Pre-processing of data using logarithmic transformation to improve the spatial resolution of an EIT system for biomedical applications

One of the major applications of EIT is in medical imaging where low values of current are injected at low frequencies owing to safety concerns. Due to low values of injected current, the differences between the boundary voltages are quite small, especially as we go farther from the injected electrodes. In this paper we propose the use of logarithmic transformation to increase the difference between the boundary data, making them distinguishable enough for high resolution imaging. Simulation and practical phantom experiments are carried out and the reconstructed images are analysed before and after the logarithmic transformation. Results are also compared with the pre-processing technique based on root transformations. Limitations of the proposed logarithmic transformation technique are also discussed.