S.P. Skvortsov – Ph.D. (Eng.), Associate Professor, Department of Biomedical Technical Systems, Bauman Moscow State Technical University

P.D. Yurkevich –  bachelor, Department of Biomedical Technical Systems, Bauman Moscow State Technical University

D.A. Solov’ev – Head of Laboratory, Department of Medical and Technical Management,  Bauman Moscow State Technical University

Low-frequency ultrasound techniques for biological tissues treatment in surgery and therapy are based on the combined action of drugs and energy of low-frequency ultrasonic vibrations on biological tissues. The main phenomenon that determines the effectiveness of the combined action of ultrasound and the drugs is cavitation. One of the ways to improve the efficiency of ultrasonic treatment methods is the introduction of a feedback system based on the determination of the parameters of the cavitation region in the process of exposure. Most methods of cavitation parameters control are difficult to implement in the medical application of ultrasound, so it is necessary to develop methods to determine the parameters of cavitation bubbles pulsations in real time and use them to maintain the maximum cavitation efficiency.

To study the possibility of using the method of optical probing of the cavitation region to maintain the maximum efficiency of cavitation.

Numerical simulation of the light transmission coefficient of the cavitation region based on the Tverskoy approximation of the theory of multiple scattering is performed. The calculations used a typical width of the directional diagram of the photodetector (10 degrees). The spectrum of the photodetector signal contains the fundamental frequency determined by the lifetime of the bubbles, which, in turn, determines the amplitude of the shock wave and the severity of the cavitation effects.

Experimental studies were carried out to find the maximum efficiency of cavitation depending on the amplitude of the ultrasonic instrument. The efficiency of cavitation was evaluated by erosion of aluminum foil. The obtained data were compared with the calculated dependences of the optical signal subharmonics on the amplitude of the ultrasonic instrument.

As a result of the study determined the criterion for finding the amplitude of a tool by means of recording and real-time analysis of scattered light signal that allows to implement automatic adjustment of the vibration amplitude of the instrument for maximum cavitation intensity and, consequently, to maximize the effectiveness of its medical use in the given conditions. The obtained criterion can be used in ultrasound devices for surgery and therapy.

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