Absolute measures of image quality for the Sens-A-Ray direct digital intraoral radiography system

Ulf Welander, William D. McDavid, Ann Catherine Mörner, Gunilla Tronje, Osamu Tokuoka, Hajime Fuchihata, Per Nelvig, S. Brent Dove

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


To study the noise characteristics of the Sens-A-Ray (Regam Medical Systems AB, Sundsvall, Sweden) system, 20 radiographs were obtained at each of three different exposure levels at 70 and 90 kVp with a homogeneous x-ray field. Exposures were measured with an ionization chamber. Noise power spectra were calculated over three areas within each radiograph, and ensemble averages were subsequently found from 60 data files at each exposure level. Noise equivalent quanta were calculated with the noise power spectra and modulation transfer function data from previous studies. Finally, the detective quantum efficiency was calculated by dividing the noise equivalent quanta by the estimated incident photon fluence at the different exposures. The system has a maximum detective quantum efficiency of approximately 0.030 at 70 kVp and 0.025 at 90 kVp. A broad maximum exists at approximately 2 cycles/mm, indicating that the signal-to-noise ratio is most favorable at this spatial frequency.

Original languageEnglish (US)
Pages (from-to)345-350
Number of pages6
JournalOral Surgery, Oral Medicine, Oral Pathology, Oral Radiology and
Issue number3
StatePublished - Sep 1995
Externally publishedYes

ASJC Scopus subject areas

  • Surgery
  • Oral Surgery
  • Otorhinolaryngology
  • Dentistry(all)


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