Active dual energy x-ray detector: Experimental characterization

Robert E. Alvarez, J Anthony Seibert, Thomas F. Poage

Research output: Chapter in Book/Report/Conference proceedingConference contribution

4 Scopus citations


We have developed a new, active detector for dual energy computed radiography. The active detector consists of a computer controlled x-ray generator that produces two, fast voltage switched x-ray pulses, with the high voltage pulse first. An image acquisition unit contains two storage phosphor screens arranged in a 'sandwich'. The screen nearest the x-ray tube is in an optical chamber coupled to high intensity flashlamps. These lamps produce a short duration light pulse during the inter-exposure period that erases the high voltage x-ray data from the front screen but not from the back screen. The active detector is thus able to acquire the high and low voltage images fast enough to minimize patient motion artifacts with no mechanical motion of the storage phosphor screens. The voltage switched x-ray spectra are much better conditioned for dual energy image processing than the effective spectra produced by conventional, single exposure 'sandwich' detectors. The processed dual energy images with the active detector have much lower noise for the same patient dose as single exposure detectors. We experimentally characterized the performance of the active detector and show initial human subject images. We measured the following parameters: (1) speed of tow exposure image acquisition, and (2) repeatability of x-ray spectra and flux. We characterized the imaging performance by making images of a chest phantom with our detector and a conventional sandwich detector using the same incident exposure. Finally, we show a chest image of a human subject.

Original languageEnglish (US)
Title of host publicationProceedings of SPIE - The International Society for Optical Engineering
Number of pages8
StatePublished - 1997
EventMedical Imaging 1997: Physics of Medical Imaging - Newport Beach, CA, United States
Duration: Feb 23 1997Feb 23 1997


OtherMedical Imaging 1997: Physics of Medical Imaging
Country/TerritoryUnited States
CityNewport Beach, CA


  • Active detector
  • Computed radiography
  • Detector
  • Dual-energy
  • Storage phosphor
  • X-ray

ASJC Scopus subject areas

  • Applied Mathematics
  • Computer Science Applications
  • Electrical and Electronic Engineering
  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics


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