Hi,
I'm doing a PhD in shear wave ultrasound elastography, I am looking to model two ultrasound transducers at an angle, cause them to constructively interfere and model the resulting shear wave propagation.
Before I get properly stuck into k-wave, I just want to know is this a reasonable/possible scenario to model using this software?
All the best
James
Hi James,
In principle, yes this can be achieved in k-Wave. How easy this is will depend on the details, for example, how complex your transducer is, etc, etc.
Brad
Hi Brad
Sorry for only replying now, it would just be two simple 1MHz, 1 Watt disk transducers.
Not sure how to get the setup correct so that the beams will focus at the same area.
Is there any code for available for modelling disk transducers and I can try work from there?
All the best
James
Hi James,
You can simply define your two transducers using a binary mask (see k-Wave example "Simulating Transducer Field Patterns" or my recent reply to the post "
how to generate a cylindrical transducer in 3D Space").
Then, use source.p to set the input signal (see section 3.4 of the user manual). It can be either the same for each point of your transducers or a specific one for each transducer voxel.
Regards,
Hi Anthony
I've only gotten started now, I've managed to create two source/transducers and they appear on the grid. But only one is firing. Any idea where the error is?
% create the computational grid
Nx = 128; % number of grid points in the x (row) direction
Ny = 128; % number of grid points in the y (column) direction
dx = 0.1e-3; % grid point spacing in the x direction [m]
dy = 0.1e-3; % grid point spacing in the y direction [m]
kgrid = kWaveGrid(Nx, dx, Ny, dy);
% define the properties of the propagation medium
medium.sound_speed = 1500; % [m/s]
medium.alpha_coeff = 0.75; % [dB/(MHz^y cm)]
medium.alpha_power = 1.5;
% create the time array
kgrid.makeTime(medium.sound_speed);
% define a curved transducer element
arc_pos = [20, 20]; % [grid points]
radius = 60; % [grid points]
diameter = 81; % [grid points]
focus_pos = [Nx/2, Nx/2]; % [grid points]
source1.p_mask = makeArc([Nx, Ny], arc_pos, radius, diameter, focus_pos);
% define a time varying sinusoidal source
source_freq = 0.25e6; % [Hz]
source_mag = 0.5; % [Pa]
source1.p = source_mag * sin(2 * pi * source_freq * kgrid.t_array);
% filter the source to remove any high frequencies not supported by the grid
source1.p = filterTimeSeries(kgrid, medium, source1.p);
% create a sensor mask covering the entire computational domain using the
% opposing corners of a rectangle
sensor.mask = [1, 1, Nx, Ny].';
% set the record mode to capture the final wave-field and the statistics at
% each sensor point
%sensor.record = {'p_final', 'p_max', 'p_rms'};
% define a second curved transducer element
arc_pos1 = [20, 108]; % [grid points]
radius1 = 60; % [grid points]
diameter1 = 81; % [grid points]
focus_pos1 = [Nx/2, Nx/2]; % [grid points]
source2.p_mask = makeArc([Nx, Ny], arc_pos1, radius1, diameter1, focus_pos1);
% define a time varying sinusoidal source
source_freq1 = 0.25e6; % [Hz]
source_mag1 = 0.5; % [Pa]
source2.p = source_mag1 * sin(2 * pi * source_freq1 * kgrid.t_array);
% filter the source to remove any high frequencies not supported by the grid
source2.p = filterTimeSeries(kgrid, medium, source2.p);
% create a sensor mask covering the entire computational domain using the
% opposing corners of a rectangle
sensor.mask = [1, 1, Nx, Ny].';
% create a display mask to display the transducer
display_mask = source1.p_mask + source2.p_mask;
% assign the input options
input_args = {'DisplayMask', display_mask, 'PMLInside', false, 'PlotPML', false};
% run the simulation
sensor_data = kspaceFirstOrder2D(kgrid, medium, source, sensor, input_args{:});
Got the code working, I forgot to add the sources properly.
Code below for anyone interested
% create the computational grid
Nx = 128; % number of grid points in the x (row) direction
Ny = 128; % number of grid points in the y (column) direction
dx = 0.1e-3; % grid point spacing in the x direction [m]
dy = 0.1e-3; % grid point spacing in the y direction [m]
kgrid = kWaveGrid(Nx, dx, Ny, dy);
% define the properties of the propagation medium
medium.sound_speed = 1500; % [m/s]
medium.alpha_coeff = 0.75; % [dB/(MHz^y cm)]
medium.alpha_power = 1.5;
% create the time array
kgrid.makeTime(medium.sound_speed);
% define a curved transducer element
arc_pos = [20, 20]; % [grid points]
radius = 60; % [grid points]
diameter = 81; % [grid points]
focus_pos = [Nx/2, Nx/2]; % [grid points]
source1.p_mask = makeArc([Nx, Ny], arc_pos, radius, diameter, focus_pos);
% define a time varying sinusoidal source
source_freq = 0.25e6; % [Hz]
source_mag = 0.5; % [Pa]
source1.p = source_mag * sin(2 * pi * source_freq * kgrid.t_array);
% filter the source to remove any high frequencies not supported by the grid
source1.p = filterTimeSeries(kgrid, medium, source1.p);
% create a sensor mask covering the entire computational domain using the
% opposing corners of a rectangle
sensor.mask = [1, 1, Nx, Ny].';
% set the record mode to capture the final wave-field and the statistics at
% each sensor point
%sensor.record = {'p_final', 'p_max', 'p_rms'};
% define a second curved transducer element
arc_pos1 = [20, 108]; % [grid points]
radius1 = 60; % [grid points]
diameter1 = 81; % [grid points]
focus_pos1 = [Nx/2, Nx/2]; % [grid points]
source2.p_mask = makeArc([Nx, Ny], arc_pos1, radius1, diameter1, focus_pos1);
% define a time varying sinusoidal source
source_freq1 = 0.25e6; % [Hz]
source_mag1 = 0.5; % [Pa]
source2.p = source_mag1 * sin(2 * pi * source_freq1 * kgrid.t_array);
% filter the source to remove any high frequencies not supported by the grid
source2.p = filterTimeSeries(kgrid, medium, source2.p);
source.p = source1.p + source2.p;
source.p_mask = source1.p_mask + source2.p_mask;
% create a sensor mask covering the entire computational domain using the
% opposing corners of a rectangle
sensor.mask = [1, 1, Nx, Ny].';
% create a display mask to display the transducer
display_mask = source.p_mask;
% assign the input options
input_args = {'DisplayMask', display_mask, 'PMLInside', false, 'PlotPML', false};
% run the simulation
sensor_data = kspaceFirstOrder2D(kgrid, medium, source, sensor, input_args{:});
I was trying to overlap the binary masks of two transducers inclined. The first transducer is inclined clockwise at 18 degrees from x-axis while second one is horizontal. The first few elements of second transducer and the last few elements of the first transduceroverlap. When both are transmitting plane wave at the same angle and at the same time, the second transducer (from left) doesn't start transmitting exactly from first element but a few elements after that. Any reason why?
Hi derrelldv,
I can't quite picture what you've got. Do the transducers share the same grid points?
Best wishes
Ben
You must log in to post.