Measurements of X-ray Imaging Performance of Granular Phosphors With Direct-Coupled CMOS Sensors

For Gd 2 O 2 S: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...

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Bibliographic Details
Published in:IEEE transactions on nuclear science 2008-06, Vol.55 (3), p.1338-1343
Main Authors: Min Kook Cho, Ho Kyung Kim, Graeve, T., Seung Man Yun, Chang Hwy Lim, Cho, H., Kim, J.-M.
Format: Article
Language:English
Subjects:
CMOS
CMOS image sensors
Detective quantum efficiency
digital radiography
granular phosphor
IEC
Imaging
modulation-transfer function
noise-power spectrum
Optical arrays
Optical communication
Optical devices
Optical imaging
Optical modulation
Optical noise
Optical sensors
Optical transfer function
Phosphors
Photons
Two dimensional
X-ray imaging
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Summary:For Gd 2 O 2 S: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 Gd 2 O 2 S:Tb phosphors for the relevant imaging tasks of digital radiography.
ISSN:0018-9499
1558-1578
DOI:10.1109/TNS.2007.913939