In ultrasound therapy, what does a higher beam nonuniformity ratio indicate?

In ultrasound therapy, the beam nonuniformity ratio (BNR) is a significant factor that describes the uniformity of the output from the ultrasound transducer. A higher BNR indicates that there is a greater disparity in the intensity of the ultrasound waves being emitted; in other words, it signifies that some areas of the beam are much stronger than others.

An increased BNR reflects a less uniform beam, which can lead to hot spots where the ultrasound intensity is significantly higher than the surrounding areas. This can cause discomfort or even injury to the tissue if not properly managed. Conversely, a lower BNR suggests a more uniform beam, which is generally associated with more consistent dosing of ultrasound energy to the targeted area, minimizing the risk of tissue damage and discomfort.

Understanding the implications of the BNR is crucial in ultrasound therapy since it directly impacts treatment safety and effectiveness. Therefore, recognizing that a higher beam nonuniformity ratio implies less uniformity in the therapeutic ultrasound output is essential for practitioners using this modality.