 Variants include, for example, using praseodymium instead of terbium (CAS registry number , EINECS number 271-826-9), or using a mixture of dysprosium and terbium for doping (CAS number , EINECS number 271-824-8).Gadolinium oxysulfide is a promising luminescent host material, because of its high density (7.32 g/cm3) and high effective atomic number of Gd.These characteristics lead to a high interaction probability for X-ray radiation.