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Proceedings Paper

Influence of scattered x rays on object sharpness of radiographs
Author(s): Hidetaka Arimura; Takuji Date; Kaoru Morikawa; Hideaki Kubota; Masao Matsumoto; Hitoshi Kanamori
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Paper Abstract

We investigated the influence of the scattered x-rays on the object sharpness of radiographs for tube voltages of 50 to 100 kV. For the purpose, using a phantom of the polymethyl methacrylate (PMMA) with an aluminum plate of low contrast object, the edge images including the blurs due to the x-ray focal spot, the screen-film system, and the scattered x-rays were produced. However, the shape of the overall modulation transfer function (MTF) derived from the edge image is considered not to be influenced by the scattered x-rays. As a result of comparing the overall MTFs with the product of the MTFs of the x-ray focal spot and the screen-film system, we found that the scattered x-rays gave different influence on the contrast at each spatial frequency for each tube voltage. To investigate the influence of the scattered x-ray on the overall MTF in detail, considering the MTF of the x-ray focal spot, we developed a method for determining the primary and scatter components of the overall MTF, whose components are proportional to the MTFs of the screen-film system and the scattered x-rays, respectively. Using the method, it was found that (1) the overall MTF depends on the MTF of scattered x- rays as well as the MTFs of the focal spot and screen-film system; and (2) at frequencies near 0 mm-1, the influence of the blur due to the scattered x-rays on the object sharpness was greater than that occurred in the intensifying screen and increased with the tube voltage.

Paper Details

Date Published: 25 April 2000
PDF: 8 pages
Proc. SPIE 3977, Medical Imaging 2000: Physics of Medical Imaging, (25 April 2000); doi: 10.1117/12.384526
Show Author Affiliations
Hidetaka Arimura, Hiroshima International Univ. (Japan)
Takuji Date, Hiroshima International Univ. (Japan)
Kaoru Morikawa, Hiroshima International Univ. (Japan)
Hideaki Kubota, Osaka Univ. (Japan)
Masao Matsumoto, Osaka Univ. (Japan)
Hitoshi Kanamori, Fukui Univ. of Technology (Japan)

Published in SPIE Proceedings Vol. 3977:
Medical Imaging 2000: Physics of Medical Imaging
James T. Dobbins; John M. Boone, Editor(s)

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