Lateral resolution changes with which parameter?

Lateral resolution changes with which parameter?

• A. Depth
• B. Frequency
• C. Time
• D. Amplitude

Answer: (A)

Lateral resolution depends on how wide the ultrasound beam is at a given depth. As the beam travels from the transducer, diffraction causes it to widen, so the narrower beam near the focal zone gives the best lateral resolution and the resolution worsens as depth increases. Techniques that focus the beam (like curved or phased-array focusing) can improve lateral resolution at a specific depth, but away from that focus the beam broadens and resolution degrades. Time and amplitude don’t directly control this depth-dependent beam width, and while frequency influences other aspects of resolution, the primary reason lateral resolution changes with depth is the beam’s widening with distance.

Lateral resolution depends on how wide the ultrasound beam is at a given depth. As the beam travels from the transducer, diffraction causes it to widen, so the narrower beam near the focal zone gives the best lateral resolution and the resolution worsens as depth increases. Techniques that focus the beam (like curved or phased-array focusing) can improve lateral resolution at a specific depth, but away from that focus the beam broadens and resolution degrades. Time and amplitude don’t directly control this depth-dependent beam width, and while frequency influences other aspects of resolution, the primary reason lateral resolution changes with depth is the beam’s widening with distance.