Axial resolution is determined by which parameter?

Axial resolution is determined by which parameter?

• A. Pulse length
• B. Wavelength
• C. Depth
• D. Time

Answer: (A)

Axial resolution is governed by how long the ultrasound pulse lasts in space, called the spatial pulse length. This length is determined by the number of cycles in the pulse multiplied by the wavelength. Shorter spatial pulse length means two closely spaced reflectors along the beam can be distinguished better, so the best way to affect axial resolution is to shorten the pulse length. That’s why pulse length directly sets axial resolution. Wavelength matters because shorter wavelengths (from higher frequency) help reduce the pulse length, but the fundamental parameter you’re measuring here is the pulse length itself. Depth and time do not set axial resolution.

Axial resolution is governed by how long the ultrasound pulse lasts in space, called the spatial pulse length. This length is determined by the number of cycles in the pulse multiplied by the wavelength. Shorter spatial pulse length means two closely spaced reflectors along the beam can be distinguished better, so the best way to affect axial resolution is to shorten the pulse length. That’s why pulse length directly sets axial resolution. Wavelength matters because shorter wavelengths (from higher frequency) help reduce the pulse length, but the fundamental parameter you’re measuring here is the pulse length itself. Depth and time do not set axial resolution.