| Popis: |
One of the best adaptive beamformers in medical ultrasound is the minimum variance (MV) beamformer which presents better resolution and edge definition with respect to the traditional delay-and-sum (DAS) beamformer. In real situations, as a result of variations of density through soft tissue and contradiction of assuming constant sound speed for medical ultrasound imaging systems, phase aberration is made which causes ambiguity in targets' location and degradation in resolution. This effect has influence on MV beamformer as DAS. In this paper, different levels of near field phase screens have been applied to simulate the manner of MV in the presence of phase aberration. In the next step, a conventional phase aberration correction method is performed before beamforming to retrieve the efficiency of the MV beamformer. Simulations are performed in majority resolution which has the lowest robustness. The results show that the correction algorithm improves the performance of the MV in both terms of resolution and contrast, even in the presence of strong aberrations. |
