Improvement of signal-to-noise ratio and image stability in magnetic inductance tomography by exploiting transient response analysis

This study presents a method to increase the signal-to-noise ratio (SNR) and image stability in magnetic inductance tomography (MIT) data acquisition by exploiting transient response analysis. In front-end circuits for inductance measurements in MIT, a critical step is the phase sensitive demodulation, which includes a low pass filter. When the excitation source is switched from one coil to the next, a transient response occurs as the received voltage level changes. Normally, data acquisition takes place after the transient response finishes and the voltage level becomes nearly constant. In this study, a method is proposed to increase the SNR by exploiting the information embedded in the transient response. Simulation and experimental tests have confirmed the validity of the method; standard deviations of the measured inductance decrease more than 50%. The impact of improvement in SNR in raw inductance measurement on image stability is considered with different image reconstruction algorithms. The error propagation in the image reconstruction process is discussed.