Mr. Xu U. Zhang Profile

Xu U. Zhang

PhD Researcher at Amsterdam UMC

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Publications (6)

Proceedings Article | 1 April 2020 Presentation

Subdiffuse model to measure tissue optical properties with single fiber reflectance spectroscopy applied to esophageal cancer (Conference Presentation)

Anouk Post, Dirk Faber, Jeroen A. de Groof, Xu Zhang, Martijn D. de Bruin, Theo J. Ruers, Dick J. C. Sterenborg, Wouter Curvers, Jacques J.G.H. Bergman, Ton van Leeuwen

Proceedings Volume 11362, 113620C (2020) https://doi.org/10.1117/12.2554171

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The most common type of cancer are carcinomas: cancers which originate from the epithelial tissue lining the outer surfaces of organs. To detect carcinomas at an early stage, techniques are required with small sampling volumes. Single Fiber Reflectance spectroscopy (SFR) is a promising technique to detect early-stage carcinomas since it has a measurement volume in the order of hundreds of microns. SFR uses a single fiber to emit and collect broadband light. The model from Kanick et al. to relate SFR reflectance to tissue optical properties provided accurate results for tissue with a modified Henyey Greenstein phase function only. However, in many tissues other types of phase functions have been measured. We have developed a new model to relate SFR reflectance to the scattering and absorption properties of tissue, which provides accurate results for a large range of tissue phase functions. SFR measurements fall into the sub-diffuse regime. We, therefore, describe the SFR reflectance as a diffuse plus a semi-ballistic component. An accurate description of the diffuse SFR signal requires double integration of spatially resolved reflectance over the fiber surface. We use approaches from Geometric Probability and have derived the first analytic solution for the diffuse contribution to SFR. For the semi-ballistic contribution to the SFR signal we introduce a new phase function dependent parameter, psb, to describe the semi-ballistic part of the SFR signal. We will use the model to derive optical properties from SFR measurements performed endoscopically in patients with Barrett’s esophagus. These patients are at an increased risk to develop esophageal adenocarcinoma and, therefore, undergo regular endoscopic surveillance. When detected at an early stage, endoscopic treatment is possible, thereby avoiding extensive surgery. Based on the concept of field cancerization, we investigated whether SFR could be used as a tool to identify which patients are developing esophageal adenocarcinoma.

SPIE Journal Paper | 9 December 2019 Open Access

Multidiameter single-fiber reflectance spectroscopy of heavily pigmented skin: modeling the inhomogeneous distribution of melanin

Xu Zhang, Piet van der Zee, Isabella Atzeni, Dirk Faber, Ton van Leeuwen, Henricus J. C. Sterenborg

JBO, Vol. 24, Issue 12, 127001, (December 2019) https://doi.org/10.1117/12.10.1117/1.JBO.24.12.127001

KEYWORDS: Skin, Scattering, Absorption, Tissue optics, Reflectivity, Reflectance spectroscopy, Rayleigh scattering, Optical properties, Photons, Light scattering

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Proceedings Article | 15 March 2018 Presentation

Single fiber reflectance spectroscopy calibration (Conference Presentation)

Xu Zhang, Anouk Post, Dirk Faber, Ton van Leeuwen, Dick Sterenborg

Proceedings Volume 10492, 104920O (2018) https://doi.org/10.1117/12.2289587

KEYWORDS: Calibration, Reflectance spectroscopy, Reflectivity, Optical properties, Spectral calibration, Fiber optics, Spectroscopes, Tissue optics, Diagnostics, Light scattering

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SPIE Journal Paper | 30 October 2017 Open Access

Single fiber reflectance spectroscopy calibration

Xu Zhang, Anouk Post, Dirk Faber, Ton van Leeuwen, Henricus J. C. Sterenborg

JBO, Vol. 22, Issue 10, 100502, (October 2017) https://doi.org/10.1117/12.10.1117/1.JBO.22.10.100502

KEYWORDS: Calibration, Reflectivity, Mirrors, Water, Reflectance spectroscopy, Optical properties, Refractive index, Monte Carlo methods, Scattering, Reflection

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SPIE Journal Paper | 1 March 2017 Open Access

Noninvasive fluence rate mapping in living tissues using magnetic resonance thermometry

Tom J. Schreurs, Robbert van Gorkum, Xu Zhang, Dirk Faber, Ton van Leeuwen, Klaas Nicolay, Gustav Strijkers

JBO, Vol. 22, Issue 03, 036001, (March 2017) https://doi.org/10.1117/12.10.1117/1.JBO.22.3.036001

KEYWORDS: Tissues, Absorption, Tumors, Thermometry, In vivo imaging, Magnetism, Temperature metrology, Magnetic resonance imaging, Photodynamic therapy, Scattering

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Proceedings Article | 28 April 2016 Presentation

Measuring the reduced scattering coefficient and y with SFR spectroscopy: studying the phase function dependence (Conference Presentation)

Anouk Post, Xu Zhang, Nienke Bosschaart, Ton Van Leeuwen, Henricus J. C. Sterenborg, Dirk Faber

Proceedings Volume 9703, 970316 (2016) https://doi.org/10.1117/12.2208848

KEYWORDS: Scattering, Optical coherence tomography, Tissues, Spectroscopy, Tissue optics, Anisotropy, Reflectivity, Reflectance spectroscopy, Optical properties, Scatter measurement

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