Ms. Xuejin Liu Profile

Xuejin Liu

at KTH Royal Institute of Technology

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Publications (5)

SPIE Journal Paper | 25 October 2016 Open Access

Errata: Spectral response model for a multibin photon-counting spectral computed tomography detector and its applications

Xuejin Liu, Mats Persson, Hans Bornefalk, Staffan Karlsson, Cheng Xu, Mats Danielsson, Ben Huber

JMI, Vol. 3, Issue 04, 049801, (October 2016) https://doi.org/10.1117/12.10.1117/1.JMI.3.4.049801

KEYWORDS: Spectral models, Optical computing, Computed tomography, Sensors, Data processing, Medical imaging, Physics, Image processing

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SPIE Journal Paper | 11 September 2015

Spectral response model for a multibin photon-counting spectral computed tomography detector and its applications

Xuejin Liu, Mats Persson, Hans Bornefalk, Staffan Karlsson, Cheng Xu, Mats Danielsson, Ben Huber

JMI, Vol. 2, Issue 03, 033502, (September 2015) https://doi.org/10.1117/12.10.1117/1.JMI.2.3.033502

KEYWORDS: Sensors, Spectral models, Polymethylmethacrylate, Iodine, Computed tomography, Aluminum, X-rays, Optical computing, Gadolinium, Calibration

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Variations among detector channels in computed tomography can lead to ring artifacts in the reconstructed images and biased estimates in projection-based material decomposition. Typically, the ring artifacts are corrected by compensation methods based on flat fielding, where transmission measurements are required for a number of material-thickness combinations. Phantoms used in these methods can be rather complex and require an extensive number of transmission measurements. Moreover, material decomposition needs knowledge of the individual response of each detector channel to account for the detector inhomogeneities. For this purpose, we have developed a spectral response model that binwise predicts the response of a multibin photon-counting detector individually for each detector channel. The spectral response model is performed in two steps. The first step employs a forward model to predict the expected numbers of photon counts, taking into account parameters such as the incident x-ray spectrum, absorption efficiency, and energy response of the detector. The second step utilizes a limited number of transmission measurements with a set of flat slabs of two absorber materials to fine-tune the model predictions, resulting in a good correspondence with the physical measurements. To verify the response model, we apply the model in two cases. First, the model is used in combination with a compensation method which requires an extensive number of transmission measurements to determine the necessary parameters. Our spectral response model successfully replaces these measurements by simulations, saving a significant amount of measurement time. Second, the spectral response model is used as the basis of the maximum likelihood approach for projection-based material decomposition. The reconstructed basis images show a good separation between the calcium-like material and the contrast agents, iodine and gadolinium. The contrast agent concentrations are reconstructed with more than 94% accuracy.

Proceedings Article | 18 March 2015 Paper

Modelling the channel-wise count response of a photon-counting spectral CT detector to a broad x-ray spectrum

Xuejin Liu, Han Chen, Hans Bornefalk, Mats Danielsson, Staffan Karlsson, Mats Persson, Cheng Xu, Ben Huber

Proceedings Volume 9412, 941215 (2015) https://doi.org/10.1117/12.2081776

KEYWORDS: Sensors, Calibration, X-rays, Photons, Polymethylmethacrylate, X-ray detectors, Aluminum, Iodine, Gadolinium, Photodetectors

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Proceedings Article | 19 March 2014 Paper

Energy-resolved CT imaging with a photon-counting silicon-strip detector

Mats Persson, Ben Huber, Staffan Karlsson, Xuejin Liu, Han Chen, Cheng Xu, Moa Yveborg, Hans Bornefalk, Mats Danielsson

Proceedings Volume 9033, 90333L (2014) https://doi.org/10.1117/12.2043519

KEYWORDS: Sensors, Iodine, Gadolinium, X-ray computed tomography, Calcium, Signal attenuation, Calibration, Silicon, Magnesium, Photodetectors

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Proceedings Article | 19 March 2014 Paper

Characterization of a silicon strip detector for photon-counting spectral CT using monoenergetic photons from 40 keV to 120 keV

Xuejin Liu, Hans Bornefalk, Han Chen, Mats Danielsson, Staffan Karlsson, Mats Persson, Cheng Xu, Ben Huber

Proceedings Volume 9033, 90333O (2014) https://doi.org/10.1117/12.2042862

KEYWORDS: Sensors, Photons, X-rays, Monte Carlo methods, Silicon, X-ray detectors, Electrodes, Photodetectors, Microchannel plates, Synchrotrons

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