Sapozhnikov and Dr. Michael Bailey of APL are currently investigating what factors influence the dissolution rate of lithotripter-induced bubbles. Experiments have included using a high-speed camera to film the bubble cloud produced in water by a lithotripter, and Sapozhnikov has developed a new numerical model for predicting the growth and collapse of the cloud. Acoustic Surgery Acoustic surgery also utilizes a focused field of ultrasound, but the field is applied for a longer time than in lithotripsy. This has the effect of heating, and actually cauterizing, the spot of tissue where the sound is focused. This spot can be deep inside the body, raising the possibility of noninvasive surgery.
Applications range from destroying tumors to stopping internal bleeding.
The APL-MSU research centers on controlling the deposition of the heat. Although the APL-MSU research team is obtaining promising experimental results, numerical modeling necessarily leads the way. Khokhlova is an expert in modeling sound fields. Together with Dr. Pierre Mourad and graduate student Francesco Curra of APL, she has constructed a model of the heating generated by an intense, axisymmetric, focused field of ultrasound. The model is complex because in an intense focused field the sound waves develop many frequency components.