k-Wave

1. lokesh
   

   Member
   Joined: Jan '15
   Posts: 7

   Hi,
   I am working with high frequency photoacoustic simulations (12-30 MHz). Please help me to simulate a photoacoustic image that has speckle patten similar to US image.
   Thanks.

   Posted 3 years ago #

2. Bradley Treeby
   

   Developer
   Joined: Mar '10
   Posts: 1,640

   Hi lokesh,

   What part are you stuck on?

   Brad

   Posted 3 years ago #

3. lokesh
   

   Member
   Joined: Jan '15
   Posts: 7

   Hi Bradley, sorry for the late update I didn't see the forum for many days.

   I struck at defining a medium that is similar to US imaging, where the medium is defined with a number of scatterers.
   In PA imaging, the source is defined as PA absorbers and gives the US signal. I have a confusion between the source and the medium.

   Posted 3 years ago #

4. bencox
   

   Developer
   Joined: Mar '10
   Posts: 285

   Hi lokesh,

   US scattering is caused by spatial variations in a medium's acoustic properties, so in k-Wave the way to do it has to be via the medium.sound_speed and medium.density inputs. Making these properties random (with different means and standard deviations for different regions perhaps) might be worth a try.

   It's tricky, though, because speckle arises when scattering occurs from scatterers that can't be separately resolved by the imaging system, so if the resolution length is L, to model speckle you need to be able to model scatterers spaced by distances much shorter than L. Perhaps many tens of scatterers in a L^3 volume would be needed. That is difficult to achieve in k-Wave as it is grid based, so you end up needing a very finely spaced grid.

   Something else to ponder is that speckle is essentially a narrowband phenomenon, and k-Wave is designed for modelling broadband signals, because photoacoustic waves are naturally broadband.

   Does that help?

   Posted 3 years ago #

5. lokesh
   

   Member
   Joined: Jan '15
   Posts: 7

   Hi Ben,
   Yes, it helps me for a better understanding of simulations.

   I tried simulating PA signals with random initialization of medium.sound_speed and medium.density. But, no success.

   As you mentioned the issue maybe with the grid size since the simulation was done using a higher frequency (21 MHz).

   Posted 3 years ago #

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