Dr. Xiaolan Wang Profile

Dr. Xiaolan Wang

at Canon Medical Research USA Inc

SPIE Involvement:

Author

Publications (8)

SPIE Journal Paper | 28 April 2015

Evaluation of position-estimation methods applied to CZT-based photon-counting detectors for dedicated breast CT

Andrey Makeev, Martin Clajus, Scott Snyder, Xiaolang Wang, Stephen Glick

JMI, Vol. 2, Issue 02, 023501, (April 2015) https://doi.org/10.1117/12.10.1117/1.JMI.2.2.023501

KEYWORDS: Sensors, X-rays, Photodetectors, X-ray detectors, Detection and tracking algorithms, Photons, X-ray computed tomography, Breast, Spatial resolution, Computer simulations

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Semiconductor photon-counting detectors based on high atomic number, high density materials [cadmium zinc telluride (CZT)/cadmium telluride (CdTe)] for x-ray computed tomography (CT) provide advantages over conventional energy-integrating detectors, including reduced electronic and Swank noise, wider dynamic range, capability of spectral CT, and improved signal-to-noise ratio. Certain CT applications require high spatial resolution. In breast CT, for example, visualization of microcalcifications and assessment of tumor microvasculature after contrast enhancement require resolution on the order of 100 μm. A straightforward approach to increasing spatial resolution of pixellated CZT-based radiation detectors by merely decreasing the pixel size leads to two problems: (1) fabricating circuitry with small pixels becomes costly and (2) inter-pixel charge spreading can obviate any improvement in spatial resolution. We have used computer simulations to investigate position estimation algorithms that utilize charge sharing to achieve subpixel position resolution. To study these algorithms, we model a simple detector geometry with a 5×5 array of 200 μm pixels, and use a conditional probability function to model charge transport in CZT. We used COMSOL finite element method software to map the distribution of charge pulses and the Monte Carlo package PENELOPE for simulating fluorescent radiation. Performance of two x-ray interaction position estimation algorithms was evaluated: the method of maximum-likelihood estimation and a fast, practical algorithm that can be implemented in a readout application-specific integrated circuit and allows for identification of a quadrant of the pixel in which the interaction occurred. Both methods demonstrate good subpixel resolution; however, their actual efficiency is limited by the presence of fluorescent K-escape photons. Current experimental breast CT systems typically use detectors with a pixel size of 194 μm, with 2×2 binning during the acquisition giving an effective pixel size of 388 μm. Thus, it would be expected that the position estimate accuracy reported in this study would improve detection and visualization of microcalcifications as compared to that with conventional detectors.

Proceedings Article | 19 March 2014 Paper

Noise balance in pre-reconstruction decomposition in spectral CT

Xiaolan Wang, Yu Zou

Proceedings Volume 9033, 90333K (2014) https://doi.org/10.1117/12.2042175

KEYWORDS: Sensors, Data acquisition, Photon counting, Signal attenuation, Image quality, Computed tomography, CT reconstruction, X-ray computed tomography, Absorption, Compton scattering

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Proceedings Article | 24 February 2012 Paper

Dose reduction potential with photon counting computed tomography

Xiaolan Wang, Alexander Zamyatin, Daxin Shi

Proceedings Volume 8313, 831349 (2012) https://doi.org/10.1117/12.911631

KEYWORDS: Sensors, Photon counting, X-ray computed tomography, Computed tomography, X-ray detectors, Image quality, Interference (communication), Scanners, Infrared sensors, Infrared imaging

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Proceedings Article | 16 March 2011 Paper

Material separation in x-ray CT with energy resolved photon-counting detectors

X. Wang, D. Meier, K. Taguchi, D. Wagenaar, B. Patt, E. Frey

Proceedings Volume 7961, 79611V (2011) https://doi.org/10.1117/12.877469

KEYWORDS: Signal attenuation, Sensors, Photodetectors, X-rays, Iodine, Gadolinium, X-ray detectors, Absorption, X-ray computed tomography, Polymethylmethacrylate

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Proceedings Article | 19 March 2010 Paper

Microcomputed tomography with a second generation photon-counting x-ray detector: contrast analysis and material separation

X. Wang, D. Meier, P. Oya, G. Maehlum, D. Wagenaar, B. M. Tsui, B. Patt, E. Frey

Proceedings Volume 7622, 76221B (2010) https://doi.org/10.1117/12.844301

KEYWORDS: Sensors, Signal attenuation, X-ray detectors, X-rays, Photodetectors, Gadolinium, Iodine, Bone, Photons, Polymethylmethacrylate

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Proceedings Article | 19 March 2010 Paper

An analytical model of the effects of pulse pileup on the energy spectrum recorded by energy resolved photon counting x-ray detectors

Katsuyuki Taguchi, Eric Frey, Xiaolan Wang, Jan Iwanczyk, William Barber

Proceedings Volume 7622, 76221C (2010) https://doi.org/10.1117/12.843753

KEYWORDS: Monte Carlo methods, Sensors, Microchannel plates, Photon counting, X-ray detectors, Personal protective equipment, Shape analysis, X-rays, Medical imaging, Time correlated photon counting

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Proceedings Article | 14 March 2009 Paper

Enhanced discrimination of calcified and soft arterial plaques using computed tomography with a multi-energy-window photon counting x-ray detector

Xiaolan Wang, Jingyan Xu, Katsuyuki Taguchi, Bradley Patt, Douglas Wagenaar, Eric Frey

Proceedings Volume 7258, 72583W (2009) https://doi.org/10.1117/12.813877

KEYWORDS: Sensors, Signal to noise ratio, Photon counting, X-ray detectors, Calcium, Blood, Iodine, X-rays, Tissues, Arteries

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Proceedings Article | 16 March 2007 Paper

Investigation of the use of photon counting x-ray detectors with energy discrimination capability for material decomposition in micro-computed tomography

E. Frey, X. Wang, Y. Du, K. Taguchi, J. Xu, B. Tsui

Proceedings Volume 6510, 65100A (2007) https://doi.org/10.1117/12.711711

KEYWORDS: Sensors, X-rays, Polymethylmethacrylate, X-ray detectors, Calibration, Photon counting, Monte Carlo methods, Data modeling, Signal attenuation, Aluminum

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Showing 5 of 8 publications

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