RBE-weighted doses for Radiosensitizers

[naninano1]

Hi,

I was wondering how we can apply a certain RBE value, caused by a radiosensitizer agent, into the CTV (in voxel or whole CTV scale) in dose calculations to see RBE-weighted dose distribution and DVHs for a PHOTON beam.

[naninano1]

Hi @wahln ,
I hope you don't mind mentioning you here. I was wondering if you could please guide me in this regard.
Thank you.

[wahln]

Hi @nanino1,
there is no pre-defined way to do it in matRad, I would just work on the output cubes you get after optimization (if you want to optimize for RBE-weighted photon dose, things would get a little messier, but it would also be possible). Steps would be:

1. Do a normal photon optimization, you obtain a resultGUI struct that has the cube physicalDose stored.
2. Get the index list of your ct voxels (let's call it ix and the corresponding vector of RBE for each index
3. Create the RBE map from the command line: resultGUI.RBE = ones(size(resultGUI.physicalDose)); resultGUI.RBE(ix) = RBE; This makes sure that the RBE is 1 everywhere you have not assigned a special value.
4. Create the RBE weighted dose: resultGUI.RBExD = resultGUI.physicalDose .* resultGUI.RBE(ix) = RBE;

After this, you should be able to select your RBE-weighted dose cube in the matRadGUI after refreshing.

[naninano1]

Hi Niklas,
Thank you very much for your reply.
For part 2, I did ix = cst{1,4}{1}; RBE= [1.2]; for the first index , GTV.
However, when I run resultGUI.RBExD = resultGUI.physicalDose .* resultGUI.RBE(ix) = RBE;, I get this error:
"Error: Incorrect use of '=' operator. To assign a value to a variable, use '='. To compare values for equality, use '=='."

[wahln]

Sorry, I was not really available last week. I see you could solve the issue?

[naninano1]

Hi Niklas,
No problem. Thanks for your consideration.
Yes, I could solve the issue. I redefined ix and RBE, also the dose map