Re: FLUKA defaults and necessary cards for medical applications =

=20
  (i.e. low energy)
Sender: owner-fluka-discuss_at_mi.infn.it

In my opinion, PRECISIO is unnecessarily resource-consuming for your task,
unless you are also interested in photoneutron production, which is
possible at the highest end of your energy range. (But in that case,
don't forget to add a PHOTONUC and a LAM-BIAS card!)

For a pure electron-photon calculation, I would suggest to use the=20
default EM-CASCA. It has already a low energy cut-off (10 keV, I think), bu=
t you
can still lower it by command EMFCUT as suggested by Giuseppe.
The delta ray production, for electrons and positrons, is not governed by
DELTARAY, but also by EMFCUT, but with SDUM=3DPROD-CUT. The default is not
always reliable, so I recommend that you set it yourself to the value you w=
ant.
Ionization fluctuations are on by default with EM-CASCA, so you don't need
to request them.
For more accuracy, you may consider decreasing the value of energy loss
per step from the default 20% to 5-10% by means of EMFFIX (with some penalt=
y
in CPU time, of course).

With EM-CASCA, it is not possible to request photonuclear reactions. But
in its restricted area of application, it will give you as good results as
PRECISIO and will probably be more efficient.

Alberto

On Wed, 14 Jan 2009, Giuseppe Battistoni wrote:

> (smtp1.mi.infn.it [192.84.138.69]); Wed, 14 Jan 2009 19:56:32 +0100 (CET)
> X-Greylist: Sender DNS name whitelisted, not delayed by
> milter-greylist-4.0 (smtp1.mi.infn.it [192.84.138.69]); Wed, 14 Jan 2009
> 19:56:32 +0100 (CET)
> Sender: owner-fluka-discuss_at_mi.infn.it
>
> Dear Roger
> it is indeed a low energy application, but other people already apply
> FLUKA with success in similar medical applications.
> PRECISION is already a good default set, but you can do even better if yo=
u
> like. You can see in the manual that the energy threshold for particles i=
s
> set at 100 keV when using PRECISIO.
> You can overwrite settings. For instance you can lower the production
> threshold for e+,e-,gammas, down to 1 keV using EMF-CUT (you can adjust
> separately production threshold and transport threshold). You can also
> lower delta-ray cut-off with DELTARAY.
> Of course the lower is the energy cut for e+e- the larger will be the
> CPU time demand. It's up to you to find the trade-off suitable for your
> case...
> Best regards
> Giuseppe Battistoni
>
> On Mer, 14 Gennaio 2009 2:11 pm, Roger H??lg wrote:
>>
>> Dear FLUKA experts
>>
>> I am preparing some simulations for medical applications in radiation
>> oncology. Therefore I am dealing with electron beams of 6 MeV and 15 MeV=
=2E
>> Comparing with other problems I would say that this is a real low energy
>> application for FLUKA.
>>
>> My question is now what specific cards do I need or do I have to be awar=
e
>> of to handle this energy regime best?
>>
>> Concerning the DEFAULTS card I think that PRECISIO is the best choice
>> according to the manual. Any comments about this?
>>
>> I also had a look once again at the lecture notes about "Voxels and
>> Medical
>> Applications". But I couldn't find any hints for my questions.
>>
>> Thank you very much for your help!
>>
>> Greetz
>>
>> Roger
>>
>
>
>

--=20
Alberto Fass=F2
SLAC-RP, MS 48, 2575 Sand Hill Road, Menlo Park CA 94025
Phone: (1 650) 926 4762 Fax: (1 650) 926 3569
fasso_at_slac.stanford.edu
--1334205520-1208622578-1231962542=3D:5945--
Received on Wed Jan 14 2009 - 21:17:32 CET