C12A7:0.5%Tb3+, x%Sr2+ X-ray phosphors with various concentrations were prepared by a combustion method. For the phosphor with the optimal concentration (x = 5), the strongest green photostimulated luminescence (PSL), originating from the D-5(4)-F-7(5) transition of Tb3+ ion, can be achieved. It was found that its X-ray absorption capacity was increased and its X-ray dynamic range was extended after Sr doping. For this phosphor, the conversion efficiency (CE) (similar to 1.42 pJ/mm(2)/mR) is higher than that of C12A7:0.5%Tb3+ phosphor (similar to 1.28 pJ/mm(2)/mR) because of the substitution of Ca by Sr with higher atomic number. Meanwhile, for the Sr doped C12A7:0.5%Tb3+ X-ray phosphors, the change in the local environment near the electrons captured by the enlarged empty cages will lead to the variation in the trap distribution. High-quality X-ray imaging (15 1p/mm) of the X-ray phosphor suggests that it is a potential candidate material for computed radiography system or erasable/rewritable optical memory media. (C) 2017 Elsevier Ltd. All rights reserved.