Validation of software for QC assessment of MTF and NPS

Walter Peppler, Wei Hong, Robert Steinhauser, Bruce Whiting, Ehsan Samei, Michael Flynn, Steven Don, Nathan Corradini

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review


Modulation transfer function (MTF), noise power spectrum (NPS), and detective quantum efficiency (DQE) are widely accepted measures of digital radiographic system performance. However the implementation of these measurement methodologies has been limited to a handful of researchers using an assortment of techniques. A prototype edge tool and easy-to-use software program, which can generate MTF, NPS, and DQE results quickly and easily in the field, have been developed. The edge tool consists of 1mm or 250 μ thick tungsten with two polished edges. Edge and NPS data were obtained and analyzed by 3 investigators using three analysis methods: Method A, the software under development for this report; Method B, code available on the web site of one of the investigators [Saunders and Samei, Med. Phys. 33, 308-319 (2006)]; and Method C, code developed by two other of the investigators [Samei and Flynn, Med Phy. 30, 608-622, (2003)]. In all cases the differences between the results using Method B and Method A were less than 1%. The differences between Method A and Method C were larger, up to 5.26%. NPS were calculated using Method A and B. The results were very close, with average errors less than 2.5% for exposures of 27.3, 9.3, and 2.7 uGy. Analysis of data for a 10 cm misalignment shows no significant error for either the 250μ or 1mm edge. The method developed gives results that correlate closely with results obtained from established methods. The software is easy-to-use and flexible in its application. The Edge Tool developed has the necessary precision to accurately determine the MTF values of the system. Further validation of NPS and DQE is ongoing.

Original languageEnglish
Title of host publicationMedical Imaging 2007
Subtitle of host publicationPhysics of Medical Imaging
EditionPART 3
StatePublished - 2007
EventMedical Imaging 2007: Physics of Medical Imaging - San Diego, CA, United States
Duration: Feb 18 2007Feb 22 2007

Publication series

NameProgress in Biomedical Optics and Imaging - Proceedings of SPIE
NumberPART 3
ISSN (Print)1605-7422


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


  • Detective quantum efficiency (DQE)
  • Digital radiography
  • Edge
  • IEC 62220
  • Image quality
  • Modulation transfer function (MTF)
  • Noise power spectrum (NPS)


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