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At least 307 records · Page 17Linked to original sources

PubMed1999

Virtual reality based surgery simulation for endoscopic gynaecology.

Virtual reality (VR) based surgical simulator systems offer very elegant possibilities to both enrich and enhance traditional education in endoscopic surgery. However, while a wide range of VR simulator systems have been proposed and realized in the past few years, most of these systems are far from able to provide a reasonably realistic surgical environment. We explore the basic approaches to the current limits of realism and ultimately seek to extend these based on our description and analysis of the most important components of a VR-based endoscopic simulator. The feasibility of the proposed techniques is demonstrated on a first modular prototype system implementing the basic algorithms for VR-training in gynaecologic laparoscopy.

Computer Graphics↗

PubMedDate not supplied

Elastodynamic shape modeler: a tool for defining the deformation behavior of virtual tissues.

A main goal of surgical simulators is the creation of virtual training environments for prospective surgeons. Thus, students can rehearse the various steps of surgical procedures on a computer system without any risk to the patient. One main condition for realistic training is the simulated interaction with virtual medical devices, such as endoscopic instruments. In particular, the virtual deformation and transection of tissues are important. For this application, a neuro-fuzzy model has been developed, which allows the description of the visual and haptic deformation behavior of the simulated tissue by means of expert knowledge in the form of medical terms. Pathologic conditions affecting the visual and haptic tissue response can be easily changed by a medical specialist without mathematical knowledge. By using the personal computer-based program Elastodynamic Shape Modeler, these conditions can be adjusted via a graphical user interface. With a force feedback device, which is similar to a real laparoscopic instrument, virtual deformations can be performed and the resulting haptic feedback can be felt. Thus, use of neuro-fuzzy technologies for the definition and calculation of virtual deformations seems applicable to the simulation of surgical interventions in virtual environments.

Computer Graphics↗

PubMed1998

Deformable modeling of facial tissue for craniofacial surgery simulation.

While deformable object modeling has been studied by computer graphics specialists for more than two decades, only a few applications in the field of surgical simulation have been developed which provide both real-time and physically realistic modeling of complex, nonlinear tissue deformations. Particularly in craniofacial surgery, the prediction of soft-tissue changes--which result from alterations in the underlying bone structure--is critical to the surgical outcome. The prediction these tissue changes and, therefore, the prognosis of the postoperative appearance of the patient, is still based on empirical studies of the relationship between bone and tissue movements: There exists no physical model which takes into account the individual patient anatomy to simulate the resulting tissue changes during craniofacial surgery. In this article we present two different deformable tissue models which are intergrated in an interactive surgical simulation test bed. Both techniques allow precise preoperative simulation of the resulting soft tissue changes during craniofacial surgery and visualization of the patient's postoperative appearance. The different deformable models are described in detail and both are applied to the same craniofacial case study. The simulation results are shown and compared with regard to the speed and accuracy of the prediction of the patient's postoperative appearance.

Computer Simulation↗

PubMed2006

Simulation improves resident performance in catheter-based intervention: results of a randomized, controlled study.

OBJECTIVES: Surgical simulation has been shown to enhance the training of general surgery residents. Since catheter-based techniques have become an important part of the vascular surgeon's armamentarium, we explored whether simulation might impact the acquisition of catheter skills by surgical residents. METHODS: Twenty general surgery residents received didactic training in the techniques of catheter intervention. Residents were then randomized with 10 receiving additional training with the Procedicus, computer-based, haptic simulator. All 20 residents then participated in 2 consecutive mentored catheter-based interventions for lower extremity occlusive disease in an OR/angiography suite. Resident performance was graded by attending surgeons blinded to the resident's training status, using 18 procedural steps as well as a global rating scale. RESULTS: There were no differences between the 2 resident groups with regard to demographics or scores on a visuospatial test administered at study outset. Overall, residents exposed to simulation scored higher than controls during the first angio/OR intervention: procedural steps (simulation/control) (50 +/- 6 vs. 33 +/- 9, P = 0.0015); global rating scale (30 +/- 7 vs. 19 +/- 5, P = 0.0052). The advantage provided by simulator training persisted with the second intervention (53 +/- 6 vs. 36 +/- 7, P = 0.0006); global rating scale (33 +/- 6 vs. 21 +/- 6, P = 0.0015). Moreover, simulation training, particularly for the second intervention, led to enhancement in almost all of the individual measures of performance. CONCLUSION: Simulation is a valid tool for instructing surgical residents and fellows in basic endovascular techniques and should be incorporated into surgical training programs. Moreover, simulators may also benefit the large number of vascular surgeons who seek retraining in catheter-based intervention.

