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k-Wave User Forum » User Favorites: Arlen arlen Support for the k-Wave MATLAB toolbox en-US Fri, 06 Mar 2026 02:53:15 +0000 http://bbpress.org/?v=1.0.2 <![CDATA[Search]]> q http://www.k-wave.org/forum/search.php Bradley Treeby on "wrong Pressure of Focus in bowl focused transducer simulation" http://www.k-wave.org/forum/topic/wrong-pressure-of-focus-in-bowl-focused-transducer-simulation#post-8980 Thu, 07 Dec 2023 10:26:38 +0000 Bradley Treeby 8980@http://www.k-wave.org/forum/ Are you extracting the amplitude at the fundamental and the harmonics? Note, you can avoid start-up transients in your sensor data (including the <code>p_max</code> calculation) by defining <code>sensor.record_start_index</code>. Arlen on "wrong Pressure of Focus in bowl focused transducer simulation" http://www.k-wave.org/forum/topic/wrong-pressure-of-focus-in-bowl-focused-transducer-simulation#post-8978 Thu, 07 Dec 2023 05:17:34 +0000 Arlen 8978@http://www.k-wave.org/forum/ Dear Bradley Treeby, Thanks for your advice! I found that this problem happens when simulation is in nonlinear condition. And I try to use sensor.record = {'p'} and extractAmpPhase() to find the max pressure, then the results are converged. I think maybe when use sensor to record 'p_max', the sound field is unstable at the beginning, the max pressure of which is larger than when the sound field is stable, and the wrong max pressure is recorded. Bradley Treeby on "High intensity focused ultrasound simualtion" http://www.k-wave.org/forum/topic/high-intensity-focused-ultrasound-simualtion#post-8958 Fri, 24 Nov 2023 16:38:16 +0000 Bradley Treeby 8958@http://www.k-wave.org/forum/ See response <a href="http://www.k-wave.org/forum/topic/wrong-pressure-of-focus-in-bowl-focused-transducer-simulation">here</a>. Bradley Treeby on "wrong Pressure of Focus in bowl focused transducer simulation" http://www.k-wave.org/forum/topic/wrong-pressure-of-focus-in-bowl-focused-transducer-simulation#post-8956 Fri, 24 Nov 2023 16:33:42 +0000 Bradley Treeby 8956@http://www.k-wave.org/forum/ It sounds like the simulation hasn't converged. When you run nonlinear simulations, the grid needs to be fine enough to supported the generated higher frequency harmonics. If it's not, you will get a numerical error called spectral blocking. So in short, either reduce the amplitude of your source, or keep decreasing the grid size until the simulation output doesn't depend on the computational settings. Arlen on "wrong Pressure of Focus in bowl focused transducer simulation" http://www.k-wave.org/forum/topic/wrong-pressure-of-focus-in-bowl-focused-transducer-simulation#post-8931 Mon, 09 Oct 2023 09:23:04 +0000 Arlen 8931@http://www.k-wave.org/forum/ Hi, Bradley I have changed the number of grid points (Nx, Ny, Nz), keeping the x_size (y_size, z_size) nearly same. But when I delete 'medium.BonA=7', the pressure of focus converges, changing the grid size (dx, dy, dz). Bradley Treeby on "wrong Pressure of Focus in bowl focused transducer simulation" http://www.k-wave.org/forum/topic/wrong-pressure-of-focus-in-bowl-focused-transducer-simulation#post-8929 Sun, 08 Oct 2023 12:05:13 +0000 Bradley Treeby 8929@http://www.k-wave.org/forum/ Do you also change the number of grid points (Nx etc) as you change the grid spacing to keep the overall grid size constant? Arlen on "High intensity focused ultrasound