Estimation of sound velocity based on evaluation of edge conspicuity

In this paper, a new method is proposed to minimize defocusing effects dueto wrong selection of sound velocity used in dynamic receive beamforming. Tofind an optimal sound velocity, the proposed method calculates the degree ofedge conspicuity by using a nonlinear anisotropic diffusion (NAD) technique. Forthis, images are formed with different sound velocities ranging 1400 to 1600m/s and subsequently the region of interest (ROI) is chosen. In ROI, the degreesof edge conspicuity are calculated. The sound velocity can be considered as anoptimal one for the ROI if it is used for the image that provides the maximumdegree of edge conspicuity. To evaluate the performances of proposed method,pre-beamformed RF data were acquired from a phantom with a sound velocity of1460 m/s by using a commercial ultrasound scanner (SA-9900, Medison, Corp.,Korea) and the edge gradient was calculated. The estimation error and variancewere 0.99% and 9.89%, respectively. These results indicate that the proposedmethod for sound velocity estimation is capable of providing accurate andconsistent sound velocity in the ROI.