http://www.k-wave.org/forum/topic/alpha-power-coefficient-for-hifu-propagating-through-a-heterogenous-medium Support for the k-Wave MATLAB toolbox en-US Tue, 12 May 2026 22:31:15 +0000 http://bbpress.org/?v=1.0.2 q http://www.k-wave.org/forum/search.php http://www.k-wave.org/forum/topic/alpha-power-coefficient-for-hifu-propagating-through-a-heterogenous-medium#post-9148 Fri, 04 Oct 2024 15:16:44 +0000 scmmw 9148@http://www.k-wave.org/forum/ <p>Hi Ben,</p> <p>That makes sense, thanks so much!</p> <p>Best wishes,</p> <p>Manisha </p> http://www.k-wave.org/forum/topic/alpha-power-coefficient-for-hifu-propagating-through-a-heterogenous-medium#post-9132 Wed, 28 Aug 2024 18:23:53 +0000 bencox 9132@http://www.k-wave.org/forum/ <p>Hi scmmw,</p> <p>Yes, `medium.alpha_power' must be a scalar. It's a restriction of the method that k-Wave uses to compute the absorption term. As you're doing a HIFU simulation it's presumably at a single driving frequency, so you just have to ensure that the value of the absorption coefficient alpha = alpha_coeff * f^alpha_power is the correct value for that frequency, eg. set alpha_power to 2 and then adjust alpha_coeff until alpha is the value you need.</p> <p>Hope that helps.</p> <p>Best wishes<br /> Ben </p> http://www.k-wave.org/forum/topic/alpha-power-coefficient-for-hifu-propagating-through-a-heterogenous-medium#post-9109 Thu, 11 Jul 2024 15:51:43 +0000 scmmw 9109@http://www.k-wave.org/forum/ <p>Hi, I am trying to model HiFU through a heterogeneous medium but I am struggling with how best to approach assigning the alpha power coefficient as I am propagating the ultrasound through three different regions: water, fat and tissue. </p> <p>Each region has a different alpha power value based on experimental data values. However, kWave only allows for a scalar value of alpha_power rather than a matrix. I discovered on the forum the function fitPowerLawParamsMulti, but this still requires picking a reference value y_ref.</p> <p>Currently, the three values for alpha power are the following,</p> <p> % define different absorption properties for different regions<br /> medium.alpha_power = 1 * ones(Nx, Ny); % [dB/(MHz^y cm)] - Water<br /> medium.alpha_power(Region_2{j}) = 0.4; % [dB/(MHz^y cm)] Region 2 - Fat<br /> medium.alpha_power(Region_3{j}) = 1.41; % [dB/(MHz^y cm)] Region 3 - Tissue</p> <p>When I use the function, it plots a graph, and based on the point where the lines overlap for each three regions, I changed the y_ref to be a value in between the points of overlap for Region 2 and 3, which is roughly 0.55. Is this the correct approach to define a y_ref, or am I misunderstanding how best to define y_ref? Any advice on how to go about this would be much appreciated! </p>