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Proceedings Paper

Modelling the channel-wise count response of a photon-counting spectral CT detector to a broad x-ray spectrum
Author(s): Xuejin Liu; Han Chen; Hans Bornefalk; Mats Danielsson; Staffan Karlsson; Mats Persson; Cheng Xu; Ben Huber
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Paper Abstract

Variations among detector channels in CT very sensitively lead to ring artefacts in the reconstructed images. For material decomposition in the projection domain, the variations can result in intolerable biases in the material line integral estimates. A typical way to overcome these effects is to apply calibration methods that try to unify spectral responses from different detector channels to an ideal response from a detector model. However, the calibration procedure can be rather complex and require excessive calibration measurements for a multitude of combinations of x-ray shapes, tissue combinations and thicknesses. In this paper, we propose a channel-wise model for a multibin photon-counting detector for spectral CT. Predictions of this channel-wise model match well with their physical performances, which can thus be used to eliminate ring artefacts in CT images and achieve projection-basis material decomposition. In an experimental validation, image data show significant improvement with respect to ring artefacts compared to images calibrated with flat-fielding data. Projection-based material decomposition gives basis material images showing good separation among individual materials and good quantification of iodine and gadolinium contrast agents. The work indicates that the channel-wise model can be used for quantitative CT with this detector.

Paper Details

Date Published: 18 March 2015
PDF: 15 pages
Proc. SPIE 9412, Medical Imaging 2015: Physics of Medical Imaging, 941215 (18 March 2015); doi: 10.1117/12.2081776
Show Author Affiliations
Xuejin Liu, Royal Institute of Technology (Sweden)
Han Chen, Royal Institute of Technology (Sweden)
Hans Bornefalk, Royal Institute of Technology (Sweden)
Mats Danielsson, Royal Institute of Technology (Sweden)
Staffan Karlsson, Royal Institute of Technology (Sweden)
Mats Persson, Royal Institute of Technology (Sweden)
Cheng Xu, Royal Institute of Technology (Sweden)
Ben Huber, Royal Institute of Technology (Sweden)

Published in SPIE Proceedings Vol. 9412:
Medical Imaging 2015: Physics of Medical Imaging
Christoph Hoeschen; Despina Kontos, Editor(s)

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