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Device Technologies and Biomedical Robotics

Device Technologies and Biomedical Robotics - Poster Session E

Poster W6 - Reliability of a head-mounted laser pointer position to access target-tracking tasks

Saturday, October 26, 2024

10:00 AM - 11:00 AM EST

Location: Exhibit Hall E, F & G

Presenting Author(s)

Bat Baasan, MA

Graduate Research Assistant
Department of Computational Social Science
Fairfax, Virginia, United States

Co-Author(s)

SS

Siddhartha Sikdar

Professor
Department of Bioengineering, George Mason University, United States

Primary Investigator(s)

Samuel A. Acuna, PhD (he/him/his)

Research Assistant Professor
George Mason University
Fairfax, Virginia, United States

Introduction: Introduction
Neck pain is a significant global issue [1] that necessitates accurate assessment and treatment, especially in medical, ergonomic, and rehabilitation contexts. Traditional methods for measuring cervical (neck) movement, such as goniometers, inclinometers, visual estimation, and tape measurements, are considered the accepted standard practice but have faced scrutiny regarding their intra- and inter-observer reliability. These manual methods often suffer from limitations in accuracy, precision, and repeatability. Some emerging technologies have been introduced to improve the assessment of neck pain and movement. Techniques such as head-mounted laser pointing and video recording [2], [3], [4], [5] are increasingly employed by clinicians and physical therapists to evaluate and treat neck-related disorders, including impaired proprioception. However, these methods still rely on visual assessment by experts, which can introduce bias and subjectivity into the evaluation process. To address these limitations and enhance the assessment process, we are investigating the feasibility of incorporating video processing techniques with head-mounted laser pointing to support objective, quantitative assessments of cervical control. For example, tracking the accuracy of the projected laser on a wall to measure quality of the cervical range of motion and movement performance over time. This technology paves the way for implementing more complex target-tracking tasks to better assess the quality of impaired cervical control. It also offers opportunities to gain insights into cervical coordination and proprioceptive accuracy. Therefore, the objective of this pilot study was to investigate the reliability of the laser pointer position during cervical motion tasks.

Materials and

Methods: Four healthy participants (age: 20±3 years) participated in this pilot study. Participants wore a headband with a laser pointer affixed over their forehead and sat facing a wall 90 cm away. A 3.5 cm circular target was projected in front of the participant. The moving target was created using MATLAB and would traverse the horizontal or vertical direction at a constant speed approximately 126.29 pixels/second. We instructed the participant to move their head so that the laser pointer dot followed the moving target as closely as possible. Thus, during these tasks, the participants were performing cervical flexion, extension, and rotation to the left and right. After three practice trials for a specific movement, a GoPro video camera recorded the position of the laser pointer dot and the circular target on the wall. Each task was repeated 6 times [1]. We extracted the centroids of the laser point and the circular target using “regionprop” function in MATLAB that is consistent with prior studies [4], [6], [1]. To determine the reliability of the laser pointer position across subject, we calculated the intraclass correlation coefficient (ICC) [7] using the Python library “pingouin” [8].

Results, Conclusions, and Discussions: Results, Discussion, Conclusion
The extracted position of the laser pointer was reliable and consistent across the subjects (Flexion: ICC = 0.83, p = 0.007; Extension: ICC = 0.73, p = 0.036; Left rotation: ICC = 0.84, p = 0.006; Right rotation: ICC = 0.92, p < 0.001). ICC estimates greater than 0.90 are considered excellent [9], [6] which suggests that the participants were most consistent for the rotation target tracking tasks.
Our findings suggest that combining head-mounted laser pointing with video processing techniques could feasibly quantify the quality of the cervical control. For example, asking participants to follow a target moving in a straight line back and forth provides a simple yet effective way to assess cervical range of motion and movement consistency. The target motion could also be more complex, such as sinusoid movement pattern, which may help evaluate the smoothness and control of neck movements, as well as detect irregularities in proprioception. We could also employ a figure-eight pattern [4], [10] to challenge the neck’s ability to perform complex, multi-directional movements. Future studies will explore the inherent variability of the projected laser (e.g., vibrations of a cantilevered beam) and limitations of standard consumer-grade video recording (e.g., frame rate, resolution, contrast) that may negatively impact the reliability of any assessments with this technology. Therefore, we are anticipated to validate the cervical motion measures against an optical motion capture system and develop normative measures within target tracking tasks that could be used to detect impaired cervical control.

Acknowledgements (Optional): Efforts are sponsored by George Mason University Bioengineering Department and Quality of Life Plus.