What is greatest during a pulse?

• A. Temporal Peak
• B. Temporal Average
• C. Spatial Peak
• D. Spatial Average

Answer: (A)

When considering how ultrasound intensity behaves during a pulse, the key idea is that the waveform reaches a maximum amplitude at the crest of the pulse. Intensity is proportional to the square of the pressure, so that peak pressure translates to the highest instantaneous intensity. The temporal peak measures exactly that highest instantaneous value during the pulse. The temporal average, by contrast, is the mean intensity over the entire pulse duration, so it will be lower because it includes times when the waveform is not at its crest. The spatial metrics describe energy distribution across the beam at a given moment (spatial peak) or averaged across space (spatial average); they are not capturing the single highest moment of the pulse over time. Hence, the greatest value observed during the pulse is the temporal peak intensity.