Spatial pulse length is equal to which of the following?

Spatial pulse length is equal to which of the following?

• A. The wavelength times the number of cycles in the pulse
• B. The wavelength minus the number of cycles in the pulse
• C. The wavelength times the axial resolution
• D. The wavelength times the beam width

Answer: (A)

Spatial pulse length is the physical length of the ultrasound pulse as it travels through tissue. It equals the distance covered by all the cycles in the pulse, which is the wavelength multiplied by the number of cycles in that pulse. In formulas, SPL = λ × N, where λ is the wavelength (speed of sound in the medium divided by the transmitted frequency) and N is the number of cycles in the pulse. Shorter SPL, achieved by fewer cycles or a higher frequency, leads to better axial resolution because echoes from nearby structures are more distinctly separated. The other descriptions don’t describe a length: subtracting cycles isn’t a length, and tying SPL to axial resolution or beam width mixes different properties rather than defining the physical pulse length.

Spatial pulse length is the physical length of the ultrasound pulse as it travels through tissue. It equals the distance covered by all the cycles in the pulse, which is the wavelength multiplied by the number of cycles in that pulse. In formulas, SPL = λ × N, where λ is the wavelength (speed of sound in the medium divided by the transmitted frequency) and N is the number of cycles in the pulse. Shorter SPL, achieved by fewer cycles or a higher frequency, leads to better axial resolution because echoes from nearby structures are more distinctly separated. The other descriptions don’t describe a length: subtracting cycles isn’t a length, and tying SPL to axial resolution or beam width mixes different properties rather than defining the physical pulse length.