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PubMedDate not supplied

Virtual reality surgical simulator. The first steps.

The virtual-reality surgical simulator signals the beginning of an era of computer simulation for surgery. The surgical resident of the future will learn new perspectives on surgical anatomy and repeatedly practice surgical procedures until they are perfect before performing surgery on patients. Primitive though these initial steps are, they represent the foundation for an educational base that will be as important to surgery as the flight simulator is to aviation. It is anticipated that the full development of the surgical simulator will take less than the 40 years which was required for flight simulators to become an indispensable ingredient of pilot training. As the system evolves, many new and yet-to-be-imagined applications will arise, but we must have understanding and patience as we wait for computer power to improve to a point where VR surgical simulation can emerge from its PacMan era.

Computer Graphics↗

PubMed2006

A meta-analysis of the training effectiveness of virtual reality surgical simulators.

The increasing use of virtual reality (VR) simulators in surgical training makes it imperative that definitive studies be performed to assess their training effectiveness. Indeed, in this paper we report the meta-analysis of the efficacy of virtual reality simulators in: 1) the transference of skills from the simulator training environment to the operating room, and 2) their ability to discriminate between the experience levels of their users. The task completion time and the error score were the two study outcomes collated and analyzed in this meta-analysis. Sixteen studies were identified from a computer-based literature search (1996-2004). The meta-analysis of the random effects model (because of the heterogeneity of the data) revealed that training on virtual reality simulators did lessen the time taken to complete a given surgical task as well as clearly differentiate between the experienced and the novice trainees. Meta-analytic studies such as the one reported here would be very helpful in the planning and setting up of surgical training programs and for the establishment of reference 'learning curves' for a specific simulator and surgical task. If any such programs already exist, they can then indicate the improvements to be made in the simulator used, such as providing for more variety in their case scenarios based on the state and/or rate of learning of the trainee.

Computer Simulation↗

PubMed2001

Validity of surgical simulation for the assessment of operative skill.

BACKGROUND: Surgical simulators are being promoted as a means of assessing a surgeon's technical skills. Little evidence exists that simulator performance correlates with actual technical ability. This study was undertaken to determine the criterion and construct validity of currently available surgical simulations in the evaluation of technical skill. METHODS: Simulator assessment was carried out on 36 basic surgical trainees, 37 surgically naïve first-year medical students and 16 experienced general surgical consultants. Some 26 trainees and 36 students underwent repeat assessment after 6 months. A previously validated, 19-point technical skill assessment form, based on direct observation of trainee performance in the operating theatre, was also completed by each trainee's supervising consultant. RESULTS: An insignificant or weak correlation was found between simulator performance and both duration of basic surgical experience and consultant assessment of technical skill. Six months of basic surgical training led to an improvement in performance, not seen in an untrained control group, in only one of the six simulations tested. Discrimination between surgically naïve and experienced subjects was only demonstrated, in part, for four of the six tasks. CONCLUSION: The assessment of technical skill needs to be improved. Work is needed to establish the reliability and validity of currently available simulation models before they are formally introduced for high-stakes assessment.

Clinical Competence↗

PubMed1981

Myocardial contracture: the predominant causes of impeded reperfusion in simulated surgical ischemia.

"Worst-case" surgical conditions were simulated using the isolated model of a parabiotically perfused rabbit heart septum. Such conditions occur clinically in regional myocardium distal to stenosed coronary arteries and are characterized by inadequate or absent ionic influence on the myocardium by chemical cardioplegia and equilibration to room temperature. This study tested the hypothesis that ischemic contracture, rather than intracellular or extracellular edema, critical closing or delayed critical opening, was the predominant cause of impeded reperfusion that damages myocardium. In 20 reperfused ischemic septa, conductance (flow per unit pressure) decreased significantly (P less than 0.05) as ischemia at 24 degrees C was prolonged from 15 to 90 minutes and as contracture became more severe. Conductance was not decreased significantly by even large amounts of extracellular edema. Intracellular edema did not occur. In 17 normal septa, the critical closing pressure was 9.3 mm Hg. Critical opening pressures following 5 to 90 minutes ischemia at 24 degrees C did not differ significantly. Although early reflow was impeded progressively with longer ischemic intervals, it was not significant as was due to contracture rather than critical closing or delayed critical opening. This study confirmed the hypothesis that contracture is the predominant cause of impeded reperfusion in simulated surgical ischemia.