Angiography↗

PubMed2002

Virtual reality training improves operating room performance: results of a randomized, double-blinded study.

OBJECTIVE: To demonstrate that virtual reality (VR) training transfers technical skills to the operating room (OR) environment. SUMMARY BACKGROUND DATA: The use of VR surgical simulation to train skills and reduce error risk in the OR has never been demonstrated in a prospective, randomized, blinded study. METHODS: Sixteen surgical residents (PGY 1-4) had baseline psychomotor abilities assessed, then were randomized to either VR training (MIST VR simulator diathermy task) until expert criterion levels established by experienced laparoscopists were achieved (n = 8), or control non-VR-trained (n = 8). All subjects performed laparoscopic cholecystectomy with an attending surgeon blinded to training status. Videotapes of gallbladder dissection were reviewed independently by two investigators blinded to subject identity and training, and scored for eight predefined errors for each procedure minute (interrater reliability of error assessment r > 0.80). RESULTS: No differences in baseline assessments were found between groups. Gallbladder dissection was 29% faster for VR-trained residents. Non-VR-trained residents were nine times more likely to transiently fail to make progress (P <.007, Mann-Whitney test) and five times more likely to injure the gallbladder or burn nontarget tissue (chi-square = 4.27, P <.04). Mean errors were six times less likely to occur in the VR-trained group (1.19 vs. 7.38 errors per case; P <.008, Mann-Whitney test). CONCLUSIONS: The use of VR surgical simulation to reach specific target criteria significantly improved the OR performance of residents during laparoscopic cholecystectomy. This validation of transfer of training skills from VR to OR sets the stage for more sophisticated uses of VR in assessment, training, error reduction, and certification of surgeons.

Cholecystectomy, Laparoscopic↗

PubMed1994

Temporal bone dissection for display.

Increasing concern with medicolegal issues has heightened the need for surgical simulation in training. Familiarity with the surgical anatomy of the temporal bone is essential for effective and safe otological surgery. Refinement of surgical technique and intimate knowledge of temporal bone anatomy can be gained by accurate dissection. The products of such endeavours are both illustrative and instructive. The issues, methods and techniques necessary for display of anatomical dissections are discussed.

Connective Tissue↗

PubMed1999

Spinal biomodeling.

STUDY DESIGN: A prospective trial of stereolithographic biomodeling in complex spinal surgery. OBJECTIVES: To investigate the use of stereolithographic biomodeling as an aid to complex spinal surgery. SUMMARY OF BACKGROUND DATA: Of the array of imaging methods available to assist the spinal surgeon, no single method provides a complete overview of the anatomy, although three-dimensional imaging has been shown to have advantages. METHODS: Stereolithographic biomodeling is a new technology that allows data from three-dimensional computed tomographic scans to be used to generate exact plastic replicas of anatomic structures. Five patients with complex deformities were selected: two children with congenital deformities, a patient with an osteoblastoma, a patient with basilar invagination caused by osteogenesis imperfecta, and a patient with a failed lumbar fusion. Computed tomographic scanning was performed and stereolithographic biomodels generated. The stereolithographic biomodels were used for patient education, operative planning, and surgical navigation. RESULTS: The surgeons reported that biomodeling was useful in complex spinal surgery and was an effective technology. Stereolithographic biomodels were found to be particularly useful in morphologic assessment, in the planning and rehearsal of surgery, for intraoperative navigation, and for informing patients about surgical procedures. CONCLUSIONS: Stereolithographic biomodeling allows imaging data to be displayed in a physical form. This intuitive medium may improve data display and allows surgical simulation on a proxy of the surgical site. Draw-backs of the technology were a minimum 24 hours' manufacturing time and the cost.

Adult↗

PubMed2003

Virtual endoscopic images by 3D FASE cisternography for neurovascular compression.

