Electrical capacitance tomography (ECT) is a non-intrusive and non-invasive imaging technique that creates a cross-sectional image of the distribution of dielectric materials inside a pipe or vessel. ECT measures the capacitance between pairs of electrodes mounted on the outside of the pipe, and reconstructs a cross-sectional image using the measured capacitance data and a suitable algorithm, to reflect the inside permittivity distribution. ECT is particularly useful for visualising the multiphase flow of non-conductive substances in industrial processes.