http://www.k-wave.org/forum/topic/focused-ultrasound-beam-using-round-emitter Support for the k-Wave MATLAB toolbox en-US Tue, 12 May 2026 21:33:21 +0000 http://bbpress.org/?v=1.0.2 q http://www.k-wave.org/forum/search.php http://www.k-wave.org/forum/topic/focused-ultrasound-beam-using-round-emitter#post-6414 Mon, 16 Apr 2018 14:07:06 +0000 lbruju 6414@http://www.k-wave.org/forum/ <p>Hi Bradley,<br /> thanks a lot for your help.<br /> lbruju </p> http://www.k-wave.org/forum/topic/focused-ultrasound-beam-using-round-emitter#post-6400 Mon, 09 Apr 2018 10:43:25 +0000 Bradley Treeby 6400@http://www.k-wave.org/forum/ <p>Hi lbruju,</p> <p>You could do it manually fairly easily, or use <code>numpy.unravel_index</code> with the column-wise flag.</p> <p>Brad. </p> http://www.k-wave.org/forum/topic/focused-ultrasound-beam-using-round-emitter#post-6399 Mon, 09 Apr 2018 10:07:03 +0000 lbruju 6399@http://www.k-wave.org/forum/ <p>Hi Brad, </p> <p>Thanks for your answer.<br /> I am simulating with the C++ code and I am creating the hdf5 file with python, so I don't have the function makeMultiBowl. That's why it seems to be hard to obtain the index of all the points defining all the 256 disc elements.<br /> If there isn't an easier way to simulate this, I will simplify the issue and try to simulate the pressure field with a transducer made of 8 rings, with a different input signal for each ring. </p> <p>I am a little bit lost concerning the index. If I know that a point which has coordinates (x,y,z) in the 3D grid is a source point, how could I calculate the index associated to this point (to define correctly <code>p_source_index</code>) ? (Knowing that I am generating that in python)</p> <p>Thanks a lot,<br /> lbruju </p> http://www.k-wave.org/forum/topic/focused-ultrasound-beam-using-round-emitter#post-6398 Sun, 08 Apr 2018 19:12:44 +0000 Bradley Treeby 6398@http://www.k-wave.org/forum/ <p>Hi lbruju,</p> <p>The function <code>makeMultiBowl</code> will also return a labelled matrix. You can then use this to decipher how to arrange the source terms in <code>source.p</code>. For example, let's say you have the driving signals for each physical element stored in a matrix called <code>source_sigs</code> which has dimensions <code>num_bowls</code> by <code>Nt</code>. You could then do something like the following:</p> <pre><code>clearvars; % define grid parameters x_size = 150e-3; Nx = 128; dx = x_size / Nx; grid_size = [Nx, Nx, Nx]; % create a Cartesian sphere with the x, y, z positions of the bowls sphere_radius = 70e-3; num_bowls = 32; bowl_pos = makeCartSphere(sphere_radius, num_bowls, [1, 1, 1] * x_size / 2).&#39;; % convert the Cartesian bowl positions to grid points bowl_pos = round(bowl_pos/dx); % define element parameters radius = round(x_size / (2 * dx)); diameter = 13; focus_pos = [1, 1, 1] * Nx/2; % create bowls [bowls_binary, bowls_labelled] = makeMultiBowl(grid_size, bowl_pos, radius, diameter, focus_pos); % create source signals (random in this example) Nt = 200; source_sigs = rand(num_bowls, Nt); % assign source mask source.p_mask = bowls_binary; % collapse the labelled bowl matrix to remove zeros bowls_labelled = bowls_labelled(bowls_labelled ~= 0); % assign source signals, looping through each grid point that forms part of % the source source.p = zeros(sum(bowls_binary(:)), Nt); for loop_index = 1:length(bowls_labelled) source.p(loop_index, :) = source_sigs(bowls_labelled(loop_index), :); end</code></pre> <p>Hope that helps,</p> <p>Brad. </p> http://www.k-wave.org/forum/topic/focused-ultrasound-beam-using-round-emitter#post-6378 Tue, 03 Apr 2018 08:18:11 +0000 lbruju 6378@http://www.k-wave.org/forum/ <p>Hi, </p> <p>I want to mimic the evolution of pressure using an ultrasound probe. This probe has a bowl shape and is made of 256 'disc elements' with, each, different input signal. </p> <p>How it could be possible to model that? Define the index of all these elements in <code>p_source_index</code> is possible. But define the matrix <code>p_source_input</code> with a size <code>np.size(p_source_index)</code>x<code>np.size(input_signal)</code> seems to be impossible. </p> <p>Thanks a lot,</p> <p>lbruju </p> http://www.k-wave.org/forum/topic/focused-ultrasound-beam-using-round-emitter#post-5806 Wed, 04 Jan 2017 14:40:39 +0000 Bradley Treeby 5806@http://www.k-wave.org/forum/ <p>Hi ultrasoundlearner,</p> <p>We are working on a new release at the moment, and hope to have it out sometime in the next few months.</p> <p>Brad. </p> http://www.k-wave.org/forum/topic/focused-ultrasound-beam-using-round-emitter#post-5789 Wed, 14 Dec 2016 20:44:06 +0000 ultrasoundlearner 5789@http://www.k-wave.org/forum/ <p>Hi Bradley, </p> <p>I'm interested in using the makeMultiBowl function as introduced in your recent UFFC paper to simulate a HIFU phased array comprised of 256 circular elements. You mentioned that this function will be included in the next k-Wave release. May I ask, when will the next release be available. Forgive me if the information has already been posted on this website. I'm new to the forum. </p> <p>Thanks! </p> http://www.k-wave.org/forum/topic/focused-ultrasound-beam-using-round-emitter#post-5427 Thu, 17 Mar 2016 14:44:43 +0000 Bradley Treeby 5427@http://www.k-wave.org/forum/ <p>Hi Songwriter45,</p> <p>It might be possible to use a circular radiator with the appropriate time delays to mimic a focused bowl transducer near the focal region, but the radius and focus parameters will likely need to be optimised (e.g., see <a href="http://scitation.aip.org/content/aip/proceeding/aipcp/10.1063/1.4934443">this reference</a>, Fig. 1). Keep in mind that the two will not agree over the whole field.</p> <p>If you want to model focused emitters, the best approach would be to model the source geometry explicitly. We have written a new function called <code>makeBowl</code> (described in <a href="http://www.homepages.ucl.ac.uk/~rmapbtr/papers/CONF_24_2015_Ling_IEEE_DiscreteBowlModel.pdf">this paper</a>) which will be included in the next k-Wave release that gives very good agreement. I'm happy to send you an early version of this function if that would be helpful.</p> <p>To mimic the field of an unfocussed plane piston transducer, just use <code>makeDisc</code> and drive it uniformly, i.e., don't use the <code>focus</code> function.</p> <p>Hope that helps,</p> <p>Brad. </p> http://www.k-wave.org/forum/topic/focused-ultrasound-beam-using-round-emitter#post-5410 Fri, 04 Mar 2016 14:24:43 +0000 Songwriter45 5410@http://www.k-wave.org/forum/ <p>Hello.</p> <p>I'm researching into ultrasound propagation through human skull, and firstly, I'm trying to define the emitter in a 3D medium.<br /> In our laboratory we have round and curved emitters, so I decided to create the emitter mask with the function "makeDisc" and then using the function "focus" to finally obtain the simulated round and curved focused emitter.</p> <p>The problem I found is that I obtained the pressure in the central axis, and I compared it to the analytical solution of O'Neil (Theory of focusing radiators), and the results are different. So, why are they different? The combination of the two functions "makeDisc" and "focus" is not realistic? Is there any other possibility of simulating a round and curved focused ultrasound emitter?</p> <p>Thank you. </p>