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9 May 2005 Sizing of microbubbles in blood stream based on ultrasound velocity
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Microbubbles, are produced inside the human body by several mechanisms which may cause many serious health problems or even death. The ability of a gas bubble to scatter ultrasound waves has led to the testing of various ultrasonic devices to monitor microbubble formation in the blood stream. These have included pulsed echo, acoustic-optical imaging, Doppler technique and the through-transmission technique. In this work, a pulse through transmission method for measuring ultrasound velocity in bubbly gel phantoms was used. The bubble size has been assessed by measurement of the pulse-wave velocity. A specially designed pressure chamber ensured the measured velocity was directly related to the volume of microbubble by Boyle's law. This velocity is an average indicator of the bubble size between transmitting and receiving transducers. The average bubble radius was 0.1 mm. For best results the measurement were carried out around 1-3 MHz frequency range. It is shown that a large change in velocity of ultrasound occurs as a result of small changes in the volume of microbubble. When the fraction by volume of gas in gel is changed from 0.6 percent to 0.8 percent the velocity changed from 1500 to 500 m/s respectively. This large change in velocity should provide a good base for detecting and more importantly, sizing microbubbles in the blood stream. The measured results were compared with theoretical prediction with good agreement between theory and experiment. This technique can be used as a simple real time method to monitor and measure the volume of the microbubles in the blood stream. This technique has many application in medical field such as; open heart surgery, blood dialysis and deep sea diving (decompression sickness).
© (2005) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Behrooz Kanani "Sizing of microbubbles in blood stream based on ultrasound velocity", Proc. SPIE 5768, Health Monitoring and Smart Nondestructive Evaluation of Structural and Biological Systems IV, (9 May 2005); doi: 10.1117/12.598154;

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