Tao Chen

Nanjing University, Nan-ching, Jiangsu Sheng, China

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Publications (4)9.62 Total impact

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    ABSTRACT: Prediction and measurement of the acoustic field emitted from a high intensity focused ultrasound (HIFU) is essential for the accurate ultrasonic treatment. In this study, the acoustic field generated from a strongly focused HIFU transmitter was characterized by a combined experiment and simulation method. The spheroidal beam equation (SBE) was utilized to describe the nonlinear sound propagation. The curve of the source pressure amplitude versus voltage excitation was determined by fitting the measured ratio of the second harmonic to the fundamental component of the focal waveform to the simulation result; finally, the acoustic pressure field generated by the strongly focused HIFU transmitter was predicted by using the SBE model. A commercial fiber optic probe hydrophone was utilized to measure the acoustic pressure field generated from a 1.1 MHz HIFU transmitter with a large half aperture angle of 30°. The maximum measured peak-to-peak pressure was up to 72 MPa. The validity of this combined approach was confirmed by the comparison between the measured results and the calculated ones. The results indicate that the current approach might be useful to describe the HIFU field. The results also suggest that this method is not valid for low excitations owing to low sensitivity of the second harmonic.
    Journal of Applied Physics 03/2014; 115(11):114902-114902-7. DOI:10.1063/1.4868597 · 2.18 Impact Factor
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    ABSTRACT: High intensity focused ultrasound (HIFU)-induced hyperthermia is a promising tool for cancer therapy. Three-dimensional nonlinear acoustic-bioheat transfer-blood flow-coupling model simulations and in vivo thermocouple measurements were performed to study hyperthermia effects in rabbit auricular vein exposed to pulsed HIFU (pHIFU) at varied duty cycles (DCs). pHIFU-induced temperature elevations are shown to increase with increasing DC. A critical DC of 6.9% is estimated for temperature at distal vessel wall exceeding 44 °C, although different tissue depths and inclusions could affect the DC threshold. The results demonstrate clinic potentials of achieving controllable hyperthermia by adjusting pHIFU DCs, while minimizing perivascular thermal injury.
    Applied Physics Letters 09/2012; 101(12):124102. DOI:10.1063/1.4754113 · 3.30 Impact Factor
  • Tao Chen · Tingbo Fan · Liyang Xia · Jimin Hu · Ru Liu · Dong Zhang ·
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    ABSTRACT: Acoustic characterization of high Intensity focused ultrasound (HIFU) is essential for its development in clinical treatment. In the present study, a combined measurement and modeling approach is proposed. At relative low amplitude excitation, acoustic measurement in water is performed to calibrate the transmitter parameters; then the acoustic fields of HIFU transmitter can be predicted based on the SBE model. To verify the validity of this approach, a 1 MHz HIFU transmitter with large aperture is utilized in the study, and the HIFU field is measured by a HFO-660 fiber optic hydrophone. This study is helpful for the accurate characterization of HIFU fields. [This work is supported by the National Basic Research Program 973 (Grant No. 2011CB707900) from Ministry of Science and Technology, China, National Natural Science Foundation of China (10974093 and 11011130201), and the Fundamental Research Funds for the Central Universities (Grant Nos. 1103020402, 1116020410 and 1112020401)].
    The Journal of the Acoustical Society of America 04/2012; 131(4):3365. DOI:10.1121/1.4708686 · 1.50 Impact Factor
  • Tingbo Fan · Zhenbo Liu · Tao Chen · Faqi Li · Dong Zhang ·
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    ABSTRACT: In this work, the authors propose a modeling approach to compute the nonlinear acoustic field generated by a flat piston transmitter with an attached aluminum lens. In this approach, the geometrical parameters (radius and focal length) of a virtual source are initially determined by Snell's refraction law and then adjusted based on the Rayleigh integral result in the linear case. Then, this virtual source is used with the nonlinear spheroidal beam equation (SBE) model to predict the nonlinear acoustic field in the focal region. To examine the validity of this approach, the calculated nonlinear result is compared with those from the Westervelt and (Khokhlov-Zabolotskaya-Kuznetsov) KZK equations for a focal intensity of 7 kW/cm(2). Results indicate that this approach could accurately describe the nonlinear acoustic field in the focal region with less computation time. The proposed modeling approach is shown to accurately describe the nonlinear acoustic field in the focal region. Compared with the Westervelt equation, the computation time of this approach is significantly reduced. It might also be applicable for the widely used concave focused transmitter with a large aperture angle.
    Medical Physics 09/2011; 38(9):5033-9. DOI:10.1118/1.3622602 · 2.64 Impact Factor