Research On The Characteristics Of Focused Acoustic Field In Water Containing Microbubbles

with the development of ultrasonic medical technology,Ultrasound Contrast Agents(UCAs)have been widely used.The combination of focused ultrasound and microbubbles produces nonlinear vibration and cavitation effects that can be used to treat major diseases.In this paper,by studying the interaction between focused ultrasound and microbubbles to complete the correction of scattering attenuation and nonlinear parameters caused by microbubbles in water containing UCA,and analyze the mechanism of action between focused ultrasound and cavitation bubble in water,and establish the propagation model of the focused acoustic wave in water containing microbubble.For the purpose and significance of this research,the main contents are as follows:(1)The theoretical basis of acoustics is introduced.First,the transition from simple linear acoustic theory to nonlinear acoustics focuses on the KZK equation and its two solutions in the nonlinear acoustic field(time domain solution and frequency domain solution).Then,the development history of the microbubbles is introduced and the mechanism of the UCA used in the experiment is given.Finally,the interaction model between the focused ultrasound and microbubbles is established.(2)The characteristics of acoustic field in water containing microbubbles are studied.First,the analytical expression of the bubble group attenuation coefficient is derived from the single bubble scattering attenuation model.Then,the B/A and C/A calculation expressions in the plane acoustic field and the focused acoustic field are corrected.Finally,according to the interaction model between the bubble and the acoustic field,the motion state of the bubble is simulated.(3)The variation of the attenuation coefficient with time and frequency in water containing UCA is measured,and compares it with the theoretical model.Then,the B/A and C/A in water and in water containing UCA are measured by using the plane piston transducer and the focusing transducer together with the film hydrophone,and the results of two measurements are compared.(4)The focus field of the acoustic field by the focus transducer and the probe hydrophone.On the basis of this,the influence of the bubble on the acoustic field distribution before and after cavitation in water at different frequencies is measured.Finally,the influence of high and low frequency ultrasound combination and single frequency ultrasound on bubble cavitation degree are discussed and the results are analyzed.The research of this subject is of great significance to promote the safe and effective application of UCA in the field of ultrasound medicine.