Evaluation of an optically coupled CCD digital radiography system

J. Anthony Seibert, Alexander Kwan, John M. Boone, Paul Brown, Robin Winsor

Research output: Contribution to journalConference articlepeer-review

4 Scopus citations


A digital radiography system comprised of a large field of view (43×43cm) high luminance CsI scintillator, optically coupled to a 4096×4096 element CCD sensor with 12:1 demagnification was evaluated by measuring the modulation transfer function (MTF), noise power spectrum (NPS), and detective quantum efficiency (DQE). Detector evaluation was performed using IEC standard #62220-1 methodologies for beam quality. In this study, RQA-5 (21 mm Al added filtration, 74 kVp, 7.1 mm half value layer (HVL)) and RQA-9 (40 mm Al added filtration, 119 kVp, 11.5 mm HVL) qualities were used at several incident exposures from <0.1 mR to >50 mR. Two detector modes of operation included high resolution (HR) and high efficiency (HE), with 108 and 216 μm pixel dimensions, respectively. The detector system responded to 60 mR incident exposure prior to saturation for the HR mode and up to 30 mR in the HE mode. The pre-sampled MTF(f) had 50% modulation at 0.95 mm -1 (HR) and 0.85 mm -1 (HE); and 10%MTF(f) was reached at 2.4 mm -1 (HR) and 2.0 mm -1 (HE). At a frequency of 0.5 mm -1, the DQE was 40% to 50%, and at 1 mm -1 was 12% to 20% for HR and HE modes, respectively. The DQE at low exposures was substantially better for the HE mode. Little dependence of the DQE on beam energy was found, but the RQA 9 beam had lower values. Above a frequency of 2 mm -1 the DQE dropped to zero, attributed to low MTF. Results suggest that patient radiation exposures equivalent or better than a conventional 400 speed screen-film detector can be achieved for many imaging procedures with sufficient SNR and spatial resolution required for a wide range of diagnostic radiography applications.

Original languageEnglish (US)
Article number52
Pages (from-to)458-467
Number of pages10
JournalProgress in Biomedical Optics and Imaging - Proceedings of SPIE
Issue numberI
StatePublished - 2005
Externally publishedYes
EventMedical Imaging 2005 - Physics of Medical Imaging - San Diego, CA, United States
Duration: Feb 13 2005Feb 15 2005


  • CCD
  • DQE
  • Digital radiography
  • Dose efficiency
  • Large area digital detector
  • Lens coupling
  • MTF
  • NPS

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Atomic and Molecular Physics, and Optics
  • Radiology Nuclear Medicine and imaging


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