Thomas Kerwin

Virtual temporal bone dissection system: OSU virtual temporal bone system: development and testing.

The objective of this project was to develop a virtual temporal bone dissection system that would provide an enhanced educational experience for the training of otologic surgeons.

Enhancing Realism of Wet Surfaces in Temporal Bone Surgical Simulation

We present techniques to improve visual realism in an interactive surgical simulation application: a mastoidectomy simulator that offers a training environment for medical residents as a complement to using a cadaver. As well as displaying the mastoid bone through volume rendering, the simulation allows users to experience haptic feedback and appropriate sound cues while controlling a virtual bone drill and suction/irrigation device. The techniques employed to improve realism consist of a fluid simulator and a shading model. The former allows for deformable boundaries based on volumetric bone data, while the latter gives a wet look to the rendered bone to emulate more closely the appearance of the bone in a surgical environment. The fluid rendering includes bleeding effects, meniscus rendering, and refraction. We incorporate a planar computational fluid dynamics simulation into our three-dimensional rendering to effect realistic blood diffusion. Maintaining real-time performance while drilling away bone in the simulation is critical for engagement with the system.

Automatic scoring of virtual mastoidectomies using expert examples

PurposeAutomatic scoring of resident performance on a virtual mastoidectomy simulation system is needed to achieve consistent and efficient evaluations. By not requiring immediate expert intervention, the system provides a completely objective assessment of performance as well as a self-driven user assessment mechanism.MethodsAn iconic temporal bone with surgically important regions defined into a fully partitioned segmented dataset was created. Comparisons between expert-drilled bones and student-drilled bones were computed based on gradations with both Euclidean and Earth Mover’s Distance. Using the features derived from these comparisons, a decision tree was constructed. This decision tree was used to determine scores of resident surgical performance. The algorithm was applied on multiple expert comparison bones and the scores averaged to provide reliability metric.ResultsThe reliability metrics for the multi-grade scoring system are better in some cases than previously reported binary classification metrics. The two scoring methods given provide a trade-off between accuracy and speed.ConclusionsComparison of virtually drilled bones with expert examples on a voxel level provides sufficient information to score them and provide several specific quality metrics. By merging scores from different expert examples, two related metrics were developed; one is slightly faster and less accurate, while a second is more accurate but takes more processing time.

The role of multisensory feedback in haptic surface perception

In performing most everyday tasks, we use information from several different sensory modalities, yet our understanding of how these inputs are integrated is limited. The present study investigated the role of multisensory feedback in the perception of surface roughness, specifically focusing on whether the threshold for distinguishing the roughness of two virtual surfaces was different under visual + haptic conditions, as compared to visual-only or haptic-only conditions. Haptic stimuli were presented via the PHANToM; visual stimuli were presented via computer monitor. The virtual surfaces were sinusoidal gratings that varied in spatial period across trials. Overall, results suggested that threshold was determined by haptic input at low surface amplitudes, and by visual input at high surface amplitudes. At intermediate amplitude values, it appeared that observers were combining information across modalities to produce a percept in the combined condition that was better than that obtained under either single modality condition.

Translating the Simulation of Procedural Drilling Techniques for Interactive Neurosurgical Training

BACKGROUND: Through previous efforts we have developed a fully virtual environment to provide procedural training of otologic surgical technique. The virtual environment is based on high-resolution volumetric data of the regional anatomy. These volumetric data help drive an interactive multisensory, ie, visual (stereo), aural (stereo), and tactile, simulation environment. Subsequently, we have extended our efforts to support the training of neurosurgical procedural technique as part of the Congress of Neurological Surgeons simulation initiative. OBJECTIVE: To deliberately study the integration of simulation technologies into the neurosurgical curriculum and to determine their efficacy in teaching minimally invasive cranial and skull base approaches. METHODS: We discuss issues of biofidelity and our methods to provide objective, quantitative and automated assessment for the residents. RESULTS: We conclude with a discussion of our experiences by reporting preliminary formative pilot studies and proposed approaches to take the simulation to the next level through additional validation studies. CONCLUSION: We have presented our efforts to translate an otologic simulation environment for use in the neurosurgical curriculum. We have demonstrated the initial proof of principles and define the steps to integrate and validate the system as an adjuvant to the neurosurgical curriculum.

