If the transducer diameter increases, the lateral resolution at its smallest dimension is:

If the transducer diameter increases, the lateral resolution at its smallest dimension is:

• A. Increased
• B. Decreased
• C. Unchanged
• D. Not specified

Answer: (A)

Lateral resolution depends on how wide the ultrasound beam is across the image slice. The beam spreads due to diffraction, and this spreading is tied to the transducer’s aperture size. A larger diameter makes the central beam lobe narrower, so the distance required to distinguish two side‑by‑side reflectors decreases. With a fixed frequency (and hence a fixed wavelength), the lateral beamwidth is roughly proportional to wavelength divided by the aperture diameter. Therefore, increasing the diameter reduces the beamwidth and improves lateral resolution, meaning you can resolve smaller features side to side. This improvement is most evident near the focus, where the beam is most tightly confined.

Lateral resolution depends on how wide the ultrasound beam is across the image slice. The beam spreads due to diffraction, and this spreading is tied to the transducer’s aperture size. A larger diameter makes the central beam lobe narrower, so the distance required to distinguish two side‑by‑side reflectors decreases. With a fixed frequency (and hence a fixed wavelength), the lateral beamwidth is roughly proportional to wavelength divided by the aperture diameter. Therefore, increasing the diameter reduces the beamwidth and improves lateral resolution, meaning you can resolve smaller features side to side. This improvement is most evident near the focus, where the beam is most tightly confined.