What term denotes the distance over which a single ultrasound pulse extends in space?

What term denotes the distance over which a single ultrasound pulse extends in space?

• A. Spatial
• B. Spatial pulse length
• C. Speckle
• D. Temporal

Answer: (B)

The distance a single transmitted ultrasound pulse travels in tissue during its duration is called the spatial pulse length. This measures how far the pulse extends in space, not how long it lasts in time. It depends on how many cycles are in the pulse and the wavelength: SPL = number of cycles × wavelength. Since wavelength equals the speed of sound divided by frequency (λ = c/f), SPL can also be written as SPL = number of cycles × (c/f). You can also think of it as SPL = speed of sound × pulse duration. In soft tissue, with typical speeds around 1540 m/s, longer pulses (more cycles or lower frequency) yield a longer SPL, which affects axial resolution (shorter SPL generally gives better axial resolution). The other terms don’t describe a distance a pulse travels in space: temporal refers to time, and speckle is the granular interference pattern seen in images. Spatial alone isn’t specific enough to denote the pulse length in space.

The distance a single transmitted ultrasound pulse travels in tissue during its duration is called the spatial pulse length. This measures how far the pulse extends in space, not how long it lasts in time. It depends on how many cycles are in the pulse and the wavelength: SPL = number of cycles × wavelength. Since wavelength equals the speed of sound divided by frequency (λ = c/f), SPL can also be written as SPL = number of cycles × (c/f). You can also think of it as SPL = speed of sound × pulse duration. In soft tissue, with typical speeds around 1540 m/s, longer pulses (more cycles or lower frequency) yield a longer SPL, which affects axial resolution (shorter SPL generally gives better axial resolution). The other terms don’t describe a distance a pulse travels in space: temporal refers to time, and speckle is the granular interference pattern seen in images. Spatial alone isn’t specific enough to denote the pulse length in space.