Optimal experiments in electrical impedance tomography

Abstract

Electrical impedance tomography (EIT) is a noninvasive imaging technique which aims to image the impedance within a body from electrical measurements made on the surface. The reconstruction of impedance images is a ill-posed problem which is both extremely sensitive to noise and highly computationally intensive. The authors define an experimental measurement in EIT and calculate optimal experiments which maximize the distinguishability between the region to be imaged and a best-estimate conductivity distribution. These optimal experiments can be derived from measurements made on the boundary. The analysis clarifies the properties of different voltage measurement schemes. A reconstruction algorithm based on the use of optimal experiments is derived. It is shown to be many times faster than standard Newton-based reconstruction algorithms, and results from synthetic data indicate that the images that it produces are comparable.

Propagation of measurement noise through backprojection reconstruction in electrical impedance tomography

“…where is the noise equivalent bandwidth defined by [31] and is the transfer function of the lowpass filter placed after the demodulator (5) The approximation introduced in (4) is reasonable if we consider that , in EIT systems, is typically several hundred hertz while is typically above 10 kHz. Therefore, .…”

“…A more serious disadvantage of iterative algorithms is that they suffer from convergence problems when applied to (noisy) acquired data since the inverse problem in EIT is very ill posed [1], [2]. A related class of reconstruction techniques includes the adaptive methods [3], [4], in which the applied current patterns are adjusted to get the best signal [5]- [8]. A second family of reconstruction algorithms is noniterative, based on a linearization of the equation that governs the potential distribution within the object.…”

Magnetoacoustic tomography with magnetic induction for imaging electrical impedance of biological tissue

“…This would be a reasonable approximation as long as the excitation coil is sending pulse stimulations that are short enough. Using Green's function, the solution of equation (1) can be written as in (2): (2) where R = |r − r′|, and V is the volume containing the acoustic source. The pressure on a surface surrounding the object can be measured to reconstruct the source term ∇ · (J × B 0 ) using the time reversing technique 1, 14 as in equation (3): (3) where r d is a point on the detection surface Σ, n is the normal vector of Σ at r d , r is a point in the object, the double prime refers to the second derivative over time.…”

A novel method of modeling and simulation for electrical resistance tomography system

“…The visualization measurement of conductive two/multi-phase flow in the closed pipe and process vessel inside is achieved by Electrical Resistance Tomography (ERT) [1,2]. In view of the research and development in recent years, ERT was in the stage of combining the application basic with applied research.…”