The URO Mentor: development and evaluation of a new computer-based interactive training system for virtual life-like simulation of diagnostic and therapeutic endourological procedures

Authors


Abstract

Objective To overcome the current disadvantages of traditional training methods for ureterorenoscopy and percutaneous nephrolitholapaxy, using the URO Mentor (Simbionix, Tel Aviv, Israel) computer-assisted simulator.

Methods The URO Mentor device for training and quality control in ureterorenoscopy was developed using virtual reality, multimedia technology and intelligent tutoring systems. The central software system features a proprietary visualization engine (the SVE) which allows real-time simulation by offering a high-level object-orientated application program interface (written in C++) available for use with either Microsoft®, DirectX 7® or OpenGL as platforms. The SVE includes general procedures to allow two- (2D) and three-dimensional (3D) rendering, collision detection, collision correction, 3D morphing, 2D image manipulation, texture mapping, ‘bump’ mapping, video texture, X-ray rendering, special effects (blood, smoke, stone fragments and more) and reflections.

Results The system allows a complete training session on a wide range of procedures by offering different types of cases and virtual patients, and features a full representation of the endourological procedures under direct vision and by using interactive fluoroscopy with a contrast agent. The supported tools include: baskets, graspers, intracorporal lithotripters, guidewires, catheters, stents, biopsy and dilatation devices. The endourological procedures that can be performed are lithotripsy, tumour resection, treatment of strictures and obstructions, stent placement and biopsies.

Conclusion The URO Mentor introduces a new generation of mannequin equipped with a special haptic device, providing trainees with an unparalleled life-like sensation while training for diagnostic and therapeutic endourological procedures. By bringing key advances into urological simulation (e.g. with the real-time X-ray renderer) and by integrating in a single system both high-quality simulation and learning tools, the URO Mentor provides new perspectives for computer-based urological training systems and methods.

Introduction

The safe and effective performance of diagnostic and therapeutic endourological procedures requires long-term practical experience. Training opportunities for urologists are diminishing because of reductions in the length of surgical training, an appreciation of the true costs of operating room time and the pressures of long waiting lists. Several methods have been introduced for endourological training; the currently available training models include animal models as well as human or animal cadaver organs and synthetic-organ models. Historically, the first endoscopic training models were cadaver models [1–4]. Particular interest has focused on using this model primarily for prostatic resection and secondarily for ureterorenoscopy [5,6]. The performance of the procedures is similar to the clinical situation, but they are restricted by the lack of bleeding, haptic force-feedback and fluoroscopic control. Because of this, most of the synthetic ‘phantom’ models of the upper urinary tract have limitations for training, and therefore the level of trainee interaction is restricted. However, they are widely used in many training courses. In the past several attempts were made to overcome these problems [7]. In 1999, the first realistic computer-generated interactive simulator for TURP was published by Ballaro et al.[8], but this simulator was restricted to TURP. Furthermore, the simulator had no real-time interactivity or tactile feedback. Therefore, the aim of the present study was to develop and evaluate a new and improved computer-based simulation system which would closely resemble diagnostic and therapeutic rigid and flexible ureterorenoscopy in humans.

Methods

The URO Mentor simulator (Symbionix, Tel Aviv, Hashomer, Israel) comprises a personal computer system located under a workstation (Fig. 1). The central software system includes a proprietary visualization engine (the SVE) which allows real-time simulation by offering a high-level object-orientated application program interface (written in C++) available for use with either Microsoft® DirectX 7® or OpenGL platforms. The SVE includes general procedures that allow for two- (2D) and three-dimensional (3D) rendering, collision detection, collision correction, 3D morphing, 2D image manipulation, texture mapping, ‘bump’ mapping, video texture, X-ray rendering, special effects (blood, smoke, stone fragments, etc.) and reflections. On the operating table a mannequin is placed under a monitor showing the real-time endoscopic view (2D) and fluoroscopic image (2D). A cystoscope and rigid and flexible ureterorenoscope are available at the workstation. The following virtual working instruments and intracorporal lithotripsy probes are also available; guidewires, baskets, forceps, biopsy devices, laser-, lithoclast- and electrohydraulic probes, stents, and dilators. To create the endoscopic texture of the urinary tract several videotapes were taken during various endoscopic procedures. All these data, with data gained from CT and MRI, were digitized and the computer simulation constructed using special software. The real-time simulation process is based on creating a 3D geometric model; therefore, the computer stores all the information about the endoscope position and movement until the endoscope is inserted into the proximal urethra of the mannequin. The information about the location and the movements of the endoscope are transmitted from a sensor on the endoscope and three sensors in the workstation. Between August 2000 and May 2001 the URO Mentor was implemented in six internal endourological workshops and one international meeting at the authors' institution. The system was used by several endourological experts in live demonstrations for teaching purposes and in training sessions. During this time simulator system and cases were continuously developed in collaboration with Simbionix.

Figure 1.

