Date: Thu, 30 Jun 2016 13:30:32 +0000
Hi Vasilis,
Thank you very much for details. So only dose per 1 decay? So how to get a dose map for the experiment I described? Ok let's say for sake of example I estimate 1e6 decays from my source per s, in total 30 s => 30e6 decays. Should I use this estimation as normalization factor, when I want to see the overall dose map in the volume? In other words multiply the result by 30e6 and then multiply by 1.602e-7 to convert the GeV/g to Gy ?
Or is there any relation to START and number of primary histories?
Reg DCYSCORE: it is used in the example
https://indico.cern.ch/event/334606/contributions/779776/attachments/653352/898390/AdvancedActivation_2014.pptx.pdf
It's such a nice example, however, due to huge gaps in my knowledge I am even unable to clearly understand it, see attached picture. TCQUENCH is set to 3600 s, so does it mean that USRBIN 1hpdose is accumulating dose per one decay for 3600 s or what ?
I feel I am asking very basic questions and do not get the fundamental principles; however, if I could get through them, I think I could go on more easily, so I appreciate your answers very much
Regards
Aleksandras
________________________________
From: Vasilis Vlachoudis <Vasilis.Vlachoudis_at_cern.ch>
Sent: Thursday, June 30, 2016 2:33:59 PM
To: Ševčik Aleksandras; fluka-discuss_at_fluka.org
Subject: RE: modelling radioisotope in the water container - medical applications -
Hi Alexander,
1. PRECISION
the cards you are mentioning are correct
2. As it is mentioned in Note.8 of the BEAM card you get the results per DECAY. It is up to you
to calculate the number of decays for your volume.
3. As it is also mentioned in Note.8 you cannot use the IRRPROFI nor DCYTIMES, so you cannot
model the isotope to be present for 30s.
Again you have to do the normalization by hand assuming how many decays you will have in 30s.
TCQUENCH can be used to limit the USRBIN scoring for the first 30s
When you score DOSE is already divided by the density. The note refers if you want to score ENERGY
and convert it to DOSE.sa
Just multiply the result with 1.602e-7 to convert the GeV/g to Gy
4. DCYSCORE cannot be used in the semi-analogue decay run, only in the normal activation
run where you have a prompt beam with a certain irradiation profile generating activated nuclei
and you want to simulate their decays.
Voxels geometry can be used if you want to model something that normal combinatorial geometry
is not sufficient like a full body from a CT scan.
Cheers
Vasilis
________________________________
From: owner-fluka-discuss_at_mi.infn.it [owner-fluka-discuss_at_mi.infn.it] on behalf of Ševčik Aleksandras [aleksandras.sevcik_at_ktu.edu]
Sent: Thursday, June 30, 2016 09:20
To: fluka-discuss_at_fluka.org
Subject: [fluka-discuss]: modelling radioisotope in the water container - medical applications -
Dear all,
I'm new to Fluka and some misc details are hard to grasp with available tutorials. I didnt not have any such experience before and I am medical physicist student (more oriented into the medicine than theoretical physics) so I spent a great deal of time in trying to understand the code. If someone could help me with the case below, hopefully one day I'll be able to be an active Fluka community member myself and help others as well.
I am interested in modelling brachytherapy. For the initial setup I have a water container and incapsulated iridium-192 source.
For the sake of experiment: activity of the source 1.665e+13 bq (mass 1 g), and I want to keep it in the container for 30 sec. I would like to get a dose map in Gy.
1) DEFAULTS: EM–CASCAde enough or PRECISION?
BEAM: sdum ISOTOPE, no other values needed. Then using HI-PROPE for declaring isotope (A & Z) and selecting BEAMPOS.First BEAMPOS with no SDUM, stating the center of source, and adding 2nd BEAMPOS with sdum CYLI-VOL.
Adding RADDECAY: semi-analogue, the rest is default
Adding DCYSCORE: semi- analogue, USRBIN
2) question: in such mode, how should I specify the amount (activity) of radioisotope? Is it calculated automatically (volume*density) by FLUKA in regards to BEAMPOS CYLI-VOL ?
3) question: how to specify the time the radioisotope is allowed to be in the water container? TCQUENCH card?
Finally, adding USRBIN, X-Y-Z, DOSE. As I understand I'll get DOSE in GeV/g. How should I apply normalization factor 1.602 E-7/r, where r is a water density in this case, r= 1 g/ cm3, so norm factor 1.602 E-7
4) question: where should I put this norm factor? and why sometimes I can see several USRBIN in similar examples, associated later with DCYSCORE?
Last question: maybe it is necessary to use a voxel geometry in such cases? But USRBIN allows to get doses and without it? So in which cases voxel geometry is preferred?
Kind thanks to anyone willing to share,
Regards
Alexander
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(image/jpeg attachment: example.jpg)