http://www.k-wave.org/forum/topic/artifact-in-b-mode-image-near-transmit-focus Support for the k-Wave MATLAB toolbox en-US Tue, 12 May 2026 23:44:40 +0000 http://bbpress.org/?v=1.0.2 q http://www.k-wave.org/forum/search.php http://www.k-wave.org/forum/topic/artifact-in-b-mode-image-near-transmit-focus#post-7100 Mon, 21 Oct 2019 08:47:36 +0000 Farnaz 7100@http://www.k-wave.org/forum/ <p>Hi ncRubert,</p> <p>I had this artifact before, I think the reason was that my grid was too coarse to support the frequency. Maybe checking frequency would help... (If you plot the spectrum of your signal you might see a peak in higher frequencies than your transmit frequency)<br /> Similar artifact can also happen if you set your dt manually that do not meet the requirement for stability. </p> <p>Best,<br /> Farnaz </p> http://www.k-wave.org/forum/topic/artifact-in-b-mode-image-near-transmit-focus#post-7096 Fri, 18 Oct 2019 20:31:15 +0000 Bradley Treeby 7096@http://www.k-wave.org/forum/ <p>Hi ncRubert,</p> <p>Hard to say unfortunately. A PML of 25 grid points sounds sufficient along with the default PML absorption.</p> <p>Brad. </p> http://www.k-wave.org/forum/topic/artifact-in-b-mode-image-near-transmit-focus#post-7077 Wed, 16 Oct 2019 23:11:10 +0000 ncRubert 7077@http://www.k-wave.org/forum/ <p>Did a little more simulation. This seems to have nothing to do with the focusing. I've adjusted the focal depth to 35 mm and the artifact seems unchanged.</p> <p>Perhaps the artifact is from an insufficiently thick PML? My PML is currently 2 mm thick with dx = 0.08 mm, so 25 grid points. I will increase the thickness and see if it reduces the artifact. </p> http://www.k-wave.org/forum/topic/artifact-in-b-mode-image-near-transmit-focus#post-7075 Wed, 16 Oct 2019 17:55:08 +0000 ncRubert 7075@http://www.k-wave.org/forum/ <p>Hi forum,</p> <p>I'm simulating ultrasound B-mode images according to the example_us_bmode_transducer.m example. I tried adjusting the magnitude of the fluctuations in the medium's sound speed and density scattering map, and I notice if I reduce the standard deviation then I get an artifact in the resulting B-mode image.</p> <p>Has anyone seen this artifact before? Here is a link to the simulated B-mode image showing the artifact.</p> <p><a href="https://drive.google.com/file/d/1w7eSKPvDg-XVI0EJGs7yLDApFzQ6gx2a/view?usp=sharing" rel="nofollow">https://drive.google.com/file/d/1w7eSKPvDg-XVI0EJGs7yLDApFzQ6gx2a/view?usp=sharing</a></p> <p>The artifact is the change in image texture at a depth of around 23 mm. It looks like a series of bright horizontal bands.</p> <p>I'll note that the transmit focus for this image is at a depth of 25 mm. I've tried turning elevational focusing and receive focusing on and off and it doesn't seem to change the appearance of the artifact. </p>