mplementation, platform)|
% 
% where |x|, |y| and |z| are the detector coordinates corresponding to every 
% element of the input measurement data (vector or matrix), |Nx/y/z| are the image 
% size in x/y/z-directions, |FOVtr| the FOV size in transaxial direction (length 
% of one side of the square), |axial_fov| the size of the FOV in axial direction, 
% |subsets| is an optional number of subsets (can be omitted), |implementation| 
% the optional implementation that should be used (4 is default, can be omi