Fig. 2

Projection images of the number of uncorrected true events (a, c) and corrected true events (b, d) for the centered (a, b) and off-centered phantom (c, d) acquisition and for increasing ¹³¹I activity in the background. The corrected number of trues corresponds to the number of trues recorded by the PET system multiplied by the dead-time correction factor, the normalization factor, and the attenuation correction factor