When pulsed and continuous wave beams have the same Spatial Peak Temporal Peak (SPTP) intensities, what intensity is higher for Continuous Wave?

When pulsed and continuous wave beams have the same Spatial Peak Temporal Peak (SPTP) intensities, the Continuous Wave beam will have a higher Spatial Peak Average Intensity (SPTA). This is due to the nature of continuous wave ultrasound, which emits a consistent energy output over time, as opposed to pulsed ultrasound, which transmits energy in short bursts followed by periods of inactivity.

In continuous wave ultrasound, the spatial peak average intensity integrates the power output over time while maintaining a constant energy delivery. This means that the average intensity, when calculated over the time of the emission, will reflect a higher value because the energy is continuously supplied.

In contrast, pulsed wave ultrasound includes periods where no energy is transmitted, thus lowering the average intensity over time when compared to a continuous wave. The average intensity for pulsed beams (SPTA) reflects the pulsed nature of the transmission, which inherently reduces its average intensity relative to a continuous wave beam with the same peak intensity values.

For the other choices, the Temporal Peak Intensity is a measure of the intensity at the peak of the pulse and does not factor in the average energy output over time relative to continuous wave. Pulsed Average Intensity considers the duty cycle and is typically lower for a