[Gate-users] Simple Particle Counting Actor

[Andreas Resch]

Am 2017-06-07 18:46, schrieb Akiv Jhirad:
> Hello,
> 
> I have currently been using the DoseActor attached to a small geometry
> (representing my detector) with a resolution of 1x1x1 along with the
> NumberOfHits parameter, to find the total number of particles
> interacting with my detector. Is there a better alternative to achieve
> the same task?
> 
> I wanted to try the FluenceActor but don't want my output being of
> .mhd format. Will I simply get the number of particles detected in my
> detector if I just change the output format to .txt instead of .mhd?
> 
> --
> Best Regards,
> Akiv Jhirad
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Hi,

I didn't know that there is the number of Hits option in the dose actor. 
However, I checked in the source code and this is the line of interest 
(version 7.2):
if (mIsNumberOfHitsImageEnabled) mNumberOfHitsImage.AddValue(index, 
weight);

so, this is definitely not the fluence, but rather gives you the number 
of energy depositions in a voxel. You could try to half or double your 
step limiter, then you should see an increase or decrease of number of 
hits.

The second option, the fluence actor implementation is more complex. It 
seems, that number of particles is scored if a geometry boundary is 
crossed. So, this actor using the option "/enableNumberOfHits true" 
would probably give you the total number of particles entering your 
detector.

Note that this number of hits is not the fluence, as fluence is 
according to ICRU report 85 defined as:
"The fluence, Phi, is the quotient of dN by da, where dN is the number 
of particles incident on a sphere of cross-sectional area da"

Yes, if you want txt output instead of mhd, just change the extension in 
the actor.


Cheers,
Andreas