Accuracy of video observation and a three-dimensional head tracking system for detecting and quantifying robot-simulated head movements in cone beam computed tomography

Publication date: Available online 28 February 2017
Source:Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology
Author(s): Rubens Spin-Neto, Louise H. Matzen, Lars Schropp, Thomas S. Sørensen, Erik Gotfredsen, Ann Wenzel
ObjectivesTo assess the accuracy of detecting robot-simulated head movements using video observation (VO) and three-dimensional head tracking (HT) in a CBCT examination set-up.Study designA mannequin head was mounted on a robot programmed to simulate patient head movements. Six types of movement (tremor, nodding, lateral rotation, lifting, swallowing, and antero-posterior translation), three distances (0.25, 1, and 5mm), and two speeds (1 and 5mm/s) were tested in triplicate (108 examinations). An additional 18 videos and HT of no-motion served as controls for a total of 126 examinations. Three blinded observers viewed video recordings of the examinations, scoring if the head moved and movement type. HT provided quantitative measures of movement distance. Accuracy, sensitivity, and specificity for movement detection by VO and HT were calculated, related to true type, distance, and speed of movement. Differences between the true and the measured movement distances were assessed for HT.ResultsVO movement detection presented accuracy=0.86, sensitivity=0.85, and specificity=0.94. Antero-posterior translation (33.3%) and 0.25mm movements (41.7%) were often not detected by VO. HT correctly detected all cases (accuracy=1). HT presented small differences between the true and the measured movement distances (average 20-54μm).ConclusionsVO missed 41.7% of the 0.25 mm movements. HT correctly detected all movements and quantified movements with an average error <55μm.



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