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Proceedings Paper

Physics-based modeling of computed tomography systems
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Paper Abstract

We present a theoretical framework describing projections obtained from computed tomography systems considering physics of each component consisting of the systems. The projection model mainly consists of the attenuation of x-ray photons through objects including x-ray scatter and the detection of attenuated/scattered x-ray photons at pixel detector arrays. X-ray photons are attenuated by the Beers-Lambert law and scattered by using the Klein-Nishina formula. The cascaded signal-transfer model for the detector includes x-ray photon detection and light photon conversion/spreading in scintillators, light photon detection in photodiodes, and the addition of electronic noise quanta. On the other hand, image noise is considered by re-distributing the pixel signals in pixel-by-pixel ways at each image formation stage using the proper distribution functions. Instead of iterating the ray tracing over each energy bin in the x-ray spectrum, we first perform the ray tracing for an object only considering the thickness of each component. Then, we assign energy-dependent linear attenuation coefficients to each component in the projected images. This approach reduces the computation time by a factor of the number of energy bins in the x-ray spectrum divided by the number of components in the object compared with the conventional ray-tracing method. All the methods developed in this study are validated in comparisons with the measurements or the Monte Carlo simulations.

Paper Details

Date Published: 18 March 2015
PDF: 11 pages
Proc. SPIE 9412, Medical Imaging 2015: Physics of Medical Imaging, 94122N (18 March 2015); doi: 10.1117/12.2081827
Show Author Affiliations
Hanbean Youn, Pusan National Univ. (Korea, Republic of)
Ho Kyung Kim, Pusan National Univ. (Korea, Republic of)
Soohwa Kam, Pusan National Univ. (Korea, Republic of)
Seung Ho Kim, Pusan National Univ. (Korea, Republic of)
Ji Woong Park, Pusan National Univ. (Korea, Republic of)
Hosang Jeon, Pusan National Univ. Yangsan Hospital (Korea, Republic of)

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

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