Re: [fluka-discuss]: Normalization of results for x-ray tube output / source.f

From: Santana, Mario <msantana_at_slac.stanford.edu>
Date: Mon, 21 Aug 2017 01:46:24 +0000

Hi Alex,

Yes, it is viable.

But you can’t just count the total number of photons via USRBDX as this would simply lead you to the number of primaries (unless you used biased sampling), which is not what you want.

From the other question on the list I understand that you will score the spectrum of photons, which is the way to go.

This would be a way to do it:


1- Score spectrum with USRTRACK, as you suggested.

2- Multiply each value of USRTRACK by its energy width and convert cm^-2 to mm^-2

3- Integrate the spectrum of 2 (sum all bins)

4- Divide the peak in your function ‘spektasjpg.jpg’ (close to 1.85E4 photons/mm^2/mAs) by the peak of the histogram in step 2

5- Multiply the result of step 3 by the scaling factor of step 4

6- Divide 5 by (Emax-Emin)

-Mario



From: Ševčik Aleksandras <aleksandras.sevcik_at_ktu.edu>
Date: Saturday, August 19, 2017 at 1:57 AM
To: "Santana, Mario" <msantana_at_slac.stanford.edu>, fluka-discuss <fluka-discuss_at_fluka.org>
Subject: Re: [fluka-discuss]: Normalization of results for x-ray tube output / source.f


Hi, Mario,



Thank you very much, I was thinking about integration of the curve but could you please tell how viable is the option to place the plane detector in the front of phantom and to score the number of photon crossing it, thus I can calculate average number of photons per mm^2 - just for double check. USRBDX would be suitable for this?



Alex

________________________________
From: Santana, Mario <msantana_at_slac.stanford.edu>
Sent: Saturday, August 19, 2017 1:10:43 AM
To: Ševčik Aleksandras; fluka-discuss_at_fluka.org
Subject: Re: [fluka-discuss]: Normalization of results for x-ray tube output / source.f

Hi Alex,

If you take the function photons(E) that you plot in “spektasjpg.jpg’ and you compute <photons> = INT_{Emin,Emax}(photons(E) x dE) / (Emax-Emin), this will tell you how many photons/mm^2 in average you will produce per mAs of current for your x-ray source.
So, for a long enough simulation, you could just multiply the usual fluka normalization by that number:
(pSv/primary) x (photons/mAs) -------> (pSv/mAs) because primary=photons

of course this assumes that in your sampling ‘source.f’ routine you haven’t biased the weights of the starting photons.

-Mario

From: <owner-fluka-discuss_at_mi.infn.it> on behalf of Ševčik Aleksandras <aleksandras.sevcik_at_ktu.edu>
Date: Friday, August 18, 2017 at 1:25 PM
To: fluka-discuss <fluka-discuss_at_fluka.org>
Subject: [fluka-discuss]: Normalization of results for x-ray tube output / source.f


Dear experts,



I have made a test simulation but now I am not sure about the correct way to normalize the results.



I generated x-ray spectrum sample with SPEKTR 3.0 software, and using the help provided in this forum I was able to use modified source.f routine to re-create the beam and score the dose. I understand that that I get effective dose in pSv / primary. My question is what would be the correct approach to convert pSv/photon to pSv/mAs (x-ray Milliamp Seconds). Any comment / insight would be help,



Regards

Alex

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Received on Mon Aug 21 2017 - 05:05:37 CEST

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