THE DEPENDENCE OF EIT IMAGES ON THE ASSUMED INITIAL CONDUCTIVITY DISTRIBUTION - A STUDY OF PELVIC IMAGING

EIT measurements on humans are often made in regions of the body where the conductivity distribution is far from uniform. This paper address es the problem of deriving accurate quantitative data in one such regi on: the conductivity changes associated with the accumulation of blood in the pelvic bowl. A computer map of the bone in the pelvic region w as constructed, from which an appropriate reconstruction matrix was ge nerated. Both computer simulations and tank tests were performed to as sess whether this bone reconstruction matrix produced impedance images with closer fidelity to the measured object than images produced usin g a reconstruction based on a uniform conductivity distribution. As ex pected, images produced by the computer simulation indicated that the bone reconstruction matrix produced images of better fidelity than did the uniform reconstruction matrix. However, in the case of the tank d ata only a moderate improvement was achieved. The reconstruction matri x based on a uniform conductivity distribution was found to produce sa tisfactory images for both bone and near-uniform objects, but for regi ons further into the pelvic bowl, where the signal was lower, the unif orm reconstruction matrix was less satisfactory.