What is the duty factor for continuous wave (CW) ultrasound imaging?

The duty factor in ultrasound imaging refers to the proportion of time that the ultrasound system is actively transmitting sound waves compared to the total time of the pulse cycle. In continuous wave (CW) ultrasound, the system continuously emits ultrasound signals without pauses or gaps between pulse transmissions. This results in a duty factor of 100%, signifying that the ultrasound beam is on at all times during the imaging process.

This continuous emission allows for the measurement of high-velocity blood flow and provides excellent sensitivity for certain applications, particularly in Doppler ultrasound. Because the sound waves are transmitted continuously without interruption, the entire time frame is devoted to producing ultrasound energy, thus confirming that the duty factor is effectively at its maximum value. Other choices reflect different duty factors, implying either pulsed settings or inactive periods, which do not apply in the context of CW ultrasound.