Purpose: To evaluate Gd2O2S:Eu powder phosphor as a radiographic image receptor and to compare
it to phosphors often used in radiography. Gd2O2S:Eu is nonhygroscopic, emitting red light
with decay time close to that of Gd2O2S:Tb.
Methods: The light intensity emitted per unit of x-ray exposure rate absolute luminescence efficiency
was measured for laboratory prepared screens with coating thicknesses of 33.1, 46.4, 63.1,
78.3, and 139.8 mg/cm2 and tube voltages ranging from 50 to 140 kVp. Parameters related to
image quality such as the modulation transfer function MTF and the detective quantum efficiency
DQE were also experimentally examined. In addition, a previously validated Monte Carlo code
was used to estimate intrinsic x-ray absorption and optical properties, as well as the MTF and the
Swank factor I of the Gd2O2S:Eu scintillators.
Results: Gd2O2S:Eu light intensity was found higher than that of single CsI:Tl crystal for tube
voltages up to 100 kVp. The MTF and the DQE were found to be comparable with those of
Gd2O2S:Tb and CsI:Tl screens. MTF estimated by the Monte Carlo code was found very close to
the experimental MTF values. Gd2O2S:Eu showed peak emission in the wavelength range 620–630
nm. Its emission spectrum was excellently matched to various optical detectors photodiodes, photocathodes,
CCDs, and CMOS employed in flat panel detectors.
Conclusions: Gd2O2S:Eu is an efficient phosphor potentially well suited to radiography and especially
to some digital detectors sensitive to red light.
(EN)
