EIDORS: Electrical Impedance Tomography and Diffuse Optical Tomography Reconstruction Software

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GN reconstruction vs Backprojection

Define a regular GN solver

%$Id: nodal_jacobian01.m 4839 2015-03-30 07:44:50Z aadler $
imdl_e= mk_common_model('b2c2',16);
imdl_e.hyperparameter.value= 0.2;
imdl_e.RtR_prior = @prior_laplace;

fmdl= imdl_e.fwd_model;
imdl_n= imdl_e;
imdl_n.fwd_model.jacobian = @jacobian_elem2nodes;
imdl_n.fwd_model.jacobian_elem2nodes.fwd_model = fmdl;
imdl_n.RtR_prior = @RtR_prior_elem2nodes;
imdl_n.RtR_prior_elem2nodes.RtR_prior = @prior_laplace;
imdl_n.RtR_prior_elem2nodes.fwd_model = fmdl;
imdl_n.reconst_to = 'nodes';

img_e= mk_image( imdl_e );
img_n= img_e;
img_n.fwd_model= imdl_n.fwd_model;
img_n= rmfield(img_n,'elem_data');
img_n.node_data= mapper_nodes_elems(fmdl)*img_e.elem_data;


J_e= calc_jacobian( img_e);
J_n= calc_jacobian( img_n);

Examples with tank data

% load some lung data
load iirc_data_2006;
vi = v_rotate(:,50);
vh = v_reference;

img1= inv_solve(imdl_e,vh,vi);
subplot(121)
show_slices(img1);

img2= inv_solve(imdl_n,vh,vi);
subplot(122)
show_slices(img2);


print -r125 -dpng nodal_jacobian_solver02.png;

Figure: Left: Tank data reconstructed on the element mesh Right:Tank data reconstructed on the nodal mesh

Examples with lung data

% load some lung data
load montreal_data_1995;
vi = zc_resp(:,2); 
vh = zc_resp(:,19); 

% Lung forward model - with electrode #1 on back
imdl_lung= mk_common_model('b2t2',16);
fmdl_lung= imdl_lung.fwd_model;
fmdl_lung.electrode= fmdl_lung.electrode([9:16,1:8]); 

% Put lung models into the inv_model for elems
imdl_e.fwd_model= fmdl_lung;

% Put lung models into the inv_model for nodes
fmdl_lung.jacobian_elem2nodes.fwd_model = fmdl_lung;
fmdl_lung.jacobian = @jacobian_elem2nodes;
imdl_n.fwd_model= fmdl_lung;
imdl_n.RtR_prior_elem2nodes.fwd_model = fmdl_lung;

img1= inv_solve(imdl_e,vh,vi);
subplot(121)
show_slices(img1);
img2= inv_solve(imdl_n,vh,vi);
subplot(122)
show_slices(img2);


%print -r125 -dpng nodal_jacobian_solver.png;

Figure: Left: Lung data reconstructed on the element mesh Right:Lung data reconstructed on the nodal mesh