What defines dynamic focusing in ultrasound transducers?

• A. It uses a fixed focal point.
• B. Dynamic focusing uses depth-dependent delays to adjust focus during transmission and reception, providing optimal beam width at multiple depths.
• C. It eliminates the need for focusing altogether.
• D. It relies on mechanical steering of the entire array.

Answer: (B)

Dynamic focusing means applying depth-dependent delays across the transducer elements so the emitted wavefront converges at a chosen depth, and the same idea is used on receive to refocus echoes as they arrive. This electronic timing lets the beam stay narrow and well focused over a range of depths, giving good lateral resolution at multiple depths rather than just at one fixed plane. It relies on adjusting delays with depth, which is how phased or dynamic receive focusing works. It’s not about a single fixed focal point or eliminating focusing, and it’s separate from mechanical steering of the array.