Estimating Homogeneous Reference Frame for Absolute Electrical Impedance Tomography Through Measurements and Scale Feature

Abstract

Electrical impedance tomography (EIT) is a noninvasive imaging technology that is widely used in industrial and medical applications. The reconstruction methods are ill-posed and sensitive to the scale of perturbations and prior assumptions, so differential reconstruction is mostly used in practice. Absolute reconstruction is promising but has always been a challenge in practical applications. One of the obstacles is to determine the reference measurement frame from a uniform distributed domain. In this article, we develop a reference measurement estimation technique for a homogeneous conductivity distribution with proportional variations. The concept of measurement-scale feature (MSF) is proposed to represent the scale of measurements, and five MSF operators are defined for EIT measurements. The proposed method estimates the prior reference measurements using the MSF of present measurements. The baseline reference frame is simulated with arbitrary conductivity with the same domain shape and electrode positions as the measured domain and the MSF of the baseline frame. Simulations and experiments were carried out to verify the validity of the estimated reference measurements for absolute EIT (aEIT) reconstruction. Evaluations on the reconstruction results and reference estimation errors show the effectiveness of this method for aEIT in various scenarios with a wide range of conductivity and different domain shapes. This study demonstrates an effective approach for determining the homogeneous reference frame, providing more potential for the application of aEIT in real-time pipeline detection and online clinical monitoring.