Pulsed ultrasound uses higher instantaneous intensity due to what reason?

Pulsed ultrasound uses higher instantaneous intensity due to what reason?

• A. Higher because it's not the whole time
• B. Lower because it's not continuous
• C. No change in intensity
• D. Less energy per cycle

Answer: (A)

Pulsed ultrasound delivers energy in short bursts rather than continuously. The peak or instantaneous intensity is the power during the on-time of each pulse, so when the device is on, the energy is concentrated into a brief interval. Because energy is not being delivered all the time, the power in that on-time is higher, even though the overall energy delivered over time can be kept low by the off-times. This is why pulsed ultrasound can have a higher instantaneous intensity while still not overheating tissue—the off periods allow cooling, reducing the average intensity.

Pulsed ultrasound delivers energy in short bursts rather than continuously. The peak or instantaneous intensity is the power during the on-time of each pulse, so when the device is on, the energy is concentrated into a brief interval. Because energy is not being delivered all the time, the power in that on-time is higher, even though the overall energy delivered over time can be kept low by the off-times. This is why pulsed ultrasound can have a higher instantaneous intensity while still not overheating tissue—the off periods allow cooling, reducing the average intensity.