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Proceedings Paper

Signal and noise characteristics of a CdTe-based photon counting detector: cascaded systems analysis and experimental studies
Author(s): Xu Ji; Ran Zhang; Yongshuai Ge; Guang-Hong Chen; Ke Li
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Paper Abstract

Recent advances in single photon counting detectors (PCDs) are opening up new opportunities in medical imaging. However, the performance of PCDs is not flawless. Problems such as charge sharing may deteriorate the performance of PCD. This work studied the dependence of the signal and noise properties of a cadmium telluride (CdTe)-based PCD on the charge sharing effect and the anti-charge sharing (ACS) capability offered by the PCD. Through both serial and parallel cascaded systems analysis, a theoretical model was developed to trace the origin of charge sharing in CdTe-based PCD, which is primarily related to remote k-fluorescence re-absorption and spatial spreading of charge cloud. The ACS process was modeled as a sub-imaging state prior to the energy thresholding stage, and its impact on the noise power spectrum (NPS) of PCD can be qualitatively determined by the theoretical model. To validate the theoretical model, experimental studies with a CdTe-based PCD system (XC-FLITE X1, XCounter AB) was performed. Two x-ray radiation conditions, including an RQA-5 beam and a 40 kVp beam, were used for the NPS measurements. Both theoretical predictions and experimental results showed that ACS makes the NPS of the CdTe-based PCD flatter, which corresponds to reduced noise correlation length. The flatness of the NPS is further boosted by increasing the energy threshold or reducing the x-ray energy, both of which reduce the likelihood of registering multiple counts from the same incidenting x-ray photon.

Paper Details

Date Published: 9 March 2017
PDF: 6 pages
Proc. SPIE 10132, Medical Imaging 2017: Physics of Medical Imaging, 1013207 (9 March 2017); doi: 10.1117/12.2255063
Show Author Affiliations
Xu Ji, Univ. of Wisconsin School of Medicine and Public Health (United States)
Ran Zhang, Univ. of Wisconsin School of Medicine and Public Health (United States)
Yongshuai Ge, Univ. of Wisconsin School of Medicine and Public Health (United States)
Guang-Hong Chen, Univ. of Wisconsin School of Medicine and Public Health (United States)
Ke Li, Univ. of Wisconsin School of Medicine and Public Health (United States)


Published in SPIE Proceedings Vol. 10132:
Medical Imaging 2017: Physics of Medical Imaging
Thomas G. Flohr; Joseph Y. Lo; Taly Gilat Schmidt, Editor(s)

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