k-Wave User Forum » Topic: Phased Array Imaging

k-Wave User Forum » Topic: Phased Array Imaging http://www.k-wave.org/forum/topic/phased-array-imaging Support for the k-Wave MATLAB toolbox en-US Wed, 03 Jun 2026 02:19:03 +0000 http://bbpress.org/?v=1.0.2 <![CDATA[Search]]> q http://www.k-wave.org/forum/search.php CharlesLoh on "Phased Array Imaging" http://www.k-wave.org/forum/topic/phased-array-imaging#post-5723 Thu, 27 Oct 2016 08:56:48 +0000 CharlesLoh 5723@http://www.k-wave.org/forum/ Hi Brad, I'm attempting to simulate a phased array transducer with the specific details: Number of elements = 64 Element Width = 0.53mm Element Pitch = 0.63mm Centre frequency = 5MHz Bandwidth(-6dB) = 50% The sampling frequency is supposed to be 100MHz. I noticed a few issues: 1)The waves are propagating from both the bottom and top at the start and just bounces back at the 0 mark. 2)I can't change the element width. 3)When I changed the tone burst frequency to 5MHz, the waves started out with an irregular shape. What are the problems causing this? What I'd like to know is: 4)Is my current method of simulating Aluminum(with velocity of sound 6300ms^-1, and density of 2700kg/m^3) correct? 5)How do I input my sampling frequency of 100MHz? 6)How do I define the element pitch? (I read the manual, but couldn't find the method to do so) 7)The element width remains at 750micrometers no matter what value I change to. When it goes above 1, it shows an error. How do I rectify this? 8)By making all 64 elements active, am I achieving "full matrix capture"? Whereby when 1 element TX, the others are RX. As I'm really new in MATLAB, it'll be best if things can be explained out according to my point form. I've been thrown to do a Final Year Project that invovles MATLAB(Which I am extremely bad at) Thanks Brad! Here is my code as shown below: clc clear all close all DATA_CAST='single'; % set the size of the perfectly matched layer (PML) PML_X_SIZE = 2; % [grid points] PML_Y_SIZE = 1; % [grid points] PML_Z_SIZE = 1; % [grid points] % set total number of grid points not including the PML Nx = 196 - 2*PML_X_SIZE; % [grid points] Ny = 126 - 2*PML_Y_SIZE; % [grid points] Nz = 62 - 2*PML_Z_SIZE; % [grid points] % set desired grid size in the x-direction not including the PML x = 0.75/1000; % [m] % calculate the spacing between the grid points dx = x; % [m] dy = dx; % [m] dz = dx; % [m] % create the k-space grid kgrid = makeGrid(Nx, dx, Ny, dy, Nz, dz); % define the properties of the propagation medium medium.sound_speed = 6300*ones(Nx,Ny,Nz) ; % [m/s] 2nd medium.sound_speed(1:Nx/2,:,:) = 1000 ; % [m/s] 1st 101 medium.density = 2700*ones(Nx,Ny,Nz); % [kg/m^3] 2nd medium.density(1:round(Nx/2),:,:) = 1134 ; % [kg/m^3] 1st medium.alpha_coeff = 0.001*ones(Nx,Ny,Nz); % [dB/(MHz^y cm)] 2nd medium.alpha_coeff(1:round(Nx/2),:,:)=0.01 ; % [dB/(MHz^y cm)] 1st medium.alpha_power = 1.5; medium.BonA = 6; % create the time array t_end = 120e-6; % [s] kgrid.t_array = makeTime(kgrid, medium.sound_speed, [], t_end); % define properties of the input signal source_strength = 10e6; % [Pa] tone_burst_freq = 2.25e6; % [Hz] tone_burst_cycles = 5; % create the input signal using toneBurst input_signal = toneBurst(1/kgrid.dt, tone_burst_freq, tone_burst_cycles); % scale the source magnitude by the source_strength divided by the % impedance (the source is assigned to the particle velocity) input_signal = (source_strength./(1000*1134)).