How does transducer frequency affect resolution and penetration?

• A. Higher frequency improves axial and lateral resolution but reduces penetration due to higher attenuation.
• B. Higher frequency reduces penetration but improves resolution.
• C. Frequency has no effect on penetration.
• D. Higher frequency increases penetration.

Answer: (A)

Frequency sets a trade-off between resolution and penetration. A higher frequency means a shorter wavelength, which sharpens axial resolution because echoes from closely spaced reflectors along the beam path are more easily distinguished. It also lets the beam be focused more tightly, improving lateral resolution where the beam is narrow. But higher frequency experiences greater attenuation in tissue, so the signal loses energy faster with depth and the usable imaging depth decreases. In soft tissue, attenuation rises with frequency, so you get crisper images at shallow depths but poorer penetration into deeper structures.