Accuracy validation of incident photon fluence on detective quantum efficiency in mammography

  • Tomonobu HabaEmail author
  • Shuji Koyama
  • Natsuki Otani
Scientific Paper


X-ray image evaluation is commonly performed by determining the detective quantum efficiency (DQE). DQE is calculated with a presampled modulation transfer function (MTF), incident photon fluence, and digital noise power spectrum (NPS). Accurate evaluation of MTF, incident photon fluence, and NPS is important for precise DQE determination. In this study, we focused on the accuracy of the incident photon fluence in mammography. The incident photon fluence is calculated using the squared signal-to-noise ratio (SNRin2) value as specified in the International Electrotechnical Commission (IEC) 62220-1-2 report. However, the reported SNRin2 values were determined using a computer program, and the reported values may differ from those calculated from an X-ray spectrum that is measured with actual mammography equipment. Therefore, we evaluated the error range of reported SNRin2 values in mammography to assess the accuracy of the incident photon fluence. First, X-ray spectra from various mammography systems were measured with a CdTe spectrometer. Six mammographic X-ray units were used in this study. Second, the SNRin2 values were calculated from the measured X-ray spectra. The calculated values were compared to the reported values. The results show that the percentage differences between the calculated and reported SNRin2 values were within − 4.1% of each other. The results obtained in this study indicate that the SNRin2 values provided in the IEC report are a robust and convenient tool for calculating the incident photon fluence for DQE evaluation in mammography.


Detective quantum efficiency Incident photon fluence Mammographic X-ray spectroscopy CdTe spectrometer 


Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Ethical approval

This article does not contain any studies with human participants or animals performed by any of the authors.


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Copyright information

© Australasian College of Physical Scientists and Engineers in Medicine 2018

Authors and Affiliations

  1. 1.Department of RadiologyFujita Health University HospitalToyoakeJapan
  2. 2.Brain & Mind Research CenterNagoya UniversityNagoyaJapan
  3. 3.Department of Radiological Technology, Graduate School of MedicineNagoya UniversityNagoyaJapan

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