Which technology enables adjustable focusing in ultrasound transducers?

Which technology enables adjustable focusing in ultrasound transducers?

• A. Fixed focus
• B. Mechanical lens
• C. Digital lens
• D. Phased array

Answer: (B)

Adjustable focusing comes from beamforming across multiple elements with precise timing, so the waves constructively interfere at a chosen point. In a phased array, each element can be given a specific transmission and reception delay. By tweaking these delays, the ultrasound beam focuses at different depths and can also be steered, all without moving the probe. This real-time electronic control is what makes phased array transducers capable of dynamic focusing during imaging. A mechanical lens, by contrast, changes the wavefront with a physical curved surface or a fixed lens shape, producing a predetermined focal point. It can’t be adjusted on the fly to different depths, so it’s not suitable for dynamic focusing during a scan. Digital beamforming plays a role in processing the received signals to form and refine the image, but the core capability to adjust focus in real time comes from the phased array’s programmable delays.

Adjustable focusing comes from beamforming across multiple elements with precise timing, so the waves constructively interfere at a chosen point. In a phased array, each element can be given a specific transmission and reception delay. By tweaking these delays, the ultrasound beam focuses at different depths and can also be steered, all without moving the probe. This real-time electronic control is what makes phased array transducers capable of dynamic focusing during imaging.

A mechanical lens, by contrast, changes the wavefront with a physical curved surface or a fixed lens shape, producing a predetermined focal point. It can’t be adjusted on the fly to different depths, so it’s not suitable for dynamic focusing during a scan.

Digital beamforming plays a role in processing the received signals to form and refine the image, but the core capability to adjust focus in real time comes from the phased array’s programmable delays.