Physics-based modeling of computed tomography systems

Hanbean Youn; Ho Kyung Kim; Soohwa Kam; Seung Ho Kim; Ji Woong Park; Hosang Jeon

doi:10.1117/12.2081827

18 March 2015 Physics-based modeling of computed tomography systems

Hanbean Youn, Ho Kyung Kim, Soohwa Kam, Seung Ho Kim, Ji Woong Park, Hosang Jeon

Proceedings Volume 9412, Medical Imaging 2015: Physics of Medical Imaging; 94122N (2015) https://doi.org/10.1117/12.2081827
Event: SPIE Medical Imaging, 2015, Orlando, Florida, United States

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.

Citation Download Citation

Hanbean Youn, Ho Kyung Kim, Soohwa Kam, Seung Ho Kim, Ji Woong Park, and Hosang Jeon "Physics-based modeling of computed tomography systems", Proc. SPIE 9412, Medical Imaging 2015: Physics of Medical Imaging, 94122N (18 March 2015); https://doi.org/10.1117/12.2081827

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