Which term represents the strength of the ultrasound beam?

The strength of the ultrasound beam is best represented by intensity. Intensity refers to the amount of energy carried by the ultrasound wave per unit area and is generally defined as power per unit area. It is measured in watts per square centimeter (W/cm²) and reflects how much energy is delivered to the tissue being examined.

On the other hand, amplitude relates to the maximum displacement of particles in the wave; it can give insights into the loudness or strength of the wave, but it does not directly measure the energy transmitted. Power indicates the total energy emitted by the ultrasound source but does not account for how that energy is distributed over an area. Frequency refers to the number of cycles of the wave that occur in a second and influences resolution and imaging depth, but it does not pertain to the strength of the beam. Focusing specifically on how ultrasound interacts with tissues and its effectiveness in clinical applications, intensity is the most relevant measure of the beam's strength.