Investigation of imaging performance of amorphous selenium flat-panel detectors for digital mammography

Wei Zhao; W. G. Ji; John A. Rowlands; Anne Debrie

doi:10.1117/12.430876

28 June 2001 Investigation of imaging performance of amorphous selenium flat-panel detectors for digital mammography

Wei Zhao, W. G. Ji, John A. Rowlands, Anne Debrie

Proceedings Volume 4320, Medical Imaging 2001: Physics of Medical Imaging; (2001) https://doi.org/10.1117/12.430876
Event: Medical Imaging 2001, 2001, San Diego, CA, United States

Abstract

Our work is to investigate and understand the factors affecting the imaging performance of amorphous selenium (a-Se) flat-panel detectors for digital mammography. Both theoretical and experimental methods were developed to investigate the spatial frequency dependent detective quantum efficiency [DQE(f)] of a-Se flat-panel detectors for digital mammography. Since the k-edge of a-Se is 12.66 keV and within the energy range of a mammographic spectrum, a cascaded linear system model was developed which takes into account the effect of k-fluorescence on the modulation transfer function (MTF), noise power spectrum (NPS) and DQE(f) of the detector. This model was used to understand the performance of a prototype detector with 85 mm pixel size. The presampling MTF, NPS and DQE(f) of the prototype were measured, and compared to the theoretical calculation by the model. The calculation showed that k-fluorescence reduces the MTF by 15% at the Nyquist frequency (f_NY) of the prototype detector, and the NPS at f_NY was reduced to 82% of that at zero spatial frequency. Because of the decrease in both MTF and NPS at high spatial frequencies, k-fluorescence only has a small degradation effect on DQE(f) for mammography. The measurement of presampling MTF of the prototype detector revealed an additional source of blurring, which was attributed to the blocking layer at the interface between a-Se and the active matrix. This introduced high frequency drop in both presampling MTF and NPS, and reduced aliasing in the NPS. As a result, the DQE(f) of the prototype detector at f_NY approaches 50% of that at zero spatial frequency.

Citation Download Citation

Wei Zhao, W. G. Ji, John A. Rowlands, and Anne Debrie "Investigation of imaging performance of amorphous selenium flat-panel detectors for digital mammography", Proc. SPIE 4320, Medical Imaging 2001: Physics of Medical Imaging, (28 June 2001); https://doi.org/10.1117/12.430876

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