With linear sequential array transducers the sound pulses originate from __________ when different sets of crystals are excited.

• A. The light source
• B. The transducer casing
• C. Different locations along the face of the probe
• D. The patient

Answer: (C)

With linear sequential array transducers, the transmit beam comes from different spots along the probe’s face because energy is sent from different, contiguous groups of crystals in sequence. Each fired group creates a pulse from a new location on the face, so the origin of the ultrasound wave shifts along the transducer as the sequence progresses. This is because the piezoelectric crystals, not any light source, casing, or the patient, generate the sound when electrically driven. The patient is the source of the echoes, but the initial pulses originate from the active crystal locations on the probe.