How is duty factor calculated?

The duty factor is a measure that expresses the fraction of time the ultrasound system is actively transmitting sound compared to the total time the system is in a pulse repetition period (PRP). It is calculated by taking the pulse duration (the time the ultrasound transmits a single pulse) and dividing it by the pulse repetition period (the total time from the start of one pulse to the start of the next pulse), then multiplying by 100 to express it as a percentage.

This calculation reflects the proportion of the cycle in which the ultrasound is generating a signal versus the period when the system is idle or waiting for the next pulse. A higher duty factor indicates more time spent transmitting sound, which can have implications for imaging quality and thermal effects in tissues.

The other formulas provided do not accurately represent the relationship required for calculating duty factor. For instance, using PRF (pulse repetition frequency) in the denominator does not correctly relate to the definition of duty factor as it does not take into account the correct timing dynamics involved in ultrasound pulsing. The correct relationship emphasizes the timing of the individual pulse compared to the complete cycle of sending and receiving pulses.