Precision Boundary Detection for EIT Leg Swelling Imaging Using Rotational ToF Sensors

This study proposes a boundary sensor system for Electrical Impedance Tomography (EIT) to estimate the swollen area boundaries in legs affected by lymphedema. Lymphedema imaging poses significant challenges in defining accurate boundary geometry models, as conventional EIT systems often provide imprecise geometric data. The proposed system utilizes a Time of Flight (ToF) VL53L0X sensor mounted on a rotating platform, enabling the capture of variable data points independently of the number of sensors and thereby addressing the limitations of traditional methods. The experimental setup involved testing the VL53L0X ToF sensor for distance and angle variations, with the sensor mounted on a platform driven by a stepper motor for precise angular positioning. Results revealed that the VL53L0X ToF sensor consistently misread distances with a mean absolute error of 32.0111 mm, and angle variations introduced a measurement error percentage of 8.2%. The system exhibited an average base platform rotation angle error of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$0.65^{\circ}$</tex>, indicating precise angular shifts. Overall, the ToF VL53L0X-based boundary sensor system successfully estimated non-homogeneous body boundary shapes with an error percentage of 3.9751%. These findings suggest that while there is room for improvement in sensor accuracy, the proposed method provides a cost-effective and accurate means of obtaining geometric data, enhancing EIT imaging for better lymphedema diagnosis and monitoring.