Image Reconstruction for 3D Lung Imaging - Department of Systems ...
Image Reconstruction for 3D Lung Imaging - Department of Systems ...
Image Reconstruction for 3D Lung Imaging - Department of Systems ...
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plane located halfway between the electrode planes. This is expected as resolution or its<br />
counterpart, sensitivity, decreases as position moves from current injecting or measuring<br />
electrodes. Thus resolution will be worse half way between the electrode planes. Radial<br />
position error as shown in figure 5.8(b) is lowest <strong>for</strong> contrasts at the centre <strong>of</strong> the tank and<br />
increases as contrasts move radially outward. In general however, the radial position error<br />
is small.<br />
true target height<br />
reconstructed target height<br />
<strong>Image</strong> Energy<br />
25<br />
20<br />
25<br />
20<br />
15<br />
10<br />
15<br />
10<br />
5<br />
0<br />
0.38 0.4 0.42 0.44 0.46 0.48<br />
Resolution (BR)<br />
0.5 0.52 0.54<br />
5<br />
(a) Resolution<br />
Tik - centre<br />
diag - centre<br />
laplacian - centre<br />
Tik - half<br />
diag - half<br />
laplacian - half<br />
0<br />
0 5 10 15<br />
true target height<br />
20 25 30<br />
13<br />
12<br />
11<br />
10<br />
9<br />
8<br />
7<br />
6<br />
5<br />
4<br />
(c) Height Error<br />
3<br />
0 5 10 15 20 25<br />
true target height<br />
(e) <strong>Image</strong> Energy<br />
target height<br />
target height<br />
SNR<br />
25<br />
20<br />
15<br />
10<br />
5<br />
0<br />
-0.1 0 0.1 0.2 0.3 0.4 0.5 0.6<br />
radial error (%)<br />
30<br />
25<br />
20<br />
15<br />
10<br />
5<br />
(b) Radial Position Error<br />
Electrode Planes<br />
0<br />
-20 0 20 40 60 80 100<br />
Position error (%)<br />
0.3<br />
0.28<br />
0.26<br />
0.24<br />
0.22<br />
0.2<br />
0.18<br />
0.16<br />
0.14<br />
0.12<br />
(d) Position Error<br />
Electrode Planes<br />
0.1<br />
0 5 10 15 20 25<br />
target height<br />
(f) SNR<br />
Figure 5.8: Per<strong>for</strong>mance Measures <strong>for</strong> <strong>3D</strong> <strong>Reconstruction</strong>s <strong>of</strong> Two Simulated Data Sets.<br />
Legend in figure (c) applies to all figures. Electrode Planes are centered at heights <strong>of</strong> 8.5<br />
and 19.5cm as indicated in 5.8(d) and 5.8(f)<br />
Height error as shown in figure 5.8(c) is common <strong>for</strong> all priors. There is a general<br />
tendency <strong>for</strong> contrasts to be reconstructed closer to the electrode planes than they actually<br />
are.<br />
Position error is shown in figure 5.8(d) is a combination <strong>of</strong> the radial and vertical position<br />
errors and mainly indicates an asymmetry in the vertical axis. Figure 5.8(e) shows the<br />
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