Answer #40

The correct answer is Choice E: None of the above. This is because all of the above parameters apply to PW Doppler. As shown below in the figure [insert Advanced wave parameters], Pulse Duration (Choice A) is the time for the whole pulse (number of cycles x the period, or time for each cycle). Spatial Pulse Length (Choice B) is the distance of the pulse (number of cycles x the wavelength, or distance for each cycle. Pulse Repetition Period (Choice D) is the time between pulses. Duty Factor is the amount of time the transducer spends sending a pulse and can be calculated by the Pulse Duration over the Pulse Repetition Period. This is typically a very low number for PW Doppler whereas for CW Doppler it is 1 by definition since the transducer is constantly sending out ultrasound waves.