Elevational diffraction effect in estimating the local attenuation-coefficient slope using synthetic-transmit-aperture ultrasound imaging

<p dir="ltr">Accurate estimation of attenuation coefficient slope (ACS) enhances quantitative ultrasound imaging. We investigate diffraction bias in reference-phantom-free ACS estimation for synthetic transmit aperture (STA) imaging with a one-dimensional linear array. Simulations and experiments show that the elevational focus, rather than the lateral focus, introduces depth-dependent bias: ACS underestimation before focus and overestimation beyond. Applying a Gaussian diffraction correction reduced the ACS error from $\pm 0.28$ to $\pm 0.06$ dB/ cm.MHz in simulations and from $\pm 0.32$ to $\pm 0.09$ dB/ cm.MHz in the experiments. These results indicate that accounting for elevational diffraction reduces bias in reference-phantom-free ACS estimation in STA imaging.</p><p><br></p>