When creating anatomic images, duty factors are in the range of _____, indicating that ultrasound systems spend a very small percentage of time transmitting and a very large percentage of time receiving.

When creating anatomic images, duty factors are in the range of _____, indicating that ultrasound systems spend a very small percentage of time transmitting and a very large percentage of time receiving.

• A. 0.2% - 0.5%
• B. 2% - 5%
• C. 20% - 50%
• D. 50% - 75%

Answer: (A)

Duty factor is the fraction of time the transducer spends transmitting during each ultrasound cycle. In diagnostic imaging, the transmit pulse is very short, while the system spends most of the time waiting for echoes from tissues. That makes the duty factor a very small percentage. A typical value falls around 0.2% to 0.5%, which reflects a brief transmit period (a few microseconds) followed by a much longer listening period (milliseconds) as echoes return. For example, with a transmit pulse about 2 microseconds long and a pulse repetition period of about 1 millisecond, the duty factor is 2 μs / 1 ms = 0.2%, which sits in this range. If the duty factor were much higher, more time would be spent transmitting, reducing the time available to receive echoes and increasing potential tissue heating; that isn’t how standard anatomic imaging operates.

Duty factor is the fraction of time the transducer spends transmitting during each ultrasound cycle. In diagnostic imaging, the transmit pulse is very short, while the system spends most of the time waiting for echoes from tissues. That makes the duty factor a very small percentage. A typical value falls around 0.2% to 0.5%, which reflects a brief transmit period (a few microseconds) followed by a much longer listening period (milliseconds) as echoes return. For example, with a transmit pulse about 2 microseconds long and a pulse repetition period of about 1 millisecond, the duty factor is 2 μs / 1 ms = 0.2%, which sits in this range. If the duty factor were much higher, more time would be spent transmitting, reducing the time available to receive echoes and increasing potential tissue heating; that isn’t how standard anatomic imaging operates.