Changing the depth of view of a scan also changes the duty factor.

Changing the depth of view of a scan also changes the duty factor.

• A. Depth of view
• B. Frame rate
• C. Number of transducers
• D. Frequency

Answer: (A)

Duty factor is the fraction of time the system spends transmitting during one ultrasound cycle. The key thing that changes this fraction is how long you have to wait for echoes to return from the farthest depth you’re imaging—the listening time. When you increase the depth of view, the round‑trip travel time for echoes lengthens, so the listening portion of the cycle gets longer while the transmit duration stays roughly the same. That makes the total cycle longer and the transmit time becomes a smaller share of it, reducing the duty factor. Conversely, imaging a shallower depth shortens the listening time and raises the duty factor. So the depth of view directly controls how much of each cycle is spent transmitting. Frame rate will change with depth as a consequence of the longer cycle time, but the factor that directly dictates the duty factor itself is the imaging depth. The number of transducers and the frequency don’t determine this transmit/listen ratio in the same direct way.

Duty factor is the fraction of time the system spends transmitting during one ultrasound cycle. The key thing that changes this fraction is how long you have to wait for echoes to return from the farthest depth you’re imaging—the listening time. When you increase the depth of view, the round‑trip travel time for echoes lengthens, so the listening portion of the cycle gets longer while the transmit duration stays roughly the same. That makes the total cycle longer and the transmit time becomes a smaller share of it, reducing the duty factor. Conversely, imaging a shallower depth shortens the listening time and raises the duty factor. So the depth of view directly controls how much of each cycle is spent transmitting.

Frame rate will change with depth as a consequence of the longer cycle time, but the factor that directly dictates the duty factor itself is the imaging depth. The number of transducers and the frequency don’t determine this transmit/listen ratio in the same direct way.