Image Reconstruction for 3D Lung Imaging - Department of Systems ...

the total amount of applied current. In this environment the distinguishability should be
maximized with respect to this constraint. This is furthered by Lionheart in [69] where he
points out that the maximum Ohmic power dissipated in the body must be limited.
2.5.1.5 Other Patterns
In [99] Polydorides and McCann described a novel “scrolling” current injection pattern
using a single current source instrument. The current source is simultaneously connected
to several neighbouring electrodes while voltages are measured between single electrodes.
The current injection electrodes are then “scrolled” around the object by connecting new
electrodes at one side and leaving some free at the other. Voltage measurements are repeated
for each new configuration.
2.5.1.6 Compound Electrodes
In [72] Hua et al introduced compound electrodes comprised of a larger outer electrode with
a small, electrode in the centre. Current is injected in the larger outer electrode, and voltage
us measured from a small inner electrode. They show that using compound electrodes can
make reconstructions less dependent on the contact impedance value thus minimizing its
effects.
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