What is the maximum recommended Beam Uniformity Ratio (BNR) value?

What is the maximum recommended Beam Uniformity Ratio (BNR) value?

• A. 2
• B. 4
• C. 8
• D. 16

Answer: (C)

Beam Uniformity Ratio describes how uneven the energy distribution is in the ultrasound beam—the higher the BNR, the more pronounced the hot spots can be because the peak intensity is much higher than the average. A lower BNR means a more uniform beam and safer, more predictable heating. The maximum recommended value is eight because it provides a practical upper limit that keeps the beam reasonably uniform while still delivering enough energy for therapeutic effect. Values like two or four would indicate tighter uniformity than necessary for a maximum limit, while a BNR of sixteen would allow excessive nonuniform heating and increase the risk of hotspots.

Beam Uniformity Ratio describes how uneven the energy distribution is in the ultrasound beam—the higher the BNR, the more pronounced the hot spots can be because the peak intensity is much higher than the average. A lower BNR means a more uniform beam and safer, more predictable heating. The maximum recommended value is eight because it provides a practical upper limit that keeps the beam reasonably uniform while still delivering enough energy for therapeutic effect. Values like two or four would indicate tighter uniformity than necessary for a maximum limit, while a BNR of sixteen would allow excessive nonuniform heating and increase the risk of hotspots.