Measurements of X-ray imaging performance of granular phosphors with direct-coupled CMOS sensors

Min Kook Cho, Ho Kyung Kim, Thorsten Graeve, Seung Man Yun, Chang Hwy Lim, Hyosung Cho, Jung Min Kim

Research output: Contribution to journalArticlepeer-review

41 Citations (Scopus)


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 μm 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.

Original languageEnglish
Article number4545083
Pages (from-to)1338-1343
Number of pages6
JournalIEEE Transactions on Nuclear Science
Issue number3
Publication statusPublished - 2008 Jun


  • Detective quantum efficiency
  • Digital radiography
  • Granular phosphor
  • Modulation-transfer function
  • Noise-power spectrum

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Nuclear Energy and Engineering
  • Electrical and Electronic Engineering


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