Radiation effects on the performance of CMOS photodiode array detectors and the role of gain-offset corrections

Ho Kyung Kim, Min Kook Cho, Thorsten Achterkirchen, Wonho Lee

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)


We report the observation of performance degradation in a detector consisting of a phosphor screen and a CMOS (complementary metal-oxide- semiconductor) photodiode array under the continuous irradiation of 45-kVp x-rays. The performance was assessed in terms of dark pixel signal, dynamic range, modulation-transfer function (MTF), noise-power spectrum (NPS), and detective quantum efficiency (DQE). From the measurement results, it has been observed that the increase of dark pixel signal and the related noise gradually reduces the dynamic range as the cumulative input exposure to the detector increases. Severe degradation in NPS was observed, which gives rise to reduction in DQE as the cumulative input exposure increases. With carefully updated offset and gain correction, however, we can overcome the detrimental effects of increased dark current on NPS and DQE.

Original languageEnglish
Article number5075992
Pages (from-to)1179-1183
Number of pages5
JournalIEEE Transactions on Nuclear Science
Issue number3
Publication statusPublished - 2009 Jun

Bibliographical note

Funding Information:
Manuscript received June 27, 2008; revised November 25, 2008. Current version published June 10, 2009. This work was supported by the Korea Research Foundation Grant ("KRF-2008-313-D01339) and the Basic Research Program of the Korea Science & Engineering Foundation (R01-2006-000-10233-0) funded by the Korean Government. *H. K. Kim was the corresponding author for this article. *H. K. Kim and M. K. Cho are with the Mechanical Engineering Department, Pusan National University, Busan 609-735, Korea (e-mail: hokyung@pusan.ac.kr; mk2000@pusan.ac.kr)..


  • CMOS detector
  • CMOS devices
  • Detective quantum efficiency
  • Digital radiography
  • Flat-field correction
  • Image evaluation
  • Image sensors
  • Noise-power spectrum
  • Radiation effects
  • X-ray imaging

ASJC Scopus subject areas

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


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