Three-dimensional fast asymmetric spin echo (3D FASE) cisternography provides high spatial resolution and excellent contrast as a water image acquisition technique. It is also useful for the evaluation of various anatomical regions. This study investigated the usefulness and limitations of virtual endoscopic images obtained by 3D FASE MR cisternography in the preoperative evaluation of patients with neurovascular compression. The study included 12 patients with neurovascular compression: 10 with hemifacial spasm and two with trigeminal neuralgia. The diagnosis was surgically confirmed in all patients. The virtual endoscopic images obtained were judged to be of acceptable quality for interpretation in all cases. The areas of compression identified in preoperative diagnosis with virtual endoscopic images showed good agreement with those observed from surgery, except in one case in which the common trunk of the anterior inferior cerebellar artery and posterior inferior cerebellar artery (AICA-PICA) bifurcated near the root exit zone of the facial nerve. The veins are displayed in some cases but not in others. The main advantage of generating virtual endoscopic images is that such images can be used for surgical simulation, allowing the neurosurgeon to perform surgical procedures with greater confidence.

Adult↗

PubMed1999

Simulation of tissue cutting and bleeding for laparoscopic surgery using auxiliary surfaces.

Realistic simulation of tissue cutting and bleeding is important components of a surgical simulator that are addressed in this study. Surgeons use a number of instruments to perform incision and dissection of tissues during minimally invasive surgery. For example, a coagulating hook is used to tear and spread the tissue that surrounds organs and scissors are used to dissect the cystic duct during laparoscopic cholecystectomy. During the execution of these procedures, bleeding may occur and blood flows over the tissue surfaces. We have developed computationally fast algorithms to display (1) tissue cutting and (2) bleeding in virtual environments with applications to laparoscopic surgery. Cutting through soft tissue generates an infinitesimally thin slit until the sides of the surface are separated from each other. Simulation of an incision through tissue surface is modeled in three steps: first, the collisions between the instrument and the tissue surface are detected as the simulated cutting tool passes through. Then, the vertices along the cutting path are duplicated. Finally, a simple elastic tissue model is used to separate the vertices from each other to reveal the cut. Accurate simulation of bleeding is a challenging problem because of the complexities of the circulatory system and the physics of viscous fluid flow. There are several fluid flow models described in the literature, but most of them are computationally slow and do not specifically address the problem of blood flowing over soft tissues. We have reviewed the existing models, and have adapted them to our specific task. The key characteristics of our blood flow model are a visually realistic display and real-time computational performance. To display bleeding in virtual environments, we developed a surface flow algorithm. This method is based on a simplified form of the Navier-Stokes equations governing viscous fluid flow. The simplification of these partial differential equations results in a wave equation that can be solved efficiently, in real-time, with finite difference techniques. The solution describes the flow of blood over the polyhedral surfaces representing the anatomical structures and is displayed as a continuous polyhedral surface drawn over the anatomy.

Algorithms↗

PubMed2003

Virtual instruments: a generalized implementation.

The proliferation of surgical simulators would be increased if a common framework and set of virtual instruments existed for use by the application developer. We describe such a framework consisting of a powerful abstraction of a user interaction device, a functional taxonomy of surgical instruments, and a method for linking these components together. A series of example virtual instruments is also provided.

Computer Simulation↗

PubMed2004

Interactive cutting simulation with adaptive refinements using digital logic design analogy.

A major requirement for surgical simulation is to allow virtual tissue cutting. This paper presents a scalable and adaptive cutting technique based on a mass-spring mesh. By the analogy of digital logic design, an arbitrary incision is modeled systematically by translating the cutting process into a state diagram. Subdivision of mesh elements is driven by the state transitions. Node redistribution, local re-meshing and deformation are applied to refine the subdivided mesh.

Computer Simulation↗

PubMed2004

Cerebrovascular stereolithographic biomodeling for aneurysm surgery. Technical note.

