k-Wave User Forum » Topic: FUS transducer composed of discrete (modular) elements in 2D

k-Wave User Forum » Topic: FUS transducer composed of discrete (modular) elements in 2D http://www.k-wave.org/forum/topic/fus-transducer-composed-of-discrete-modular-elements-in-2d Support for the k-Wave MATLAB toolbox en-US Wed, 13 May 2026 12:44:55 +0000 http://bbpress.org/?v=1.0.2 <![CDATA[Search]]> q http://www.k-wave.org/forum/search.php Bradley Treeby on "FUS transducer composed of discrete (modular) elements in 2D" http://www.k-wave.org/forum/topic/fus-transducer-composed-of-discrete-modular-elements-in-2d#post-7017 Thu, 22 Aug 2019 17:50:50 +0000 Bradley Treeby 7017@http://www.k-wave.org/forum/ HI Ellen, The arc positions don't seem to lie on a circle around the geometric focus. For example, try: <pre><code>d = sqrt((rows - 409).^2 + (cols - 377).^2); d(rows >= Nx/2) d(rows < Nx/2)</code></pre> You can see the elements at the bottom are all more-or-less equidistant, but the elements at the top aren't. Worth checking how your Elem_X and Elem_Z values are calculated. Brad. yeatsem on "FUS transducer composed of discrete (modular) elements in 2D" http://www.k-wave.org/forum/topic/fus-transducer-composed-of-discrete-modular-elements-in-2d#post-6968 Wed, 10 Jul 2019 17:20:29 +0000 yeatsem 6968@http://www.k-wave.org/forum/ I've posted the entire script, though it may be confusing. The relevant portion is below the section titled %% build the transducer. The coordinates used in Elem_X(coords) and Elem_Z(coords) are as follows: Elem_X(coords) -0.0496 -0.0736 -0.0956 -0.1142 -0.1293 0.0496 0.0736 0.0956 0.1142 0.1293 Elem_Z(coords) -0.1410 -0.1299 -0.1149 -0.0964 -0.0750 -0.1410 -0.1299 -0.1149 -0.0964 -0.0750 These are the coordinates of elements pertaining to a section of a (nearly) hemispherical array with geometrical focus at (0,0,0). These coordinates get shifted in the script to facilitate placement into the kgrid. Thank you, Ellen yeatsem on "FUS transducer composed of discrete (modular) elements in 2D" http://www.k-wave.org/forum/topic/fus-transducer-composed-of-discrete-modular-elements-in-2d#post-6967 Wed, 10 Jul 2019 17:13:45 +0000 yeatsem 6967@http://www.k-wave.org/forum/ addpath('C:\Users\labadmin\Desktop\k-Wave') clear all; clc; %experimental properties water_speed = 1480; gly_speed = 1560; gt = 1 %glycerin thickness in. gt = gt*2.54*1e-2; %glycerin thickness m % grid properties pts_per_lam = 8; c0_min = water_speed; f_max = 500000; x_size = .4; dx = c0_min/(pts_per_lam*f_max); dy = dx; Nx = round(x_size/dx); Ny = round(Nx/2); % check prime factors checkFactors(Ny - 40,Ny + 40) checkFactors(Nx - 20, Nx + 20) close all %% %set final grid properties Nx = 1024; Ny = 512; %% % create the grid and time array kgrid = makeGrid(Nx,dx,Ny,dy); CFL = .2; c0_max = gly_speed; dt = CFL*dx/c0_max; kgrid.t_array = 0:dt:120e-6; %medium properties medium.sound_speed = water_speed*ones(Nx,Ny); % [m/s] Water medium.density = 997*ones(Nx,Ny); % [kg m^-3] Water %medium.BonA = 5*ones(Nx,Ny); %assume linear at first %medium.alpha_coeff = .0022*ones(Nx,Ny); %assume lossless at first %medium.alpha_power = 1.05*ones(Nx,Ny); %assume lossless at first medium.alpha_mode = 'no_dispersion'; load('Elem_X') load('Elem_Z') coords = [3 7 13 20 28 85 88 92 98 105]; %elem # %shift in x to fit in the kgrid x_shift = min(Elem_X(coords)) - min(min(kgrid.x)) -.01; y_shift = min(Elem_Z(coords)) - min(min(kgrid.y)) -.01; [grid_data,order_id,re_order_id] = cart2grid(kgrid,[Elem_X(coords)-x_shift Elem_Z(coords)-y_shift]'); [val id]= max(Elem_Z(coords)); [rows cols] = find(grid_data); gly_start = round(cols(order_id(id)) + .013/dx); gt = round(gt/dy); % medium.sound_speed(28:727,gly_start:gly_start+gt) = gly_speed; % [m/s] Glycerin % medium.density(28:727,gly_start:gly_start+gt) = 1034.2; % [kg/m^3] % Glycerin medium.sound_speed_ref = c0_min; %ensures phase error is bounded %check dt kmax = pi/dx; dt < 2/(medium.sound_speed_ref*kmax)*asin(medium.sound_speed_ref/c0_max) %% % build transducer diam = floor(.02/dx); if rem(diam,2) == 0 diam = diam + 1; end [rows,cols] = find(grid_data); bm = makeMultiArc([Nx, Ny],[rows cols], 9999, diam, [409 377]); %geometric focus array in gridpoints imagesc(bm) axis equal source.p_mask = bm; source_freq = 0.5e6; % [Hz] source_mag = -10; % [Pa] tc = gauspuls('cutoff',source_freq,0.6,[],-50); time = -tc : kgrid.dt : kgrid.t_array(end) ; pulse = gauspuls(time,source_freq,0.6); source.p = filterTimeSeries(kgrid, medium, source_mag*pulse); sensor.mask = zeros(Nx,Ny); sensor.mask(190,205) = 1; % Define data types to be stored in sensor_data sensor.record = {'p', 'p_final','p_max_all','p_min_all'}; %[ p is acoustic pressure at each sensor, p_final is acoustic field across grid] %Define Record start index sensor.record_start_index = 1; %Start recording at kgrid.t_array( x ) %% Run the Sim input_args = {'DataCast', 'single','PMLInside',false}; %put PML outside of grid sensor_data = kspaceFirstOrder2D(kgrid, medium, source, sensor,input_args{:}); Bradley Treeby on "FUS transducer composed of discrete (modular) elements in 2D" http://www.k-wave.org/forum/topic/fus-transducer-composed-of-discrete-modular-elements-in-2d#post-6962 Wed, 10 Jul 2019 13:47:16 +0000 Bradley Treeby 6962@http://www.k-wave.org/forum/ Hi yeatsem, Can you post the code you use to create the array (or the entire script)? Brad. yeatsem on "FUS transducer composed of discrete (modular) elements in 2D" http://www.k-wave.org/forum/topic/fus-transducer-composed-of-discrete-modular-elements-in-2d#post-6958 Tue, 09 Jul 2019 23:11:05 +0000 yeatsem 6958@http://www.k-wave.org/forum/ Hello, I am trying to model a section of a hemispherical phased array transducer with discrete circular elements in just two dimensions. I am modeling each element as an arc using the makeMultiArc command. There are 5 elements symmetrically distributed on each side of a circular section representing a slice through the hemispherical phased array (10 elements in total). The makeMultiArc command appears to be working well for the 5 elements on one side of the slice, but on the other side, the 5 arcs appear to be slightly misaligned with respect to the focus. I am assigning the same focal point to all of the arcs but am nonetheless encountering this problem. I believe the misalignment is affecting the output of the simulation. When I plot the 2D image of the maximum pressure over the entire field, the beam has appropriate lobes on the side where the elements are properly aligned yet lacks this pattern on the misaligned side. This is causing the maximum pressure in the field to shift laterally. Has anyone else encountered a similar problem? Am I misusing the makeMultiArc function?