What is the duty factor in ultrasound?

What is the duty factor in ultrasound?

• A. The percentage of time the system transmits sound
• B. The energy of the wave
• C. The distance traveled per cycle
• D. The frequency

Answer: (A)

The duty factor is the fraction of time the ultrasound system is actively transmitting during each pulse sequence. It’s defined as the transmit (on) time divided by the total time of the pulse repetition period, usually expressed as a percentage. For example, if the transducer emits for a very short interval within a longer cycle, the duty factor will be a small percentage. This matters because a higher duty factor means more energy is delivered over time, increasing the average intensity and potential tissue heating. The energy of the wave is not the same concept—it depends on amplitude and duration but is not simply the on/off fraction. The distance traveled per cycle is related to wavelength and speed of sound, not to how long the system is transmitting in a cycle. Frequency is how many cycles occur per second, again separate from the on/off timing within a cycle.

The duty factor is the fraction of time the ultrasound system is actively transmitting during each pulse sequence. It’s defined as the transmit (on) time divided by the total time of the pulse repetition period, usually expressed as a percentage. For example, if the transducer emits for a very short interval within a longer cycle, the duty factor will be a small percentage.

This matters because a higher duty factor means more energy is delivered over time, increasing the average intensity and potential tissue heating. The energy of the wave is not the same concept—it depends on amplitude and duration but is not simply the on/off fraction. The distance traveled per cycle is related to wavelength and speed of sound, not to how long the system is transmitting in a cycle. Frequency is how many cycles occur per second, again separate from the on/off timing within a cycle.