  Phase aberration is one of the main contributors to image degradation in
ultrasound imaging. Normalized-Cross-Correlation (NCC) is one of the most
extensively studied techniques to estimate the arrival delay error and the
aberration profile. \textit{However, the performance of NCC can be compromised
when the data have a poor signal-to-noise-ratio.} Here we propose an iterative
filtered NCC (f-NCC) method to estimate phase aberration in speckle regions
from the noisy radio-frequency data of a single frame of synthetic transmit
aperture (STA) image. First, two-dimensional filters were applied in the
aperture and temporal domains to suppress noise and off-axis signals in the
transmit beamformed data from an arbitrary speckle region. Second, an iterative
method that included the phase aberration in both the transmission and
receiving process was used to estimate the phase aberration. Third, the
estimation were improved by correcting the edge effect with an iterative
zero-padding technique. Last, in the experimental study, we proposed and
validated a formula to estimate the arrival time error caused by a sound speed
error. The results from both the numerical simulations and experimental studies
confirm that the proposed filtered NCC method can estimate the phase aberration
profile correctly from noisy STA RF data in a speckle region. Image quality in
terms of contrast, resolution and image signal-to-noise-ratio was improved.
Potential applications of the proposed method to map local speed of samples are
also discussed.
