Phase aberration measurement and correction in medical ultrasound
An apparatus to measure time-of-flight profiles in living tissues and an experimental phased-array imaging system capable of correcting unknown phase errors induced by inhomogeneities in the acoustic velocities in tissue are presented. The procedure utilizes regional target brightness to adjust the phasing of individual elements iteratively. The results of in vivo measurements of phase-error profiles in abdominal, breast and transcranial imaging applications are given. The success of the phase-correction system in restoring the quality of images degraded by these errors is demonstrated.