Which transducer type was most likely used to acquire a sector display that narrows to a point at the transducer surface?

• A. Linear array
• B. Curved array
• C. Annular array
• D. Phased array

Answer: (D)

The essential idea is that a sector-shaped display results when scan lines emanate from a single origin at the transducer face. A phased array achieves this by applying precise time delays across many tiny elements to steer beams electronically into multiple angles while all beams originate from the same point on the probe. This creates a fan-shaped image with the apex at the transducer surface.

Other transducer types don’t produce that same apex-focused sector as cleanly. A linear array creates parallel scan lines for a rectangular image. A curved array produces sector-like geometry due to its curved footprint, but the apex and beam steering aren’t defined in the same way. An annular array uses concentric rings to focus and can generate different shapes, but the distinct, clean sector with a point at the surface is characteristic of phased array beam steering.