Re: [fluka-discuss]: isotope source anisotropy

From: 委v鋱k Aleksandras <>
Date: Mon, 20 Mar 2017 20:35:51 +0000

Hi Paola,

Thanks :) I forgot to mention that I'm modeling the encapsulated source - I did not expect that the encapsulation will have such a big effect on the dose homogeneity. Yet it seems I was very wrong.

I run the simulation with and without encapsulation, see attached picture. Poor statistics, but fits for an illustration.

It seems that with the encapsulation I'm getting the same similar shapes the one can find in the literature.

I found one paper with measured dose in the phantom, see attached picture (source :Hurley, C., et al. "High-resolution gel dosimetry of a HDR brachytherapy source using normoxic polymer gel dosimeters: preliminary study." )

By the way, I'm running the simulation with defaults PRECISIO, which has 100 keV particle transport threshold - so for any generated electron <100 keV the dose is scored immediately at that point ? Would lower threshold, let's say, 50 keV, be more accurate, if I can say so ? Wouldn't be defaults EM-CASC with lower particle threshold be the most optimal setup regarding time and accuracy of the dose scoring in the water/tissue for this specific radionuclide (Ir192)?

The insights would be much appreciated,


From: Paola Sala <>
Sent: Monday, March 20, 2017 9:10:18 AM
To: 委v鋱k Aleksandras
Cc: Alfredo Ferrari
Subject: Re: [fluka-discuss]: isotope source anisotropy

Dear Aleksandras
I tried to reproduce your simulation, but I get a completely symmetric
plot, no apples.Could you, please, send me the input file, and the details
of the plotting axis/limits ?

> Dear experts,
> I am comparing my modelling results of Ir192 isotope source in the water
> and would expect slightly different shape instead of "apple" I got. See
> the picture with included result and comparison pictures.
> Source Ir192, cylindrical 3,5x0,6 mm, water cube 20x20x20 cm, rad-decay
> semi-analogue, no cuts, usrbin x-y-z scoring 20x20x20 containing
> 150x150x150 bins.
> Any comments much appreciated,
> Regards
> Aleksandras

Paola Sala
INFN Milano
tel. Milano +39-0250317374
tel. CERN +41-227679148

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Received on Mon Mar 20 2017 - 22:52:04 CET

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