Contactless Electrical Impedance Tomography for Lung Ventilation Monitoring: Feasibility and Reconstruction Evaluation

Contactless Electrical Impedance Tomography (CEIT) enables non-contact measurement through capacitive coupling between electrodes and the subject, offering potential advantages for long-term lung ventilation monitoring. However, the reconstruction characteristics of CEIT for lung ventilation monitoring (LVM) and its adaptability to different reconstruction algorithms under experimental conditions remain insufficiently validated. This study presents a CEIT-based LVM method that uses impedance amplitude and phase-angle information for separate image reconstruction and conductivity-distribution evaluation, and establishes a synchronous testing system for CEIT and conventional Electrical Impedance Tomography (EIT). Water-tank experiments with cylindrical targets were conducted to evaluate four classic reconstruction algorithms for CEIT and conventional EIT, including Linear Back Projection (LBP), Tikhonov regularization, Newton-Raphson (N-R) iteration, and Landweber iteration, and to identify the more suitable reconstruction strategy for each system. Preliminary simulated lung imaging was then performed to assess the practical feasibility of CEIT. The results show that CEIT can achieve imaging performance comparable to that of conventional EIT under the reported experimental conditions, while exhibiting different reconstruction behaviors. Among the tested algorithms, Landweber iteration provided the most stable performance for CEIT, whereas Tikhonov regularization was more suitable for conventional EIT in this study. These findings support the feasibility of CEIT as a non-contact method for lung ventilation monitoring.