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Subject: search.filters.subject.Acoustic field

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    Computational algorithm of high-intensity focused ultrasound beams in cancer tissue model for hyperthermia therapy
    (2020-01-01)
    Songkaitiwong, Kittiphot
    ;
    Locharoenrat, Kitsakorn
    We calculate the acoustic field of a high-intensity focused ultrasound field in a 2D-model of human breast carcinoma and induce temperature elevation for the generation of necrosis. The computational operation is based on the Pennes bioheat concept. This method provides precise heat transfer values based upon thermal conduction in soft tissue and thermal convection in the domain of the blood. An ultrasound beam at 1 MHz was laterally focused on a tumor of 15.0 mm x 28.5 mm at different focal depths without elevational focalization. The length of each focus point of the ultrasound beam was 6.8 - 45.4 mm on the vertical axis, whereas the full width at half maximum was 1.1-2.5 mm on the horizontal axis. Simulated results showed that a discrepancy of the acoustic pressure around the focus area rises with focal depth. Like the pressure profile, when the focal depth is close to the ultrasound source, the thermal homogeneity around the focus area is attained, whereas thermal uniformity around the focus area becomes worse with increasing focal depth. Using the data visualization arrangement, a temperature profile corresponding to the obtained pressure profile is converted to attain a 2D image of a model of human breast carcinoma to show that tumor ablation was achieved and the healthy surrounding tissues were safe.
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    Comparison study of ultrasonic diffraction tomography and ultrasonic non-diffraction tomography
    (2007-01-01)
    Onemanisone, Thongsamlith
    ;
    Pintavirooj, C.
    ;
    Jaruwongrungsee, K.
    ;
    Sangworasil, Manas
    Diffraction tomography is a technique for imaging with acoustic fields in which parameter, such as reflective index, sound velocity, etc., can be mapped from scatter wave resulting from insonifying the object with a plane wave at a single temporal frequency. By solving the direct scattering problem, the scattered field can be presented in term of scattering parameters. Different inversion techniques can be applied to takes advantage of the linearization process of the nonlinear wave equation describing wave propagation in heterogeneous media under for limited class of scattering. Specifically, when the scattering effect is weak, one can invoke the Born or Rytov approximation and thus derive the generalized Fourier Slice Theorem to reconstruct the cross-section of the insonified object. The objective of this paper is to compare the quality of the reconstructed image derived from diffraction tomography and non-diffraction tomography.