Hi Alex,
you do not get the photon number, you get a more meaningful quantity
that is the photon tracklength [cm], namely the path travelled by photons
over that region. If you divide this quantity by the region volume, you
get the *average* photon fluence [cm-2] over that region. Other kinds of
USRBIN (Cartesian and cylindrical) give you directly photon fluence, since
they already divide by the respective regular bin volume. If in turn you
multiply that by the latter, then you get again photon tracklength. All
physical effects (energy deposition, i.e. dose, and detector response)
depend on the particle tracklength, not the particle number.
Kind regards
Francesco
**************************************************
Francesco Cerutti
CERN-EN/STI
CH-1211 Geneva 23
Switzerland
tel. +41 22 7678962
On Wed, 30 Jan 2019, Ševčik Aleksandras wrote:
>
> Dear all,
>
> It seems that my question most likely unclear, so let me rephrase it to be
> more specific and technical:
>
>
>
> When scoring PHOTONS using usrbin region, do you get the total or average
> photon number in the region for that specific simulation? Then total number
> of photons in the region can be get by integrating usrbin photon x-y-z
> scoring?
>
>
>
> A.
>
>
>
> From: owner-fluka-discuss_at_mi.infn.it <owner-fluka-discuss_at_mi.infn.it> On
> Behalf Of Ševcik Aleksandras
> Sent: Friday, 25 January, 2019 01:13
> To: fluka-discuss_at_fluka.org
> Subject: [fluka-discuss]: spectrum normalization and actual dose
>
>
>
> Dear experts,
>
>
>
> I would like to get the actual dose values from the simulation and want to
> know if the approach below is valid.
>
> I am using source.f to generate realistic x-ray beam from specialized x-ray
> simulation software which gives me the spectrum and fluence. Integrating it
> I can get the estimated actual number of photon, let’s say 10E7. In the
> simulation I can use USRBIN for all regions to score the overall number of
> photons detected in the simulation, let’s say 10E2. So in the same
> simulation I can use this factor 10E7/10E2 for dose values as well to get
> the actual dose values for the specific x-ray tube.
>
> I have tried to run the test simulation with 100x100x100 water cube in the
> vacuum. In the beginning I was integrating usrtrack fluence energy spectrum
> but later saw that usrbin region photon scoring gives the same value. So
> multiplying usrbin total dose value by this fluence actual/simulated factor
> and converting it to Gy gives me around 7E5 Gy – as it was expected from 80
> kvp *1 mAs_at_1meter x-ray beam.
>
> However if this approach is not valid, I would appreciate any comment what
> would be the correct way to do this.
>
>
>
> Regards
>
> Alexander
>
>
>
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Received on Wed Jan 30 2019 - 10:59:46 CET