A sub-mm spatial resolution LYSO: Ce detector for small animal PET

Current high-resolution scintillators are fabricated using mechanical pixelation technique. However the fabrication cost of finely pitched scintillator arrays together with their lack of flexibility to accommodate new depth of interaction designs has remained a significant issue with mechanical pixelation. Another pitfall of mechanically pixelated scintillators is their relatively large inter-pixel gaps that adversely affect their sensitivity to the incident gamma-ray. The main objective of our ongoing efforts is to fabricate high-spatial resolution and high sensitivity PET detectors with depth of interaction (DOI) capability and single-side readout in a cost-effective manner using laser-induced optical barriers (LIOB) technique. We have simulated the behavior of simple optical barriers in LYSO:Ce crystal using the DETECT simulation code. We have also created optical barriers with different size and barrier density in LYSO:Ce at various depths up to 20 mm to form pixel-like shapes similar to mechanically pixelated crystals. In order to process 20mm thick crystals we corrected for laser beam defocusing effect and its adverse effect on laser energy density which results in smaller barrier size and reflectivity. The fabrication time for 10x10x1 and 10x10x20 mm3 LYSO crystals (with lmm pixels) was similar to 8 and 95 minutes respectively.