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1. ncRubert
   

   Member
   Joined: Jan '19
   Posts: 2

   Hi forum,

   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.

   Has anyone seen this artifact before? Here is a link to the simulated B-mode image showing the artifact.

   https://drive.google.com/file/d/1w7eSKPvDg-XVI0EJGs7yLDApFzQ6gx2a/view?usp=sharing

   The artifact is the change in image texture at a depth of around 23 mm. It looks like a series of bright horizontal bands.

   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.

   Posted 4 years ago #

2. ncRubert
   

   Member
   Joined: Jan '19
   Posts: 2

   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.

   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.

   Posted 4 years ago #

3. Bradley Treeby
   

   Developer
   Joined: Mar '10
   Posts: 1,640

   Hi ncRubert,

   Hard to say unfortunately. A PML of 25 grid points sounds sufficient along with the default PML absorption.

   Brad.

   Posted 4 years ago #

4. Farnaz
   

   Member
   Joined: Oct '18
   Posts: 20

   Hi ncRubert,

   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)
   Similar artifact can also happen if you set your dt manually that do not meet the requirement for stability.

   Best,
   Farnaz

   Posted 4 years ago #

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