What frequency range is typical for superficial imaging targets?

• A. 7–15 MHz.
• B. 2–5 MHz.
• C. 20–60 MHz.
• D. 1–3 MHz.

Answer: (A)

Imaging targets close to the surface benefits most from higher frequency because it provides finer detail. Higher frequency ultrasound has shorter wavelengths, which improves both axial and lateral resolution, but it also attenuates more quickly, so it doesn’t penetrate very deeply. For routine superficial imaging—like skin, shallow vessels, thyroid, or musculoskeletal surfaces—the mid-to-high MHz range offers a good balance between resolution and usable depth. That’s why 7–15 MHz is commonly used. Lower frequencies (2–5 MHz or 1–3 MHz) would sacrifice too much detail for superficial structures, while very high frequencies (20–60 MHz) give excellent surface detail but only for extremely shallow layers and are used in more specialized dermatologic imaging rather than general superficial imaging targets.