“…In order to examine the influence of the crystal material on the information content of the final PET image, the system was also simulated by replacing the BGO crystal arrays with crystals of various quantum detection efficiency (QDE) [45] values, i.e., yttrium orthoaluminate perovskite (YAlO 3 :Ce or YAP, QDE = 0.75) [36,43,44], lutetium orthoaluminate perovskite LuAlO 3 :Ce or LuAP:Ce, lutetium yttrium orthoaluminate perovskite ((LuY)AlO 3 :Ce or LuYAP:Ce, QDE = 0.90) with 70% lutetium (Lu) atomic fraction, LuYAP:Ce with 80% Lu atomic fraction (QDE = 0.91) [44,46], lutetium oxyorthosilicate (Lu 2 SiO 5 :Ce or LSO, QDE = 0.93) [46][47][48][49][50], and gadolinium oxyorthosilicate (Gd 2 SiO 5 :Ce or GSO, QDE = 0.88) [43,44,51] crystals with dimensions equal to those of BGO (QDE = 0.94) (6.3 × 6.3 × 30 mm) in the tangential, axial, and radial directions, respectively.…”