RE: [fluka-discuss]: Stopping powers for proton therapy applications

From: Ferreira De Almeida Lourenco, Ana <am.lourenco_at_ucl.ac.uk>
Date: Mon, 11 Aug 2014 14:29:32 +0000

Dear all,

After looking to the manual carefully, p 299, pdf manual:
(i) dE/dx tabulations (if requested, see DELTARAY , p. 97)
For each assigned material and for each charged heavy particle (hadrons, muons, recoil ions) a
table is printed with the following data:
energy, unrestricted stopping power, (= ), shell correction, restricted stopping power (ac-
cording to the threshold specified by the user with DELTARAY, WHAT(1) ).

Looking at the DELTARAY description is stated that dp/dx tabulations are printed but this is not in agreement with the explanation that is stated in the manual regarding the main output (p 299)...

Many thanks,
ana
________________________________________
De: Ferreira De Almeida Lourenco, Ana
Enviado: 11 de agosto de 2014 13:11
Para: Anna Ferrari; Luke Bird
Cc: francesco.cerutti_at_cern.ch; fluka-discuss_at_fluka.org
Assunto: RE: [fluka-discuss]: Stopping powers for proton therapy applications

Dear Anna and all,

Many thanks for your reply.
I understand that FLUKA output refers to momentum loss as is stated in the manual. But I have two questions:
1- Why does the momentum loss (dp/dx) is showed as energy loss (dE/dx) in the output file?
2- Why do not PRINT the results as energy loss (dE/dx) since it is common and useful for medical applications?

Many thanks,
Ana
________________________________________
De: Anna Ferrari <a.ferrari_at_hzdr.de>
Enviado: 11 de agosto de 2014 12:55
Para: Ferreira De Almeida Lourenco, Ana; Luke Bird
Cc: francesco.cerutti_at_cern.ch; fluka-discuss_at_fluka.org
Assunto: Re: [fluka-discuss]: Stopping powers for proton therapy applications

Dear Ana, dear Luke,

Stopping powers as printed in FLUKA output refer to momentum loss (dp/dx), not
to energy loss (dE/dx) as reported by NIST. If you did not take into account
this difference you compared different quantities and this can explain the
"discrepancies" you see.
At high energies the value of proton momentum is very close to energy, so
FLUKA numbers seem to agree with NIST. But at lower energies, and especially
for particles heavier than protons, there can be no agreement. In the case of
Ana the discrepancy -as expected- can be observed better for graphite, which
has half density compared with water.

This point was already clarified by Mario Santana:
http://www.fluka.org/web_archive/earchive/new-fluka-discuss/6985.html

Hope this helps,
best regards,
Anna



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Anna Ferrari
Institute of Radiation Physics
Helmholtz-Zentrum Dresden-Rossendorf e.V.
a.ferrari_at_hzdr.de


Am Fri, 11 Jul 2014 14:05:21 +0000 schrieb "Ferreira De Almeida Lourenco, Ana"
<am.lourenco_at_ucl.ac.uk>:
> Dear FLUKA experts,
>
>
> I'm using FLUKA for clinical proton dosimetry applications. For validation
>proposes, I'm comparing the stopping powers from FLUKA with the stopping
>powers from ICRU.
>
>
> The graph below shows the ratio between FLUKA and ICRU stopping powers for
>water (blue) and graphite (green). As you can see I get a good agreement for
>water, but for graphite, specially for low energies. Could please someone
>explain me why do I get this disagreement for graphite? I'm using the same
>I-value (78eV) and density (1.7g.cm-3) that ICRU uses for graphite.
>
> [cid:8c77f38a-d52f-4644-8e83-71ffc41c5a3a]
>
>
> Please find attached my inp file.
>
> Many thanks,
>
> Ana
Received on Mon Aug 11 2014 - 17:49:31 CEST

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