[Gate-users] Simulation problems with time-activity curves (TAC)

[David Sarrut]

Hi,

sorry, personally, I never used such a feature, so not sure I can help. You
may found related source code:
https://github.com/OpenGATE/Gate/blob/develop/source/physics/src/GateVSourceVoxelReader.cc
https://github.com/OpenGATE/Gate/blob/develop/source/physics/src/GateSourceVoxellized.cc

Why not using time-integrated TAC as input activity rather than a dynamic
simulation?

regards,
David


On Mon, Apr 26, 2021 at 9:02 AM Benoît Presles <
benoit.presles at u-bourgogne.fr> wrote:

> Dear gate users,
>
> I am reaching out to you to ask for your help concerning a GATE simulation
> that I am working on at the moment. I am trying to perform a dynamic
> simulation by integrating time-activity curves (TAC) to a voxelized NEMA
> phantom geometry. I use a CT image as the phantom (*CT.mha)* and a
> labeled image (*CTMuliLabel.mha), *of the same size as the phantom image,
> as my activity image. In order to perform the TAC implementation I followed
> the example provided on the GateContrib on
> github: https://github.com/OpenGATE/GateContrib/tree/master/imaging/TimeActivityCurve
> <https://github.com/OpenGATE/GateContrib/tree/master/imaging/TimeActivityCurve>
>
> However, I noticed that GATE doesn't seem to be taking into account my TAC
> even though I believe to have correctly followed the example. In my
> experience, Gate only seems to consider the *activityRange.dat *file when
> defining the activity and not the *acti.range* which indexes the TAC to
> be used. What is weird is that while compiling the simulation, the verbose
> I get in the terminal shows that the TAC file has been read but the
> activity values contained in the file are not given to the corresponding
> voxels. In order to verify this, I did a simulation with and without the
> TAC integration while keeping an identical seed and the generated results
> are identical. Therefore, I concluded that my simulation only takes into
> account the activities entered in the *activityRange.dat* file and
> completely ignores the TAC indexed in the *acti.range *file.
>
> Linked below in the email you can find a link
> <https://drive.google.com/drive/folders/1NeWu2e1eojkL03pUZKUqq_-9IKmK8MUN?usp=sharing>to
> a simplified version of my simulations with and without TAC along with the
> necessary data (in the data folder). To run the simulation you simply need
> to run one of the main macros:
>   - for the simulation with TAC: *Gate mac/main_with_TAC.mac*
>   - for the simulation without TAC: *Gate mac/main_with_NO_TAC.mac*
>
> Pay attention to the fact that "total activity (Bq)" provided by the Voxel
> reader verbose only takes into account the value provided in the *activityRange.dat
> *(the value in this field is obtained by multiplying the activity
> provided in the *activityRange.dat *file, which is 8 Bq for voxels with
> an intensity of 8, and the number of pixels which have an intensity of 8,
> which are 13939 in my example):
> [image: image.png]
>
> Other than wanting to know why the simulation doesn't take into account
> the TACs, I have some other questions as well:
>
> 1) Why do we still need the activityRange.dat file in a dynamic setting?
> Since we use TACs, I do not understand the use of using a rangeTranslator
> and the activityRange.dat
>
> 2) Is there a better or newer method to attribute TACs to a voxelized
> geometry?
>
> Thank you for your time.
>
> Best regards,
> Ben
>
>
>
> https://drive.google.com/drive/folders/1NeWu2e1eojkL03pUZKUqq_-9IKmK8MUN?usp=sharing
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> Gate-users at lists.opengatecollaboration.org
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-- 
David Sarrut, Phd
Directeur de recherche CNRS
CREATIS, UMR CNRS 5220, Inserm U1294
Centre de lutte contre le cancer Léon Bérard
28 rue Laënnec, 69373 Lyon cedex 08
Tel : 04 78 78 51 51 / 06 74 72 05 42
http://dsarrut.github.io <http://www.creatis.insa-lyon.fr/~dsarrut>
_________________________________
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