Performance evaluation of a direct computed radiography system by means of physical characterization and contrast detail analysis

Stefano Rivetti, Nico Lanconelli, Marco Bertolini, Giovanni Borasf, Domenico Acchiappati, Aldo Burani

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


The aim of this study is to determine the performance of a direct CR reader, named "FCR Velocity U Focused Phosphor (FP)". The system is based on a CsBr columnar structured crystal, and the system's read out is based on the "linescan technology" that employs a wide-view CCD. The system's physical performance was tested by means of a quantitative analysis, with calculation of the modulation transfer function (MTF), noise power spectrum (NPS) and detective quantum efficiency (DQE). Image quality was assessed by performing a contrast-detail analysis. The results are compared with those obtained with the well known CR system Fuji FCR XG5000, and the new one Kodak Direct View CR 975. For all the measurements the standard radiation quality RQA-5 was used. The relationship between signal amplitude and entrance air kerma is logarithmic for all the systems and the response functions were used to linearize the images before the MTF (edge method) and NPS calculations. The contrast detail analysis has been achieved by using the well known CDRAD phantom and a customized software designed for automatic computation of the contrast-detail curves. The three systems present similar MTFs, whereas the Fuji Velocity U FP system, thanks to its greater efficiency, has a better behavior in terms of NNPS, especially at low frequencies. That allows the system based on columnar phosphor to provide a better DQE. CDRAD analysis basically confirms that the structured phosphor used in the Velocity system improves the visibility of some details. This is especially true for medium and large details.

Original languageEnglish
Title of host publicationProgress in Biomedical Optics and Imaging - Proceedings of SPIE
EditionPART 3
Publication statusPublished - 2007
EventMedical Imaging 2007: Physics of Medical Imaging - San Diego, CA, United States
Duration: Feb 18 2007Feb 22 2007


OtherMedical Imaging 2007: Physics of Medical Imaging
Country/TerritoryUnited States
CitySan Diego, CA


  • Contrast detail
  • Digital radiography
  • DQE
  • MTF

ASJC Scopus subject areas

  • Engineering(all)


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