Electrical Impedance Tomography for deformable media

Abstract

In Electrical Impedance Tomography (EIT), electrical energy is applied and measured at the boundary of a medium to produce an image of its internal conductivity distribution. When imaging pulmonary ventilation, rib cage expansion and body posture introduce severe image artefacts in the reconstructed images due to electrode position error. This thesis proposes a method to reduce such artefacts by determining the net displacement of electrodes between measurement frames, and effectively, adjusting the geometry of the reconstruction model. A novel regularization method is proposed and validated using data acquired from simulation, phantom, and human in vivo measurements. The proposed method reduces artefacts by more than 70% in simulated reconstructions and phantom experiments. The in vivo images reveal the various breathing manoeuvres and thoracic movements recorded. Furthermore, the displacement of each electrode is calculated, indicating the deformed boundary shape. This thesis supports EIT for clinical diagnostics and monitoring of pulmonary ventilation.