FIG. 2.

The schematic representation of the effects of finite intrinsic spatial resolution. T₁ and T₂ indicate the exact locations of photon interactions within each detector voxel. These are unknown therefore usually it is assumed that the interactions happen at the centers of the detector elements in both detectors (${\overline{M}}_1$ and ${\overline{M}}_2$). The conical surface indicated by the solid line corresponds to the true interaction locations. An incorrect assumption about the interaction locations will lead to the loss of spatial resolution.