[fluka-discuss]: RE:Scoring of annihilation photons

From: Ricardo Manuel Dos Santos Augusto <r.s.augusto_at_cern.ch>
Date: Wed, 22 Jul 2020 14:40:41 +0000

Dear Karolina,

Regarding the scoring of annihilation events at rest, this can be done directly in FLUKA using the ANNIHRST particle type in USRBIN.

The FLUKA PET tools are not (yet) available in the standard distribution. This said, you might still extract meaningful results using user routines.
You might want to have a look at the lectures on user routines and scoring in the last advanced fluka course, and the exercise on the use on mgdraw

Maybe you could use the mgdraw routine and an user-defined USERDUMP to print events of interest. For instance, you can use mgdraw's BXDRAW entry to define a boundary crossing into your detector and filter it to register only photons originating from annihilation events at rest in your target. Additional filters can be added (coordinates, direction cosines...among many others). You might also want to use stupre.f, set a user flag in the IESPAK array when the flag for annihilation at rest LANNRS is true (see common EVTFLG). This will be propagated to all daughters, and used for select scoring either in BXDRAW or in comscw.f or fluscw.f depending on the use. If you wish to filter out the rescattered photons from compton, you can un-set the flag again in stupre each time LCMPTN is true.
Note that this user-routine methodology is not as powerful as the PET tools since it does not allow for the signal reconstruction or the reproduction of the PET functionality but it might still provide valuable indicators.

Hope it helps.
Best regards,

//Ricardo dos Santos Augusto
Office: +1 604 222 10 47 (6375)
4004 Wesbrook Mall,
Vancouver, BC V6T 2A3, Canada//
De : owner-fluka-discuss_at_mi.infn.it [owner-fluka-discuss_at_mi.infn.it] de la part de Karolina Kokurewicz [karolina.kokurewicz_at_strath.ac.uk]
Envoyé : lundi 20 juillet 2020 17:14
À : fluka-discuss
Objet : [fluka-discuss]: Scoring of annihilation photons

Dear Fluka Experts,

I would like to investigate efficiency of a custom plastic detector for PET. I propagate 200 MeV electron beam through a 10x10x60 cm^3 PMMA phantom and I score all photons coming out of the phantom through the side walls. I would like to filter only the annihilation photons. I believe there are photons with energies of 511 keV that are not from annihilations (bremsstrahlung) and those that are from annihilations but scattered in the phantom and have energy lower than 511 keV. I would like to count all photons which were produced through positron annihilation and simulate the 2D map of annihilation events in my target using the USRBIN card. I used the EMCUT card to set kinetic energy threshold for e+/e- bremsstrahlung, higher than incident electron energy, to obtain 511 keV peak only from annihilations.


However, these photons could eventually produce positrons which could potentially annihilate. Therefore, I believe this is not the right way to do that. My other concern is that I get also prompt gammas from de-excitations of the target nuclei. How can I filter them?

I've been using fluka for dosimetry applications, therefore this topic is very new to me. Eventually, I plan to use the PET tool for more complex simulations but I can't find a tutorial about scoring. I created my detector geometry through the tool but there are no scoring cards inside the created input file. What I would like to obtain is listed on the page 13 of the presenation:



Sadly, I can't find anything about how to implement scoring (there is only a list of fluka routines on the last page). How can I generate the 'coincidences file in list mode' from the pages 16-23? Is the reconstruction algorithm available? This tool is everything I need, but apart from the tool which allows to define a PET gantry, I don't see any extra scoring cards for detection of photon pairs with the option to change the time window (time resolution) and filter only annihilation photons (without prompt gammas and bremsstrahlung).

Is this tool available from the standard fluka version?

Thanks in advance,


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Received on Wed Jul 22 2020 - 18:56:57 CEST

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