What defines the frequency range of ultrasound used in diagnostic imaging?

• A. Typically between 1 to 5 megahertz (MHz)
• B. Typically between 2 to 18 megahertz (MHz)
• C. Typically between 5 to 30 megahertz (MHz)
• D. Typically between 10 to 20 megahertz (MHz)

Answer: (B)

The frequency range of ultrasound used in diagnostic imaging is typically between 2 to 18 megahertz (MHz). This range is optimal for achieving a balance between resolution and penetration into the tissues. Higher frequencies provide better resolution and detail, which is crucial for visualizing smaller structures, while lower frequencies allow for deeper penetration into the body, which is important for examining deeper organs and tissues.

In practice, frequencies at the lower end of this range, around 2 to 5 MHz, are often used for imaging deeper structures such as the liver or kidneys, while frequencies toward the upper end, closer to 15 to 18 MHz, are more suited for superficial structures, like musculoskeletal structures or vascular imaging. The variety within this frequency range helps sonographers tailor their approach based on the specific imaging requirements of each case, leading to better diagnostic outcomes.