What does the SP/SA factor represent?

The SP/SA factor, which stands for Spatial Peak to Spatial Average, is a critical component in assessing the beam uniformity in ultrasound applications. Specifically, the SP/SA factor indicates the relationship between the maximum intensity of the ultrasound beam (spatial peak) to the average intensity across a larger area (spatial average).

This measurement is essential in understanding how uniformly the ultrasound energy is distributed throughout the tissue. A higher SP/SA value suggests that the beam is highly focused and that the maximum intensity differs significantly from the average intensity, which may indicate a risk of overheating or damage to tissues at that focal point.

In various applications of ultrasound, ensuring that the beam is uniform helps in safe and effective imaging and treatment delivery. Therefore, recognizing the SP/SA factor as a beam uniformity coefficient is vital for optimizing ultrasound applications and preventing potential issues related to energy distribution.