| 释义 |
beam nonuniformity ratio beam nonuniformity ratio, BNRA 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. |