Special Section on Pioneers in Medical Imaging: Honoring the Memory of Robert F. Wagner

Energy weighting improves dose efficiency in clinical practice: implementation on a spectral photon-counting mammography system

[+] Author Affiliations
Johan Berglund, Henrik Johansson, Mats Lundqvist, Björn Cederström, Erik Fredenberg

Philips Healthcare, Smidesvägen 5, 171 41 Solna, Sweden

J. Med. Imag. 1(3), 031003 (Aug 28, 2014). doi:10.1117/1.JMI.1.3.031003
History: Received April 1, 2014; Revised June 27, 2014; Accepted July 16, 2014
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Abstract.  In x-ray imaging, contrast information content varies with photon energy. It is, therefore, possible to improve image quality by weighting photons according to energy. We have implemented and evaluated so-called energy weighting on a commercially available spectral photon-counting mammography system. The technique was evaluated using computer simulations, phantom experiments, and analysis of screening mammograms. The CNR benefit of energy weighting for a number of relevant target-background combinations measured by the three methods fell in the range of 2.2 to 5.2% when using optimal weight factors. This translates to a potential dose reduction at constant CNR in the range of 4.5 to 11%. We expect the choice of weight factor in practical implementations to be straightforward because (1) the CNR improvement was not very sensitive to weight, (2) the optimal weight was similar for all investigated target-background combinations, (3) aluminum/PMMA phantoms were found to represent clinically relevant tasks well, and (4) the optimal weight could be calculated directly from pixel values in phantom images. Reasonable agreement was found between the simulations and phantom measurements. Manual measurements on microcalcifications and automatic image analysis confirmed that the CNR improvement was detectable in energy-weighted screening mammograms.

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© 2014 Society of Photo-Optical Instrumentation Engineers

Citation

Johan Berglund ; Henrik Johansson ; Mats Lundqvist ; Björn Cederström and Erik Fredenberg
"Energy weighting improves dose efficiency in clinical practice: implementation on a spectral photon-counting mammography system", J. Med. Imag. 1(3), 031003 (Aug 28, 2014). ; http://dx.doi.org/10.1117/1.JMI.1.3.031003


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