Lutetium–yttrium oxyorthosilicate, also known as LYSO, is an inorganic chemical compound with main use as a scintillator crystal for gamma radiation detection.[4] Its chemical formula is Lu2(1-x)Y2xSiO5. The percentage of yttrium varies considerably, with values in the literature ranging from 5% to 70%.[5] It is commonly used to build screens and electromagnetic calorimeters in particle physics. LYSO crystals have the advantages of high light output and density, quick decay time, excellent energy resolution.[6] The crystals are often grown in boules using the Czochralski process, and cutting or polishing can be challenging because LYSO is brittle and hard.[7]