In the present work, we designed the new type of photonic crystals (PCs) as reflectors. Reflections from single layer of Al₂O₃/MgO PC help us in recapturing the light that does escape from the scintillation surface. Photonic crystals in one dimension array of Al₂O₃ and MgO with silver at periodicities N = 1, 2 and 3 were used as a reflector around the surface of the scintillation volume. Scintillation detectors are widely used in nuclear medicine. The efficiency is an important parameter for characterizing the capability of the detectors. The counting efficiency of the detectors depends on the light emission induced by radiation. The light then was converted by the photomultiplier tube into electrical pulses. The efficiency may increase by an amount of 1.64% if MgO-Ag photonic crystals are used at periodicity N = 1 as a reflector.