Measurements of X-ray Imaging Performance of Granular Phosphors With Direct-Coupled CMOS Sensors
Authors:
- Ho Kyung KimHKHo Kyung Kim
- Thorsten GraeveTGThorsten Graeve
- Seung Man YunSYSeung Man Yun
- Chang Hwy LimCLChang Hwy Lim
- Hyosung ChoHCHyosung Cho
- Jung-Min KimJKJung-Min Kim
- 17 June 2008
- journal article
- Published by Institute of Electrical and Electronics Engineers (IEEE) in IEEE Transactions on Nuclear Science
- Vol. 55 (3) , 1338-1343
Abstract
For Gd2O2S:Tb granular phosphor screens having a wide range of mass thicknesses, we have investigated the fundamental imaging performance in terms of modulation-transfer function (MTF), noise-power spectrum (NPS) and detective quantum efficiency (DQE). As an optical photon readout device, a CMOS photodiode array with a pitch of 48 mum was used. Under the representative radiation quality, RQA 5, recommended by the IEC (International Electrotechnical Commission, Report 1267), the MTF was measured using a slanted-slit method to avoid aliasing and the NPS was determined by two-dimensional (2D) Fourier analysis of white images. The DQE was assessed from the measured MTF, NPS and the estimated photon fluence. Figure-of-merit (FOM) curves are presented to describe the tradeoff between the X-ray sensitivity and spatial resolution of screens as a function of mass thickness. This study will be useful for the selection guidance of Gd2O2S:Tb phosphors for the relevant imaging tasks of digital radiography.Keywords
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