Fast Phase Aberration Correction In Ultrasound Imaging Using Fat Layer Model

摘要

Phase aberration is one of the most important factors that limit improvement to lateral resolution of ultrasound imaging system. In this paper we propose a computationally efficient method to correct the phase aberration problem arises from the subcutaneous fat layer. The method is based on the determination of thickness of the fat layer and the velocity in it to calculate the focusing delay perfectly. The thickness and velocity can be determined manually by the user through a qualitative assessment or automatically using a quantitative measure as an objective function. Minimizing the value of the entropy was selected as the cost function. The effect of the fat layer thickness and velocity were simulated as a time delays added to the radio frequency (RF) data. Experimental studies addressing that the entropy can be used to accurately determine the thickness and velocity of the fat layer depending on the selected region of interest (ROI). Images of a six pins phantom were reconstructed by two method in frequency domain by Fourier transform and in time domain, and different images were reconstructed using different aperture size. We drive the evaluation of results simulation in image reconstructed by two method and evaluation phase aberration correction when we used best thickness only and when we used optimum velocity also we do it by execution time and accuracy of image using entropy cost function.