BNR is determined by what factor?

• A. Intrinsic biophysical properties of the piezoelectric transducer.
• B. Patient age.
• C. Room temperature.
• D. Operator experience.

Answer: (A)

BNR, or beam nonuniformity ratio, reflects how uniform the emitted ultrasound beam is across the image. This uniformity is set by the transducer itself—the piezoelectric material, how the crystals are damped, and the arrangement and construction of the elements (including backing, matching layers, and overall design). These intrinsic physical properties determine how evenly energy is radiated, which establishes the BNR. Patient age, room temperature, or operator experience don’t define the beam’s intrinsic uniformity, though they can affect image quality in other ways. So, BNR is determined by the transducer’s intrinsic properties.