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Proceedings Paper

Imaging properties of the magnification factor in digital mammography by the generalized MTF (GMTF)
Author(s): Hye-Suk Park; Hee-Joung Kim; Hyo-Min Cho; Chang-Lae Lee; Dae-Hong Kim; Seung-Wan Lee; Yu-Na Choi
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Paper Abstract

Our aim in this study was to examine the resolution effects of breast thickness in magnification technique by evaluating generalized modulation transfer function (GMTF) including the effect of focal spot, effective pixel size and the scatter. The PMMAs ranging from 10 to 40 mm in thickness were placed on a standard supporting platform that was positioned to achieve magnification factors ranging from 1.2 to 2.0. As the magnification increased, the focal spot MTF degraded while the detector MTF improved. A small focal spot resulted in an improvement of GMTF due to a smaller effective pixel size by magnification. In contrast, a large focal spot resulted in significant degradation of GMTF due to dominating the effect of focal spot blurring. The resolution of small focal spot did improve slightly with increasing PMMA thickness for magnification factors less than 1.8. System resolution decreased with increasing PMMA thickness for magnification factors greater than 1.8, since focal spot blur begins to dominate spatial resolution. In particular, breast thickness had a large effect on the resolution at lower frequencies as a low frequency drop effect. Hence, the effect of compressed breast thickness should be considered for the standard magnification factor of 1.8 that is most commonly used in clinical practice. Our results should provide insights for determining optimum magnification in clinical application of digital mammography, and our approaches can be extended to a wide diversity of radiological imaging systems.

Paper Details

Date Published: 17 March 2011
PDF: 9 pages
Proc. SPIE 7961, Medical Imaging 2011: Physics of Medical Imaging, 79610G (17 March 2011); doi: 10.1117/12.878372
Show Author Affiliations
Hye-Suk Park, Yonsei Univ. (Korea, Republic of)
Hee-Joung Kim, Yonsei Univ. (Korea, Republic of)
Hyo-Min Cho, Yonsei Univ. (Korea, Republic of)
Chang-Lae Lee, Yonsei Univ. (Korea, Republic of)
Dae-Hong Kim, Yonsei Univ. (Korea, Republic of)
Seung-Wan Lee, Yonsei Univ. (Korea, Republic of)
Yu-Na Choi, Yonsei Univ. (Korea, Republic of)

Published in SPIE Proceedings Vol. 7961:
Medical Imaging 2011: Physics of Medical Imaging
Norbert J. Pelc; Ehsan Samei; Robert M. Nishikawa, Editor(s)

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