Consider the projection data shown in Figure 1. Starting with 0 activity in each pixel and using the algebraic reconstruction technique, determine the activity in the 9 image pixels after 1 (full) iteration, 2 (full) iterations, and at convergence of the algorithm (where the change in the pixel values is < 0.01% of the pixel values). Ignore attenuation and scatter effects.
NB: Assume that each projection ray intersects with 3 (and only 3) of the pixels.