Dosimetric Monte Carlo calculations for heavy ion beams

Postgraduate Thesis uoadl:2758714 443 Read counter

Unit:
Διατμηματικό ΠΜΣ Ιατρική Φυσική-Ακτινοφυσική
Library of the School of Health Sciences
Deposit date:
2018-05-14
Year:
2018
Author:
Chatzinikolaou Athanasios
Supervisors info:
Παναγιώτης Παπαγιάννης, Αναπληρωτής Καθηγητής ,Ιατρική Σχολή, ΕΚΠΑ
Παντελής Καραϊσκος, Καθηγητής ,Ιατρική Σχολή, ΕΚΠΑ
Κωνσταντίνος Λουκάς, Επίκουρος Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Original Title:
Δοσιμετρικοί υπολογισμοί Monte Carlo για δέσμες βαρέων ιόντων
Languages:
Greek
Translated title:
Dosimetric Monte Carlo calculations for heavy ion beams
Summary:
Abstract
Purpose: The purpose of this master thesis is the construction of methods for the creation of spread out bragg peak (SOBP) dose-depth curve with the use of Geant4 program and the comparison with equivalent methods made for Fluka.
Methods: Monoenergetic heavy ion Bragg peak dose-depth curves in water cube of 30 cm side were created with modifications in an existing Geant4 example (Hadrontherapy example (A)). Also a ridge flattening filter for Geant 4 was made that was modelled with the properties of a mathematical filter written in Fortran for Fluka, that was applied in a published research [B]. A comparison of the physical Βragg peak dose-depth curves between Fluka and Geant4 were made for the testing of the similarity between the different programs and the similar ridge filters for different heavy ions . The Fluka settings were in agreement with research [B]. Furthermore dose-side dispersion curves vertical to the beam direction in Geant4 for heavy ions were created for the comparison of heavy ions. Finally a C++ code for the creation of the speed out Bragg peak was written. Due to time limitations it was not possible to create a method for connecting biological and physical dose.
Results: There are differences in the physical Βragg peak dose-depth curves without filter of 6 % that are caused due to the differences in the programs, the differences continue with filter the use of the filter and they become greater (10 %), with the exception of helium-3 with a difference of 20 % in both simulations. There cannot be a conclusion for potential differences between the ridge filters because there is the underlying difference in the programs. Due to the bad statistics in the vertical dose distribution, in perspective to the beam direction, there cannot be accurate results in the comparison of the heavy ions but there is a tendency where heavy ions have smaller lateral deviation from the beam. Finally the spread out Βragg peak creation program has a good behaviour, but the limitation of using only peaks leads to wave like patterns and influence from calculation statistics.
Conclusions: Although the differences in the results it has been found that the two programs have similar behavior and they can be used interchangeably but they require attention and experience in their usage and validation with real data. Fluka code retains better behavior at ions fragments. Ions with medium atomic weight like lithium and boron are good options for hadrontherapy, but further research is needed for proving. With further improvement of the SOBP code as using data other than peaks and better calculation statistics the SOBP will be approached even further.In this master thesis important progress has been made to open the road towards Geant4 usage in future research and the target of creating biological dose spread out Βragg peaks in Geant4.
A. G.A.P. Cirrone, L. Pandola, G. Petringa, F.Romano, hadrontherapy, available online: https://twiki.cern.ch/twiki/bin/view/Geant4/AdvancedExamplesHadrontherapy (last accessed on:11/5/2018).
B. I.Kantemiris P.Karaiskos P.Papagiannis A.Angelopoulos (2011) Dose and dose averaged LET comparison of 1H, 4He, 6Li, 8Be, 10B, 12C, 14N, and 16O ion beams forming a spread-out Bragg peak. Med. Phys. 38,12 p6586.
Main subject category:
Health Sciences
Keywords:
Heavy ions ,Flattening filter, Bragg peak, Geant4, Fluka, SOBP, Hadrontherapy, Dose
Index:
No
Number of index pages:
0
Contains images:
Yes
Number of references:
24
Number of pages:
61
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