Eidors-logo    

EIDORS: Electrical Impedance Tomography and Diffuse Optical Tomography Reconstruction Software

EIDORS (mirror)
Main
Documentation
Tutorials
− Image Reconst
− Data Structures
− Applications
− FEM Modelling
− GREIT
− Old tutorials
Workshop
Install
Contrib Data
GREIT
Browse Docs
Browse SVN

News
Mailing list
(archive)
FAQ
Developer
                       

 

Hosted by
SourceForge.net Logo

 

Using EIDORS to image lungs

2D EIT for lung imaging

Use mk_common_model to create a thorax shaped model with 16 electrodes. Ensure the model uses 1) Correct stimulation patterns (adjacent is default), 2) Normalized difference imaging
% Lung images
% $Id: tutorial310a.m 3343 2012-07-01 21:28:44Z bgrychtol $

% 2D Model
imdl= mk_common_model('c2t2',16);

% Make correct stimulation pattern
[st, els]= mk_stim_patterns(...
   16, ... % electrodes / ring
    1, ... % 1 ring of electrodes
   '{ad}','{ad}', ... % adj stim and measurement
   { 'no_meas_current', ... %  don't mesure on current electrodes
     'no_rotate_meas',  ... %  don't rotate meas with stimulation
     'do_redundant', ...    %  do redundant measurements
   }, 10 );  % stimulation current (mA)
imdl.fwd_model.stimulation= st;
imdl.fwd_model.meas_select= els;

% most EIT systems image best with normalized difference
imdl.fwd_model = mdl_normalize(imdl.fwd_model, 1);
imdl.RtR_prior= @prior_gaussian_HPF;


subplot(221);
show_fem(imdl.fwd_model);

axis equal
print_convert tutorial310a.png;


Figure: 2D FEM of thorax (units in mm). Electrode #1 (o) and electrode #2 (o) are shown in different colours than the others (o).
Electrodes in the FEM must match those on the subject. This example shows two possible repositioning of electrodes
% Lung images
% $Id: tutorial310b.m 2762 2011-07-14 16:04:40Z aadler $

% If electrodes are counter-clockwise, then do this
imdl_ccw = imdl;
imdl_ccw.fwd_model.electrode([1,16:-1:2])=  ...
   imdl.fwd_model.electrode;

subplot(221);
show_fem(imdl_ccw.fwd_model);

% If electrodes start on back (dorsal), then do this
imdl_d = imdl;
imdl_d.fwd_model.electrode([9:16,1:8])=  ...
   imdl.fwd_model.electrode;

subplot(222);
show_fem(imdl_d.fwd_model);

axis equal
print_convert tutorial310b.png;


Figure: Left: electrodes placed counter-clockwise starting at 12 O'clock. Right: electrodes placed clockwise starting at 6 O'clock (on the dorsal side)
% Lung images
% $Id: tutorial310c.m 2762 2011-07-14 16:04:40Z aadler $

load montreal_data_1995
imdl_d.hyperparameter.value=5e-2;
img= inv_solve(imdl_d, zc_resp(:,1), zc_resp);

clf; show_slices(img)
axis equal

print_convert tutorial310c.png;


Figure: Lung image slices (frame rate of 1/7 seconds). Image progression is from left to right, top to bottom. One breath is shows. There also appears to be a movement of blood dorsally during the cardiac cycle.

Last Modified: $Date: 2011-07-15 06:48:46 -0400 (Fri, 15 Jul 2011) $ by $Author: aadler $