Re: FLUKA defaults and necessary cards for medical applications (i.e. low energy)

Thank you very much for your hints!

For the 6 MeV electron beam I will try the EM-CASCA defaults, since I am
only interested in neutrons in case of the 15 MeV beam. But there the
photoneutron production is necessary since the neutron doses get more and
more attention in radiation therapy.

Best regards

Roger

On Wed, 14 Jan 2009 11:49:02 -0800 (PST), "Alberto Fasso'"
<fasso_at_slac.stanford.edu> wrote:
> 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
> default EM-CASCA. It has already a low energy cut-off (10 keV, I think),
> but 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=PROD-CUT. The default is not
> always reliable, so I recommend that you set it yourself to the value you
> want.
> 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
> penalty
> 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
>> you
>> like. You can see in the manual that the energy threshold for particles
>> is
>> 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.
>>> 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
>>> aware
>>> 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
>>>
>>
>>
>>
Received on Thu Jan 15 2009 - 22:57:18 CET