Validation of a rhinologic virtual surgical simulator for performing a Draf 3 endoscopic frontal sinusotomy.

Background: We recently introduced a patient-specific rhinologic virtual surgical environment (VSE) that has shown potential for surgical rehearsal of various skull base lesions. Our aim in this study was to validate the usefulness of the rhinology VSE in performing the Draf 3 procedure.

Methods: An outside-in Draf 3 procedure was performed on 4 cadaver heads.

Early experience with a patient-specific virtual surgical simulation for rehearsal of endoscopic skull-base surgery.

Background: With the help of contemporary computer technology it is possible to create a virtual surgical environment (VSE) for training. This article describes a patient-specific virtual rhinologic surgical simulation platform that supports rehearsal of endoscopic skull-base surgery. We also share our early experience with select cases.

Anatomy-Specific Virtual Reality Simulation in Temporal Bone Dissection: Perceived Utility and Impact on Surgeon Confidence.

Objective To evaluate the effect of anatomy-specific virtual reality (VR) surgical rehearsal on surgeon confidence and temporal bone dissection performance. Study Design Prospective pre- and poststudy of a novel virtual surgical rehearsal platform. Setting Academic otolaryngology-head and neck surgery residency training programs.

High-fidelity haptic and visual rendering for patient-specific simulation of temporal bone surgery.

Medical imaging techniques provide a wealth of information for surgical preparation, but it is still often the case that surgeons are examining three-dimensional pre-operative image data as a series of two-dimensional images. With recent advances in visual computing and interactive technologies, there is much opportunity to provide surgeons an ability to actively manipulate and interpret digital image data in a surgically meaningful way. This article describes the design and initial evaluation of a virtual surgical environment that supports patient-specific simulation of temporal bone surgery using pre-operative medical image data.

Haptic feedback improves surgeons' user experience and fracture reduction in facial trauma simulation.

Computer-assisted surgical (CAS) planning tools are available for craniofacial surgery, but are usually based on computer-aided design (CAD) tools that lack the ability to detect the collision of virtual objects (i.e., fractured bone segments).

The effect of haptic degrees of freedom on task performance in virtual surgical environments.

Force and touch feedback, or haptics, can play a significant role in the realism of virtual reality surgical simulation. While it is accepted that simulators providing haptic feedback often outperform those that do not, little is known about the degree of haptic fidelity required to achieve simulation objectives. This article evaluates the effect that employing haptic rendering with different degrees of freedom (DOF) has on task performance in a virtual environment.

Virtual reality simulation in neurosurgery: technologies and evolution.

Neurosurgeons are faced with the challenge of learning, planning, and performing increasingly complex surgical procedures in which there is little room for error. With improvements in computational power and advances in visual and haptic display technologies, virtual surgical environments can now offer potential benefits for surgical training, planning, and rehearsal in a safe, simulated setting. This article introduces the various classes of surgical simulators and their respective purposes through a brief survey of representative simulation systems in the context of neurosurgery.

High-fidelity, inexpensive surgical middle ear simulator.

Hypothesis: A high-fidelity, inexpensive middle ear simulator could be created to enhance surgical training that would be rated as having high face validity by experts.

Background: With rapid prototyping using additive manufacturing technology (AMT), one can create high-resolution 3-dimensional replicas of the middle ear at low cost and high fidelity. Such a simulator could be of great benefit for surgical training, particularly in light of new resident training guidelines.

Online image-based monitoring of soft-tissue displacements for radiation therapy of the prostate.

Purpose: Emerging prolonged, hypofractionated radiotherapy regimens rely on high-dose conformality to minimize toxicity and thus can benefit from image guidance systems that continuously monitor target position during beam delivery. To address this need we previously developed, as a potential add-on device for existing linear accelerators, a novel telerobotic ultrasound system capable of real-time, soft-tissue imaging. Expanding on this capability, the aim of this work was to develop and characterize an image-based technique for real-time detection of prostate displacements.

A virtual surgical environment for rehearsal of tympanomastoidectomy.

This article presents a virtual surgical environment whose purpose is to assist the surgeon in preparation for individual cases. The system constructs interactive anatomical models from patient-specific, multi-modal preoperative image data, and incorporates new methods for visually and haptically rendering the volumetric data. Evaluation of the system's ability to replicate temporal bone dissections for tympanomastoidectomy, using intraoperative video of the same patients as guides, showed strong correlations between virtual and intraoperative anatomy.

Telerobotic system concept for real-time soft-tissue imaging during radiotherapy beam delivery.

Purpose: The curative potential of external beam radiation therapy is critically dependent on having the ability to accurately aim radiation beams at intended targets while avoiding surrounding healthy tissues. However, existing technologies are incapable of real-time, volumetric, soft-tissue imaging during radiation beam delivery, when accurate target tracking is most critical. The authors address this challenge in the development and evaluation of a novel, minimally interfering, telerobotic ultrasound (U.

In vivo micro-image mosaicing.

Recent advances in optical imaging have led to the development of miniature microscopes that can be brought to the patient for visualizing tissue structures in vivo. These devices have the potential to revolutionize health care by replacing tissue biopsy with in vivo pathology. One of the primary limitations of these microscopes, however, is that the constrained field of view can make image interpretation and navigation difficult.

Reconstruction and exploration of virtual middle-ear models derived from micro-CT datasets.

Background: Middle-ear anatomy is integrally linked to both its normal function and its response to disease processes. Micro-CT imaging provides an opportunity to capture high-resolution anatomical data in a relatively quick and non-destructive manner. However, to optimally extract functionally relevant details, an intuitive means of reconstructing and interacting with these data is needed.

