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α0 and x0 are the attenuation coefficient (assumed to be 1 dB/cm-MHz) and length of the intervening tissue above the ROI, respectively. α1 and x1 are the local attenuation coefficient estimate (ACE) of the ROI and the distance from the top of the ROI to the center of RF block. A(f) is the total attenuation from the top of the image to the center of the RF block.
