Figure 3.

Incorporation of TOF information into the OE algorithm (schematic drawing). The shaded area under the TOF weight function ${\tilde{\mathcal{N}}}_k$ is directly proportional to the TOF-weighted system matrix element ${\text{α}}_{i{j}_k}^{\left(\text{TOF}\right)}$, as well as approximately equal to the probability to propose pixel i as a new location for event k, Q_k(i).