Which acronym denotes Spatial Peak, Pulse Average?

• A. Sppa
• B. Spta
• C. Sapa
• D. Sptp

Answer: (A)

The concept here is how ultrasound exposure intensities are labeled by two ideas: where the intensity is measured in space, and how that intensity is averaged over time. The acronym that matches a peak intensity in space (the highest value at any point in the beam) and that is averaged over the duration of a single pulse is SPPA—Spatial Peak, Pulse Average. This means you take the maximum spatial point of the beam and average its intensity over one pulse length, not over the whole exposure time. That’s distinct from SPTA (Spatial Peak, Temporal Average), which averages over the entire exposure time, or SAPA (Spatial Average, Pulse Average), which would use a spatial average instead of a peak. So SPPA is the correct designation for Spatial Peak, Pulse Average.