INFLUENCE OF MISSING ARRAY ELEMENTS ON PHASE ABERRATION CORRECTION FOR MEDICAL ULTRASOUND

The influence of missing array elements on aberration correction based on time delay estimation using radio frequency signals of neighboring elements is experimentally investigated. Normalized cross correlation and sum of absolute differences are employed as the cost functions in aberration estimation. Their performance is tested through various me asurements using radio frequency data acquired with a 3.3 MHz, 64-elem ent phased array. Variation of cost functions and phase estimation err or are obtained for different combinations of number of missing elemen ts, amount of aberration, and noise level. For a particular combinatio n of these parameters, a set of B-scan images is reconstructed and pre sented to examine the effects of residual phase errors on image qualit y.