Performance studies of a depth encoding multicrystal detector for PET

The authors report the results of design studies for a multicrystal detector with the capacity to encode the depth-of-interaction (DOI). These studies are based on a simulation that treats the interactions of γ-rays and tracks scintillation photons in state-of-the-art position encoding PET detectors. The simulation was used to study the impact of a simple modification to the standard surface treatment of the EXACT HR PLUS block that induces a significant sensitivity of the photopeak pulse height upon the DOI of 511 keV γ-rays. The depth resolution achieved with the altered block as well as the impact of the modification on its energy and position resolutions are presented. The results show a depth resolution of 6 to 7 mm for the inner crystals of the modified block. This is achieved at the cost of 16% less position addressing accuracy