A Model of Ultrasound Contrast Agent for Blood Flow Investigation at Higher Harmonics
Primary radiation force subjects contrast agent particles to movement which can yield wrong Doppler shift. A known model of this movement is extended to include bubble oscillations. This allows to predict full spectrum of the returned signal, hence the model is useful for second–harmonic imaging. Analytical method to calculate steady–state velocity from parameters like bubble diameter, ultrasound pressure and frequency is provided; some simulation peculiarities are explained. Trajectory and response of a single bubble for two different Doppler angles were simulated using Matlab. A resonant bubble carried by 10 cm/s water flow exhibits almost no Doppler shift if irradiated forward flow by 46 kPa CW ultrasound. A drawback of the model – very long simulation time. Il. 4, bibl. 4 (in English; summaries in English, Russian and Lithuanian).
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