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

 

GREIT Reconstruction for multiple electrode layers

The GREIT formulation can be directly used to reconstruct a single plane in the centre of an EIT configuration in which two (or more) planes of electrodes are used.

Simulation model

% $Id: mk_GREIT_mat_2layer01.m 2554 2011-04-28 19:14:20Z aadler $
n_elecs = 8;
layers = [0.8,1.2];
stim =  mk_stim_patterns(n_elecs*length(layers),1,[0,1],[0,1], ...
             {'no_meas_current'}, 1);

extra={'lungs','solid lungs = sphere(0.9,0.1,1.65;0.3) or sphere(-0.9,0.1,1;0.3);'};
[fmdl,midx] = ng_mk_ellip_models([2, 2,1.4,0.2] ,[n_elecs,layers],[0.1], extra);
fmdl.stimulation =  stim;

img = mk_image(fmdl,1); % Homogeneous background
vh = fwd_solve(img);
img.elem_data(midx{2}) = 0.5; % Lung regions
vi = fwd_solve(img);

show_fem(img,[0,1]); view(0,70);
print_convert mk_GREIT_mat_2layer01a.png '-density 60'
view(0,10);
print_convert mk_GREIT_mat_2layer01b.png '-density 60'


Figure: Simulation of data on an elliptical model with lung shaped contrasting regions

Calculate GREIT reconstruction matrix

% $Id: mk_GREIT_mat_2layer02.m 4341 2013-09-24 16:08:49Z aadler $
opt.imgsz = [32 32];
opt.distr = 3; % non-random, uniform
opt.Nsim = 1000;
opt.target_size = 0.05; % Target size (frac of medium)
opt.noise_figure = 1.0; % Recommended NF=0.5;
% opt.target_layer = 1.0; % Default is in the centre

fmdl = ng_mk_ellip_models([2, 2,1.4,0.2] ,[n_elecs,layers],[0.1]);
fmdl.stimulation =  stim;
fmdl = mdl_normalize(fmdl, 0);
img = mk_image(fmdl,1);

imdl = mk_GREIT_model(img, 0.25, [], opt);

show_fem(fmdl); view(0,70);

print_convert mk_GREIT_mat_2layer02a.png '-density 60'


Figure: Simulation of data on an elliptical model with lung shaped contrasting regions

Reconstruct Images

% $Id: mk_GREIT_mat_2layer03.m 2553 2011-04-28 19:03:58Z aadler $

rimg = inv_solve(imdl,vh,vi); %Reconstruct
rimg.calc_colours.ref_level=0;

show_fem(rimg); axis square;

print_convert mk_GREIT_mat_2layer03a.png '-density 60'


Figure: Reconstructed images

Last Modified: $Date: 2017-02-28 13:12:08 -0500 (Tue, 28 Feb 2017) $ by $Author: aadler $