An experimental method based on the light emission properties of scintillators has been developed to evaluate the quality of medical images. Information entropy (IE) and information capacity (IC) of scintillating screens were evaluated as functions of emitted optical fluence and incident x-ray fluence. Scintillator screens with various coating thickness were prepared in laboratory, and were irradiated by x-rays. Experimental data were obtained in both transmission and reflection modes of measurement (light emission from both screen sides). Results showed that IE and IC decrease slightly with scintillator thickness and depend strongly on the intrinsic absorption and optical properties of the scintillator materials.