What parameter is primarily responsible for axial resolution?

What parameter is primarily responsible for axial resolution?

• A. Pulse duration
• B. Gain
• C. Frame rate
• D. Acoustic impedance

Answer: (A)

Axial resolution is determined by how short the sound pulse is along the beam direction. The shorter the pulse duration, the shorter the spatial pulse length, meaning echoes from two closely spaced reflectors along the axis return at more distinct times and can be resolved as separate structures. Pulse duration directly controls this spatial length because it reflects how many cycles and how long each cycle lasts in the pulse. Gain only changes brightness, not the ability to separate two points along the beam. Frame rate affects how often images are updated (temporal resolution), and acoustic impedance affects reflection strength at tissue boundaries, not the axial spacing that defines resolution.

Axial resolution is determined by how short the sound pulse is along the beam direction. The shorter the pulse duration, the shorter the spatial pulse length, meaning echoes from two closely spaced reflectors along the axis return at more distinct times and can be resolved as separate structures. Pulse duration directly controls this spatial length because it reflects how many cycles and how long each cycle lasts in the pulse. Gain only changes brightness, not the ability to separate two points along the beam. Frame rate affects how often images are updated (temporal resolution), and acoustic impedance affects reflection strength at tissue boundaries, not the axial spacing that defines resolution.