*input_signal; % physical properties of the transducer transducer.number_elements = 64; % total number of transducer elements transducer.element_width = 1; % width of each element [grid points/voxels] transducer.element_length = 12*4/3; % length of each element [grid points/voxels] transducer.element_spacing = 0; % spacing (kerf width) between the elements [grid points/voxels] transducer.radius = inf; % radius of curvature of the transducer [m] % calculate the width of the transducer in grid points transducer_width = transducer.number_elements*transducer.element_width ... + (transducer.number_elements - 1)*transducer.element_spacing; % use this to position the transducer in the middle of the computational grid transducer.position = round([1, Ny/2 - transducer_width/2, Nz/2 - transducer.element_length/2]); % properties used to derive the beamforming delays transducer.sound_speed = 1000; % sound speed [m/s] transducer.focus_distance = 70/1000; % focus distance [m] transducer.elevation_focus_distance = 68/1000; % focus distance in the elevation plane [m] transducer.steering_angle = 0; % steering angle [degrees] % apodization transducer.transmit_apodization = 'Hanning'; transducer.receive_apodization = 'Rectangular'; % define the transducer elements that are currently active number_active_elements = 64; transducer.active_elements = ones(transducer.number_elements, 1); %transducer.active_elements = zeros(transducer.number_elements, 1); %transducer.active_elements(21:52) = 1; % append input signal used to drive the transducer transducer.input_signal = input_signal; % create the transducer using the defined settings transducer = makeTransducer(kgrid, transducer); % print out transducer properties transducer.properties; % set the input settings input_args = {'DisplayMask', transducer.active_elements_mask, ... 'PMLInside', true, 'PlotPML', true, 'PMLSize', [PML_X_SIZE, PML_Y_SIZE, PML_Z_SIZE], ... 'DataCast', DATA_CAST, 'PlotScale', [-source_strength/32, source_strength/32]}; % run the simulation %[sensor_data] = kspaceFirstOrder3D(kgrid, medium, transducer, transducer, input_args{:}); [sensor_data] = kspaceFirstOrder3D(kgrid, medium, transducer, transducer, input_args{:}); % extract a single scan line from the sensor data using the current % beamforming settings scan_line = transducer.scan_line(sensor_data); % plot the recorded time series figure; stackedPlot(kgrid.t_array*1e6, sensor_data); xlabel('Time [\mus]'); ylabel('Transducer Element'); title('Recorded Pressure'); % plot the scan line figure; plot(kgrid.t_array*1e6, scan_line, 'k-'); xlabel('Time [\mus]'); ylabel('Pressure [au]'); title('Scan Line After Beamforming'); CharlesLoh on "Phased Array Imaging" http://www.k-wave.org/forum/topic/phased-array-imaging#post-5719 Mon, 24 Oct 2016 19:01:54 +0000 CharlesLoh 5719@http://www.k-wave.org/forum/ Got it! Thanks Brad! I'm currently working on a transducer simulator now, will let you know how it goes! Bradley Treeby on "Phased Array Imaging" http://www.k-wave.org/forum/topic/phased-array-imaging#post-5715 Mon, 24 Oct 2016 09:38:45 +0000 Bradley Treeby 5715@http://www.k-wave.org/forum/ Hi Charles, k-Wave is a general wave equation solver that can be used in a wide range of applications. There is some in built functionality to create linear phased arrays. It is possible to use an experimental signal. As far as image processing, that depends entirely on what you want to do. I would suggest going through some of the examples in the MATLAB help browser and reading the k-Wave manual to see what it is capable of. Hope that helps, Brad. CharlesLoh on "Phased Array Imaging" http://www.k-wave.org/forum/topic/phased-array-imaging#post-5712 Fri, 21 Oct 2016 12:38:34 +0000 CharlesLoh 5712@http://www.k-wave.org/forum/ Hi, Is this toolbox capable of: 1)Modelling out a phased array ultrasonic transducer? Is it using Full matrix capture> 2)Using an experimental signal from an actual transducer as input signal to run the simulation? 3)Image post processing from the gathered data? Regards, Charles