Which intensity is defined as the spatial average intensity?

Which intensity is defined as the spatial average intensity?

• A. Isa
• B. Isp
• C. Ita
• D. Ipa

Answer: (A)

Spatial average intensity describes the energy per unit area averaged across the ultrasound beam’s cross-section. It takes the intensity distribution over the beam footprint and averages it by integrating I(x,y) over the beam area and dividing by that area. This is different from the spatial peak intensity, which is simply the highest value anywhere in the beam, and from the temporal average intensity, which averages I over time (including how the beam is pulsed). Pulse average intensity is the average during the actual pulse duration. Since the question asks for the descriptor defined as the spatial average, the term that fits is Isa.

Spatial average intensity describes the energy per unit area averaged across the ultrasound beam’s cross-section. It takes the intensity distribution over the beam footprint and averages it by integrating I(x,y) over the beam area and dividing by that area. This is different from the spatial peak intensity, which is simply the highest value anywhere in the beam, and from the temporal average intensity, which averages I over time (including how the beam is pulsed). Pulse average intensity is the average during the actual pulse duration. Since the question asks for the descriptor defined as the spatial average, the term that fits is Isa.