k-Wave

1. CHEN SIYU
   

   Member
   Joined: Jul '16
   Posts: 1

   hello, can anybody hello me solve the problems?
   I wanna define a circular phased array ultrasound with 16 elements and the focus point is at center of the circle.
   I have two methods to approach problem.
   the below is Matlab code.
   1:define one element of the transducer.
   source_shape1 = makeCircle(Nx, Ny, 0, 0, 100, pi/8);
   2:Rotate source_shape1 about pi/8 as the second element
   source_shape2 = imrotate(source_shape1, pi/8)
   2:Rotate source_shape1 about pi/8 as the third element
   source_shape3 = imrotate(source_shape2, pi/8)
   ..........................
   16:source_shape16 = imrotate(source_shape2, pi/8);

   add all the source_shape together

   but Matlab generate:
   Error using +
   Matrix dimensions must agree.

   The second approach:Nx = Ny = 360
   define the first elements
   source_shape1 = makeCircle(Nx, Ny, 0, 0, 100, pi/8);
   define the second element
   source_shape2 = makeCircle(Nx, Ny, 0, 0, 100, pi/4);
   cut the unwanted element of the source_shape2
   source_shape2(180-50sin(pi/8:360, :);
   source_shape3 use the same method as source_shape2;

   add all the source_shapes together
   source.p_mask = zeros(Nx, Ny);
   source.p_mask(:, :) = source_shape1 + source_shape2 + ...........source.shape16 ;
   but output of the matlab only come out the largest element, why?

   Posted 8 years ago #

2. Bradley Treeby
   

   Developer
   Joined: Mar '10
   Posts: 1,643

   Hi CHEN SIYU,

   When using imrotate in MATLAB, the output matrix will not be the same size as the input. You need to add the option 'crop' and it should work.

   Regarding your second option, I'm not sure what the line of code source_shape2(180-50sin(pi/8:360, :); does.

   Hope that helps,

   Brad.

   Posted 8 years ago #

3. liuhao
   

   Member
   Joined: Dec '17
   Posts: 1

   Hello, Dr. Bradley Treeby

   I am a new guy in Ultrasonic Imaging, I might have the same problem on circle transducers.

   I need to build 128 transducers on the boundary of a circle area, and using them both as transducers and sensors. I noticed that in "makeTransducer" part of the User's guide, the "tr.radius" should be inf, but how can I put them in a circle way?

   Thank you very much!

   Posted 6 years ago #

4. Bradley Treeby
   

   Developer
   Joined: Mar '10
   Posts: 1,643

   Hi liuhao,

   Unfortunately it's not possible to use the kWaveTransducer class in this way (only linear arrays are supported). For other geometries, you will need to define the sources and sensors directly using source.p_mask (or source.u_mask) and sensor.mask.

   Brad.

   Posted 6 years ago #

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