Animals↗

PubMed2002

A tutorial platform suitable for surgical simulator training (SimMentor).

BACKGROUND: The introduction of simulators in surgical training entails the need to develop pedagogic platforms adapted to the potentials and limitations provided by the information technology. As a solution to the technical challenges in treating all possible interaction events and to obtain a suitable pedagogic approach, we have developed a pedagogic platform for surgical training, SimMentor. METHODS: In SimMentor the procedure to be practiced is divided into a number of natural phases. The trainee will practice on one phase at a time, however he can select the sequence of phases arbitrarily. A phase is taught by letting the trainee alternate freely between 2 modes: 1: A 3-dimensional animated guidance designed for learning the objectives and challenges in a procedure. 2: An interactive training session through the instrument manipulator device designed for training motoric responses based on visual and tactile responses produced by the simulator. The two modes are interfaced with the same virtual reality platform, thus SimMentor allows a seamless transition between the modes. RESULTS: We have developed a prototype simulator for robotic assisted endoscopic CABG (Coronary Artery Bypass Grafting) procedure by first focusing on the anastomosis part of the operation. Tissue, suture and instrument models have been developed and integrated with a simulated model of a beating heart comprises the elements in the simulator engine that is used in construction a training platform for learning different methods for performing a coronary anastomosis procedure. CONCLUSION: The platform is designed for integrating the following features: 1) practical approach to handle interactivity events with flexible-objects 3D simulators, 2) methods for quantitative evaluations of performance, 3) didactic presentations, 4) effective ways of producing diversity of clinical and pathological training scenarios.

Anastomosis, Surgical↗

PubMed2002

Fast surface and volume rendering based on shear-warp factorization for a surgical simulator.

Fast simultaneous visualization of 3D medical images and medical instruments is necessary for a surgical simulator. Because unconstrained motion of a medical instrument is more frequent than that of the patient, the visualization of medical instruments is performed in real time using surface rendering. However, volume rendering is usually used for realistic visualization of the 3D medical image. We have developed an algorithm to combine a volume-rendered image and a surface-rendered image using a Z-buffer for depth cueing, which is applied to a surgical simulator. Surface rendering is used for visualization of a medical instrument, whereas 3D medical images such as CT and MRI are usually visualized by volume rendering, because segmentation of the medical image is difficult. In this study, when the volume-rendered image is combined with the surface-rendered image, the amount of computation is reduced by early ray termination and instrument-region masking in the sheared image space. Using these methods, a fast combination of volume-rendered and surface-rendered images is performed with high image quality. The method is appropriate for real-time visualization of 3D medical images and medical instrument motion in the images, and can be applied to image-guided therapy and surgical simulators.

Algorithms↗

PubMed2001

A surgical simulation system of skin sutures using a three-dimensional finite element method.

OBJECTIVE: To establish a surgical simulation system of skin sutures using a three-dimensional finite element method. DESIGN: Three-dimensional finite element models were developed from point data obtained with a rapid three-dimensional surface-measuring device and postoperative profiles were evaluated using these models. BACKGROUND: Since suturing a wound may result in undesirable skin extrusion, it is important to make the extrusion as inconspicuous as possible. We have investigated a means of determining appropriate suture methods to decrease the extrusion. METHODS: Affected body parts were measured non-invasively with a rapid three-dimensional surface-measuring device. Finite element models were prepared, and an appropriate method for reducing skin extrusion was evaluated by attempting various suturing methods. RESULTS: Two kinds of finite element models were prepared: a conventional spindle model and a modified S-shape model. The height of the extrusion of the modified S-shape model was decreased by 40% in comparison with that of the spindle model. These results agreed with clinical findings. CONCLUSIONS: Due to this surgical simulation system of skin sutures, with a rapid three-dimensional surface-measuring device and three-dimensional finite element analysis, it was possible to design an appropriate suturing method and to evaluate the postoperative skin profiles. The modified S-shape suture method would be a recommendable method. RELEVANCE: Using this surgical simulation system of skin sutures, a surgeon can evaluate an appropriate suturing method before operation. It is expected that this system will reduce a surgeon's labor.

Computer Simulation↗

PubMed2003

Physically based hybrid approach in real time surgical simulation with force feedback.

