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    Wyświetlanie 1-5 z 5
    Tytuł:
    Dynamic ultrasonic model of left ventricle
    Autorzy:
    Trawiński, Z.
    Wójcik, J.
    Nowicki, A.
    Olszewski, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/332195.pdf
    Data publikacji:
    2013
    Wydawca:
    Polskie Towarzystwo Akustyczne
    Opis:
    Two different tissue phantoms of the left ventricle to imitate a beating left ventricle were developed: first was prepared using a sponge material and second phantom was constructed using a polyvinyl alcohol material modeled into a homogeneous hollow cylinder: approximately 10 cm and 12 cm in length for the first and second phantom, respectively. Both phantoms were 5 cm in diameter, with a wall thickness of 1.0 cm. Additionally, a small part of the wall of the second phantom was processed to simulate the stiffness of myocardial infarction. The phantoms were connected at the end to an adjustable external pump. The pulse volume inside the cylinder was set between 12 to 50 ml at rates of 40, 60, 100, 120 beats/minute. The phantoms were immersed in water for ultrasound scanning with two different insonation angles (90 and 65 degrees). Strain and strain rate were measured with different combinations of angles and pulse rates. The main aim of this work was to develop the new method for validation of the human infarct wall strain calculation procedures using the speckles tracking.
    Źródło:
    Hydroacoustics; 2013, 16; 231-236
    1642-1817
    Pojawia się w:
    Hydroacoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Possible temperature increases in soft tissues in the case of nonlinear and linear wave propagation
    Autorzy:
    Filipczyński, L.
    Kujawska, T.
    Tymkiewicz, R.
    Wójcik, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/332225.pdf
    Data publikacji:
    1997
    Wydawca:
    Polskie Towarzystwo Akustyczne
    Opis:
    It is well known that the nonlinear propagation increases the absorption of acoustic waves in the medium thus increasing the temperature effects. According to the recently developed new theoretical approach it is possible to determine in a simple way the effective absorption in the case of nonlinear propagation basing on the pulse spectrum analysis [Wójcik, 1996]. In this way it was possible to find the corresponding absorption values occuring in ultrasonography. In this case a classical PVDF membrane hydrophone was used to demonstrate and to measure nonlinear effects. Analysing the obtained wave spectra it was possible to determine the increase of the effective tissue absorption and hence to find the rate of heat generation per unit volume which is crucial for temperature elevations In this way possible temperature increases for the case of nonlinear and linear propagation can be determined.
    Źródło:
    Hydroacoustics; 1997, 1; 329-332
    1642-1817
    Pojawia się w:
    Hydroacoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Ilościowa ocena nieliniowej propagacji w wodzie i w tkance
    Autorzy:
    Filipczyński, L.
    Kujawska, T.
    Tymkiewicz, R.
    Wójcik, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/331916.pdf
    Data publikacji:
    2000
    Wydawca:
    Polskie Towarzystwo Akustyczne
    Opis:
    Nonlinear propagation effects were investigated numerically and experimentally u wate r and In blood from the point of view of ultrasonic diagnostic applications in cardlology. Pressure distributions of short and long pulses with the frequency of 3 and 3.5 MHz, radiated by a typical cardiological probe, were found along the ultrasonic beam axis. The numerial results were obtained by means of the numerical code Wf developed previously. The experimental pressure distributions were measured by memu of a membrane PYDF hydrophone. The obtained numerical and experimental results show ing the distributions of the 2-nd and I -st harmonics have shown good agreement allowing us to determine some diagnostic conclusions.
    Źródło:
    Hydroacoustics; 2000, 3; 53-56
    1642-1817
    Pojawia się w:
    Hydroacoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Influence of absorption and scattering on the velocity of acoustic streaming
    Autorzy:
    Secomski, W.
    Wójcik, J.
    Klimonda, Z.
    Olszewski, R.
    Nowicki, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/332699.pdf
    Data publikacji:
    2017
    Wydawca:
    Polskie Towarzystwo Akustyczne
    Tematy:
    ultrasound
    radiation force
    starch
    contrast agent
    blood
    thrombolysis
    Opis:
    Streaming velocity depends on intensity and absorption of ultrasound in the media. In some cases, such as ultrasound scattered on blood cells at high frequencies, or the presence of ultrasound contrast agents, scattering affects the streaming speed. The velocities of acoustic streaming in a blood-mimicking starch suspension in water and Bracco BR14 contrast agent were measured. The source of the streaming was a plane 20MHz ultrasonic transducer. Velocity was estimated from the averaged Doppler spectrum. The single particle driving force was calculated as the integral of the momentum density tensor components. For different starch concentrations, the streaming velocity increased from 8.9 to 12.5mm/s. This corresponds to a constant 14% velocity increase for a 1 g/l increase in starch concentration. For BR14, the streaming velocity remained constant at 7.2mm/s and was independent of the microbubbles concentration. The velocity was less than in reference, within 0.5mm/s measurement error. Theoretical calculations showed a 16% increase in streaming velocity for 1 g/l starch concentration rise, very similar to the experimental results. The theory has also shown the ability to reduce the streaming velocity by low-density scatterers, as was experimentally proved using the BR14 contrast agent.
    Źródło:
    Hydroacoustics; 2017, 20; 159-168
    1642-1817
    Pojawia się w:
    Hydroacoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Assessment of left ventricle phantom wall compressibility by ultrasound and computed tomography methods
    Autorzy:
    Trawiński, Z.
    Wójcik, J.
    Nowicki, A.
    Balcerzak, A.
    Olszewski, R.
    Frankowska, E.
    Zegadło, A.
    Rydzyński, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/331815.pdf
    Data publikacji:
    2014
    Wydawca:
    Polskie Towarzystwo Akustyczne
    Opis:
    The present work concerns the sonographic model of the left ventricle (LV) examined in the Computed Tomography (CT) environment and compare radial strain calculations obtained by two different techniques: the speckle tracking ultrasonography and the Multislices Computed Tomography (MSCT). The Left Ventricular (LF) phantom was fabricate from 10% solution of the poly(vinyl alcohol) (PVA). Our model of the LV was driven by the computer-controlled hydraulic piston Super-Pump (Vivitro Inc., Canada) with adjustable fluid volumes. The stroke volume was set at of 24ml. The fluid pressure was changed within range of 0-60 mmHg, and the pulse rate was of 60 cycles/per minute. The relationships between computer controlled left ventricular wall deformations and its visualizations of the echocardiographic and CT imaging, both in the normal and pathological conditions were examined. The difference of assessment the Radial Strain between two methods was not exceeding 1.1%.
    Źródło:
    Hydroacoustics; 2014, 17; 211-218
    1642-1817
    Pojawia się w:
    Hydroacoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-5 z 5

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