X-RAY-INDUCED LUMINESCENCE AND SPATIAL-RESOLUTION OF LA2O2S-TB PHOSPHOR SCREENS

Absolute efficiency and modulation transfer function of laboratory pre pared La2O2S:Tb phosphor screens of various coating thickness were stu died. Detailed experimental data on the variation of absolute efficien cy with x-ray tube voltage up to 200 kVp and screen coating thickness in transmission and reflection observation mode are given. Data were c ompared with similar results from other rare earth phosphor materials. Theoretical calculations were in good agreement with experimental dat a to permit estimation of intrinsic efficiency and coefficients relate d to light scattering and absorption within the phosphor material. The MTF of La2O2S:Tb screens was also experimentally and theoretically ev aluated.