simualtion" http://www.k-wave.org/forum/topic/high-intensity-focused-ultrasound-simualtion#post-8924 Fri, 06 Oct 2023 10:15:47 +0000 Arlen 8924@http://www.k-wave.org/forum/ hi everyone， I'm doing simulation about a HIFU transducer, but I found that when I set the grids' size smaller, the pressure of focus doesn't converge. But when I set the medium linear(delete medium.BonA=7), the results show convergency. Can anyone help me to solve this problem? Here are my codes: Nx = 380; % number of grid points in the x direction Ny = 240; % number of grid points in the y direction Nz = 240; % number of grid points in the z direction dx =0.3e-3; % grid point spacing in the x direction [m] dy =0.3e-3; % grid point spacing in the y direction [m] dz =0.3e-3; % grid point spacing in the z direction [m] x_size=dx*Nx; y_size=dy*Ny; z_size=dz*Nz; sound_speed=1500; % [m/s]媒介声速 density = 1000 ; % [kg/m^3]媒介密度 kgrid = kWaveGrid(Nx, dx, Ny, dy, Nz, dz); % define the properties of the propagation medium medium.BonA=7; %水里的超声非线性参数 medium.sound_speed = sound_speed * ones(Nx, Ny, Nz); % [m/s] medium.density = density * ones(Nx, Ny, Nz); % [kg/m^3] kgrid.makeTime(medium.sound_speed,0.3,80e-6); % define a centered circular sensor % define a series of Cartesian points to collect the data sensor.mask = zeros(Nx, Ny, Nz); sensor.mask(:, :, Nz/2) = 1; sensor.record = {'p_max'}; % % input arguments input_args = {'PlotPML', true, ... 'DataCast', 'single', 'CartInterp', 'linear','PlotSim',true,'PlotLayout',true,'PMLInside',true,'PMLSize',[20,20,20]}; % define a time varying sinusoidal source source_mag = 543.36e3; % [Pa] % create empty array karray = kWaveArray('SinglePrecision',true); %position = [1, Ny/2, Nz/2]; position = [-x_size/2+20e-3,0,0]; % define arc properties radius = 63.2e-3; % [m] diameter = 64e-3; % [m] focus_pos = [x_size/2, 0, 0]; karray.addBowlElement(position, radius, diameter, focus_pos); source.p_mask = karray.getArrayBinaryMask(kgrid); voxelPlot(double(source.p_mask)); source_freq = 1e6; sig1 = source_mag * sin(2 * pi * source_freq * kgrid.t_array); % smooth the source sig1 = filterTimeSeries(kgrid, medium, sig1,'PlotSignals',true,'PlotSpectrums',true); source_signal = zeros(1,length(sig1)); source_signal(1,1:length(sig1)) = sig1; source.p = karray.getDistributedSourceSignal(kgrid, source_signal); sensor_data = kspaceFirstOrder3DG(kgrid, medium, source, sensor, input_args{:}); sensor_data.p_max = reshape(sensor_data.p_max, [Nx, Ny]); sensor_data.p_max = reshape(sensor_data.p_max, [Nx, Ny]); figure; imagesc(kgrid.x_vec, kgrid.y_vec,sensor_data.p_max); xlabel('x [m]'); ylabel('y [m]'); %zlabel('z [m]'); title('Maximum Pressure'); c = colorbar; c.Label.String = 'pressure()'; max = sensor_data.p_max(1,1); maxi = [1,1]; [max, maxi]; for a=floor(0.3*Nx):Nx for b=1:Ny if sensor_data.p_max(a,b)>max max= sensor_data.p_max(a,b); maxi=[a,b]; end end end focus_x = 0; focusx_max = 0; focusy_max = 0; focus_y = 0; focus_l = 0; focus_r = 0; focus_u = 0; focus_d = 0; [focus_x,focus_y]; for a=floor(0.3*Nx):(Nx - 1) for b=1:(Ny - 1) if sensor_data.p_max(a,b)<0.71*max&&sensor_data.p_max(a,b+1)>0.71*max %sensor_data.p_max(a,b)=0; focus_l = b+1; end if sensor_data.p_max(a,b)>0.71*max&&sensor_data.p_max(a,b+1)<0.71*max %sensor_data.p_max(a,b)=0; focus_r = b+1; end if sensor_data.p_max(a,b)<0.71*max&&sensor_data.p_max(a+1,b)>0.71*max focus_u = a+1; end if sensor_data.p_max(a,b)>0.71*max&&sensor_data.p_max(a+1,b)<0.71*max %sensor_data.p_max(a,b)=0; focus_d = a+1; end end focus_x = focus_r - focus_l; focus_y = focus_d - focus_u; if focus_x > focusx_max focusx_max = focus_x; end if focus_y > focusy_max focusy_max = focus_y; end end %ONeil solution % define transducer parameters radius = 63.2e-3; % [m] diameter = 64e-3; % [m] frequency = 1e6; % [Hz] sound_speed = 1500; % [m/s] density = 1000; % [kg/m^3] Z = density*sound_speed; p = 543.36e3; velocity = p/Z; % [m/s] % define position vectors axial_position = 0:5e-4:150e-3; % [m] lateral_position = -15e-3:5e-4:15e-3; % [m] % evaluate pressure [p_axial, p_lateral] = focusedBowlONeil(radius, diameter, velocity, ... frequency, sound_speed, density, axial_position, lateral_position); % plot figure; subplot(4, 1, 1); plot(axial_position .* 1e3, p_axial .* 1e-6, 'k-'); xlabel('Axial Position [mm]'); ylabel('Pressure [MPa]'); subplot(4, 1, 2); plot((0:dx:(Nx-1)*dx) .* 1e3, sensor_data.p_max(:,Ny/2).* 1e-6, 'k-'); xlabel('Axial Position [mm]'); ylabel('Pressure [MPa]'); subplot(4, 1, 3); plot(lateral_position .* 1e3, p_lateral .* 1e-6, 'k-'); xlabel('Lateral Position [mm]'); ylabel('Pressure [MPa]'); subplot(4, 1, 4); plot((0:dy:(Ny-1)*dy).* sensor_data.p_max(Ny/2,:) .* 1e-6, 'k-'); xlabel('Lateral Position [mm]'); ylabel('Pressure [MPa]'); figure; imagesc(kgrid.x_vec, kgrid.y_vec,sensor_data.p_max); xlabel('x [m]'); ylabel('y [m]'); title('Maximum Pressure'); c = colorbar; c.Label.String = 'pressure()'; Arlen on "High intensity focused ultrasound simualtion" http://www.k-wave.org/forum/topic/high-intensity-focused-ultrasound-simualtion#post-8923 Fri, 06 Oct 2023 08:40:31 +0000 Arlen 8923@http://www.k-wave.org/forum/ hi jackYANG, I have omes problems with the High intensity focused ultrasound simualtion, can you give some help to me?I'm a Chinese too. Arlen on "wrong Pressure of Focus in bowl focused transducer simulation" http://www.k-wave.org/forum/topic/wrong-pressure-of-focus-in-bowl-focused-transducer-simulation#post-8917 Mon, 25 Sep 2023 14:09:21 +0000 Arlen 8917@http://www.k-wave.org/forum/ Hi， I'm doing bowl focused transducer simulation, with signal of 1Mhz and 543.36e3 pa. But when I use smaller dx, dy, dz ,the pressure of focus(max pressure) is getting higher. And when I use 0.3mm of grid size, the max pressure is about 30 Mpa, and 0.2mm of grid size, the max pressure is about 40 Mpa! While the same parameters I put in focusedBowlONeil() to calculate, the max pressure at focus is just about 20 Mpa, almost the same 20 Mpa results when I use 0.5mm of grid size(dx,dy,dz). Am I use so large amplitude? My English isn't very well , hope you understand my confusion and help me to solve this problem. Thanks!!! Here are my codes: clear; clf; close all; addpath('D:\k-wave-toolbox-version-1.4\k-Wave'); Nx = 130*3; % number of grid points in the x direction Ny = 80*3; % number of grid points in the y direction Nz = 80*3; % number of grid points in the z direction dx =0.3e-3; % grid point spacing in the x direction [m] dy =0.3e-3; % grid point spacing in the y direction [m] dz =0.3e-3; % grid point spacing in the z direction [m] x_size=dx*Nx; y_size=dy*Ny; z_size=dz*Nz; sound_speed=1500; % [m/s]媒介声速 density = 1000 ; % [kg/m^3]媒介密度 % radius = 63*2; %换能器曲率半径 % diameter = 63*2 - 1; %换能器直径（奇数） kgrid = kWaveGrid(Nx, dx, Ny, dy, Nz, dz); % define the properties of the propagation medium medium.BonA=7; %水里的超声非线性参数 medium.sound_speed = sound_speed * ones(Nx, Ny, Nz); % [m/s] medium.density = density * ones(Nx, Ny, Nz); % [kg/m^3] kgrid.makeTime(medium.sound_speed,0.3,80e-6); % define a centered circular sensor % define a series of Cartesian points to collect the data sensor.mask = zeros(Nx, Ny, Nz); sensor.mask(:, :, Nz/2) = 1; % set the record mode such that only the max and peak values are stored sensor.record = {'p_max'}; % % input arguments input_args = {'PlotPML', true, ... 