Which term describes the likelihood of cavitation occurring?

• A. Mechanical Index
• B. Spatial Peak
• C. Pulse Average
• D. Temporal Average

Answer: (A)

The main idea being tested is how cavitation risk is quantified in diagnostic ultrasound. The term that describes the likelihood of cavitation is the Mechanical Index. It combines the peak negative (rarefaction) pressure with the square root of the center frequency, so higher pressure and lower frequency raise the index and indicate a greater chance of bubble formation and growth under the ultrasound beam. This is why MI is used to gauge cavitation potential and keep exposure within safe limits.

The other terms describe different aspects of the beam’s output but not cavitation likelihood. Spatial peak refers to the location where intensity is highest in space, not the tendency for bubbles to form. Temporal average and pulse average relate to how much energy is delivered over time or per pulse, rather than the specific propensity for cavitation to occur.