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Simulations of microdosimetric quantities with the Monte Carlo code FLUKA for carbon ions at therapeutic energies
Stockholm University, Faculty of Science, Department of Physics.
Stockholm University, Faculty of Science, Department of Physics.
2012 (English)In: International Journal of Radiation Biology, ISSN 0955-3002, E-ISSN 1362-3095, Vol. 88, no 1-2, 176-182 p.Article in journal (Refereed) Published
Abstract [en]

Purpose: Microdosimetric quantities can be used to estimate the biological effectiveness of radiation fields. This study evaluates the capability of the general-purpose Monte Carlo code FLUKA to simulate microscopic patterns of energy depositions for mixed radiation fields which are created by carbon ions at therapeutic energies in phantoms. Materials and methods: Measured lineal energy spectra and linear energy transfer (LET) spectra produced by carbon ions of about 300 MeV/n at different depths in phantoms representing human tissue were chosen from published literature and were compared with results from simulations of the measurement set-ups with FLUKA. Results: Simulations of the dose-weighted lineal energy spectra yd(y) and dose-weighted LET spectra describe the main features of the respective measured spectra. All simulated frequency mean and dose mean lineal energy values are, respectively, within 21% and 11% of the measured ones. A slight underestimation of fragment fluences is notable. It is shown that the simultaneous detection of several charged fragments in the TEPC ('V effect') has considerable impact on the measured lineal energy spectra of fragments. Conclusions: Agreement between measurements and FLUKA results is encouraging and shows that FLUKA can predict microdosimetric spectra of mixed radiation fields created by therapeutic carbon ions in phantoms reasonably well.

Place, publisher, year, edition, pages
2012. Vol. 88, no 1-2, 176-182 p.
Keyword [en]
Monte Carlo; FLUKA; hadron therapy; carbon ion; microdosimetry; benchmarking
National Category
Physical Sciences
URN: urn:nbn:se:su:diva-81155DOI: 10.3109/09553002.2011.620062ISI: 000298666000028OAI: diva2:560048
Available from: 2012-10-11 Created: 2012-10-11 Last updated: 2012-10-12Bibliographically approved
In thesis
1. Monte Carlo particle transport codes for ion beam therapy treatment planning: Validation, development and applications
Open this publication in new window or tab >>Monte Carlo particle transport codes for ion beam therapy treatment planning: Validation, development and applications
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

External radiotherapy with proton and ion beams needs accurate tools for the dosimetric characterization of treatment fields. Monte Carlo (MC) particle transport codes, such as FLUKA and GEANT4, can be a valuable method to increase accuracy of dose calculations and to support various aspects of ion beam therapy (IBT), such as treatment planning and monitoring. One of the prerequisites for such applications is however that the MC codes are able to model reliably and accurately the relevant physics processes. As a first focus of this thesis work, physics models of MC codes with importance for IBT are developed and validated with experimental data. As a result suitable models and code configurations for applications in IBT are established. The accuracy of FLUKA and GEANT4 in describing nuclear fragmentation processes and the production of secondary charged nuclear fragments is investigated for carbon ion therapy. As a complementary approach to evaluate the capability of FLUKA to describe the characteristics of mixed radiation fields created by ion beams, simulated microdosimetric quantities are compared with experimental data. The correct description of microdosimetric quantities is also important when they are used to predict values of relative biological effectiveness (RBE). Furthermore, two models describing Compton scattering and the acollinearity of two-quanta positron annihilation at rest in media were developed, validated and integrated in FLUKA. The detailed description of these processes is important for an accurate simulation of positron emission tomography (PET) and prompt-γ imaging. Both techniques are candidates to be used in clinical routine to monitor dose administration during cancer treatments with IBT. The second objective of this thesis is to contribute to the development of a MC-based treatment planning tool for protons and ions with atomic number Z ≤ 8 using FLUKA. In contrast to previous clinical FLUKA-based MC implementations for IBT which only re-calculate a given treatment plan, the developed prototype features inverse optimization of absorbed dose and RBE-weighted dose for single fields and simultaneous multiple-field optimization for realistic treatment conditions. In a study using this newly-developed tool, the robustness of IBT treatment fields to uncertainties in the prediction of RBE values is investigated, while comparing different optimization strategies.

Place, publisher, year, edition, pages
Stockholm: Department of Physics, Stockholm University, 2012. 86 p.
Monte Carlo, ion beam therapy, treatment planning, cancer therapy, microdosimetry
National Category
Physical Sciences
Research subject
Medical Radiation Physics
urn:nbn:se:su:diva-81111 (URN)978-91-7447-551-7 (ISBN)
Public defence
2012-11-29, föreläsningssalen, Radiumhemmet, Karolinska universitetssjukhuset, Solna, 09:00 (English)
EU, FP7, Seventh Framework Programme, PITN-GA-2008-215840-PARTNEREU, FP7, Seventh Framework Programme, ENVISION FP7 Grant Agreement N. 241851

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 5: Submitted. Paper 6: Manuscript.

Available from: 2012-11-07 Created: 2012-10-10 Last updated: 2013-04-08Bibliographically approved

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Böhlen, Till TobiasGudowska, Irena
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