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Keywords: Hadrontherapy Example
Forum: Medical Applications
Re: None Hadrontherapy example for carbon ions and physic (Bernd)
Date: 22 Sep, 2007
From: Maria Grazia Pia <Maria Grazia Pia>

The Geant4 Standard electromagnetic package mutuated the ICRU49 modelling approach of hadron ionisation originally devised, designed and implemented in the lowenergy electromagnetic package. The copy of original ideas and work was not acknowledged by the Standard package, so this is prone to generate confusion among users (apart from other considerations of code duplication, difficulty of maintenance, underlying software design, professional ethics etc.).

A systematic evaluation of all Geant4 electromagnetic and hadronic models pertinent to the proton Bragg peak simulation against hadrontherapy experimental data is close to conclusion and will be submitted for publication shortly. The measurements were performed at the CATANA hadrontherapy facility at INFN LNS by the same authors of the geometry model of the Geant4 hadrontherapy advanced example.

A subset of results associated to this paper were presented at the CHEP conference this month; they are available at http://www.ge.infn.it/geant4/talks/chep2007/bragg_chep2007.pdf. The conference presentation covers only part of the paper content, due to the limited time allocation for the talk and the need to finalize some of the current results prior to public distribution.

The paper contains a complete comparison of physics models through statistical goodness-of-fit tests: the big table in the conference slides gives a preview of the extent of the analysis and its rigorous nature. The purpose of this work is indeed to provide objective guidance to users in their selection of simulation models based on sound mathematical analysis of their performance against experimental data.

We intend to circulate a preprint as soon as the paper is ready for submission to facilitate users' access to the information; a rough estimate of the time scale is after the IEEE NSS conference in November.

The various Ziegler parameterisations produce significantly different results with respect to the ICRU 49 ones. It is worth reminding the readers that ICRU 49 largely acknowledges the basis of Ziegler 1977 review, with some documented improvements over it. Other more recent Ziegler compilations are either available in literature or, regretfully, only distributed in software code executables rather than in published tabulations as the older ones.

So, objective guidance through the various models relevant to hadrontherapy simulation will be available shortly; thanks for your patience until the results are finalized for the paper.

A further improved version of the hadrontherapy advanced example will be included in the next Geant4 release to reflect closely the content and results of the paper; we hope that this will also be useful to Geant4 users to find practical guidance for usage among the various physics models available in the toolkit.

The introduction of ICRU73-based models for ions is planned in the lowenergy package in 2008 (associated to a PhD thesis related to this topic); we intend to release a first version in June 2008. We hope that in this case there won't be other occurrences of duplication prone to generate confusion among users. Contacts with experimental groups for collaborating experimental validation projects are in progress; if you (or other user groups) are interested to collaborate with us on this topic, please feel free to contact me for any further information.

Best wishes,

Maria Grazia Pia

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