Anatomical volume visualization with weighted distance fields

We describe the use of the weighted distance transform (WDT) to enhance applications designed for volume visualization of segmented anatomical datasets. The WDT is presented as a general technique to generate a derived characteristic of a scalar field that can be used in multiple ways during rendering. We obtain real-time interaction with the volume by calculating the WDT on the graphics card. Several examples of this technique as it applies to an application for teaching anatomical structures are detailed, including rendering embedded structures, fuzzy boundaries, outlining, and indirect lighting estimation.

Virtual Temporal Bone Dissection System: Development and Testing

The objective of this project was to develop a virtual temporal bone dissection system that would provide an enhanced educational experience for the training of otologic surgeons.

Performance Assessment for Mastoidectomy State of the Art Review

Objective The aim of this report is to provide a review of the current literature for assessment of performance for mastoidectomy, to identify the current assessment tools available in the literature, and to summarize the evidence for their validity. Data Sources The MEDLINE database was accessed via PubMed. Review Methods Inclusion criteria consisted of English-language published articles that reported use of a mastoidectomy performance assessment tool. Studies ranged from 2007 to November 2015 and were divided into 2 groups: intraoperative assessments and those performed with simulation (cadaveric laboratory or virtual reality). Studies that contained specific reliability analyses were also highlighted. For each publication, validity evidence data were analyzed and interpreted according to conceptual definitions provided in a recent systematic review on the modern framework of validity evidence. Conclusions Twenty-three studies were identified that met our inclusion criteria for review, including 4 intraoperative objective assessment studies, 5 cadaveric studies, 10 virtual reality simulation studies, and 4 that used both cadaveric assessment and virtual reality. Implications for Practice A review of the literature revealed a wide variety of mastoidectomy assessment tools and varying levels of reliability and validity evidence. The assessment tool developed at Johns Hopkins possesses the most validity evidence of those reviewed. However, a number of agreed-on specific metrics could be integrated into a standardized assessment instrument to be used nationally. A universally agreed-on assessment tool will provide a means for developing standardized benchmarks for performing mastoid surgery.

Virtual temporal bone dissection system: OSU virtual temporal bone system†‡§

The objective of this project was to develop a virtual temporal bone dissection system that would provide an enhanced educational experience for the training of otologic surgeons.

Enabling Data-Intensive Biomedical Science: Gaps, Opportunities, and Challenges

The challenges of data-intensive computing have been summarized (Gorton et al., 2008) as ‘‘managing and processing exponentially growing data volumes, often arriving in time-sensitive streams from arrays of sensors and instruments’’ and ‘‘significantly reducing data analysis cycles so that researchers can make timely decisions.’’ The management of such data requires integrated services for the (high-speed) transfer, storage, indexing, and retrieval of data. Enabling technologies for data management are under active development and investigation (including high-speed networks such as those studied by GENI (http://www.geni.net/), high-performance file systems and semantic ontologies for data access). In addition to existing cluster-based highperformance computing solutions, data-intensive cloud programming environments (e.g., MapReduce and Dryad) are emerging technologies that show promise. The Ohio Supercomputer Center (OSC) has supported data-intensive science projects in the physical sciences [e.g., ALICE—A Large Ion Collider Experiment (http://www .osc.edu/press/releases/2010/supercollider.shtml)] and the environmental sciences [e.g., ASR—Arctic System Reanalysis (http://www.osc.edu/press/releases/2007/bromwich.shtml)]. In biomedical sciences, OSC is actively supporting dataintensive biomedical research groups located at the Comprehensive Cancer Center (CCC) at The Ohio State University’s Medical Center as well as those at the Research Institute at Nationwide Children’s Hospital (RINCH). These organizations contain a number of core facilities, common laboratories providing analysis to a collection of research and clinical groups. Currently, OSC is engaged with the following core facilities at the CCC: