Lu 2 SiO 5 :Ce optical ceramic scintillator

Abstract

Lutetium oxyorthosilicate (Lu 2 SiO 5 :Ce 3+ , commonly known as LSO) is a scintillator of choice for medical imaging applications such as Positron Emission Tomography (PET) because of its high light output, high gamma ray stopping power and fast response. In the current study, phase-pure LSO ceramics were obtained with a high degree of optical transparency and excellent scintillation properties. These LSO optical ceramics were prepared by combining nanotechnology with a sinter-HIP approach. We found that the densities of the LSO ceramics increased with increasing sintering temperature, which corresponds to a systematic decrease in porosity as found by SEM examination. The residual pores were found to segregate at grain boundaries after sintering, and were essentially removed by subsequent hot isostatic pressing (HIPing), which raised the density to essentially the value characteristic of the single crystal and produced polycrystalline LSO ceramics with a high degree of transparency. Under excitation a 22 Na source such specimens displayed a light output as high as 30,100 ph/MeV. The LSO ceramics showed an energy resolution of 15% (FWHM) at 662 keV ( 137 Cs source) and a fast scintillation decay of 40 ns due to the 5d → 4f transition of Ce 3+ . The excellent scintillation and optical properties make LSO ceramic a promising candidate for future gamma-ray spectroscopy as well as medical imaging applications.