Dean Korosec

Building interactive virtual environments for simulated training in medicine using VRML and Java/JavaScript

Medicine is a difficult thing to learn. Experimenting with real patients should not be the only option; simulation deserves a special attention here. Virtual Reality Modelling Language (VRML) as a tool for building virtual objects and scenes has a good record of educational applications in medicine, especially for static and animated visualisations of body parts and organs. However, to create computer simulations resembling situations in real environments the required level of interactivity and dynamics is difficult to achieve. In the present paper we describe some approaches and techniques which we used to push the limits of the current VRML technology further toward dynamic 3D representation of virtual environments (VEs). Our demonstration is based on the implementation of a virtual baby model, whose vital signs can be controlled from an external Java application. The main contributions of this work are: (a) outline and evaluation of the three-level VRML/Java implementation of the dynamic virtual environment, (b) proposal for a modified VRML Timesensor node, which greatly improves the overall control of system performance, and (c) architecture of the prototype distributed virtual environment for training in neonatal resuscitation comprising the interactive virtual newborn, active bedside monitor for vital signs and full 3D representation of the surgery room.

Parametric estimation of the continuous non-stationary spectrum and its dynamics in surface EMG studies

Frequency spectrum of surface electromyographic signals (SEMGs) exhibit a non-stationary nature even in the case of constant level isometric muscle contractions due to changes related to muscle fatigue processes. These changes can be evaluated by methods for estimation of time-varying (TV) spectrum. The most widely adopted non-parametric approach is a short time Fourier transform (STFT), from which changes of mean frequency (MF) as well as other parameters for qualitative description of spectrum variation can be calculated. Similar idea of a sliding-window generalisation can also be used in case of parametric spectrum analysis methods. We applied such approach to obtain TV linear models of SEMGs, although its large variance due to independence of estimations in consequent windows represents a major drawback. This variance causes unrealistic abrupt changes in the curve of overall spectrum dynamics, calculated either as the second derivative of the MF or, as we propose, autoregressive moving average (ARMA) distance between subsequent linear models forming the TV parametric spectrum. A smoother estimation is therefore sought and another method shows to be superior over a simple sliding window technique. It supposes that trajectories of TV linear model coefficients can be described as linear combinations of known basis functions. We demonstrate that the later method is very appropriate for description of slowly changing spectra of SEMGs and that dynamics measures obtained from such estimations can be used as an additional indication of the fatigue process.

Computer-assisted decomposition of the electromyograms

Analyses the scope of multimodal parametric searching (MPS) as a means for the decomposition of electromyograms (EMGs). The approach is based on a predefined set of signal sources that are described by some parameters. These signal sources are searched for in a superimposed signal by calculation of the Euclidian distance and by looking for its minimum. The signal sources are applied successively, according to the changes in their parameters, and peeled off at the minimum Euclidian distance found. The minima detected are then displayed in parametric space as a parametric representation. We show that such a technique is reliable enough for the decomposition of needle EMGs at low contraction forces. Applied to surface EMGs, it still discerns different phenomena, although not always with a direct relationship to reality. This is because of the methods ambiguity, amplitude ratio dependency and a bias in the distribution of the detected signal components. Finally, we introduce a novel approach based on the wavelet transform and using the elements of the parametric search. Both approaches give comparable decomposition results when applied to the EMGs.

Quest for Effective Use of Computer Technology in Education: From Natural Sciences to Medicine

Some of the reasons for relatively low impact of computer technology on university education are discussed. Promising approaches of the CoLoS (Conceptual Learning of Science) consortium 1 to teaching natural sciences are presented. Then some new tools that could further impact the efficiency of teaching in various domains are discussed. Finally the question is raised how to extend the application of computer technology into domains outside of natural sciences. Medical education, which still relies on in‐residence random opportunity training is singled out. An example of training on virtual patients that can be subjected to an unlimited number of critical illnesses is demonstrated.

