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Limitations (and merits) of PENELOPE as a track-structure code
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Radiology, Oncology and Radiation Science, Oncology.
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2012 (English)In: International Journal of Radiation Biology, ISSN 0955-3002, E-ISSN 1362-3095, Vol. 88, no 1-2, 66-70 p.Article in journal (Refereed) Published
Abstract [en]

Purpose: To outline the limitations of PENELOPE (acronym of PENetration and Energy LOss of Positrons and Electrons) as a track-structure code, and to comment on modifications that enable its fruitful use in certain microdosimetry and nanodosimetry applications. Methods: Attention is paid to the way in which inelastic collisions of electrons are modelled and to the ensuing implications for microdosimetry analysis. Results: Inelastic mean free paths and collision stopping powers calculated with PENELOPE and two well-known optical-data models are compared. An ad hoc modification of PENELOPE is summarized where ionization and excitation of liquid water by electron impact is simulated using tables of realistic differential and total cross sections. Conclusions: PENELOPE can be employed advantageously in some track-structure applications provided that the default model for inelastic interactions of electrons is replaced by suitable tables of differential and total cross sections.

Place, publisher, year, edition, pages
2012. Vol. 88, no 1-2, 66-70 p.
Keyword [en]
Radiation physics, Monte Carlo simulation, microdosimetry
National Category
Medical and Health Sciences
URN: urn:nbn:se:uu:diva-168096DOI: 10.3109/09553002.2011.598209ISI: 000298666000012OAI: oai:DiVA.org:uu-168096DiVA: diva2:492432
Available from: 2012-02-08 Created: 2012-02-06 Last updated: 2014-03-06Bibliographically approved
In thesis
1. Protons, other Light Ions, and 60Co Photons: Study of Energy Deposit Clustering via Track Structure Simulations
Open this publication in new window or tab >>Protons, other Light Ions, and 60Co Photons: Study of Energy Deposit Clustering via Track Structure Simulations
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Radiotherapy aims to sterilize cancer cells through ionization induced damages to their DNA whilst trying to reduce dose burdens to healthy tissues. This can be achieved to a certain extent by optimizing the choice of radiation to treat the patient, i.e. the types of particles and their energy based on their specific interaction patterns. In particular, the formation of complex clusters of energy deposits (EDs) increases with the linear energy transferred for a given particle. These differences cause variation in the relative biological effectiveness (RBE). The complexity of ED clusters might be related to complex forms of DNA damage, which are more difficult to repair and therefore prone to inactivate the cells. Hence, mapping of the number and complexity of ED clusters for different radiation qualities could aid to infer a surrogate measure substituting physical dose and LET as main predictors for the RBE .  

In this work the spatial patterns of EDs at the nanometre scale were characterized for various energies of proton, helium, lithium and carbon ions. A track structure Monte Carlo code, LIonTrack, was developed to accurately simulate the light ion tracks in liquid water. The methods to emulate EDs at clinical dose levels in cell nucleus-sized targets for both 60Co photons and light ions were established, and applied to liquid water targets. All EDs enclosed in such targets were analyzed with a specifically developed cluster algorithm where clustering was defined by a single parameter, the maximum distance between nearest neighbour EDs. When comparing measured RBE for different radiation qualities, there are cases for which RBE do not  increase with LET but instead increase with the frequencies of high order ED clusters.

A test surrogate-measure based on ED cluster frequencies correlated to parameters of experimentally determined cell survival. The tools developed in this thesis can facilitate future exploration of semi-mechanistic modelling of the RBE.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2013. 55 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 930
Proton, light ion, Co-60 photon, track structure Monte Carlo code, clustering patterns of energy deposit, RBE
National Category
Medical and Health Sciences
Research subject
Medical Radiophysics
urn:nbn:se:uu:diva-206385 (URN)978-91-554-8736-2 (ISBN)
Public defence
2014-03-28, Skoogsalen, Akademiska Sjukhuset, Ing. 78-79, Uppsala, 13:00 (English)
Available from: 2014-03-06 Created: 2013-08-30 Last updated: 2014-04-29Bibliographically approved

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