Utveckling av en Ultraljudssekvens for att Undersoka Utpumpnings-beteende och Akustik-droppforangning

Ultrasound assisted drug delivery using polyvinyl alcohol (PVA) shelled microbubbles and perfluorocarbon PFC droplets shows potential in theranostics, particularly with ultrasound induced pumping out behavior and acoustic droplet vaporization (ADV). This thesis aims to investigate the pumping out behavior and ADV by developing an ultrasound sequence using the Verasonics Research System in Matlab. This was used for collecting images during experiments with PVA microbubbles and PFC droplets. The collected image’s mean pixel intensity (MPI) was investigated against time. Results confirmed the presence of the pumping out behavior in PVA microbubbles, characterized by a gradually rising and declining signal due to gas release through shell deformation under acoustic pressure. This could be confirmed using ultrafast ultrasound of both simple plane wave imaging and plane wave compounding. A comparison of the pumping out behavior was performed using data collected at different burst pulse repetition frequencies (PRF), frames per second (FPS), and the presence or absence of ultrasound compounding. The results indicated that the pumping out behavior is energy dependent and that it is possible to induce under the influence of a variety of PRFs. Using the same sequence, the ADV of PFC droplets was validated, showing rapid phase transitions to gas confirmed by a rapidly increased signal due to scattering. It was also observed that ADV can take the form of local gas clusters. In conclusion, this method was shown to be successful, but not at an optimal repeatability. Further improvements would thereby be necessary for a robust and more reproducible outcome.