Gd,La)2O2S:Tb phosphor performance was tested under x-ray excitation for medical imaging applications with tube voltages from 70 to 180 kVp and phosphor coating weights from 20 to 240 mg/cm2. The emission spectrum of (Gd,La)2O2S:Tb was also measured and it was centered at 549 nm. (Gd,La)2O2S:Tb was found efficient in a wide range of x-ray tube voltages and adequately compatible with photocathodes, photodiodes, and orthochromatic films currently used in x-ray medical imaging.