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Development of high intensity focused ultrasound transducers to deliver specified shock wave amplitudes at the focusстатья
Дата последнего поиска статьи во внешних источниках: 28 мая 2015 г.
- Авторы: Khokhlova V.A., Yuldashev P.V., Rosnitskiy P.B., Maxwell A.D., Kreider W., Sapozhnikov O.A.
- Журнал: Journal of the Acoustical Society of America
- Том: 135
- Номер: 4 (Pt 2)
- Год издания: 2014
- Издательство: Acoustical Society of America
- Местоположение издательства: United States
- Первая страница: 2312
- Последняя страница: 2313
- DOI: 10.1121/1.4877623
- Аннотация: High intensity focused ultrasound (HIFU) is currently emerging into many clinical applications. Certain applications, for example, histotripsy, rely of formation of high amplitude shocks in the focal waveform of the beam. These shocks, which are caused by nonlinear propagation effects, develop at different focal pressure levels depending on the frequency and geometry of the HIFU transducer. Certain values of the peak negative pressure, which is also a critical parameter for HIFU therapies, correspond to the shock-forming condition. The goal of this work was to determine parameters of the transducers that would result in certain shock amplitudes and corresponding peak negative pressures at the focus, optimal for a specific therapeutic application. The hypothesis was that pressure level for shocks to form is mainly determined by an F-number of the transducer. Transducers of shorter focusing distance (lower F-number) generate fields with shorter focal lobe as compared to those with longer focusing distance (higher F-number). Most of HIFU transducers are highly focused thus nonlinear effects accumulate mostly in the main diffraction lobe, where acoustic pressure is the highest. Formation of shocks within a short length of the focal lobe requires high acoustic pressures leading to high values of the shock amplitudes. Simulations based on the Khokhlov-Zapolotskaya-Kuznetsov equation were carried out to test the hypothesis. Detailed analysis of the numerical results is presented to demonstrate the effect of different parameters of the transducer on the resulting shock amplitudes and peak negative pressures at the focus. It is shown that for typical HIFU transducers of 1 – 3 MHz frequencies, the geometry of F-number close to one is the optimal one to generate 60 MPa shocks. Higher amplitude shocks will be formed for lower F-number transducers.
- Добавил в систему: Хохлова Вера Александровна