Which transducer arrangement yields a rectangular image with high near-field resolution?

• A. Curved array
• B. Phased array
• C. Mechanical sector
• D. Linear array

Answer: (D)

The arrangement of ultrasound elements directly shapes both the image field and how sharply structures near the transducer can be resolved. A linear array places many small rectangular elements in a straight line, and electronic focusing and sequential firing across that straight aperture produce a set of parallel scan lines across the width. The result is a rectangular field of view, with the beam kept narrow across the near field because the aperture is straight and densely sampled in that plane. This yields high near-field resolution, since the lateral beamwidth is small close to the transducer.

Curved and mechanical sector designs, in contrast, generate beams that fan out into wedge or sector-shaped fields, so their images are not rectangular and the near-field resolution isn’t as uniformly high. Phased arrays can steer and shape beams as well, but the classic configuration that gives a rectangular image with strong near-field detail is the linear array.