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Proceedings Paper

Slot-Beam Digital Mammography Using A Time-Delay Integration (TDI) CCD
Author(s): D. W. Holdsworth; R. M. Nishikawa; G. E. Mawdsley; M. J. Yaffe; A. Fenster
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Paper Abstract

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.

Paper Details

Date Published: 1 May 1989
PDF: 8 pages
Proc. SPIE 1090, Medical Imaging III: Image Formation, (1 May 1989); doi: 10.1117/12.953215
Show Author Affiliations
D. W. Holdsworth, University of Toronto (Canada)
R. M. Nishikawa, University of Toronto (Canada)
G. E. Mawdsley, University of Toronto (Canada)
M. J. Yaffe, University of Toronto (Canada)
A. Fenster, John P. Robarts Research Inst. (Canada)

Published in SPIE Proceedings Vol. 1090:
Medical Imaging III: Image Formation
Samuel J. Dwyer; R. Gilbert Jost; Roger H. Schneider, Editor(s)

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