A Comparison of Backscatter Measured by Phase-Sensitive and Phase-Insensitive Detection

In this study we compare phase-sensitive (PS) detection with phase-insensitive (PI) detection using a twodimensional pseudearray of point-like receivers. PI and PS backscatter measurements were made in a phantom consisting of glass beads in gelatin. PS “backscatter” measurements were made using a conventional 13 mm diameter piezoelectric receiver at a scattering angle of 170 ’. PI measurements were obtained by summing the power spectra from all elements of a pseudearray mimicked by scanning the same receiver apodized to a 1 mm aperture in 1 mm steps over the same 13 mm diameter aperture of the PS measurement. PS and PI backscatter transfer functions (BSTF) were compared on a site-by-site basis using quantitative indices. At all sites the BSTF obtained using PI detection was consistently larger in magnitude and exhibited smaller fluctuations with frequency than the corresponding PS BSTF. These results suggest that PI detection represents a means to reduce the number of measurements necessary to estimate backscatter from inhomogeneous media.