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1 May 1989 Slot-Beam Digital Mammography Using A Time-Delay Integration (TDI) CCD
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We have developed an experimental digital mammography system which incorporates a beryllium-window x-ray image intensifier (XRII), allowing efficient detection of low-energy diagnostic x rays. The optical image produced by the XRII is recorded by a low-noise charge-coupled device (CCD) operating in the time-delay integration (TDI) mode. Images are obtained by translating a 7 mm x 15 cm slot of radiation across the breast and integrating the signal over 96 image lines. By using a 7 mm slot-beam, we are able to obtain a scatter-to-primary photon fluence ratio of 0.1 for a 4 cm compressed breast. At the same time, the TDI approach results in more efficient usage of available x-ray fluence than a line-scan system, so that imaging times of about 4 seconds are possible. Detector noise is minimized by cooling the CCD to about 5° C. We report on measurements of physical parameters such as modulation transfer function, noise power spectrum and detective quantum efficiency. Our results are compared with equivalent measurements on screen-film systems. Although high-contrast spatial resolution with our digital system is currently limited to 4 mm-1, the improved signal-to-noise ratio allows better low-contrast detectability than screen-film systems.
© (1989) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
D. W. Holdsworth, R. M. Nishikawa, G. E. Mawdsley, M. J. Yaffe, and A. Fenster "Slot-Beam Digital Mammography Using A Time-Delay Integration (TDI) CCD", Proc. SPIE 1090, Medical Imaging III: Image Formation, (1 May 1989);


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