Which factor determines the proportion of time the ultrasound beam is on?

Which factor determines the proportion of time the ultrasound beam is on?

• A. Duty factor
• B. SP/SA Factor
• C. SPTA
• D. SATA

Answer: (A)

Duty factor is the proportion of time the ultrasound beam is on during each cycle. It’s defined as the pulse duration divided by the pulse repetition period. This fraction directly tells you how long the beam remains active in every cycle; increasing it means the beam is on longer, raising the average exposure and potential heating. The other terms describe different intensity concepts—SPTA and SATA relate to time-averaged energy delivery, not the on-time fraction, and SP/SA Factor isn’t the measure used to express how long the beam stays active.

Duty factor is the proportion of time the ultrasound beam is on during each cycle. It’s defined as the pulse duration divided by the pulse repetition period. This fraction directly tells you how long the beam remains active in every cycle; increasing it means the beam is on longer, raising the average exposure and potential heating. The other terms describe different intensity concepts—SPTA and SATA relate to time-averaged energy delivery, not the on-time fraction, and SP/SA Factor isn’t the measure used to express how long the beam stays active.