X G Zhao
The University of Hong Kong, Hong Kong, Hong Kong

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Publications (6)0 Total impact

  • Conference Proceeding: In vivo tumor detection on rabbit with biopsy needle as MRE driver
    X.G. Zhao, Y. Zheng, J.M. Liang, Q.C.C. Chan, X.F. Yang, G. Li, E.S. Yang
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    ABSTRACT: Magnetic Resonance Elastography (MRE) is a phase contrast imaging technique to quantitatively measure the elasticity of tissues. Typically, the oscillating driver is placed on the surface of objects to generate shear waves. When it is applied to detect tumors in deep location, the depth penetration of the wave is limited by attenuation and the biopsy procedure has to be performed separately. In this study, we describe a method using biopsy needle as the MRE driver to produce shear waves in tissues. We made comparison between the MRE acquisitions obtained with biopsy needle and surface drivers. Because the well-defined propagation wave pattern reduces the error in wavelength calculation, the acquisitions of biopsy needle driver shows better homogeneity in stiffness map. We also performed the experiment with the biopsy needle for in vivo tumor detection in rabbits. This study demonstrates that the biopsy needle driver is more effective than the surface driver for accurately measuring the stiffness and location of the tumor.
    Engineering in Medicine and Biology Society, 2008. EMBS 2008. 30th Annual International Conference of the IEEE; 09/2008
  • Conference Proceeding: Biopsy needle as MRE driver for tumor detection
    X.G. Zhao, Y. Zheng, Q.C.C. Chan, X.F. Yang, G. Li, E.S. Yang
    [show abstract] [hide abstract]
    ABSTRACT: Magnetic Resonance Elastography (MRE) is a phase contrast imaging technique to quantitatively measure the elasticity of tissues. Typically, an oscillating driver is placed on the surface to generate the shear waves. The depth penetration of the wave is limited by attenuation and the biopsy procedure has to be done separately. In this study, we use a biopsy needle as the driver to detect the 15% porcine gel inclusion in a 10% porcine gel phantom which simulates a tumor in tissues. We also perform the experiment with the biopsy needle for in-vivo tumor detection in rabbits. It is shown that the biopsy needle driver can accurately measure the stiffness and location of the tumor.
    Engineering in Medicine and Biology Society, 2007. EMBS 2007. 29th Annual International Conference of the IEEE; 09/2007
  • Article: Biopsy needle as MRE driver for tumor detection.
    X G Zhao, Y Zheng, Q C C Chan, X F Yang, G Li, E S Yang
    [show abstract] [hide abstract]
    ABSTRACT: Magnetic Resonance Elastography (MRE) is a phase contrast imaging technique to quantitatively measure the elasticity of tissues. Typically, an oscillating driver is placed on the surface to generate the shear waves. The depth penetration of the wave is limited by attenuation and the biopsy procedure has to be done separately. In this study, we use a biopsy needle as the driver to detect the 15% porcine gel inclusion in a 10% porcine gel phantom which simulates a tumor in tissues. We also perform the experiment with the biopsy needle for in-vivo tumor detection in rabbits. It is shown that the biopsy needle driver can accurately measure the stiffness and location of the tumor.
    Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference 02/2007; 2007:2050-2.
  • Source
    Article: Dynamical localization and nondispersion of energy spectrum
    Wei Zhang, X.-G. Zhao
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    ABSTRACT: Within a finite band model, we present a proof of the theorem that dynamical localization happens if and only if the energy spectrum is dispersionless for an electron in a semiconductor superlattice under the influence of time-periodic electric fields. The electron may display several localization patterns.
    Physica E: Low-dimensional Systems and Nanostructures.
  • Source
    Article: Rabi oscillations between Bloch bands beyond weak interband coupling regime
    Wei Zhang, X.-G. Zhao
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    ABSTRACT: Within a two-band tight-binding model, we investigate Rabi oscillations of electrons in superlattices driven by electric fields beyond the weak interband coupling regime. By the analytical and numerical studies, conditions for Rabi oscillations and oscillation period are obtained. A picture showing the influence of electric fields on the dynamics of Bloch electrons is given. The possibility of experimental observations is discussed.
    Physica B: Condensed Matter.
  • Source
    Article: Dynamic fractional stark ladders in dc-ac fields
    X.-G. Zhao, R. Jahnke, Q. Niu
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    ABSTRACT: A single band in a spatially periodic system splits into a series of quasienergy subbands under the action of dc-ac electric fields. These dynamic fractional Stark ladders should be observable in an investigation of optical absorption. The dependence of the quasienergy spectrum on a parameter called the electric matching ratio is presented as an electric analogue of the well known Hofstadter spectrum.
    Physics Letters A.

Institutions

  • 2007
    • The University of Hong Kong
      • Department of Electrical and Electronic Engineering
      Hong Kong, Hong Kong
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