9 March 2017 Improving material separation of high-flux whole-body photon counting computed tomography by K-edge pre-filtration
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Photon-counting detectors in computed tomography (CT) allow for measuring the energy of the incident xray photons within certain energy windows. This information can be used to enhance contrast or reconstruct CT images of different material bases. Compared to energy-integrating CT-detectors, pixel dimensions have to be smaller to limit the negative effect of pulse pile-up at high X-ray fluxes. Unfortunately, reducing the pixel size leads to increased K-escape and charge sharing effects. As a consequence, an incident X-ray may generate more than one detector signal, and with deteriorated energy information. In earlier simulation studies it has been shown that these limitations can be mitigated by optimizing the X-ray spectrum using K-edge pre-filtration. In the current study, we have used a whole-body research CT scanner with a high-flux capable photon-counting detector, in which for the first time a pre-patient hafnium filter was installed. Our measurement results demonstrate substantial improvement of the material decomposition capability at comparable dose levels. The results are in agreement with the predictions provided in simulations.
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C. Polster, R. Gutjahr, M. Berner, T. Flohr, M. Hertel, S. Kappler, K. Stierstorfer, and O. Dietrich "Improving material separation of high-flux whole-body photon counting computed tomography by K-edge pre-filtration", Proc. SPIE 10132, Medical Imaging 2017: Physics of Medical Imaging, 101320W (9 March 2017); doi: 10.1117/12.2254289; https://doi.org/10.1117/12.2254289

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