'DataCast', 'single', 'CartInterp', 'linear','PlotSim',true,'PlotLayout',true,'PMLInside',true,'PMLSize',[20,20,20]}; % grid_size = [Nx, Ny, Nz];%网格空间 % bowl_pos = [1, Ny/2,Nz/2];%bowl的中心点 % %radius = Nx/2;%曲率半径 % %diameter =Nx-1;%圆的直径 % focus_pos = [Nx/2, Ny/2, Nz/2 ];%与bowl_pos连线为对称轴（确定方向）和法向量有一点点像决定换能器姿态 % source.p_mask=makeBowl(grid_size, bowl_pos, radius, diameter, focus_pos, 'Plot', true); % define a time varying sinusoidal source source_mag = 543.36e3; % [Pa] % create empty array karray = kWaveArray('SinglePrecision',true); %position = [1, Ny/2, Nz/2]; position = [-x_size/2+20e-3,0,0]; % define arc properties radius = 63.2e-3; % [m] diameter = 64e-3; % [m] focus_pos = [x_size/2, 0, 0]; karray.addBowlElement(position, radius, diameter, focus_pos); source.p_mask = karray.getArrayBinaryMask(kgrid); voxelPlot(double(source.p_mask)); source_freq = 1e6; % [Hz]声源频率 sig1 = source_mag * sin(2 * pi * source_freq * kgrid.t_array); % smooth the source sig1 = filterTimeSeries(kgrid, medium, sig1,'PlotSignals',true,'PlotSpectrums',true); source_signal = zeros(1,length(sig1)); source_signal(1,1:length(sig1)) = sig1; source.p = karray.getDistributedSourceSignal(kgrid, source_signal); sensor_data = kspaceFirstOrder3DG(kgrid, medium, source, sensor, input_args{:}); sensor_data.p_max = reshape(sensor_data.p_max, [Nx, Ny]); sensor_data.p_max = reshape(sensor_data.p_max, [Nx, Ny]); figure; imagesc(kgrid.x_vec, kgrid.y_vec,sensor_data.p_max); xlabel('x [m]'); ylabel('y [m]'); %zlabel('z [m]'); title('Maximum Pressure'); c = colorbar; c.Label.String = 'pressure()'; max = sensor_data.p_max(1,1); maxi = [1,1]; [max, maxi]; for a=floor(0.3*Nx):Nx for b=1:Ny if sensor_data.p_max(a,b)>max max= sensor_data.p_max(a,b); maxi=[a,b]; end end end focus_x = 0; focusx_max = 0; focusy_max = 0; focus_y = 0; focus_l = 0; focus_r = 0; focus_u = 0; focus_d = 0; [focus_x,focus_y]; for a=floor(0.3*Nx):(Nx - 1) for b=1:(Ny - 1) if sensor_data.p_max(a,b)<0.71*max&&sensor_data.p_max(a,b+1)>0.71*max %sensor_data.p_max(a,b)=0; focus_l = b+1; end if sensor_data.p_max(a,b)>0.71*max&&sensor_data.p_max(a,b+1)<0.71*max %sensor_data.p_max(a,b)=0; focus_r = b+1; end if sensor_data.p_max(a,b)<0.71*max&&sensor_data.p_max(a+1,b)>0.71*max focus_u = a+1; end if sensor_data.p_max(a,b)>0.71*max&&sensor_data.p_max(a+1,b)<0.71*max %sensor_data.p_max(a,b)=0; focus_d = a+1; end end focus_x = focus_r - focus_l; focus_y = focus_d - focus_u; if focus_x > focusx_max focusx_max = focus_x; end if focus_y > focusy_max focusy_max = focus_y; end % if focus_d > 0 % break; % end end % define transducer parameters radius = 63.2e-3; % [m] diameter = 64e-3; % [m] frequency = 1e6; % [Hz] sound_speed = 1500; % [m/s] density = 1000; % [kg/m^3] Z = density*sound_speed; p = 543.36e3; velocity = p/Z; % [m/s] % define position vectors axial_position = 0:5e-4:150e-3; % [m] lateral_position = -15e-3:5e-4:15e-3; % [m] % evaluate pressure [p_axial, p_lateral] = focusedBowlONeil(radius, diameter, velocity, ... frequency, sound_speed, density, axial_position, lateral_position); % plot figure; subplot(4, 1, 1); plot(axial_position .