Duty factor is _____ related to imaging depth.

Duty factor is _____ related to imaging depth.

• A. Directly
• B. Inversely
• C. Not at all
• D. Proportional to frequency

Answer: (B)

Duty factor tells you how much of the time the transducer is actively emitting during a cycle. It depends on how long each pulse lasts and how often pulses are sent (the pulse repetition frequency). When you image deeper, echoes take longer to return, so you must wait longer between pulses. That stretches the time between pulses, lowering the pulse repetition frequency. Since duty factor rises with higher PRF, but PRF drops with depth, the overall duty factor decreases as imaging depth increases. In other words, deeper imaging reduces the duty factor, making them inversely related.

Duty factor tells you how much of the time the transducer is actively emitting during a cycle. It depends on how long each pulse lasts and how often pulses are sent (the pulse repetition frequency). When you image deeper, echoes take longer to return, so you must wait longer between pulses. That stretches the time between pulses, lowering the pulse repetition frequency. Since duty factor rises with higher PRF, but PRF drops with depth, the overall duty factor decreases as imaging depth increases. In other words, deeper imaging reduces the duty factor, making them inversely related.