beam nonuniformity ratio

beam nonuniformity ratio

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BNR

A measure of the homogeneity of a therapeutic ultrasound wave, expressed as a ratio between the ultrasound unit's average intensity (the metered output) and the peak intensity within the output wave. A completely homogeneous wave is represented by a 1:1 BNR.

CAUTION!

FDA regulations require that the BNR be clearly labeled on therapeutic ultrasound units. A BNR of greater than 8:1 is considered to be potentially harmful.