Stereolithographic (SL) biomodeling is a new technology that allows three-dimensional (3D) imaging data to be used in the manufacture of accurate solid plastic replicas of anatomical structures. The authors describe their experience with a patient series in which this relatively new visualization method was used in surgery for cerebral aneurysms. Using the rapid prototyping technology of stereolithography, 13 solid anatomical biomodels of cerebral aneurysms with parent and surrounding vessels were manufactured based on 3D computerized tomography scans (three cases) or 3D rotational angiography (10 cases). The biomodels were used for diagnosis, operative planning, surgical simulation, instruction for less experienced neurosurgeons, and patient education. The correspondence between the biomodel and the intraoperative findings was verified in every case by comparison with the intraoperative video. The utility of the biomodels was judged by three experienced and two less experienced neurosurgeons specializing in microsurgery. A prospective comparison of SL biomodels with intraoperative findings proved that the biomodels replicated the anatomical structures precisely. Even the first models, which were rather rough, corresponded to the intraoperative findings. Advances in imaging resolution and postprocessing methods helped overcome the initial limitations of the image threshold. The major advantage of this technology is that the surgeon can closely study complex cerebrovascular anatomy from any perspective by using a haptic, "real reality" biomodel, which can be held, allowing simulation of intraoperative situations and anticipation of surgical challenges. One drawback of SL biomodeling is the time it takes for the model to be manufactured and delivered. Another is that the synthetic resin of the biomodel is too rigid to use in dissecting exercises. Further development and refinement of the method is necessary before the model can demonstrate a mural thrombus or calcification or the relationship of the aneurysm to nonvascular structures. This series of 3D SL biomodels demonstrates the feasibility and clinical utility of this new visualization medium for cerebrovascular surgery. This medium, which elicits the intuitive imagination of the surgeon, can be effectively added to conventional imaging techniques. Overcoming the present limitations posed by material properties, visualization of intramural particularities, and representation of the relationship of the lesion to parenchymal and skeletal structures are the focus in an ongoing trial.

Cerebrovascular Circulation↗

PubMed2006

High-level virtual reality simulator for endourologic procedures of lower urinary tract.

OBJECTIVES: To analyze the limitations of existing simulators for urologic techniques, and then test and evaluate a novel virtual reality (VR) simulator for endourologic procedures of the lower urinary tract. Surgical simulation using VR has the potential to have a tremendous impact on surgical training, testing, and certification. Endourologic procedures seem to be an ideal target for VR systems. METHODS: The URO-Trainer features genuine VR, obtained from digital video footage of more than 400 endourologic diagnostic and therapeutic procedures, as well as data from cross-sectional imaging. The software offers infinite random variations of the anatomy and pathologic features for diagnosis and surgical intervention. An advanced haptic force feedback is incorporated. Virtual cystoscopy and resection of bladder tumors were evaluated by 24 medical students and 12 residents at our department. RESULTS: The system was assessed by more than 150 international urologists with varying experience at different conventions and workshops from March 2003 to September 2004. Because of these evaluations and constant evolutions, the final version provides a genuine representation of endourologic procedures. Objective data are generated by a tutoring system that has documented evident teaching benefits for medical students and residents in cystoscopy and treatment of bladder tumors. CONCLUSIONS: The URO-Trainer represents the latest generation of endoscopy simulators. Authentic visual and haptic sensations, unlimited virtual cases, and an intelligent tutoring system make this modular system an important improvement in computer-based training and quality control in urology.

Computer Simulation↗

PubMed2006

Integrating simulation into a surgical residency program: is voluntary participation effective?

OBJECTIVE: Surgical training programs nationwide are struggling with the integration of simulation training into their curriculum given the constraints of the 80-h work week. We examine the effectiveness of voluntary training in a simulation lab as part of the surgical curriculum. METHODS: The ProMIS simulator was introduced into the general surgery residency at Boston University Medical Center. All categorical residents (28) and non-categorical residents (23) were offered a 2-h training session and curriculum review. After the introductory session, time spent in the lab was encouraged, but voluntary. Use of the simulator was tracked for all residents. Participation in the simulation curriculum was defined as three or more uses of the simulator. After 3 months, all residents completed a survey regarding the simulation lab and their simulator usage. RESULTS: Twenty-six (93%) categorical residents and three (6%) non-categorical residents completed the introductory simulator training session. Over a 3 month period, use of the simulator at least once was 31% among all eligible residents; 80% of postgraduate year (PGY)1, 40% of PGY2, 60% of PGY3, and 0% of PGY4 and PGY5. Four residents (14%) participated in the simulation curriculum. Overall, 70% of simulator usage was during working hours, and 30% was completed post-call or when the resident was off duty. Most residents agreed that the simulator was easy to use and that its use improved their operative skills, but they did not think it was a good substitute for actual operative experience. Reported reasons for not using the simulator included off-site rotation (44%), no time (30%), and no interest (11%). CONCLUSIONS: Voluntary use of a surgical simulation lab leads to minimal participation in a training curriculum. Participation should be mandatory if it is to be an effective part of a residency curriculum.

