The number of electric pulses delivered to the active element per second is called what?

• A. Wavelength
• B. Pulse Repetition Frequency
• C. Amplitude
• D. Frequency

Answer: (C)

The number of electric pulses delivered to the active element per second is described by the Pulse Repetition Frequency. PRF tells you how many pulses the transducer emits each second. In pulsed ultrasound, you send a pulse, listen for echoes, then send another pulse; increasing the PRF means more pulses per second, but you must still allow enough listening time to receive echoes from the deepest region you image, which ties PRF to imaging depth and frame rate. Wavelength is the spatial distance between successive peaks of a single wave and depends on speed of sound and frequency. Amplitude is the height of the pulse, indicating its strength. Frequency is the number of cycles per second of a continuous wave, not the rate of pulses in a pulsed system.