Summary: Artifacts due to Conformal Deformations in
Electrical Impedance Tomography
A Boyle1, WRB Lionheart2, A Adler1
1Carleton University, Ottawa 2University of Manchester
Artifacts in the images created using Electrical Impedance Tomography (EIT) due to movement of the
boundary in difference imaging have been an issue, particularly in pulmonary EIT where chest movement
due to breathing and posture change is a regular event. With the recent development of algorithms to detect
some types of boundary movement directly from the EIT measurements, it has become possible to correct
for many of these boundary distortions by assuming an isotropic medium. The further classification of
boundary movement into two types, conformal movements and those that are not, provides the opportunity
for further refinement of this algorithm. In this paper, we discuss the conformal movements and their
properties and show, through the governing conductivity equation for EIT, that conformal movement of an
isotropic conductivity domain results in a new isotropic conductivity where the change in conductivity is
directly related to the conformal movement.
Conformal Vector Fields
Let X be a vector field, assumed to be small in magnitude. A domain is distorted by the map x x+X .
This vector field X indicates the velocity of change in shape over time everywhere over the domain, where
multiplying the vector field by some small time will give a map that is a new geometry for the domain.
A conformal map is one that preserves the angles but not necessarily lengths between vectors on the