The URO Mentor, consisting of the mannequin on the operating table, the endoscopes and the monitor.

Results

The Uro Mentor system allows the simulation of cystoscopic and ureterorenoscopic procedures, conducted using either flexible or rigid ureteroscopes. Simultaneous real-time endoscopic and fluoroscopic control during the procedures is possible, and fluoroscopic contrast agents can be injected in real-time. The simulator provides an opportunity to become familiar with a wide variety of endourological tools and thus the endo-ureteroscopy can be carried out in a clinical simulation, including cystoscopy, retrograde pyelography, insertion of a guidewire under fluoroscopic control, insertion of the ureterorenoscope beside or over the wire, stone disintegration by different lithotripsy probes, stone extraction and insertion of a stent (Fig. 2a–d). The simulator includes a wide variety of cases presenting life-like medical situations. After treating each case an analysis of performance is provided which comprises a comprehensive list of values giving important data for evaluating the trainee's performance. Many of these variables provide more information than an instructor could gain by watching the trainee. This feedback provides the instructor with data allowing an assessment of current ability and the degree of improvement over the course of training. The instructor, to facilitate the assessment, may sort the variables according to categories, e.g. safety, time measurements and diagnostic.

Figure 2.

Interactive real-time life-like simulation of a flexible ureterorenoscopy: (a) inserting the wire (b) inserting the flexible ureterorenoscope (c) laser disintegration of the stone and (d) extracting the stone.

During the seven training courses the experienced endourological instructors and the trainees reported that the URO Mentor simulates endourological procedures in real-time with a high degree of realism supported by a realistic haptic feedback. During these courses the simulator provided the instructors with a variety of didactic, self-designed training tasks, and objective assessments of performance and progress of the trainees. After training, all trainees reported that their training level was significantly better and that the time required to gain experience was reduced. Furthermore, the experienced urologists stated that, after training, they were able to cope better with complications that appear during endoscopic procedures.

Discussion

Endourology comprises some of the most difficult techniques to learn. The rate of complications, not negligible even in experienced hands, depends significantly on the frequency of endourological procedures undertaken and the skill of the urologist. In all departments where endourology is undertaken the problems are similar, i.e. how to reach the required competence considering the possible scarcity of endourological procedures, trainers or teaching time, and the many trainees compared with the number of cases. Thus most urological associations have for several years proposed and organized endourological simulator training.

Previous simulation technology has offered insufficient realism to mimic endourological procedures. Techniques have typically been learned through practice on cadavers, animals and sometimes crude models, e.g. plastic phantoms. However, these simulators lack realistic bleeding, haptic feedback and fluoroscopic control [9,10]. Although lacking real-time interactivity and tactile feedback, the computer-generated interactive TURP simulator [7,8] appears to provide a reasonably realistic view of the prostatic urethra and of the resection of prostatic tissue. This system is intriguing and was further explored in the present study for use with other endoscopic procedures.

The URO Mentor represents a fully computerized simulator system which allows life-like rigid and flexible cystoscopy, and ureterorenoscopy under endoscopic and fluoroscopic control (with or without contrast medium). In contrast to the previous computer simulator for TURP the URO Mentor offers a modular system to allow the simulation of various endoscopic procedures, and therefore represents a more cost-effective means of providing endourological simulation to urological departments.

Although there is general consent that individual practice with real patients cannot be completely replaced by simulator training, a suitable and realistic simulation model can be of great value in the initial steps before contact with a patient, and for refining techniques and tactics. In the simulator scenario, practical experience and ‘tricks’ can be transferred from senior urologists to residents, and faculty techniques and routines can be corrected without harming patients. Another important advantage of training with the URO Mentor simulator is ‘team training’ of the urologist with the assisting personal, because a well-trained and experienced assistant is as important for successful endourological procedures as is an experienced urologist.

The most important benefits of this computer-based simulation system could be a reduction in complications, procedure times, and in rates of repeated procedures. For residents, simulator practice could result in shorter training periods. In addition, as with flight simulators, this computer-based simulator may allow the continuous monitoring of competence when it has been validated in further studies. Accurate recording of success and failure throughout professional life would help resident and senior urologists to recognize fields where they need to improve. To expand the system to a complete endourological training unit, percutaneous nephrolithotomy, TURP and TURBT are currently being integrated into the URO Mentor simulator. Further studies will assess the overall benefits on learning time, treatment time, case outcome and complication rates in a prospective randomized trial.

Authors

M.S. Michel, MD, PhD, Head of the Urological Research and Scientific Laboratory.

T. Knoll, MD

K.U. Köhrmann, MD

P. Alken, MD, Head of the Department of Urology.

M.S. Michel, MD, PhD, Department of Urology, University Hospital Mannheim, Theodor-Kutzer-Ufer 1-3, 68135 Mannheim, Germany.
e-mail: maurice-stephan.michel@uro.ma.uni-heidelberg.de

Ancillary