Integration of patient-specific paranasal sinus computed tomographic data into a virtual surgical environment.

Background: The advent of both high-resolution computed tomographic (CT) imaging and minimally invasive endoscopic techniques has led to revolutionary advances in sinus surgery. However, the rhinologist is left to make the conceptual jump between static cross-sectional images and the anatomy encountered intraoperatively. A three-dimensional (3D) visuo-haptic representation of the patient's anatomy may allow for enhanced preoperative planning and rehearsal, with the goal of improving outcomes, decreasing complications, and enhancing technical skills.

Automatic preparation, calibration, and simulation of deformable objects.

Many simulation environments - particularly those intended for medical simulation - require solid objects to deform at interactive rates, with deformation properties that correspond to real materials. Furthermore, new objects may be created frequently (for example, each time a new patient's data is processed), prohibiting manual intervention in the model preparation process. This paper provides a pipeline for rapid preparation of deformable objects with no manual intervention, specifically focusing on mesh generation (preparing solid meshes from surface models), automated calibration of models to finite element reference analyses (including a novel approach to reducing the complexity of calibrating nonhomogeneous objects), and automated skinning of meshes for interactive simulation.

Representing fluid with smoothed particle hydrodynamics in a cranial base simulator.

We describe the implementation of irrigation and blood simulation using Smoothed Particle Hydrodynamics (SPH) in a cranial base surgical simulator. Graphical accuracy of virtual surgery is a significant goal for improving the realism and immersive experience of computerized training environments. For temporal bone micro-surgery fluids contribute not only to the visual integrity of the surgical field but provide relevant anatomic cues as well.

Providing metrics and performance feedback in a surgical simulator.

One of the most important advantages of computer simulators for surgical training is the opportunity they afford for independent learning. However, if the simulator does not provide useful instructional feedback to the user, this advantage is significantly blunted by the need for an instructor to supervise and tutor the trainee while using the simulator. Thus, the incorporation of relevant, intuitive metrics is essential to the development of efficient simulators.

Evaluating drilling and suctioning technique in a mastoidectomy simulator.

This paper presents several new metrics related to bone removal and suctioning technique in the context of a mastoidectomy simulator. The expertise with which decisions as to which regions of bone to remove and which to leave intact is evaluated by building a Naïve Bayes classifier using training data from known experts and novices. Since the bone voxel mesh is very large, and many voxels are always either removed or not removed regardless of expertise, the mutual information was calculated for each voxel and only the most informative voxels used for the classifier.

Validating metrics for a mastoidectomy simulator.

One of the primary barriers to the acceptance of surgical simulators is that most simulators still require a significant amount of an instructing surgeon's time to evaluate and provide feedback to the students using them. Thus, an important area of research in this field is the development of metrics that can enable a simulator to be an essentially self-contained teaching tool, capable of identifying and explaining the user's weaknesses. However, it is essential that these metrics be validated in able to ensure that the evaluations provided by the "virtual instructor" match those that the real instructor would provide were he/she present.

Real-time image mosaicing for medical applications.

In this paper we describe the development of a robotically-assisted image mosaicing system for medical applications. The processing occurs in real-time due to a fast initial image alignment provided by robotic position sensing. Near-field imaging, defined by relatively large camera motion, requires translations as well as pan and tilt orientations to be measured.

Visuohaptic simulation of bone surgery for training and evaluation.

Visual and haptic simulation of bone surgery can support and extend current surgical training techniques. The authors present a system for simulating surgeries involving bone manipulation, such as temporal bone surgery and mandibular surgery, and discuss the automatic computation of surgical performance metrics. Experimental results confirm the system's construct validity.

Virtual 3D planning and guidance of mandibular distraction osteogenesis.

We present a system for 3D planning and pre-operative rehearsal of mandibular distraction osteogenesis procedures. Two primary architectural components are described: a planning system that allows geometric bone manipulation to rapidly explore various modifications and configurations, and a visuohaptic simulator that allows both general-purpose training and preoperative, patient-specific procedure rehearsal. We provide relevant clinical background, then describe the underlying simulation algorithms and their application to craniofacial procedures.

Achieving proper exposure in surgical simulation.

One important technique common throughout surgery is achieving proper exposure of critical anatomic structures so that their shapes, which may vary somewhat among patients, can be confidently established and avoided. In this paper, we present an algorithm for determining which regions of selected structures are properly exposed in the context of a mastoidectomy simulation. Furthermore, our algorithm then finds and displays all other points along the surface of the structure that lie along a sufficiently short and straight path from an exposed portion such that their locations can be safely inferred.

Quantifying risky behavior in surgical simulation.

Evaluating a trainee's performance on a simulated procedure involves determining whether a specified objective was met while avoiding certain "injurious" actions that damage vulnerable structures. However, it is also important to teach the stylistic behaviors that minimize overall risk to the patient, even though these criteria may be more difficult to explicitly specify and detect. In this paper, we address the development of metrics that evaluate the risk in a trainee's behavior while performing a simulated mastoidectomy.

An interactive simulation environment for craniofacial surgical procedures.

Recent advances in medical imaging and surgical techniques have made possible the correction of severe facial deformities and fractures. Surgical correction techniques often involve the direct manipulation - both relocation and surgical fracture - of the underlying facial bone. The work presented here introduces an environment for interactive, visuohaptic simulation of craniofacial surgical procedures, with an emphasis on both mandibular distraction procedures and traditional orthognathic surgeries.