Performance Factors in Neurosurgical Simulation and Augmented Reality Image Guidance

Virtual reality surgical simulators have seen widespread adoption in an effort to provide safe, cost-effective and realistic practice of surgical skills. However, the majority of these simulators focus on training low-level technical skills, providing only prototypical surgical cases. For many complex procedures, this approach is deficient in representing anatomical variations that present clinically, failing to challenge users’ higher-level cognitive skills important for navigation and targeting. Surgical simulators offer the means to not only simulate any case conceivable, but to test novel approaches and examine factors that influence performance. Unfortunately, there is a void in the literature surrounding these questions. This thesis was motivated by the need to expand the role of surgical simulators to provide users with clinically relevant scenarios and evaluate human performance in relation to image guidance technologies, patient-specific anatomy, and cognitive abilities. To this end, various tools and methodologies were developed to examine cognitive abilities and knowledge, simulate procedures, and guide complex interventions all within a neurosurgical context. The first chapter provides an introduction to the material. The second chapter describes the development and evaluation of a virtual anatomical training and examination tool. The results suggest that learning occurs and that spatial reasoning ability is an important performance predictor, but subordinate to anatomical knowledge. The third chapter outlines development of automation tools to enable efficient simulation studies and data management. In the fourth chapter, subjects perform abstract targeting tasks on ellipsoid targets with and without augmented reality guidance. While the guidance tool improved accuracy, performance with the tool was strongly tied to target depth estimation – an important consideration for implementation and training with similar guidance tools. In the fifth chapter, neurosurgically experienced subjects were recruited to perform simulated ventriculostomies. Results showed anatomical variations influence performance and could impact outcome. Augmented reality guidance showed no marked improvement in performance, but exhibited a mild learning curve, indicating that additional training may be warranted. The final chapter summarizes the work presented. Our results and novel evaluative methodologies lay the groundwork for further investigation into simulators as versatile research tools to explore performance factors in simulated surgical procedures

Technology and Simulation to Improve Patient Safety.

Improving the quality and efficiency of surgical techniques, reducing technical errors in the operating suite, and ultimately improving patient safety and outcomes through education are common goals in all surgical specialties. Current surgical simulation programs represent an effort to enhance and optimize the training experience, to overcome the training limitations of a mandated 80-hour work week, and have the overall goal of providing a well-balanced resident education in a society with a decreasing level of tolerance for medical errors

Visual Perception and Cognition in Image-Guided Intervention

Surgical image visualization and interaction systems can dramatically affect the efficacy and efficiency of surgical training, planning, and interventions. This is even more profound in the case of minimally-invasive surgery where restricted access to the operative field in conjunction with limited field of view necessitate a visualization medium to provide patient-specific information at any given moment. Unfortunately, little research has been devoted to studying human factors associated with medical image displays and the need for a robust, intuitive visualization and interaction interfaces has remained largely unfulfilled to this day. Failure to engineer efficient medical solutions and design intuitive visualization interfaces is argued to be one of the major barriers to the meaningful transfer of innovative technology to the operating room. This thesis was, therefore, motivated by the need to study various cognitive and perceptual aspects of human factors in surgical image visualization systems, to increase the efficiency and effectiveness of medical interfaces, and ultimately to improve patient outcomes. To this end, we chose four different minimally-invasive interventions in the realm of surgical training, planning, training for planning, and navigation: The first chapter involves the use of stereoendoscopes to reduce morbidity in endoscopic third ventriculostomy. The results of this study suggest that, compared with conventional endoscopes, the detection of the basilar artery on the surface of the third ventricle can be facilitated with the use of stereoendoscopes, increasing the safety of targeting in third ventriculostomy procedures. In the second chapter, a contour enhancement technique is described to improve preoperative planning of arteriovenous malformation interventions. The proposed method, particularly when combined with stereopsis, is shown to increase the speed and accuracy of understanding the spatial relationship between vascular structures. In the third chapter, an augmented-reality system is proposed to facilitate the training of planning brain tumour resection. The results of our user study indicate that the proposed system improves subjects\u27 performance, particularly novices\u27, in formulating the optimal point of entry and surgical path independent of the sensorimotor tasks performed. In the last chapter, the role of fully-immersive simulation environments on the surgeons\u27 non-technical skills to perform vertebroplasty procedure is investigated. Our results suggest that while training surgeons may increase their technical skills, the introduction of crisis scenarios significantly disturbs the performance, emphasizing the need of realistic simulation environments as part of training curriculum

