class object without the |options| 
% struct, either by using the projection angles or by inputting the  detector 
% coordinates for every measurement point. In the first case  (angles), the constructor 
% is |A = forwardBackwardProjectCT(angles, ySize, xSize, Nx, Ny, Nz, FOVa_x, axial_fov, 
% dPitch, sourceToDetector, sourceToCRot, horizontalOffset, bedOffset, subsets, 
% implementation, deviceN)|. |angles| are the angles corresponding to each projection, 
% |ySize| is the number of rows in a single projec