Hi Dr. Cox and Dr. Treeby, I am a Telecommunications student from Spain (Universidad de Cantabria) conducting a photoacoustic tomography project as my final proyect. I have recently discovered k-wave and i´m trying to make a specific type of simulation.
I aim to perform an image reconstruction using as experimental data an absorption map from a sample (knowing also the sample´s properties: sound speed,medium density..) but without having an initial pressure distribution. Would it be possible?
Thanks a lot
David
k-Wave
A MATLAB toolbox for the time-domain
simulation of acoustic wave fields
Necessary data to perform image reconstruction
(6 posts) (2 voices)-
Posted 11 years ago #
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Hi David,
In photoacoustic tomography the data is measurements of the acoustic pressure (or some related quantity) on a surface (imaginary surface) surrounding the region of interest. The image you are trying to reconstruct is the initial pressure distribution.
What exactly do you have a map of? The 3D optical absorption map of the sample? If so, that is related to the initial pressure distribution by a thermodynamic quantity sometimes called the Grueneisen parameter, which is often assumed constant. (In water, for example, it is about 0.11.)
Ben
Posted 11 years ago # -
Hi Dr. Cox, I have a 2D absoption map (i also have the data in a matrix) of a depth cut from a sample of skin tissue with a single capillary. So, i would need the absorption distribution, the grüeneisen parameter and the fluence distribution? Shouldn´t the grüeneisen parameter variate between the different components of the sample (fat,blood,etc..), would it be correct to asume it to be constant (using the mean of the diferent parts)
Thanks alot
DavidPosted 11 years ago # -
Hi David,
Yes, the photoacoustic initial pressure distribution is the product of the optical absorption coefficient, optical fluence, and the Grueneisen parameter. It almost certainly does vary between tissue types, and although there are not many direct experimental measurements of it, it can be calculated from other thermodynamic parameters (search Grueneisen on wikipedia, for example). It is often assumed constant, but that is not quite right. It is also temperature dependent.
Are you working entirely in 2D?
Ben
Posted 11 years ago # -
Hi Dr. Cox,
Yes, i´m working on 2D, in fact i´m trying to simulate in MCML a multilayered sample to get the data i need (at least optical absoption and fluence) as i don´t have access to any experimental photoacoustic data. Is there any public database where i could adquire the initial pressure distribution from a real sample?
Thanks a lotPosted 11 years ago # -
Hi David,
Not that I know of, unfortunately, but if you find something please post back on here. Simulating with a light model such as Monte Carlo is a good idea as a first step, as it gives you much more control so you can test more clearly what works and what doesn't, change the noise level, etc.
Ben
Posted 11 years ago #
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