Hi
Thanks your hard work in k-wave tool. I have a problem about the kgrid. I think the
kgrid size must be greater than the Cartesian circular sensor, isn't it? In my case, I
assigning x and y = 50e-3, Nx and Ny = 100. Another hand, defining sensor_radius = 40e-3
,sensor_angle = 2*pi. But it doesn't work... The error message shows "Cartesian points
must lie within the k-space grid defined by kgrid." How can I debug this problem?
Sorry, I have solved this problem when I check the code. I think it will be available as
the x is greater 2 times than the sensor radius. Now, the program can run successfully.
But...here comes another problem. Because I already get the sinogram(360*12000) from my
photoacoustic experiment previously. So I replaced this data to "sensor_data" , set "p0
=0" and delete some syntax. Also, I have modified the Cartesian circular sensor code
just like my experiment setup. As follow:
sensor_radius = 37.5e-3; % [m]
sensor_angle = 2*pi; % [rad]
sensor_pos = [0,0]; % [m]
num_sensor_points = 360;
In the end the result of reconstructed image is not well, the image shows like a
concentric circle(◎ <- like this, and it's red in the middle ). Could you give some
advice?
It sounds like the sound speed you are using in the reconstruction doesn't match the one in the experiment (or alternatively, the radius you have set is incorrect). Do you know the sound speed accurately? You could try using the autofocus routine if not (there is an example of how to do this in the toolbox).
I assume the speed of sound is 1500 m/s, it's the velocity of soft tissue. Actually, I
have programmed a tomography by using labview, and it's work for simple source like (a)
pencil lead(s). But I don't know why it's not available by k-wave. Also I can't find the
keywords "autofocus" in the help?! Which example has this function ?
Hi, thanks to your help.
Now I have some similar reconstructed image.
But, there still have a problem I can't understand.
In the Kgrid, how the function calculate the dt?
Because I set Nx = 500, x = 150e-3, dx = x/Nx = 3e-4 and the medium assumed 1500.
I thought the dt is dx/medium speed = 3e-4/1500 = 2e-7. But in the matlab, the calculated dt is 6e-9.
I can 't sure it will affect the data that I loaded into the program, because the sinogram data (360*5000)from my experiment is acquired at 250Mhz sampling rate.
The dt sould be 1/250M = 4e-9. I guess this parameter must be the same between program and exp, right?
If you are working with experimental data, you should directly set dt and Nt based on your acquisition settings (rather than letting k-Wave estimate a suitable value). In other words, after you create kgrid using makeGrid, use something like:
kgrid.t_array = 0:dt:(Nt - 1)*dt;
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