Fig. 4

Noise vs. contrast recovery for the Small-tumor phantom (a) 3.7 mm, (b) 4.8 mm, (c) 6.5 mm, (d) 7.7 mm, (e) 8.9 mm, 9.7 mm spheres filled with ¹²⁴I and reconstructed with OSEM (1–5 iterations), OSEM+PRC simplified (1–3 iterations), OSEM+PRC (1–10 iterations), PSF (1–10 iterations), PSF+PRC simplified (1–10 iterations), and PSF+PRC (1–20 iterations). Every point corresponds to one iteration (all reconstructions done with 12 subsets). The behavior of the OSEM+PRC is similar to the stand-alone PSF reconstructions. The selected number of iterations for the comparison of the images are marked with red