* 1e3, p_axial .* 1e-6, 'k-'); xlabel('Axial Position [mm]'); ylabel('Pressure [MPa]'); subplot(4, 1, 2); plot((0:dx:(Nx-1)*dx) .* 1e3, sensor_data.p_max(:,Ny/2).* 1e-6, 'k-'); xlabel('Axial Position [mm]'); ylabel('Pressure [MPa]'); subplot(4, 1, 3); plot(lateral_position .* 1e3, p_lateral .* 1e-6, 'k-'); xlabel('Lateral Position [mm]'); ylabel('Pressure [MPa]'); subplot(4, 1, 4); plot((0:dy:(Ny-1)*dy).* sensor_data.p_max(Ny/2,:) .* 1e-6, 'k-'); xlabel('Lateral Position [mm]'); ylabel('Pressure [MPa]'); figure; imagesc(kgrid.x_vec, kgrid.y_vec,sensor_data.p_max); xlabel('x [m]'); ylabel('y [m]'); %zlabel('z [m]'); title('Maximum Pressure'); c = colorbar; c.Label.String = 'pressure()'; jackYANG on "High intensity focused ultrasound simualtion" http://www.k-wave.org/forum/topic/high-intensity-focused-ultrasound-simualtion#post-7168 Mon, 06 Jan 2020 04:51:08 +0000 jackYANG 7168@http://www.k-wave.org/forum/ hi tahere, can you help me ?are you a chinese,i am doing the same some like yours tahere on "High intensity focused ultrasound simualtion" http://www.k-wave.org/forum/topic/high-intensity-focused-ultrasound-simualtion#post-5978 Thu, 08 Jun 2017 07:51:29 +0000 tahere 5978@http://www.k-wave.org/forum/ hello dear silvia for my project i need to acquire the pressure due to a HIFU transducer in a heterogeneous soft tissue. i have a couple of questions. may you help me? thanks in advance Bradley Treeby on "High intensity focused ultrasound simualtion" http://www.k-wave.org/forum/topic/high-intensity-focused-ultrasound-simualtion#post-5879 Tue, 04 Apr 2017 08:55:12 +0000 Bradley Treeby 5879@http://www.k-wave.org/forum/ Hi Silvia, Glad you got it sorted. Let us know if you get stuck. Brad. spozzi on "High intensity focused ultrasound simualtion" http://www.k-wave.org/forum/topic/high-intensity-focused-ultrasound-simualtion#post-5841 Fri, 24 Feb 2017 08:48:28 +0000 spozzi 5841@http://www.k-wave.org/forum/ Hi again, I found all these info in manual/articles. Sorry to have bothered! Silvia spozzi on "High intensity focused ultrasound simualtion" http://www.k-wave.org/forum/topic/high-intensity-focused-ultrasound-simualtion#post-5840 Wed, 22 Feb 2017 08:53:19 +0000 spozzi 5840@http://www.k-wave.org/forum/ Hi, I am playing with kWave to see whether I can use it to estimate the effect of HIFU on tissues when used for ablation. I have a couple of questions regarding the transducer: - I have a single transducer with the shape of a spherical cap with radius of curvature 80 mm, radius of the base 25 mm and height 4 mm. I used the function makeSphericalSection(radius, height, width) but the width can be at maximum equal to half of the radius of curvature. Is there another way to create it with the correct dimensions? - These transducers are used at a central frequency of the order of MHz, however I see that the maximum supported frequency is 750 kHz, did I understand correctly? Thanks in advance, Silvia The source frequency is of the order of MHz. However in the log messages I see that the maximum supported frequency is 750kHz. Bradley Treeby on "High intensity focused ultrasound simualtion" http://www.k-wave.org/forum/topic/high-intensity-focused-ultrasound-simualtion#post-5826 Sun, 12 Feb 2017 19:24:46 +0000 Bradley Treeby 5826@http://www.k-wave.org/forum/ Hi Timo, The nonlinearity depends on