A study of response of a LuYAP:Ce array with innovative assembling for PET

We propose the characterization of a first array of 10×10 Lutetium Yttrium Orthoaluminate Perovskite (LuYAP:Ce) crystals, 2mm×2mm×10mm pixel size, with an innovative assembling designed to enhance light output, uniformity and detection efficiency. The innovation consists of the use of 0.015mm thick dielectric coating as inter-pixel light-insulators, manufactured by Crytur (Czech Republic) intended to improve crystal insulation and then light collection. Respect to the traditional treatment with 0.2mm of white epoxy, a thinner pixel gap enhances packing fraction up to 98% with a consequent improvement of detection efficiency. Spectroscopic characterization of the array was performed by a Hamamatsu R6231 photomultiplier tube. A pixel-by-pixel scanning with a collimated 99mTc radioisotope (140keV photon energy) highlighted a deviation in pulse height close to 3.5% respect to the overall mean value. Meanwhile, in term of energy resolution a difference between the response of single pixel and the array of about 10% was measured. Results were also supported and validated by Monte Carlo simulations performed with GEANT4.