Sudanthi N. R. Wijewickrema

The Construct Validity and Reliability of an Assessment Tool for Competency in Cochlear Implant Surgery

Introduction. We introduce a rating tool that objectively evaluates the skills of surgical trainees performing cochlear implant surgery. Methods. Seven residents and seven experts performed cochlear implant surgery sessions from mastoidectomy to cochleostomy on a standardized virtual reality temporal bone. A total of twenty-eight assessment videos were recorded and two consultant otolaryngologists evaluated the performance of each participant using these videos. Results. Interrater reliability was calculated using the intraclass correlation coefficient for both the global and checklist components of the assessment instrument. The overall agreement was high. The construct validity of this instrument was strongly supported by the significantly higher scores in the expert group for both components. Conclusion. Our results indicate that the proposed assessment tool for cochlear implant surgery is reliable, accurate, and easy to use. This instrument can thus be used to provide objective feedback on overall and task-specific competency in cochlear implantation.

Developing effective automated feedback in temporal bone surgery simulation.

Objective We aim to test the effectiveness, accuracy, and usefulness of an automated feedback system in facilitating skill acquisition in virtual reality surgery. Study Design We evaluate the performance of the feedback system through a randomized controlled trial of 24 students allocated to feedback and nonfeedback groups. Setting The feedback system was based on the Melbourne University temporal bone surgery simulator. The study was conducted at the simulation laboratory of the Royal Victorian Eye and Ear Hospital, Melbourne. Subjects and Methods The study participants were medical students from the University of Melbourne, who were asked to perform virtual cortical mastoidectomy on the simulator. The extent to which the drilling behavior of the feedback and nonfeedback groups differed was used to evaluate the effectiveness of the system. Its accuracy was determined through a postexperiment observational assessment of recordings made during the experiment by an expert surgeon. Its usability was evaluated using students’ self-reports of their impressions of the system. Results A Friedman’s test showed that there was a significant improvement in the drilling performance of the feedback group, χ2(1) = 14.450, P < .001. The postexperiment assessment demonstrated that the system provided timely feedback (when trainee behavior was detected) 88.6% of the time and appropriate feedback (accurate advice) 84.2% of the time. Participants’ opinions about the usefulness of the system were highly positive. Conclusion The automated feedback system was observed to be effective in improving surgical technique, and the provided feedback was found to be accurate and useful.

Algorithms for projecting points onto conics

We study the problem of projecting 2D points onto quadratic curves (ellipses, hyperbolas, parabolas). We investigate various projection algorithms focusing on those that are mathematically proven to produce (or converge to) correct results in all cases. Our tests demonstrate that those may be still unfit for practical use due to large computational errors. We present two new algorithms that are not only theoretically proven to converge, but achieve nearly perfect accuracy.

Pattern-based real-time feedback for a temporal bone simulator

Delivering automated real-time performance feedback in simulated surgical environments is an important and challenging task. We propose a framework based on patterns to evaluate surgical performance and provide feedback during simulated ear (temporal bone) surgery in a 3D virtual environment. Temporal bone surgery is composed of a number of stages with distinct aims and surgical techniques. To provide context-appropriate feedback we must be able to identify each stage, recognise when feedback is to be provided, and determine the nature of that feedback. To achieve these aims, we train pattern-based models using data recorded by a temporal bone simulator. We create one model to predict the current stage of the procedure and separate stage-specific models to provide human-friendly feedback within each stage. We use 27 temporal bone simulation runs conducted by 7 expert ear surgeons and 6 trainees to train and evaluate our models. The results of our evaluation show that the proposed system identifies the stage of the procedure correctly and provides constructive feedback to assist surgical trainees in improving their technique.

Design and Evaluation of a Virtual Reality Simulation Module for Training Advanced Temporal Bone Surgery

Surgical education has traditionally relied on cadaveric dissection and supervised training in the operating theatre. However, both these forms of training have become inefficient due to issues such as scarcity of cadavers and competing priorities taking up surgeons time. Within this context, computer-based simulations such as virtual reality have gained popularity as supplemental modes of training. Virtual reality simulation offers repeated practice in a riskfree environment where standardised surgical training modules can be developed, along with systems to provide automated guidance and assessment. In this paper, we discuss the design and evaluation of such a training module, specifically aimed at training an advanced temporal bone procedure, namelycochlear implant surgery.

