sangwoon-jeong Support for the k-Wave MATLAB toolbox en-US Fri, 15 May 2026 01:27:22 +0000 http://bbpress.org/?v=1.0.2 q http://www.k-wave.org/forum/search.php http://www.k-wave.org/forum/topic/influence-of-material-composition-on-arrival-time#post-8641 Mon, 07 Nov 2022 05:48:42 +0000 Sangwoon Jeong 8641@http://www.k-wave.org/forum/ <p>Hello, I'm sangwoon Jeong<br /> I'm studying on an acoustic wave generated by a proton beam.</p> <p>The influence of material deviation is evaluated.<br /> If the average speed of sound and the average density of a material are the same, we are confirming that the arrival time of sound waves is different between a homogeneous material and a heterogeneous material.</p> <p>Is there anything else I should consider?</p> <p>Sometimes for example,<br /> Extract the mean value and standard deviation of Hounsfiled units (HU) in the bone area and lung area from the CT image.<br /> A homogeneous material with an average value and,<br /> Produces an inhomogeneous material with the same mean but with a standard deviation.<br /> At this time, the average speed of sound and density are the same.<br /> Set the acoustic and detector at the same location of the two materials and use kspaceFirstOrder2D to check and compare the arrival times.</p> <p>As a result, it appears differently in the lung area, and it differs from the homogeneous material in the heterogeneous material that combines lung and bone or lung and tissue.</p> <p>this is my code.</p> <p>clc;<br /> clear ;<br /> close all ;</p> <p>%% PML</p> <p> input_args = {'DataCast','gpuArray-single'};</p> <p>%% K-grid input phantom image<br /> % creat the compuational grid<br /> kgrid.Nx = 300;<br /> kgrid.Ny = 300;<br /> dx = 1e-3; % 1 mm<br /> dy = 1e-3; % 1 mm<br /> kgrid = makeGrid(kgrid.Nx,dx,kgrid.Ny,dy);</p> <p>%% only one </p> <p>bone_matrix = randi([1800 1900],300, 300);<br /> bone_true = ones(300,300)*mean2(bone_matrix);<br /> lung_matrix = randi([162 305],300, 300);<br /> lung_true = ones(300,300)*mean2(lung_matrix);<br /> normal_matrix = randi([980 1105],300, 300);<br /> normal_true = ones(300,300)*mean2(normal_matrix);</p> <p>%% select bone, lung, normal tissue<br /> using_image = bone_true;</p> <p>%%</p> <p>figure, imshow(using_image,[]);<br /> [density, sound_speed] = hounsfield2density(double(using_image));<br /> medium.sound_speed = sound_speed;<br /> medium.density = density;</p> <p>mean2(sound_speed)</p> <p>%% Create the time array</p> <p>dt = 10e-9; % 10ns % [s] e-3 = ms / e-6 = 1us / e-9 = 1ns<br /> % Nt = 20000;<br /> t_end = 200e-6; % 0.2ms<br /> % kgrid.setTime(Nt, dt);<br /> kgrid.t_array = 0:dt:t_end;</p> <p>%% Source</p> <p>source.p_mask = zeros(kgrid.Nx,kgrid.Ny);<br /> source.p_mask(kgrid.Nx/2, 99) = 1;<br /> source_mag = 50e-3; % [Pa] @@@<br /> %%</p> <p>xx = [-3.5:1/300 :3.5];<br /> yy = normpdf(xx,0,1);<br /> yy = yy(1,1:size(xx,2)-1);<br /> source.p = source_mag * yy ;</p> <p>%% Sensor<br /> sensor.mask = zeros(kgrid.Nx, kgrid.Ny);<br /> sensor.mask(kgrid.Nx/2, 201) = 1; % sensor posz ition </p> <p>%% Run the simulation<br /> sensor_data_2D = kspaceFirstOrder2D(kgrid, medium, source, sensor,input_args{:});</p> <p>%% result</p> <p>[t_sc, t_scale, t_prefix] = scaleSI(t_end);<br /> result_time_array = kgrid.t_array*t_scale;</p> <p>Thanks for pointing out the problem.</p> <p>Thanks,</p> <p>Sangwoon Jeong. </p>