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Proceedings Paper

Image quality of direct conversion detectors for mammography and radiography: a theoretical comparison
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Paper Abstract

Direct conversion detectors have the potential to provide very high resolution and high detective quantum efficiency (DQE). Selection of a material that is appropriate for the task is dictated by the material properties. A linear cascaded systems analysis of DQE is used to predict the performance of several detector materials such as amorphous Se, CdZnTe, and PbI2. A model is used to predict the spatial frequency-dependent DQE(f) for each material. This model includes: (1) x-ray absorption, (2) K fluorescence, (3) conversion gain, and (4) incomplete charge collection. A depth-dependent approach is used to account for gain variations and charge transport characteristics that change throughout the detector. In the model a parallel cascade, and non-elementary stages are used to model the effect of K-fluorescence reabsorption followed by incomplete charge collection. The DQE(f) is determined across an x-ray energy range of 10 to 100 keV for each material under typical bias conditions ranging from 0.1 V/μm to 10 V/μm. K-fluorescence escape and reabsorption blurring can cause marked reductions in the DQE(f). It is further reduced by incomplete charge collection which can theoretically decrease the DQE(f) by as much as 50% in extreme situations. This model will help determine key factors that will influence material selection for direct conversion x-ray systems.

Paper Details

Date Published: 5 June 2003
PDF: 11 pages
Proc. SPIE 5030, Medical Imaging 2003: Physics of Medical Imaging, (5 June 2003); doi: 10.1117/12.479999
Show Author Affiliations
James Gordon Mainprize, Sunnybrook and Women's College Health Sciences Ctr. (Canada)
Martin J. Yaffe, Sunnybrook and Women's College Health Sciences Ctr. (Canada)

Published in SPIE Proceedings Vol. 5030:
Medical Imaging 2003: Physics of Medical Imaging
Martin J. Yaffe; Larry E. Antonuk, Editor(s)

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