Reducing uncertainties for spatial averaging at high frequencies

Detailed spatial resolution in imaging, requires high frequencies. Indeed, clinical systems with center frequencies up to 50MHz are available. However, at such frequencies, the accuracy in measurements may be compromised if the device may be of comparable size to, or larger than the smallest characteristic length scale of the wave. In such cases, spatial variations in the pressure over the surface of the measurement device will produce a different value from that at the intended location, potentially underestimating the field strength.