The region around the focal point where the beam is narrowest and intensity is greatest is called what?

• A. Focal Point
• B. Near Zone
• C. Far Field
• D. Focal Zone

Answer: (A)

The key idea is the location where the ultrasound beam comes to its smallest width and concentrates its energy the most. That point along the beam axis is the focal point—the spot where energy density is at a maximum and the beam is narrowest. While a small region around this point can also have a narrow beam and high intensity (sometimes called the focal zone), the exact location of maximum intensity with the tightest beam is the focal point. The terms near field and far field describe regions before and after this focus, whereas the focal zone specifically refers to the depth range around the focus where the beam remains relatively narrow.