What measurement indicates the degree of non-uniformity of the beam across space?

The beam uniformity coefficient is a critical measurement that indicates how uniform or consistent an ultrasound beam is as it propagates through space. A high beam uniformity coefficient means that the intensity and focus of the ultrasound beam are relatively uniform, providing consistent imaging quality across the area being examined. This measurement is essential for ensuring that the imaging process yields accurate and reliable results, as non-uniform beams can lead to artifacts or inconsistencies in the images produced.

While other terms may relate to different aspects of beam characteristics, they do not specifically address the degree of non-uniformity across the beam. For instance, beam penetration ratio typically describes the depth of tissue that the ultrasound can effectively penetrate, rather than the uniformity of the beam itself. Beam dispersion factor concerns the spreading of ultrasound energy as it propagates, which differs from uniformity across the beam's cross-section. Beam divergence measure refers to how much the beam spreads over distance, which again does not directly indicate the uniformity of the beam's intensity.

Overall, the beam uniformity coefficient directly quantifies the uniformity of the ultrasound beam, making it the most relevant measurement for assessing how consistently the beam performs across different spatial areas during a sonography examination.