  The aim of electrical impedance tomography is to form an image of the
conductivity distribution inside an unknown body using electric boundary
measurements. The computation of the image from measurement data is a
non-linear ill-posed inverse problem and calls for a special regularized
algorithm. One such algorithm, the so-called D-bar method, is improved in this
work by introducing new computational steps that remove the so far necessary
requirement that the conductivity should be constant near the boundary. The
numerical experiments presented suggest two conclusions. First, for most
conductivities arising in medical imaging, it seems the previous approach of
using a best possible constant near the boundary is sufficient. Second, for
conductivities that have high contrast features at the boundary, the new
approach produces reconstructions with smaller quantitative error and with
better visual quality.
