Which transducer design uses concentric rings to achieve consistent lateral resolution across depths?

Which transducer design uses concentric rings to achieve consistent lateral resolution across depths?

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

Answer: (A)

The main idea is how the transducer’s geometry affects how tightly the ultrasound beam can be focused in the lateral direction across different depths. An annular array uses concentric circular rings as its elements, forming multiple apertures. By carefully timing the excitation of these rings, the beam can be focused electronically at various depths, producing a narrow, symmetric beam that stays relatively tight over a wider range of depths. That means the lateral resolution remains more consistent as you image deeper, compared with other designs that either have a fixed single focus or rely on steering without the same kind of concentric, depth-adaptive focusing. Other designs don’t use concentric rings and therefore don’t offer the same depth-spanning lateral sharpness. Linear arrays focus in one direction with a fixed aperture shape, phased arrays steer and focus with a rectangular aperture, and mechanical sector scanners rotate a single element—each tends to show more variation in beamwidth and lateral resolution with depth.

The main idea is how the transducer’s geometry affects how tightly the ultrasound beam can be focused in the lateral direction across different depths. An annular array uses concentric circular rings as its elements, forming multiple apertures. By carefully timing the excitation of these rings, the beam can be focused electronically at various depths, producing a narrow, symmetric beam that stays relatively tight over a wider range of depths. That means the lateral resolution remains more consistent as you image deeper, compared with other designs that either have a fixed single focus or rely on steering without the same kind of concentric, depth-adaptive focusing.

Other designs don’t use concentric rings and therefore don’t offer the same depth-spanning lateral sharpness. Linear arrays focus in one direction with a fixed aperture shape, phased arrays steer and focus with a rectangular aperture, and mechanical sector scanners rotate a single element—each tends to show more variation in beamwidth and lateral resolution with depth.