[Gate-users] Mean energy vs. Radial distance in Elekta Precise 6MV phase-space data

[Stathis Kamperis]

Στις 9 Μαϊ 2014 10:28 π.μ., ο χρήστης "Stathis Kamperis" <ekamperi at gmail.com>
έγραψε:
>
> Hello everyone,
>
> I'm using the Elekta Precise 6MV phase space data from the site of
> IAEA. I was plotting the mean photons' energy vs. radial distance and
> there's a peak around ~6-7.5cm that I cannot explain:
>
> http://dl.dropboxusercontent.com/u/25202446/peak.png
>
> Also, the graph from here
> http://www.creatis.insa-lyon.fr/~dsarrut/articles/Grevillot2011.pdf
> lacks such a peak (not sure if it is the same exact linac model).
>
> The closest clue I could get is from Grevillot et al:
>
> "... step in the particle radial fluence is observed between 65 and 70
> mm in (b), corresponding to interactions of the photons with the flat
> bottom edge of the flattening filter."
>
> Do you have any suggestion on how to interpret my results ? Perhaps
> the simulation of the IAEA phase-space data used a smaller flattening
> filter ? And too many photons pass through its edge ?

Actually that doesnt make sense. We are plotting mean energy, not fluence.

(I think that
> the plot code is correct, since it uses the fields package of R.)
>
> Thank you for your consideration,
>
> Best regards,
> Stathis
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