Serious bug on parallel beam projections

Actual Behavior

Stripe artefacts appear in the recon

I suspect it is some numerical issue. I recommend using a large DSD/DSO for now, or slightly offseting your angles.

Code to reproduce the problem (If applicable)

% VARIABLE                                   DESCRIPTION                    UNITS
%-------------------------------------------------------------------------------------
% Distances
% This works:
geo.DSD = 2000;                              % Distance Source Detector      (mm)
geo.DSO = 1800;                               % Distance Source Origin        (mm)
% This generate striped images:
geo.DSD = 700;                              % Distance Source Detector      (mm)
geo.DSO = 500; 

geo.nDetector=[640;200];					% number of pixels     400,60         (px)
geo.dDetector=[0.25; 0.25]; 					% size of each pixel            (mm)
geo.sDetector=geo.nDetector.*geo.dDetector; % total size of the detector    (mm)

geo.nVoxel=[640;640;200];                   % number of voxels    400,400,60          (vx)
geo.sVoxel=[160;160;50];                      % total size of the image       (mm)
geo.dVoxel=geo.sVoxel./geo.nVoxel;          % size of each voxel            (mm)

geo.mode='parallel';                        % 'cone' or 'parallel'. Geometry type.


head=headPhantom(geo.nVoxel); 
angles = [0:2:358]*pi/180;

% The following also removes the stripes
% angles=angles+0.01;

proj=Ax(head,geo,angles);

img=OS_SART(proj,geo,angles,1);
plotImg(img,'dim',3)