http://www.k-wave.org/forum/topic/definition-of-cyst-phantom-1 Support for the k-Wave MATLAB toolbox en-US Wed, 13 May 2026 00:22:10 +0000 http://bbpress.org/?v=1.0.2 q http://www.k-wave.org/forum/search.php http://www.k-wave.org/forum/topic/definition-of-cyst-phantom-1#post-5389 Tue, 16 Feb 2016 02:34:02 +0000 Bradley Treeby 5389@http://www.k-wave.org/forum/ <p>Hi sepand,</p> <p>The input signal is completely arbitrary. However, keep in mind that you should restrict the maximum frequency in the input signal to the maximum frequency supported by the grid. You can do this using <code>filterTimeSeries</code> if needed.</p> <p>Regarding your cyst phantom, the code snippet doesn't run. What is the problem exactly? </p> <p>Brad. </p> http://www.k-wave.org/forum/topic/definition-of-cyst-phantom-1#post-5383 Mon, 15 Feb 2016 11:39:07 +0000 sepand 5383@http://www.k-wave.org/forum/ <p>Dear Ben Cox &amp; Bradley Treeby<br /> I am working on harmonic ultrasound imaging. I am using k-Wave for my simulations, but I have two main questions about k-Wave,<br /> The first is about the excitation signals. I want to know that can k-Wave do the simulations with other types of excitation signals (input signals) except the Gaussian pulse?<br /> The second is about the cyst phantom. I does my simulations on wire targets and I have get good images of them. I want to evaluate my simulations for cyst phantom and I want to have a cyst phantom with low intensity inside (black) and homogeneous, and random scatterers outside the cyst phantom with high intensity than inside (bright), but in simulations I can’t see the cyst clearly.<br /> My cyst phantom code is:</p> <p>background_map_mean = 1;<br /> background_map_std = 0.0008;<br /> background_map = background_map_mean + background_map_std*randn([Nz, Nx]);</p> <p>% define a random distribution of scatterers for the highly scattering<br /> % region<br /> scattering_map =randn([Nz, Nx]);<br /> scattering_c0 = c0 + 25 + 75*scattering_map;<br /> scattering_c0(scattering_c0 &gt; 1600) = 1600;<br /> scattering_c0(scattering_c0 &lt; 1400) = 1400;<br /> scattering_rho0 = scattering_c0/1.5;</p> <p>% define properties<br /> sound_speed_map = c0*ones(Nz, Nx).*background_map;<br /> density_map = rho0*ones(Nz,Nx).*background_map;</p> <p>% define a sphere for a highly scattering region<br /> scattering_region1 =sqrt(xx.^2+(zz-40e-3).^2)&lt;5e-3;<br /> scattering_region1=ones(Nz,Nx)-scattering_region1;<br /> % assign region<br /> sound_speed_map(scattering_region1 == 1) = scattering_c0(scattering_region1 == 1);<br /> density_map(scattering_region1 == 1) = scattering_rho0(scattering_region1 == 1);</p> <p>% assign to the medium inputs<br /> medium.sound_speed = sound_speed_map;<br /> medium.density = density_map;<br /> figure<br /> imagesc(medium.density)</p> <p>colormap(gray(128))</p> <p>Thanks in advanced for your help<br /> Best regards<br /> Sepand </p>