This paper describes a novel hybrid-modeling paradigm for the simulation of surgical tool-soft tissue interactions in real time medical simulations using force feedback. A local point collocation-based method of finite spheres is coupled with a global boundary element technique to capture local features of the interaction (e.g., nonlinearities of the soft tissue) without sacrificing global accuracy. The technique is demonstrated using realistic examples.

Computer Simulation↗

PubMed2001

Accomplishments and challenges of surgical simulation.

For nearly a decade, advanced computer technologies have created extraordinary educational tools using three-dimensional (3D) visualization and virtual reality. Pioneering efforts in surgical simulation with these tools have resulted in a first generation of simulators for surgical technical skills. Accomplishments include simulations with 3D models of anatomy for practice of surgical tasks, initial assessment of student performance in technical skills, and awareness by professional societies of potential in surgical education and certification. However, enormous challenges remain, which include improvement of technical fidelity, standardization of accurate metrics for performance evaluation, integration of simulators into a robust educational curriculum, stringent evaluation of simulators for effectiveness and value added to surgical training, determination of simulation application to certification of surgical technical skills, and a business model to implement and disseminate simulation successfully throughout the medical education community. This review looks at the historical progress of surgical simulators, their accomplishments, and the challenges that remain.

Anatomy, Cross-Sectional↗

PubMed2000

Improvement of surgical simulation using dynamic volume rendering.

In the last years high efforts have been taken to develop surgical simulators for computer assisted training. However, most of these simulators use simple models of the human's anatomy, which are manually created using modeling software. Nevertheless, medical experts need to perform the training directly with the patient's complex anatomy, which can be received, for example, from digital imaging datasets (CT, MR). A common technique to display these datasets is volume rendering. However, even with high-end hardware only static models can be handled interactively. In surgical simulators a dynamic component is also needed because tissues must be deformed and partially removed. With the combination of springmass models, which are improved by neuro-fuzzy systems, and the recently developed OpenGL Volumizer, surgical simulation using real-time deformable (or dynamic) volume rendering became possible. As an application example the simulator ROBOSIM for minimally invasive neurosurgery is presented.

Cephalometry↗

PubMed2000

[Computerized surgical simulation with 3D reconstruction of upper limbs].

This paper reports our study on how to realize computerized surgical simulation through reconstructing 3D anatomy of upper limbs. CT images and serial sections of upper limbs were matched to reconstruct 3D images. We compiled the computer programs of 3D reconstruction and surgical simulation with borland C++ computer language, and built 3D digital model of anatomic structure of upper limbs. The results showed that all structures reconstructed could be displayed alone, in any group or totally. While operating, we could choose one of three segments of the upper limbs model and operate on any parts and in any direction. The surgical simulation system could be used to design operative schemes, choose the best operative paths, and teach the processes of operations and anatomy. It could run in 586-personal computers.

Arm↗

PubMed2001

Surgical education and surgical simulation.

The science of virtual reality provides an entirely new opportunity in the area of simulation of surgical skills using computers for training, evaluation, and eventually certification. A taxonomy of the types of simulators is proposed based upon the level of complexity of the task which is being simulated. These tasks are precision placement, simple manipulation, complex manipulation, and integrated procedure. Representative simulators in each category are illustrated and discussed in the context of their contribution to the education and training of a surgeon. The importance of a curriculum is to give content to the role of simulators as another advanced tool for education. Simulators must be integrated into a comprehensive curriculum and not considered as a stand-alone system. The current accomplishments as well as challenges are discussed.

Clinical Competence↗

PubMedDate not supplied

Computer-aided interactive surgical simulation for craniofacial anomalies based on 3-D surface reconstruction CT images.

We developed a computer-aided interactive surgical simulation system for craniofacial anomalies based on three-dimensional (3-D) surface reconstruction CT imaging. This system has four functions: 1) 3-D surface reconstruction display with an accelerated projection method; 2) Surgical simulation to cut, move, rotate, and reverse bone-blocks over the reference 3-D image on the CRT screen; 3) 3-D display of the simulated image in arbitrary views; and 4) Prediction of postoperative skin surface features displayed as 3-D images in arbitrary views. Retrospective surgical simulation has been performed on three patients who underwent the fronto-orbital advancement procedures for brachycephaly and two who underwent the reconstructive procedure for scaphocephaly. The predicted configurations of the cranium and skin surface were well simulated when compared to the postoperative images in 3-D arbitrary views. In practical use, this software might be used for an on-line system connected to a large scale general-purpose computer.

