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Streaming velocity mainly depends on the intensity and absorption of ultrasound in the media. For high frequencies exceeding 20 MHz the speed of streaming in blood is also affected by scattering effects on the blood cells and contrast agent microbubbles. According to theoretical calculations, 12.2 % increase in streaming velocity for 1 g/l starch concentration rise should be expected. The theory has...
A new toolbox for the simulation of acoustic wave fields is described. The toolbox, USim, is designed to make an acoustic modeling of ultrasound propagation in tissues reliable and fast. The forward simulations of the wave field are based on the Born-Neumann single scattering approximation of the solution of Sturm-Liouville equation. The toolbox allows simulating the ultrasound wave propagation in...
Assessment of medium nonlinearity parameter in pulse-echo mode usually demands information on the second harmonic. However, the acquisition of quantitative data on backscattered amplitude at the fundamental and second harmonic components is difficult using the same probe due to its limited bandwidth. In this paper we propose how to assess medium nonlinearity using only the fundamental harmonic and...
In this paper we investigate how to assess the ultrasound nonlinearity coefficient using plane wave imaging. We employ the technique based on excitation of the medium with ultrasonic pulses of increasing amplitude level. As the pulse pressure is increased, due to medium nonlinearity, higher fraction of energy is transferred from the fundamental to higher harmonics during the propagation. In this case...
Acoustic streaming is a steady flow in a fluid driven by the acoustic wave propagating in a lossy medium. Streaming depends on intensity and absorption of ultrasound in the media. In some cases, such as ultrasound scattered on the blood cells at frequencies ≥ 20 MHz or the presence of ultrasound contrast agents, scattering affects the streaming speed. Parallel to measurements, the streaming theoretical...
Optimization of ultrasound applications in medical diagnostics as well as in non-destructive testing demands accuracy in prediction of ultrasound propagation. Several attempts were used and few different simulation methods were proposed as a publicly available software toolboxes. Although the Field II, k-Wave, Creanuis belong to most popular ones, we propose new toolbox for the simulation of acoustic...
Nowadays there are new modalities in ultrasound imaging allowing better characterization of tissue regions with different stiffness. We are proposing an approach based on simultaneous propagation of two waves being a combination of two pulses differing in pressure and frequency: a low frequency pulse is expected to change the local scattering properties of the tissue due to compression/rarefaction...
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