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ImageJ plugin for analysing phantom images in mammography

Abstract:
Scope:
A plugin for ImageJ was developed to enhance the accuracy and precision of quality tests in digital mammography.
The physical data obtained are the “Noise Power Spectrum” (NPS, Wiener spectrum), the Spatial Frequency Response (SFR) and the “Noise Equivalent Quanta” (NEQ), moreover the dynamic range, the signal to noise ratio, dead pixels, and the homogeneity can be measured.

Material and Methods:
Test images according to PAS1054 (standard in Germany like DIN) were generated with analogue and digital mammography systems from different manufacturers. A dedicated test inlay with two steel edges was build for the conventional phantom in order to calculate the SFR. Mathematical methods include the Fourier analysis of the oversampled edge image for the calculation of the SFR and the 2-D Fourier transform of a homogeneous image region to calculate the Noise Power Spectrum.

Results:
It is shown by comprehensive studies on DICOM mammography images obtained from all manufacturers of mammography modalities, that these physical data exceed the repeat accuracy and precision of conventional testing by a factor of ten. NPS, SFR and NEQ establish new parameters for intersystem comparability. The program notifies the radiographer of failed tests; detailed measuring results are saved and can be retrieved and evaluated by experienced technicians. The easy to use user interface is designed for quick and secure operation by medical-technical assistants and the time for a complete constancy check is minimized to a “click” on a button.

Keywords:
mammography, noise power spectrum, noise equivalent quanta, PAS 1054

Author
Holger Buhr

Organisation
Cologne University of Applied Science, Institute of Media and Imaging Technology

Homepage www.fh-koeln.de

Short Biography
Diploma in Photo Engineering and Media Technology acquired at the Cologne University of Applied Science, Institute of Media and Imaging Technology. Momentary doing a master thesis at the same faculty in the Masters course Media and Imaging Technology.
Special interest and knowledge: digital image processing in medical images, Java programming and ImageJ, developing algorithms for the solution of special problems in digital mammography.

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