If imaging depth is reduced to shallow depth, the time between pulses will be

If imaging depth is reduced to shallow depth, the time between pulses will be

• A. Remain the same
• B. Fluctuate
• C. Decrease
• D. Increase

Answer: (C)

In pulsed imaging, the time between pulses is set by how long echoes from the farthest depth take to return. The system must wait for a full round-trip echo before sending the next pulse. If imaging depth is reduced to a shallower level, those farthest echoes return sooner, so the waiting time shortens. Therefore, the time between pulses decreases. This also means the pulse repetition frequency is higher at shallower depths, enabling faster imaging. For intuition, the interval is roughly 2 × depth divided by the speed of sound in the medium; halving the depth roughly halves the interval.

In pulsed imaging, the time between pulses is set by how long echoes from the farthest depth take to return. The system must wait for a full round-trip echo before sending the next pulse. If imaging depth is reduced to a shallower level, those farthest echoes return sooner, so the waiting time shortens. Therefore, the time between pulses decreases. This also means the pulse repetition frequency is higher at shallower depths, enabling faster imaging. For intuition, the interval is roughly 2 × depth divided by the speed of sound in the medium; halving the depth roughly halves the interval.