the value of the pressure. In principle, you could see strong nonlinearity in either 2D or 3D. However, if you are using a focused transducer, the focusing gain in 2D (cylindrical focusing) is much weaker than in 3D (spherical focusing), so you will need much higher transmit pressures. The grid point spacing should be at least half the wavelength at the highest frequency harmonic. To assess this, you should do a convergence analysis (see <a href="">here, Fig. 3</a> for an example). Hope that helps. Brad. timo_kuhn on "High intensity focused ultrasound simualtion" http://www.k-wave.org/forum/topic/high-intensity-focused-ultrasound-simualtion#post-5813 Tue, 17 Jan 2017 13:01:39 +0000 timo_kuhn 5813@http://www.k-wave.org/forum/ Hi Anthony, I am trying to model a shock wave as it is used in shock wave lithotripsy. You mentioned 50 MPa, this sounds like you simulated something similar? Do you think you could send me the code you used for the simulation? It would help me a lot and I would really appreciate it! I have played with a lot of parameters (power, medium.BonA, grid spacing, wavelength etc.) but I have never managed to see the formation of a shock front. It does not matter if I define the medium.BonA value or not, the result is the same. Do you have a suggestion for the grid point spacing at a wavelength of 1.5e-3 m? Does it matter if I do the simulation in 2D or 3D? Thanks in advance, Timo Anthony on "High intensity focused ultrasound simualtion" http://www.k-wave.org/forum/topic/high-intensity-focused-ultrasound-simualtion#post-5171 Tue, 28 Jul 2015 11:14:41 +0000 Anthony 5171@http://www.k-wave.org/forum/ Hi Alex, From my personal experience (I am a simple user, not a dev), I would say that you have two main points to check: - your grid is fine enough to enable the propagation of the high harmonics - the medium heterogeity: see some topics on this forum and paragraph V.B of Brad's paper in JASA 2012 (Modeling nonlinear ultrasound propagation in heterogeneous media with power law absorption using a k-space pseudospectral method). I am not sure of what you call "strong" nonlinear case, I made a few simulations in water with B/A = 5 at quite high power (100W) at it seems to compare well with hydrophone measurements with 50 MPa peak positive pressure. However, I only have very old experimental data I did not acquire myself so it is not rigorous at all: don't consider this as a validation! See "Modelling nonlinear ultrasound propagation in absorbing media using the k-Wave toolbox: experimental validation" (2012) for a validation but the peak pressures seems quite low (a few MPa figure 2). By the way, use the C code instead of the Matlab version (it's much faster). Good luck, Anthony alex_wang on "High intensity focused ultrasound simualtion" http://www.k-wave.org/forum/topic/high-intensity-focused-ultrasound-simualtion#post-5170 Sun, 26 Jul 2015 04:09:19 +0000 alex_wang 5170@http://www.k-wave.org/forum/ Hi, I am new user of the this software, what I am want to do is to use this toolbox to simulate very strong non-linear wave propagation in water or in a layered medium, but I didn't see any discussions in this forum and didn't find any example that shows how to simulate the strong nonlinear wave propagation, is this tool box applicable for the strong non-linear wave case? can anyone give me some examples or told me what should I take care of in the simulation? regards Alex