In ultrasound terminology, the round-trip travel time refers to the time for the sound pulse to travel to a target and back. Which statement best describes this concept?

• A. Time for two-way path
• B. Time for one-way path
• C. Time not used
• D. Time for three-way path

Answer: (A)

Round-trip travel time is the total time for the ultrasound pulse to travel from the transducer to a target and back to the transducer. This reflects the two-way path: the outward journey to the reflector and the return journey as the echo. In imaging, depth is inferred from this round-trip time because the sound must cover both directions, so depth is proportional to the round-trip time (depth ≈ speed of sound × round-trip time / 2). The other descriptions don’t match how ultrasound timing works: one-way time omits the return trip, time not used ignores the essential measurement, and three-way travel isn’t part of standard ultrasound propagation.