Large-Area Crystalline Microcolumnar LaBr$_{3}$:Ce for High-Resolution Gamma Ray Imaging

Abstract

Novel fabrication methods for cost-effective and large-volume production of important lanthanide halide scintillators are currently being explored. Here we report on the growth of LaBr :Ce scintillator films in a novel light conserving morphology known as Crystalline Microcolumnar StructureTM (CMSTM), using Hot Wall Evaporation (HWE) technique. This method produces specimens which preserve the response uniformity over the area of the film, and low attenuation of light throughout its thickness. Using this approach, we have produced LaBr :Ce film samples measuring 3-7 cm in diameter and approaching 2 cm in thickness, with densely packed microcolumns averaging ~15 μm in diameter. Some of these films show bright light emissions compared to their crystalline counterparts, demonstrating energy resolution of ~9.4% at 122 keV ( Co emission) and uniformity in light response across the area of the scintillator. Imaging data acquired using the University of Arizona Bazooka SPECT detector incorporating our CMS LaBr :Ce film demonstrated m spatial resolution ~138 μm at 122 keV in single-photon counting imaging mode. This technique permits fabrication of thick films that can simultaneously provide the high absorption efficiency and high spatial resolution required for small-animal SPECT imaging and other medical and non-medical applications.