The beam nonuniformity ratio (BNR) should be within:

• A. 1:1 - 2:1
• B. 2:1 - 6:1
• C. 3:1 - 9:1
• D. 6:1 - 12:1

Answer: (B)

BNR shows how uniform the ultrasound beam is across its width. It’s the ratio of the brightest to the darkest intensity within the beam at a given depth. A lower BNR means a more uniform beam and steadier brightness, which helps produce a clearer, more reliable image. A higher BNR indicates hotspots and nonuniform brightness, leading to artifacts that can obscure or distort structures.

In diagnostic imaging, the beam nonuniformity is typically kept within a range of about 2:1 to 6:1. This window balances practical transducer design with acceptable image quality. Values below 2:1 would be unusually uniform, while values above 6:1 suggest excessive nonuniformity and greater risk of artifacts. Therefore the acceptable range is 2:1 to 6:1.