“Modeling” approaches in studying biological effects of ultrasound

Here the term “modeling” is used broadly as any procedure for investigating a complex or difficult topic by treating a simpler or more convenient one. The “difficult topic” addressed here is that of biological changes produced (intentionally or not) in medical applications of ultrasound. In biological modeling, the laboratory animal is usually regarded as a good choice for simulating human tissues. Also, plants, insects, single cells, and cellular or molecular suspensions have proved valuable for special purposes. Physical aspects of the topic can be modeled by applying acoustical theory to simplified or idealized situations. Second‐order approximations to the basic nonlinear equations have been fruitful. Especially useful is theory for time‐averaged quantities such as heat generation, radiation pressure, radiation torque, and acoustic streaming. Experimental evidence for the significance of these quantities comes mainly from “model” experiments in which special conditions are used. Examples will be discu...