Computer-assisted exercise ECG analysis: real-time scheduling within MS-DOS on PCs

Abstract Computer analysis and monitoring of exercise electrocardiograms (ECG) have been advantageously applied for a long time. Recently, the availability of personal computers (PCs) has also had a significant impact in this field. PCs have been used in the development of a software package for on-line exercise ECG analysis. This paper reveals the core of the application, i.e. a built-in real-time executive. A three-phase design approach is described: first, recognition of the tasks and their structure; second, evaluation of the task time complexities; and third, allocation of the tasks and implementation in C++ in the MS-DOS environment. The performance of the real-time multitasking environment is finally studied for the worst-case situation using a prototype PC installation.

Dynamic VRML for simulated training in medicine

Medicine is a difficult thing to learn. Experimenting with real patients should not be the only option - simulation deserves special attention. The Virtual Reality Modelling Language (VRML), as a tool to build virtual objects and scenes, has a good record of educational applications in medicine, especially for static and animated visualisations of body parts and organs. However, to create computer simulations resembling situations in real environments, the demanded level of interactivity and dynamics is difficult to achieve. In this paper, we describe some approaches and techniques which we used to push the limits of the current VRML technology further towards a dynamic 3D representation of virtual environments. Our demonstration is based on the implementation of a virtual baby model, whose vital signs can be controlled from an external Java application. The main contribution of this work is a proposal for a modified VRML timer/sensor implementation, which greatly improves the overall control of system performance.

Training scenario prototyping for VR-based simulation of neonatal decision-making

This paper presents the design and implementation of a real‐time system for virtual reality (VR)‐based training in neonatal medicine, with main emphasis on simple creation of various training scenarios. This system combines an articulated 3D model of a virtual newborn with text‐based descriptions of its physiological and behavioral responses, enabling medical experts to easily construct, simulate and revise an arbitrary postnatal critical situation. Afterwards, the resulting descriptions of newborns behavior can be used for technical specifications (and even for automatic generation) of more complex behavioral models, such as finite‐state automata.

Computer simulator of electromyographic signal

A computer program for simulation of electromyographic (EMG) signal, which represents the electric activity of a muscle during contraction, has been built. Some of the simulation models developed in this field were used in its realization. The simulator consists of three major parts: muscle model generation, muscle fiber and motor unit action potential calculation and EMG signal generation. All the parts are controlled by wide range of parameters. In its present state the simulator is capable of simulating three recording techniques: single fiber needle, concentric needle and surface recording technique. The applied simulation models has been proved to agree with the reality and so does, therefore, the generated EMG signal. The simulator has been built to be used as a verification tool for various EMG signal decomposition algorithms, and as a learning tool for young electromyographers on how different muscle parameter settings and recording techniques influence the recorded EMG signal.

A distributed virtual reality‐based system for neonatal decision‐making training

In many fields of education, there is a significant gap between theoretical study and practical apprenticeship, which training in virtual environments (VEs) can close. Recently, a standalone prototype for virtual reality (VR)‐based training in neonatal decision‐making, called Virtual Delivery Room (VIDERO) was developed. This prototype enables a simple and time‐efficient simulation of the arbitrary postnatal critical situations. The purpose behind this paper is twofold: to outline the role of trainees immersion into VIDERO environment and to addresses the need for assessment and upgrading of training scenarios. In particular, the distributed services enabling fine‐tuning of both virtual patients behavioral model and trainees interventions through the practice and user interactions in shared VE are described.

Architecture of the virtual training system for buoyancy control

In this paper we present the structure of the simulator which would allow diving beginners to experience the effect of buoyancy control mechanisms before actually entering the water. We believe such training would be less stressful and safer for all participants, but it should also reduce the time in water needed to manage basic practical diving skills. Central design requirements for the system were: realistic modelling of diving physics, various options of man-machine interface and possibility of immersion. With future studies we plan to clarify to what extent the immersive VR interfaces are able to further improve the diving training experience.