Bioeffects of ultrasound and its therapeutic application #34

Ultrasound has been safely utilized in the medical field for a long time, and its application range is still growing widely nowadays. Analyses of interactions between ultrasound and aqueous solution were studied for a long time. Free radical formation, an important chemical effect of ultrasound, which causes a major impact on bioeffects was discovered more than 30 years ago. However, the bioeffects caused by ultrasound cannot be attributed only to free radical formation. They are interactions between the living body and a wide variety of very complex effects caused by ultrasound. Thus, one would have to say that mechanism underlying the ultrasound bioeffects is a long way from full clarification. However, analyzing how the living body could respond to ultrasound at a biomolecular level has become possible. Obtained results out of such analyses have advanced therapeutic ultrasound through its development, improvement, and assurance of safety. Thus, ultrasound in the medical field will be more and more dispensable from this time forward. In this chapter, first we take a look at physical and chemical effects of ultrasound, which may provide some influence to the ultrasound bioeffects. Then, we move to ultrasound bioeffects and responses of cells and living tissues to ultrasound, particularly we review them at a biomolecular level. Later on, we discuss the therapeutic applications of ultrasound, including HIFU and LIPUS, which have already been applied clinically for cancer therapy and bone fracture healing, respectively. In addition to those, we also describe the latest research findings such as ultrasound-mediated gene therapy and drug delivery systems.