Measurement and Application of Soft-Field Effect in Electrical Tomography

Electrical tomography (ET) is an advanced visualization technique commonly used in medical diagnosis and industrial inspections. Its advantages include no radiation, non intrusiveness, rapid response, and low-cost applications. However, its imaging quality is very limited due to the so-called “soft-field” effect. In this article, we focus on a typical form of ET, namely, electrical resistance tomography (ERT), with a special emphasis on the general evaluation of the “soft-field” effect. Based on the design principle of “hard field” adopted by most of the existing ERT algorithms, a novel index to measure the soft-field effect is formulated after the detection of representative soft-field characteristics. The index can either select the best one among a group of ERT algorithms or choose the best one among all candidate parameters of any parameter-based ERT algorithm. Experimental results show that the novel index can effectively measure the “soft field” in the ET imaging process and find images with high quality.