Axial resolution is related to______.

Axial resolution is related to______.

• A. Pulse duration
• B. Amplitude
• C. Frequency
• D. Beam width

Answer: (A)

Axial resolution is the ability to distinguish two reflectors that lie along the path of the ultrasound beam, and it depends on the length of the pulse in tissue—the spatial pulse length. The shorter the pulse duration, the shorter the spatial pulse length, so two closely spaced reflectors along the beam can be resolved as separate echoes. Spatial pulse length equals the number of cycles in the pulse times the wavelength, so reducing the number of cycles or using a higher frequency (which lowers the wavelength) shortens this length and improves axial resolution. Amplitude affects echo strength, not resolution; beam width affects lateral resolution, not axial.

Axial resolution is the ability to distinguish two reflectors that lie along the path of the ultrasound beam, and it depends on the length of the pulse in tissue—the spatial pulse length. The shorter the pulse duration, the shorter the spatial pulse length, so two closely spaced reflectors along the beam can be resolved as separate echoes. Spatial pulse length equals the number of cycles in the pulse times the wavelength, so reducing the number of cycles or using a higher frequency (which lowers the wavelength) shortens this length and improves axial resolution. Amplitude affects echo strength, not resolution; beam width affects lateral resolution, not axial.