EVALUATING ZN2SIO4-MN PHOSPHOR FOR USE IN MEDICAL IMAGING RADIATION DETECTORS

Zn2SiO4:Mn phosphor was evaluated for use in radiation detectors of me dical imaging systems. Zn2SiO4:Mn was used in the form of laboratory-p repared fluorescent layers (screens) with coating weights from 18 to 1 50 mg/cm(2) The phosphor was excited to luminescence by low-energy X-r ays using X-ray tube voltages ranging from 15 to 50 kVp. The number of emitted optical photons per incident X-ray quantum was thus determine d for various X-ray energies and phosphor coating weights. The optical emission spectrum was also measured and it was used to evaluate the s pectral compatibility of Zn2SiO4:Mn with radiographic films, photocath odes and the Si photodiode, Finally, phosphor optical properties were estimated by fitting a theoretical model to experimental data. Results showed that Zn2SiO4:Mn is more efficient for low-energy X-rays. Its i ntrinsic conversion efficiency was found equal to 0.08, which is compa rable to that of actually used phosphors. Zn2SiO4:Mn was also adequate ly compatible with orthochromatic films and the ES-20 photocathode, th us being appropriate for low-voltage radiography and fluoroscopy.