Which unit is used to express axial resolution?

Which unit is used to express axial resolution?

• A. Meters
• B. Kilometers
• C. Centimeters
• D. Millimeters

Answer: (D)

Axial resolution is the ability to distinguish two reflectors along the direction the ultrasound beam travels, which is a very small distance. This short-range separation depends on the pulse length and the wavelength in tissue, so it falls in the millimeter scale. Wavelengths in soft tissue at diagnostic frequencies are fractions of a millimeter to a few millimeters, and the axial resolution is typically on the order of tenths to single millimeters. Therefore, millimeters is the appropriate unit to express this quantity. meters or kilometers are far too large to describe such fine separations, and centimeters are usually coarser than what axial resolution represents.

Axial resolution is the ability to distinguish two reflectors along the direction the ultrasound beam travels, which is a very small distance. This short-range separation depends on the pulse length and the wavelength in tissue, so it falls in the millimeter scale. Wavelengths in soft tissue at diagnostic frequencies are fractions of a millimeter to a few millimeters, and the axial resolution is typically on the order of tenths to single millimeters. Therefore, millimeters is the appropriate unit to express this quantity. meters or kilometers are far too large to describe such fine separations, and centimeters are usually coarser than what axial resolution represents.