Paper
16 March 2020 Multi-energy inter-pixel coincidence counters for charge sharing correction and compensation for photon counting detectors: assessment at a normalized spatial resolution
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Abstract
Recently, multi-energy inter-pixel coincidence counter (MEICC) has been proposed for charge sharing correction and compensation for photon counting detectors (PCDs), which uses energy-dependent coincidence counters between a pixel-of-interest (POI) and its neighboring pixels and keeps the book of charge sharing events. A Monte Carlo (MC) simulation study was performed to assess the performance of MEICC; however, the performance might have been overestimated in a previous study. The charge sharing increases the number of photons recorded at a PCD pixel at the expense of the spatial resolution and the effect on the spatial resolution was not taken into account. The aims of this study were, first, to outline a spatially-resolved irradiation scheme for a normalized spatial resolution, and second, to assess the performance of MEICC. The MC program was modified to set the x-ray spectrum and intensity for the POI and those for the neighboring pixels separately. Data were then generated by varying two basis materials, water and bone, by a small amount only for the POI, while those for neighboring pixels remained unchanged. Cramér–Rao lower bound (CRLB) of water and bone estimation was computed from the changes in the mean and covariance matrix estimated. This setting allowed for assessing the CRLB at the same spatial resolution regardless of with or without charge sharing. The CRLBs at the normalized spatial resolution were worse than those at not-normalized spatial resolutions. With eight energy windows, MEICC provided the CRLB comparable to the ideal PCD with no charge sharing. The proposed MEICC has a potential to address charge sharing in PCDs.
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Katsuyuki Taguchi "Multi-energy inter-pixel coincidence counters for charge sharing correction and compensation for photon counting detectors: assessment at a normalized spatial resolution", Proc. SPIE 11312, Medical Imaging 2020: Physics of Medical Imaging, 113120C (16 March 2020); https://doi.org/10.1117/12.2545058
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KEYWORDS
Spatial resolution

Photon counting

Sensors

Signal processing

Monte Carlo methods

Computed tomography

X-rays

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