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Wyszukujesz frazę "ultrasound imaging" wg kryterium: Wszystkie pola

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    Wyświetlanie 1-5 z 5
    Tytuł:
    Ultrasound imaging of stiffness with two frequency pulses
    Autorzy:
    Nowicki, A.
    Byra, M.
    Litniewski, J.
    Wójcik, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/332602.pdf
    Data publikacji:
    2014
    Wydawca:
    Polskie Towarzystwo Akustyczne
    Opis:
    Nowadays there are new modalities in ultrasound imaging allowing better characterization of tissue regions with different stiffness. We are proposing a novel approach based on compression and rarefaction of tissue simultaneously with imaging. The propagating wave is a combination of two pulses. A low frequency pulse is expected to change the local scattering properties of the tissue due to compression/rarefaction while a high frequency pulse is used for imaging. Two transmissions are performed for each scanning line. First, with the imaging pulse that propagates on maximum compression caused by a low frequency wave. Next, the low frequency wave is inverted and the imaging pulse propagates over the maximum rarefaction. After the processing of the subtracted echoes from subsequent transmissions including wavelet transform and band-pass filtering, differential images were reconstructed. The low frequency wave has a visible impact on the scattering properties of the tissue which can be observed on a differential image.
    Źródło:
    Hydroacoustics; 2014, 17; 151-160
    1642-1817
    Pojawia się w:
    Hydroacoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The influence of the transducer bandwidth and double pulse transmission on the encoded imaging ultrasound
    Autorzy:
    Trots, I.
    Nowicki, A.
    Lewandowski, M.
    Secomski, W.
    Litniewski, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/331651.pdf
    Data publikacji:
    2008
    Wydawca:
    Polskie Towarzystwo Akustyczne
    Tematy:
    encoded imaging ultrasound
    ultrasound imaging transducer
    CGS
    Opis:
    An influence effect of fractional bandwidth of ultrasound imaging transducer on the gain of compressed echo signal being the complementary Golay sequences (CGS) with different spectral widths is studied in this paper. Also, a new composing transmission method of CGS is discussed together with compression technique applied in order to increase the signal-to-noise ratio (SNR) and penetration. The CGS with two different bit lengths, one-cycle and two-cycles are investigated. Two transducers with fractional bandwidth of 25% and 80% at centre frequency 6 MHz are used. The experimental results are presented, clearly proofing that increasing of the code length leads to compressed echo amplitude enhancement. The smaller the bandwidth is the larger is this effect; the pulse-echo sensitivity of the echo amplitude increases by 1.88 for 25% fractional bandwidth and 1.47 for 80% while preserving time resolution. The presented results of double transmission of short codes show the penetration and SNR improvement while maintaining dead zone.
    Źródło:
    Hydroacoustics; 2008, 11; 419-430
    1642-1817
    Pojawia się w:
    Hydroacoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Application of ultrasound to noninvasive imaging of temperature distribution induced in tissue
    Autorzy:
    Karwat, P.
    Kujawska, T.
    Secomski, W.
    Gambin, B.
    Litniewski, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/332286.pdf
    Data publikacji:
    2016
    Wydawca:
    Polskie Towarzystwo Akustyczne
    Tematy:
    HIFU
    echo phase shift
    parametric imaging
    velocity/brightness CNR
    Opis:
    Therapeutic and surgical applications of High Intensity Focused Ultrasound (HIFU) require monitoring of local temperature rises induced inside tissues. It is needed to appropriately target the focal plane, and hence the whole focal volume inside the tumor tissue, prior to thermo-ablative treatment, and the beginning of tissue necrosis. In this study we present an ultrasound method, which calculates the variations of the speed of sound in the locally heated tissue. Changes in velocity correspond to temperature change. The method calculates a 2D distribution of changes in the sound velocity, by estimation of the local phase shifts of RF echo-signals backscattered from the heated tissue volume (the focal volume of the HIFU beam), and received by an ultrasound scanner (23). The technique enabled temperature imaging of the heated tissue volume from the very inception of heating. The results indicated that the contrast sensitivity for imaging of relative changes in the sound speed was on the order of 0.06%; corresponding to an increase in the tissue temperature by about 2 °C.
    Źródło:
    Hydroacoustics; 2016, 19; 219-228
    1642-1817
    Pojawia się w:
    Hydroacoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    An assessment of cleaning mechanisms driven by power ultrasound using electrochemistry and highspeed imaging techniques
    Autorzy:
    Offin, D.
    Vian, Ch.
    Birkin, P.
    Leighton, T.
    Powiązania:
    https://bibliotekanauki.pl/articles/331598.pdf
    Data publikacji:
    2008
    Wydawca:
    Polskie Towarzystwo Akustyczne
    Tematy:
    electrochemistry
    cleaning mechanisms
    high-speed imaging techniques
    Opis:
    The cleaning of a surface is monitored in real time using a number of physical measurements. In particular an electrochemically inactive material is removed from an electrode while the electrode is able to detect a redox system in the bulk liquid. The removal of the material from the surface is monitored as an increased Faradaic current at the electrode surface. This signal is used to assess the ability of the cleaning method employed, in this case the application of power ultrasound to the system, as a function of the position of the electrode with respect to the sound source. It is shown that, depending on the conditions employed, surface cleaning is driven by different mechanisms. In order to validate these findings highspeed imaging of the system was undertaken and the results correlated with the electrochemical data. In addition a number of novel electrodes were also employed to assess the cleaning efficiency as a function of the electrode geometry employed. Implications for surface cleaning in the presence of power ultrasound are suggested.
    Źródło:
    Hydroacoustics; 2008, 11; 299-312
    1642-1817
    Pojawia się w:
    Hydroacoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Parametric sonographic imaging - application of synthetic aperture technique to imaging attenuation of ultrasound in tissue structures
    Autorzy:
    Litniewski, J.
    Klimonda, Z.
    Nowicki, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/331882.pdf
    Data publikacji:
    2012
    Wydawca:
    Polskie Towarzystwo Akustyczne
    Opis:
    Ultrasonic imaging is a well-established technique in medicine. However, in most conventional applications of clinical ultrasonic scanners only the peak amplitude echogenicity is used to create the image. Moreover, signal envelope detection destroys potentially useful information about frequency dependence of acoustic properties of tissue comprised in RF backscattered echoes. We have explored the possibility of developing the method of imaging the distribution of the acoustic attenuation in tissue. We expect that the method will help in localization of the pathological states of tissue including tumors and diffuse liver diseases. The spatial resolution and precision of the method are crucial for medical diagnosis, hence the synthetic aperture technique was applied for ultrasonic data collection. The final goal of the presented project is to develop reliable diagnostic tool, which could be implemented in standard USG systems, as the new visualization mode.
    Źródło:
    Hydroacoustics; 2012, 15; 99-110
    1642-1817
    Pojawia się w:
    Hydroacoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-5 z 5

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