Scattering of a distribution of encapsulated gas bubbles, a computer model

The interest in using suspensions of polymeric encapsulated microbubbles as contrast agents in medical ultrasound imaging has increased during the last few years. Most of the knowledge on the non-linear mechanical and acoustical behaviour of encapsulated microbubbles is the result of empirical measurements, while the theoretical study of these phenomena, in particular the echo of a bubble distribution, is still an open research area. This paper presents a computer simulation program that calculates the global echo of a bubble distribution according to a modified Rayleigh-Plesset model for each bubble and by summing the contribution of each bubble to highlight the higher harmonics. Thanks to this approach, the study of the effects of the parameters of both the bubble and transmitted acoustic impulse on the higher harmonics contained in the echo is simplified. The results of this study are fundamental to the design of the microbubble or the echographic system.