What is the actual time that an ultrasound machine is creating a pulse?

• A. Duty factor
• B. Period
• C. Pulse period
• D. Pulse duration

Answer: (D)

The actual time the machine is creating a pulse is the pulse duration—the length of the transmitted burst. During this brief interval the transducer is actively emitting sound. After the pulse ends, the system switches to listening for echoes.

The other terms describe different timing aspects. A single cycle period is how long one cycle of the wave lasts, determined by the frequency. The pulse period (or PRP) is the total time from the start of one pulse to the start of the next pulse, including the listening time between bursts. Duty factor is the fraction of time spent transmitting within each PRP, essentially pulse duration divided by PRP.

For example, if the transducer operates at 3 MHz and the burst contains 5 cycles, the pulse duration is about 1.67 microseconds. If the PRP is 100 microseconds, the duty factor is roughly 1.7%.