Supporting skill acquisition in cochlear implant surgery through virtual reality simulation

Objectives: To evaluate the effectiveness of a virtual reality (VR) temporal bone simulator in training cochlear implant surgery. Methods: We compared the performance of 12 otolaryngology registrars conducting simulated cochlear implant surgery before (pre-test) and after (post-tests) receiving training on a VR temporal bone surgery simulator with automated performance feedback. The post-test tasks were two temporal bones, one that was a mirror image of the temporal bone used as a pre-test and the other, a novel temporal bone. Participant performances were assessed by an otologist with a validated cochlear implant competency assessment tool. Structural damage was derived from an automatically generated simulator metric and compared between time points. Results: Wilcoxon signed-rank test showed that there was a significant improvement with a large effect size in the total performance scores between the pre-test (PT) and both the first and second post-tests (PT1, PT2) (PT-PT1: P = 0.007, r = 0.78, PT-PT2: P = 0.005, r = 0.82). Conclusion: The results of the study indicate that VR simulation with automated guidance can effectively be used to train surgeons in training complex temporal bone surgeries such as cochlear implantation.

Automated Segmentation of Surgical Motion for Performance Analysis and Feedback

Advances in technology have motivated the increasing use of virtual reality simulation-based training systems in surgical education, as well as the use of motion capture systems to record surgical performance. These systems have the ability to collect large volumes of trajectory data. The capability to analyse motion data in a meaningful manner is valuable in characterising and evaluating the quality of surgical technique, and in facilitating the development of intelligent self-guided training systems with automated performance feedback. To this end, we propose an automatic trajectory segmentation technique, which divides surgical tool trajectories into their component movements according to spatio-temporal features. We evaluate this technique on two different temporal bone surgery tasks requiring the use of distinct surgical techniques and show that the proposed approach achieves higher accuracy compared to an existing method.

Adversarial generation of real-time feedback with neural networks for simulation-based training

Simulation-based training (SBT) is gaining popularity as a low-cost and convenient training technique in a vast range of applications. However, for a SBT platform to be fully utilized as an effective training tool, it is essential that feedback on performance is provided automatically in real-time during training. It is the aim of this paper to develop an efficient and effective feedback generation method for the provision of real-time feedback in SBT. Existing methods either have low effectiveness in improving novice skills or suffer from low efficiency, resulting in their inability to be used in real-time. In this paper, we propose a neural network based method to generate feedback using the adversarial technique. The proposed method utilizes a bounded adversarial update to minimize a L1 regularized loss via back-propagation. We empirically show that the proposed method can be used to generate simple, yet effective feedback. Also, it was observed to have high effectiveness and efficiency when compared to existing methods, thus making it a promising option for real-time feedback generation in SBT.

Simulation for Training Cochlear Implant Electrode Insertion

Cochlear implant surgery is performed to restore hearing in patients with a range of hearing disorders. To optimise hearing outcomes, trauma during the insertion of a cochlear implant electrode has to be minimised. Factors that contribute to the degree of trauma caused during surgery include: the location of the electrode, type of electrode, and the competence level of the surgeon. Surgical competence depends on knowledge of anatomy and experience in a range of situations, along with technical skills. Thus, during training, a surgeon should be exposed to a range of anatomical variations, where he/she can learn and practice the intricacies of the surgical procedure, as well as explore different implant options and consequences thereof. Virtual reality simulation offers a versatile platform on which such training can be conducted. In this paper, we discuss a prototype implementation for the visualisation and analysis of electrode trajectories in relation to anatomical variation, prior to its inclusion in a virtual reality training module for cochlear implant surgery.

Effects of anatomical variation on trainee performance in a virtual reality temporal bone surgery simulator.

OBJECTIVE To investigate the importance of anatomical variation in acquiring skills in virtual reality cochlear implant surgery. METHODS Eleven otolaryngology residents participated in this study. They were randomly allocated to practice cochlear implant surgery on the same specimen or on different specimens for four weeks. They were then tested on two new specimens, one standard and one challenging. Videos of their performance were de-identified and reviewed independently, by two blinded consultant otolaryngologists, using a validated assessment scale. The scores were compared between groups. RESULTS On the standard specimen, the round window preparation score was 2.7 ± 0.4 for the experimental group and 1.7 ± 0.6 for the control group (p = 0.01). On the challenging specimen, instrument handling and facial nerve preservation scores of the experimental group were 3.0 ± 0.4 and 3.5 ± 0.7 respectively, while the control group received scores of 2.1 ± 0.8 and 2.4 ± 0.9 respectively (p < 0.05). CONCLUSION Training on temporal bones with differing anatomies is beneficial in the development of expertise.