This is a CPU implementation of the Simultaneous Iterative Reconstruction Technique (SIRT) for 2D data sets. It takes projection data and an initial reconstruction as input, and returns the reconstruction after a specified number of SIRT iterations.

Supported geometries: parallel, fanflat, fanflat_vec, matrix.

Configuration options

name type description
cfg.ProjectorId required The astra_mex_projector ID of the projector.
cfg.ProjectionDataId required The astra_mex_data2d ID of the projection data
cfg.ReconstructionDataId required The astra_mex_data2d ID of the reconstruction data. The content of this when starting SIRT is used as the initial reconstruction.
cfg.option.SinogramMaskId optional If specified, the astra_mex_data2d ID of a projection-data-sized volume to be used as a mask.
cfg.option.ReconstructionMaskId optional If specified, the astra_mex_data2d ID of a volume-data-sized volume to be used as a mask.
cfg.option.MinConstraint optional If specified, all values below MinConstraint will be set to MinConstraint. This can, for example, be used to enforce non-negative reconstructions.
cfg.option.MaxConstraint optional If specified, all values above MaxConstraint will be set to MaxConstraint.


%% create phantom
V_exact = phantom(256);

%% create geometries and projector
proj_geom = astra_create_proj_geom('parallel', 1.0, 256, linspace2(0,pi,180));
vol_geom = astra_create_vol_geom(256,256);
proj_id = astra_create_projector('linear', proj_geom, vol_geom);

%% create forward projection
[sinogram_id, sinogram] = astra_create_sino(V_exact, proj_id);

%% reconstruct
recon_id = astra_mex_data2d('create', '-vol', vol_geom, 0);
cfg = astra_struct('SIRT');
cfg.ProjectorId = proj_id;
cfg.ProjectionDataId = sinogram_id;
cfg.ReconstructionDataId = recon_id;
cfg.option.MinConstraint = 0;
cfg.option.MaxConstraint = 255;
sirt_id = astra_mex_algorithm('create', cfg);
astra_mex_algorithm('iterate', sirt_id, 100);
V = astra_mex_data2d('get', recon_id);
imshow(V, []);

%% garbage disposal
astra_mex_data2d('delete', sinogram_id, recon_id);
astra_mex_projector('delete', proj_id);
astra_mex_algorithm('delete', sirt_id);