaluation of female pelvic floor organ disorders and associated minimally invasive interventions.

In this paper we describe the prototype of a new computational simulation system, PelvicSim. This system is being developed to simulate the in vivo biomechanics of the female pelvic floor organ system with the intent to provide clinical researchers, medical device designers with a virtual environment to understand the various biomechanical pathologies occurring in the pelvic floor. This information can then be used to develop new reconstructive surgical techniques, or design non surgical/surgical devices for the treatment of urinary incontinence and pelvic organ prolapse. In this paper, we provide the initial results from the development of the PelvicSim modules which combine in vivo sensing experiments, Ultrasound and MRI imaging datasets, and an inverse finite element modeling technology based on hyperviscoelastic constitutive modeling of the pelvic floor organs and tissues.

Biomechanical Phenomena↗

PubMed2006

Mobile peer-to-grid architecture for paramedical emergency operations.

In this paper we describe a distributed architecture that could be used to link emergency medical centres, hospitals, telephone operators, and ambulances into a hybrid Peer-to-Peer (P2P) and Grid system for the sharing of information and transport of data. Distributed computing techniques can be used to connect static and mobile systems, bringing the different tools, expertise and databases together to aggregate patient data "on-the-fly" and then integrate it into a situation and context-specific patient-centred virtual environment. The scenario presented in this paper encapsulates connecting mobile tools and medical devices from ambulances, enabling data transfer to medical centres, and aggregating patient data from numerous sources. The proposed P2G (Peer-to-Grid) framework consolidates Peer-to-Peer and Grid computing research by addressing the mobility of transiently connected devices while supporting interactive configurability of components for dynamic data-driven distributed paramedical scenarios.

Allied Health Personnel↗

PubMed2006

Perceived self-motion in two visual contexts: dissociable mechanisms underlie perception.

We evaluated the influence of moving visual scenes and knowledge of spatial and physical context on visually induced self-motion perception in an immersive virtual environment. A sinusoidal, vertically oscillating visual stimulus induced perceptions of self-motion that matched changes in visual acceleration. Subjects reported peaks of perceived self-motion in synchrony with peaks of visual acceleration and opposite in direction to visual scene motion. Spatial context was manipulated by testing subjects in the environment that matched the room in the visual scene or by testing them in a separate chamber. Physical context was manipulated by testing the subject while seated in a stable, earth-fixed desk chair or in an apparatus capable of large linear motions, however, in both conditions no actual motion occurred. The compellingness of perceived self-motion was increased significantly when the spatial context matched the visual input and actual body displacement was possible, however, the latency and amplitude of perceived self-motion were unaffected by the spatial or physical context. We propose that two dissociable processes are involved in self-motion perception: one process, primarily driven by visual input, affects vection latency and path integration, the other process, receiving cognitive input, drives the compellingness of perceived self-motion.

Adolescent↗