http://www.k-wave.org/forum/topic/tgc-for-structured-medium-doesnt-work-properly Support for the k-Wave MATLAB toolbox en-US Wed, 13 May 2026 09:49:51 +0000 http://bbpress.org/?v=1.0.2 q http://www.k-wave.org/forum/search.php http://www.k-wave.org/forum/topic/tgc-for-structured-medium-doesnt-work-properly#post-7405 Fri, 17 Apr 2020 16:08:04 +0000 Bradley Treeby 7405@http://www.k-wave.org/forum/ <p>Hi Bernie,</p> <p>Yes, thanks for pointing this out. If <code>medium.alpha_coeff</code> is heterogeneous, you will need to select a value to use for TGC as discussed also <a href="http://www.k-wave.org/forum/topic/heterogeneous-attenuation-values">here</a>.</p> <p>Brad </p> http://www.k-wave.org/forum/topic/tgc-for-structured-medium-doesnt-work-properly#post-7393 Tue, 14 Apr 2020 10:21:57 +0000 bernie 7393@http://www.k-wave.org/forum/ <p>Hi Brad,</p> <p>in release 1.3 the time gain compensation in examples _us_bode_phased_array.m and _us_bmode_linear_transducer.m was corrected.<br /> But if one now needs a structured medium that has spatially varying alpha_coefficient then<br /> (close to lines 250 in *_phased_array.m) the command:</p> <p>tgc = exp(tgc_alpha_np_m * 2 * r);</p> <p>will not execute, since variable tgc_alpha_np_m is now an (Nx,Ny,Nz)-array and no longer a scalar.</p> <p>To circumvent this error one could choose (like is done in medical equipment anyway)<br /> a constant tgc_alpha_np_m value averaged over the grid.</p> <p>Best wishes, Bernie </p>