Spatial pulse length is equal to?

Spatial pulse length is equal to?

• 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 that a pulse occupies along the direction of the ultrasound beam in tissue. It equals the number of cycles in the pulse times the wavelength of the sound in the medium. The idea is simple: each cycle spans one wavelength of space, so a pulse with N cycles covers N wavelengths. Therefore, Spatial pulse length = N × λ. Since wavelength λ is c/f, higher frequency (for the same number of cycles) shortens the SPL, which in turn improves axial resolution because the pulses are shorter along the beam axis. The other options don’t describe a spatial distance along the beam: subtracting cycles from wavelength isn’t physically meaningful for length, and multiplying wavelength by axial resolution or by beam width doesn’t give the length of the pulse itself.

Spatial pulse length is the physical length that a pulse occupies along the direction of the ultrasound beam in tissue. It equals the number of cycles in the pulse times the wavelength of the sound in the medium. The idea is simple: each cycle spans one wavelength of space, so a pulse with N cycles covers N wavelengths. Therefore, Spatial pulse length = N × λ. Since wavelength λ is c/f, higher frequency (for the same number of cycles) shortens the SPL, which in turn improves axial resolution because the pulses are shorter along the beam axis. The other options don’t describe a spatial distance along the beam: subtracting cycles from wavelength isn’t physically meaningful for length, and multiplying wavelength by axial resolution or by beam width doesn’t give the length of the pulse itself.