Re: Deposit dose

Hi,

actually just running your Si beam input one gets 0.2 cGy as measured.

DOSE values scored by USRBIN *per region* represent in fact the ratio
between the energy deposited over the whole region and the material
density (i.e. GeV*cm3/g) and need to be divided by the region volume in
order to get dose. Despite the fact that you input the region volumes,
which are used only for renormalizing the quantities scored by the SCORE
card, as pointed out in the manual (SCORE card). So applying the GeV/g->Gy
conversion and multiplying by the integrated beam intensity (24480*20*20
ions) you end up finding the expected number.

By the way, energy deposition density (GeV/cm3) and dose (GeV/g) are
intensive quantities and, as such, in an uniform radiation field do not
depend on the volume/mass extent.

All the best

Francesco

**************************************************
Francesco Cerutti
CERN-EN/STI
CH-1211 Geneva 23
Switzerland
tel. ++41 22 7678962
fax ++41 22 7668854

On Wed, 26 Jan 2011, Jean-Emmanuel Groetz wrote:

> Dear Fluka users,
>
> Further to my previous message last week, I have still problems to
> assess the dose deposited by heavy ions in a cell culture.
> Anna and Francesco (thanks to them) show me the right way to define a
> rectangular beam (especially the delta x and y parameters).
>
> To get the deposit dose in the cell culture (inside a µ-dish), I use
> USRBIN with the dose option. I have noticed that if I change the volume
> of the region corresponding to the cell culture, it has no effect on the
> dose result.
>
> I would like to know if I misunderstand something :
> - dose result is given in GeV/g/primary
> - energy deposition is given in GeV/cm3/primary
> - since the dose is in J/kg, the mass (or the volume) of the region
> should have an importance.
>
>
> In the attached example (Si ions at 600 MeV/A, 24480 ions/cm2, 20x20cm2
> for the beam size), the dose is about 0.8 cGy (the experimental dose is
> ~0.2 cGy and my MCNPX calculations give 0.27 cGy). For Fe ions (1 GeV/A,
> 8323 ions/cm2, same beam size), the dose from Fluka is the same, i.e.
> 0.8 cGy (good news!!), but it's still not the expected result, i.e 0.2
> cGy.
>
> What I am doing wrong or what I have forgotten ?
>
> Thanks in advance.
> Jean-Emmanuel
>
>
> --
> _____________________________________________
>
> Jean-Emmanuel Groetz
> Laboratory of Physical Chemistry and Radiation
> University of Franche-Comte
> 16, route de Gray
> 25030 Besancon Cedex
> France
>
> mailto: jegroetz_at_univ-fcomte.fr
> phone: +33 3 81 66 65 07
> fax : +33 3 81 66 65 22
> ______________________________________________
>
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Received on Sat Jan 29 2011 - 15:02:20 CET