Virtual and Augmented Reality in Medical Education

Virtual reality (VR) and augmented reality (AR) are two contemporary simulation models that are currently upgrading medical education. VR provides a 3D and dynamic view of structures and the ability of the user to interact with them. The recent technological advances in haptics, display systems, and motion detection allow the user to have a realistic and interactive experience, enabling VR to be ideal for training in hands-on procedures. Consequently, surgical and other interventional procedures are the main fields of application of VR. AR provides the ability of projecting virtual information and structures over physical objects, thus enhancing or altering the real environment. The integration of AR applications in the understanding of anatomical structures and physiological mechanisms seems to be beneficial. Studies have tried to demonstrate the validity and educational effect of many VR and AR applications, in many different areas, employed via various hardware platforms. Some of them even propose a curriculum that integrates these methods. This chapter provides a brief history of VR and AR in medicine, as well as the principles and standards of their function. Finally, the studies that show the effect of the implementation of these methods in different fields of medical training are summarized and presented

Development and Validation of a Hybrid Virtual/Physical Nuss Procedure Surgical Trainer

With continuous advancements and adoption of minimally invasive surgery, proficiency with nontrivial surgical skills involved is becoming a greater concern. Consequently, the use of surgical simulation has been increasingly embraced by many for training and skill transfer purposes. Some systems utilize haptic feedback within a high-fidelity anatomically-correct virtual environment whereas others use manikins, synthetic components, or box trainers to mimic primary components of a corresponding procedure. Surgical simulation development for some minimally invasive procedures is still, however, suboptimal or otherwise embryonic. This is true for the Nuss procedure, which is a minimally invasive surgery for correcting pectus excavatum (PE) – a congenital chest wall deformity. This work aims to address this gap by exploring the challenges of developing both a purely virtual and a purely physical simulation platform of the Nuss procedure and their implications in a training context. This work then describes the development of a hybrid mixed-reality system that integrates virtual and physical constituents as well as an augmentation of the haptic interface, to carry out a reproduction of the primary steps of the Nuss procedure and satisfy clinically relevant prerequisites for its training platform. Furthermore, this work carries out a user study to investigate the system’s face, content, and construct validity to establish its faithfulness as a training platform

Assessment of validity and response bias in neuropsychiatric evaluations

BACKGROUND: Forensic neuropsychiatric assessment requires thorough consideration of malingering and response bias. Neuropsychiatric evaluations are complicated due to the multiple domains in which symptoms and impairment present. Moreover, symptom exaggeration in these evaluations can also present along various symptom domains (e.g., psychological, neurocognitive,somatic). Consequently, steps must be taken to ensure adequate coverage of response bias across all three domains of function. PURPOSE: The following article reviews the conceptualization of malingering in neuropsychiatric settings, as well as various approaches and measures that can be helpful in the assessment of malingering and response bias. CONCLUSIONS: Forensic neuropsychiatric assessment requires thorough consideration of malingering and response bias. These evaluations are complicated due to the multiple domains in which symptoms and impairment present. Performance and symptom validity measures should be routinely included in these evaluations. Collaboration between psychiatry and psychology can provide the optimal multi-method approach needed for thorough neuropsychiatric assessment in forensic cases. We illustrate our points with two case studies from forensic traumatic brain injury neuropsychiatric evaluations

Endoscopic Targeting Tasks Simulator: An Approach Using Game Engines

The pervasiveness of simulators used in professions requiring the skilled control of expensive machinery such as is the case in the aviation, mining, construction, and naval industries raises an intriguing question about the relatively poor adoption within the field of medicine. Certain surgical procedures such as neuro-endoscopic and laparoscopic lend themselves well to the application of virtual reality based simulators. This is due to the innate ability to decom- pose these complex macro level procedures into a hierarchy of subtasks that can be modelled in a software simulator to augment existing teaching and training techniques. The research in this thesis is focused with the design and implementation of a targeting- based simulator having applications in the evaluation of clinically relevant procedures within the neuro-endoscopic and potentially laparoscopic domains. Existing commercially available surgical simulators within these domains are often associated with being expensive, narrowly focussed in the skills they train, and fail to show statistically significant results in the efficacy of improving user performance through repeated use. Development of a targeting tasks simulator is used to evaluate what methods can be applied to provide a robust, objective measure of human performance as it relates to targeting tasks. In addition to performance evaluation, further research is conducted to help understand the impact of different input modalities; focusing primarily on input from a gamepad style device and as well a newer, more natural user interface provided by the Leap Motion Controller

Evaluating Human Performance for Image-Guided Surgical Tasks

The following work focuses on the objective evaluation of human performance for two different interventional tasks; targeted prostate biopsy tasks using a tracked biopsy device, and external ventricular drain placement tasks using a mobile-based augmented reality device for visualization and guidance. In both tasks, a human performance methodology was utilized which respects the trade-off between speed and accuracy for users conducting a series of targeting tasks using each device. This work outlines the development and application of performance evaluation methods using these devices, as well as details regarding the implementation of the mobile AR application. It was determined that the Fitts’ Law methodology can be applied for evaluation of tasks performed in each surgical scenario, and was sensitive to differentiate performance across a range which spanned experienced and novice users. This methodology is valuable for future development of training modules for these and other medical devices, and can provide details about the underlying characteristics of the devices, and how they can be optimized with respect to human performance