Re: [fluka-discuss]: 192Ir isotope dose rate constant

From: Stefan Roesler <sroesler_at_mail.cern.ch>
Date: Sun, 9 Apr 2017 23:27:49 +0200

Dear Alex

Maybe tell exactly which value from which scoring card you used for the
100cm and 1cm doses.

For example, I see a scoring by region. Note that in this case FLUKA does
not divide by the volume of the scoring region, which you'll have to do
yourself offline.

Cheers
Stefan

On Tue, 28 Mar 2017, ?ev?ik Aleksandras wrote:

>
> Dear experts,
>
>
> In my pursuit to calculate the 192Ir dose distribution in the Zubal head
> phantom using Fluka code I got stuck again - this is time in calculating the
> dose rate constant. As no external help available for me locally, I would
> appreciate any insights or comment from you.
>
>
> As it is stated, the dose rate constant ? (cGy/U-hr) is defined as the dose
> rate to water at a distance of 1 cm on the transverse axis of a unit air
> kerma strength source in a water phantom.
>
> So it is necessary to measure both the reference air kerma rate at 100 cm
> and the absorbed dose rate to water  at 1 cm distance from the source
> perpendicular to the source axis
>
> I modelled the seed geometry and usrbin-ed the dose values in 150 cm radius
> sphere, filled with air and later- filled with water. In the air sphere the
> dose rate at 100 cm from the seed approx. 2.7E-17 Gy per decay that more
> less is what can be expected (400GBq would give ~39 mGy/hr in comparison
> with expected ~45 mGy/hr)
>
> The dose rate  in the water sphere at distance 1 cm from the seed surface is
> around 1.2E-13 Gy per decay. So here I stuck -  ther ref value for dose rate
> constant for 192Ir seed should be approx. 1.1 cGy/(U-hr). How to combine all
> this data to something like that?
>
> I assume there is a certain "obvious" thing I am missing, due to lack of
> experience.
>
> Input files are attached in case it is interesting. Dose rate values are
> scored in usrbin R-phi-z mesh then plotted as type 1D Max in Flair on R
> axis. However I tried many other options including setting detectors
> regions, etc. I also noticed that energy spectra is missing ~1.4 MeV spike
> in comparing with spectra from MCNP but maybe this is not related or there
> is other explanation for this.
>
> Regards
> Alex
>
>
>

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Received on Mon Apr 10 2017 - 00:35:40 CEST

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