http://www.k-wave.org/forum/topic/speed-of-sound-compensation-for-time-reversal Support for the k-Wave MATLAB toolbox en-US Wed, 13 May 2026 00:22:29 +0000 http://bbpress.org/?v=1.0.2 q http://www.k-wave.org/forum/search.php http://www.k-wave.org/forum/topic/speed-of-sound-compensation-for-time-reversal#post-8112 Mon, 05 Apr 2021 11:28:40 +0000 Lin 8112@http://www.k-wave.org/forum/ <p>Hi Alexander,</p> <p>I'm new in photoacoustic tomography, and I'm learning how to use back projection algorithm to compensate for the affects of heterogeneous speed of sound, could you please share your code?</p> <p>Thanks! </p> http://www.k-wave.org/forum/topic/speed-of-sound-compensation-for-time-reversal#post-7081 Fri, 18 Oct 2019 18:57:11 +0000 Bradley Treeby 7081@http://www.k-wave.org/forum/ <p>Hi Alex,</p> <p>Yes, time reversal can take a heterogeneous sound speed map. Essentially, it runs the same code as the forward model, but flips the sensor data in time and uses <code>source.p_mode = &#39;dirichlet&#39;</code>.</p> <p>Brad. </p> http://www.k-wave.org/forum/topic/speed-of-sound-compensation-for-time-reversal#post-7021 Sat, 24 Aug 2019 19:05:13 +0000 Alexander 7021@http://www.k-wave.org/forum/ <p>Thanks Dr. Treeby, I'll take a look at the attached paper.</p> <p>But time reversal is able to compensate already then? Or it just take the mean value of the heterogeneous map? If it is compensating then I'll take a look at my scripts from before and see if it was an error on my part. </p> <p>Thanks,<br /> Alex </p> http://www.k-wave.org/forum/topic/speed-of-sound-compensation-for-time-reversal#post-7006 Thu, 22 Aug 2019 15:40:49 +0000 Bradley Treeby 7006@http://www.k-wave.org/forum/ <p>Hi Alexander,</p> <p>You can perform time reversal with a heterogeneous sound speed. However, you need to consider the effects of <a href="http://bug.medphys.ucl.ac.uk/papers/2010-Cox-IEEETMI.pdf">artefact trapping</a>.</p> <p>Hope that helps,</p> <p>Brad. </p> http://www.k-wave.org/forum/topic/speed-of-sound-compensation-for-time-reversal#post-6999 Tue, 20 Aug 2019 18:08:19 +0000 Alexander 6999@http://www.k-wave.org/forum/ <p>Hi,</p> <p>I wanted to clarify if the implementation of time reversal that k-wave uses can compensate for the affects of heterogeneous speed of sound? I have a back projection algorithm for PAT that can compensated for that and was looking to compare it to time reversal. </p> <p>When I did a quick test, which just involved defining a heterogeneous speed of sound medium and homogeneous density. It appears that the time reversal algorithm doesn't compensate for sos, unless I am missing a flag or that density should also be heterogeneous. </p> <p>If that is true presumably there is a term c0 (speed of sound) when you solve the differential equations so when we solve the equation at a given point could we use the associated speed of sound of that point to compensate for its affects? Perhaps that doesn't give a perfect solution, but would it at least be a good 1st order approximation? </p>