Evaluating Accuracy, Completion Time and Usability of Everyday Touch Devices for Contouring

Abstract

<h3>Purpose/Objective(s)</h3> Adaptive radiation therapy aims to account for patients' continuous anatomical changes and update the treatment plans on a daily basis. Despite the potential benefits, technological limitations hinder clinical adoption: daily re-evaluation of contours associated with adaptive planning is time-intensive and difficult to access, and often requires direct provider input which classically involves visualizing and editing contours on immobile desktop computers. This project evaluated the efficacy of everyday touch devices (i.e., tablet and phone) for contouring using a novel cross-platform interface. <h3>Materials/Methods</h3> Guided by user-centered and iterative design principles, we developed a cross-platform web-based contouring application which facilitates CT image navigation and target delineation. In a within-subject study design, we invited 8 radiation oncology residents to contour a liver using 4 different conditions: Desktop & Mouse, Tablet & Stylus, Tablet & Finger, and Phone & Finger. We compared the time spent contouring and assessed accuracy with Dice Similarity Coefficients (DSC). With each interface we administered a System Usability Scale (SUS) questionnaire which evaluates perceived ease of use. We incorporated repeated-measure ANOVA to assess differences between groups. <h3>Results</h3> Among the participants, using a Tablet & Finger and Phone & Finger produced the shortest time spent contouring per CT slice (<i>p</i> < .001), while Desktop & Mouse led to the longest time per slice (see Table). When comparing participant contours to a baseline gold standard, results were similar between all devices, though the Desktop & Mouse yielded a slightly lower contouring accuracy, and the most accurate was the Tablet & Stylus (<i>p</i> < .0001). Usability assessment after contouring found that participants scored Tablet & Stylus the highest, followed by Tablet & Finger, Desktop & Mouse, and Phone & Finger (<i>p</i> < .01). <h3>Conclusion</h3> Everyday touch devices (i.e., tablet and phone) not only met the standard contouring efficiency with a Desktop & Mouse, but also exceeded expectations in terms of both time spent and accuracy, especially contouring with a Tablet & Stylus which also received significantly better usability scores. Given the improved mobility with touch devices, these results suggest promising implications in addressing technological challenges associated with adaptive radiation therapy.