Computer Graphics↗

PubMed2002

Impact of the endoscopic sinus surgical simulator on operating room performance.

OBJECTIVES/HYPOTHESIS: The aim of this study is to evaluate an endoscopic sinus surgical simulator (ESS) as a training device and to introduce a methodology to assess its impact on actual operating room performance. STUDY DESIGN: Prospective evaluation of the endoscopic sinus surgical simulator as a trainer. METHODS: Ten junior and senior ear, nose and throat residents served as subjects, some of whom had prior training with the simulator. The evaluation team collected several measures, which were analyzed for a statistical correlation, including simulator scores, operating room performance rating, ratings of videotaped operating room procedures, and surgical competency rating. RESULTS: These findings suggest the ESS simulator positively affects initial operating room performance across all measures as judged by senior surgeons rating anonymous videotapes of those procedures. The two simulation-trained residents were rated consistently better than the other two residents across all measures. These differences approached statistical significance for two items: anterior ethmoidectomy (P =.06; P <.05) and surgical confidence (P =.09; P <.05). In addition, the 3 subjects with the highest overall scores on the competency evaluation also had 3 of the 4 highest cumulative simulation times. CONCLUSIONS: The endoscopic sinus surgical simulator is a valid training device and appears to positively impact operating room performance among junior otolaryngology residents.

Clinical Competence↗

PubMed1992

Computerized cephalometric orthognathic surgical simulation, prediction and postoperative evaluation of precision.

A new computerized, cephalometric, orthognathic surgical program (TIOPS) has been evaluated in surgical simulation, prediction and postoperative assessment of precision. Records of 10 consecutive patients admitted for orthognathic surgical treatment were analysed and prediction plans produced by computerized surgical simulation. Predicted and postoperative positions of maxilla and mandible were compared with linear and angular measurements. No statistically significant differences between predicted and postoperative positions could be demonstrated (p greater than 0.05).

Adolescent↗

PubMed1998

Virtual environments. Surgical simulation in otolaryngology.

Advanced technology in the form of computer-generated surgical simulation has tremendous potential as an adjunctive training aid to residents in training and experienced surgeons. This article explores the state-of-the-art in surgical simulation for otolaryngologists and future directions in this area.

Computer Simulation↗

PubMed2006

GiPSiNet: an open source/open architecture network middleware for surgical simulations.

In this paper, we present the design and techniques of GiPSiNet, an open source/open architecture network middleware being developed for surgical simulations. GiPSiNet extends GiPSi (General Interactive Physical Simulation Interface), our framework for developing organ level surgical simulations, to network environments. This network extension is non-trivial, since the network settings pose several serious problems for distributed surgical virtual environments such as band-width limit, delays, and packet losses. Our goal is to enhance the quality (fidelity and realism) of networked simulations in the absence of network QoS (Quality of Service) through the GiPSiNet middleware.

Computer Simulation↗

PubMed2004

LUCY: a 3-D pelvic model for surgical simulation.

Development of 3-D models of human anatomy for use in virtual reality simulators is anticipated to enhance surgical training. These models may be a valuable resource for gaining mastery of minimal-access procedures. The pelvis portion (hip to upper-thigh) of a 32-year-old female cadaver was frozen and sectioned axially in approximately 2-mm increments as the first step in producing an accurately representative 3-D model of the human female pelvis. Photographic exposures of the entire series of 95 sections were then converted to digital format. Adobe PhotoShop masks for each structure were created and converted into wire-frame and surface-textured models; this aggregate model set was named "LUCY." To date, 3-D representations of 40 pelvic structures (over 2200 individual masks) have been modeled In conjunction with haptic technology, these virtual anatomic models will enable users to practice fundamental surgical manipulations and procedures such as tubal ligation and ovariectomy. The deployment of surgical-simulation models such as LUCY may facilitate technical-performance aspects of surgical training, particularly those associated with minimal-access procedures. Manipulations and procedures can be practiced over the Internet, providing a host of flexible options to enhance the surgical curricula.

Adult↗