The range equation relates round-trip pulse travel time to distance to the reflector.

The range equation relates round-trip pulse travel time to distance to the reflector.

• A. Distance to the reflector
• B. Speed of sound in tissue
• C. Reflector size
• D. Attenuation coefficient

Answer: (A)

The range equation is used to turn how long the ultrasound pulse takes to go to a reflector and back into how far away that reflector is. Because the pulse travels there and back, the one-way travel time is half of the round-trip time. If you know the speed of sound in tissue (about 1540 m/s in soft tissue), you can calculate distance with d = (c × t)/2. So this equation directly yields the distance to the reflector, not its size or how much the signal attenuates. The speed of sound is needed as a constant in the calculation, but the result it gives is the distance.

The range equation is used to turn how long the ultrasound pulse takes to go to a reflector and back into how far away that reflector is. Because the pulse travels there and back, the one-way travel time is half of the round-trip time. If you know the speed of sound in tissue (about 1540 m/s in soft tissue), you can calculate distance with d = (c × t)/2. So this equation directly yields the distance to the reflector, not its size or how much the signal attenuates. The speed of sound is needed as a constant in the calculation, but the result it gives is the distance.