Boston↗

PubMed2006

Effects of cognitive distraction on performance of laparoscopic surgical tasks.

HYPOTHESIS: To quantify the effects of cognitive distraction on surgical task performance in residents and medical students using a laparoscopic surgical simulator. DESIGN: Within-subjects design. SETTING: A surgical skills laboratory. PARTICIPANTS: Thirteen surgical residents and medical students who volunteered for the study. METHODS AND MATERIALS: Subjects performed six tasks on the Minimally Invasive Surgical Trainer-Virtual Reality (MIST-VR), under two different conditions (distracted and undistracted). Task order remained the same for all subjects, but the order of distraction was counterbalanced. In the distracted condition, distractions consisted of mental arithmetic problems posed sequentially so that subjects were continually distracted. MAIN OUTCOME MEASURES: Time to task completion, surgical errors committed, economy of motion, and overall performance scores were generated by the MIST-VR program software. Arithmetic error was not a factor in the overall performance score. RESULTS: Time to task completion was significantly greater when subjects were distracted for all six tasks performed. Overall score and economy of motion were negatively affected by distraction but the effect did not reach th level of statistical significance. There was no effect of distract on surgical errors. CONCLUSION: Cognitive distraction appears to negatively influence the performance of laparoscopic surgical tasks by increasing task completion time. Further study is required to determine what the effects would be on experienced surgeons and actual surgical outcomes.

Analysis of Variance↗

PubMed2001

New graphics models for PC based ocular surgery simulator.

High-end graphics workstations (GWS) have been used for surgical simulators utilizing Computer Graphics (CG) and Virtual Reality (VR) technologies. This is because the simulators need lots of computing power, mainly for collision detection among objects modeled as a set of polygons. In this paper, we propose to use mathematical functions to model objects for collision detection. However, for graphic display we continue to use polygonal representation. Using the new model, we have developed a PC based ocular surgery simulator, which creates realistic surgery image in real-time. The computation time was found to be much lower than that in the conventional method.

Computer Graphics↗

PubMed1998

Model-based surgical planning and simulation of cranial base surgery.

Plastic skull models of seven individual patients were fabricated by stereolithography from three-dimensional data based on computed tomography bone images. Skull models were utilized for neurosurgical planning and simulation in the seven patients with cranial base lesions that were difficult to remove. Surgical approaches and areas of craniotomy were evaluated using the fabricated skull models. In preoperative simulations, hand-made models of the tumors, major vessels and nerves were placed in the skull models. Step-by-step simulation of surgical procedures was performed using actual surgical tools. The advantages of using skull models to plan and simulate cranial base surgery include a better understanding of anatomic relationships, preoperative evaluation of the proposed procedure, increased understanding by the patient and family, and improved educational experiences for residents and other medical staff. The disadvantages of using skull models include the time and cost of making the models. The skull models provide a more realistic tool that is easier to handle than computer-graphic images. Surgical simulation using models facilitates difficult cranial base surgery and may help reduce surgical complications.

Adult↗

PubMed2001

Surgical skills training: simulation and multimedia combined.

CONTEXT: Basic surgical skills are needed throughout the medical profession, but current training is haphazard and unpredictable. There is increasing pressure to provide transparency about training and performance standards. There is a clear need for inexperienced learners to build a framework of basic skills before carrying out surgical procedures on patients. Effective learning of a skill requires sustained deliberate practice within a cognitive framework, and simulation offers an opportunity for safe preparation. OBJECTIVES: This paper presents a new approach to basic surgical skills training, where tuition using a specially designed computer program is combined with structured practice using simulated tissue models. This approach to teaching has evolved from practical experience with surgical skills training in workshops. METHODS: Pilot studies with 72 first-year medical students highlighted the need for separate programs for teaching and for self-directed learning. The authors developed a training approach in the light of this experience. Subsequent in-depth observational and interview studies examined (a) individual teaching sessions between surgical teachers and learners (five consultant surgeons and five senior house officers) and (b) group teaching sessions with general practitioners (14 participants in three group interviews). Further work has resulted in a self-directed learning program. CONCLUSIONS: Qualitative analysis of observational and interview data provides strong preliminary support for the effectiveness of this approach. The response of teachers and learners was extremely positive. The combination of information (presented by computer) and practice of psychomotor skill (using simulated tissue models) could be extended to other surgical and practical skills.

Clinical Competence↗