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Simulation of scattered radiation with various anti-scatter grid designs in a photon counting CT
Author(s): Xiaohui Zhan; Kevin Zimmerman; Liang Cai; Xiaochun Lai; Madhuri Kaul; Richard Thompson
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Paper Abstract

For large cone angle multi-detector CT (MDCT), the scattered radiation remains a challenging problem as it is part of the physics process in X-ray interaction. For a photon counting CT system, the scattered radiation has more profound impact to the system performance, as the scattered photons dominate the low energy regime of the measurement. Without proper corrections, the scattered radiation could introduce significant errors in the material decomposition, and degrade the material characterization and quantification accuracy. To mitigate the scatter problem, typically, hardware rejection and software correction algorithms can be both employed. The anti-scatter grids (ASG) are commonly used to absorb the scattered photons and help generate cleaner measurements. For semiconductor based photon counting detectors (CdTe/CdZnTe), due to charge sharing and cross-talk effects (k-escape, scatter), different ASG designs also change the detector spectral response by masking different detector areas. In this study, we will evaluate a CdZnTe based photon counting CT performance with various ASG designs at the low flux condition through simulations. The detector spectral responses with 2 different detector pixel sizes (250 um and 500um anode size) are generated by our internal simulation tool, using no ASG, 1-D and 2-D ASGs respectively. The scattered radiation is generated by GATE, a Geant4 based Monte Carlo simulation tool, using a large (33 cm diameter) cylindrical water phantom with concentric iodine/calcium inserts, and then added to the simulated phantom energy bin count measurements. The impact of the residual scatter with 1-D and 2-D ASGs in the basis and mono-energetic images will be evaluated and compared.

Paper Details

Date Published: 1 March 2019
PDF: 7 pages
Proc. SPIE 10948, Medical Imaging 2019: Physics of Medical Imaging, 109484Q (1 March 2019); doi: 10.1117/12.2512494
Show Author Affiliations
Xiaohui Zhan, Canon Medical Research USA, Inc. (United States)
Kevin Zimmerman, Canon Medical Research USA, Inc. (United States)
Liang Cai, Canon Medical Research USA, Inc. (United States)
Xiaochun Lai, Canon Medical Research USA, Inc. (United States)
Madhuri Kaul, Canon Medical Research USA, Inc. (United States)
Richard Thompson, Canon Medical Research USA, Inc. (United States)


Published in SPIE Proceedings Vol. 10948:
Medical Imaging 2019: Physics of Medical Imaging
Taly Gilat Schmidt; Guang-Hong Chen; Hilde Bosmans, Editor(s)

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