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Proceedings Paper

Relationship between radiation dose and reduced X-ray sensitivity surrounding breast region using CR stimulable phosphor plate for mammography
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Paper Abstract

Computed radiography (CR) systems use a photostimulable phosphor plate (imaging plate ; IP) as a sensor for digital mammography. In clinical mammography, breast is almost exposed same region of IP, and therefor, direct x-ray regions surrounding suffer from reduced x-ray sensitivity. Consequently, the difference in x-ray sensitivity between the breast regions and the unattenuated x-ray region was obtained. However, radiation dose quantity that reduces x-ray sensitivity is not known. In this study, we imaged a breast phantom under fixed conditions, and subsequently, we investigated the pixel value differences between the breast region and the unattenuated x-ray regions. We measured the entrance air-kerma using 550 sensing elements of glass dosimeter, 22x25 lines, that were placed at the surface of the cassette including the IP. In order to measure the x-ray sensitivity, pre- and post-exposure breast phantom images were acquired after 500, 1,000, 1,350, and 1,500 trials. The pixel values were measured at four points; in the breast region and in the unattenuated x-ray region. The ratio of these pixel values was compared with the cumulative exposure dose. The ratio was nearly constant until 1,000 trials, but a significant reduction was observed after 1,350 trials. Further, in the image obtained after 1,500th trials, the shape of breast phantom could be observed. This image supports the fact that the x-ray sensitivity was lowered in the unattenuated x-ray region. The difference in the pixel value between the breast region and the unattenuated x-ray region was obtained over 1,000 exposures at 100,000 mAs.

Paper Details

Date Published: 18 March 2015
PDF: 6 pages
Proc. SPIE 9412, Medical Imaging 2015: Physics of Medical Imaging, 94125K (18 March 2015); doi: 10.1117/12.2082471
Show Author Affiliations
Hiroko Nishide, Graduate School of Medicine Nagoya Univ. (Japan)
Gifu Univ. of Medical Science (Japan)
Yoshie Kodera, Graduate School of Medicine Nagoya Univ. (Japan)


Published in SPIE Proceedings Vol. 9412:
Medical Imaging 2015: Physics of Medical Imaging
Christoph Hoeschen; Despina Kontos, Editor(s)

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