Distributions of secondary particles in proton and carbon-ion therapy: a comparison between GATE/Geant4 and FLUKA Monte Carlo codes

Abstract

Monte Carlo simulations play a crucial role for in-vivo treatment monitoring based on PET and prompt gamma imaging in proton and carbon-ion therapies. The accuracy of the nuclear fragmentation models implemented in these codes might affect the quality of the treatment verification. In this paper, we investigate the nuclear models implemented in GATE/Geant4 and FLUKA by comparing the angular and energy distributions of secondary particles exiting a homogeneous target of PMMA. Comparison results were restricted to fragmentation of (16)O and (12)C. Despite the very simple target and set-up, substantial discrepancies were observed between the two codes. For instance, the number of high energy (>1 MeV) prompt gammas exiting the target was about twice as large with GATE/Geant4 than with FLUKA both for proton and carbon ion beams. Such differences were not observed for the predicted annihilation photon production yields, for which ratios of 1.09 and 1.20 were obtained between GATE and FLUKA for the proton beam and the carbon ion beam, respectively. For neutrons and protons, discrepancies from 14% (exiting protons-carbon ion beam) to 57% (exiting neutrons-proton beam) have been identified in production yields as well as in the energy spectra for neutrons.

Evaluation of the water-equivalence of plastic materials in low- and high-energy clinical proton beams

“…Plastic-to-water conversion factor measured experimentally (refer to equation (3)) and derived from Monte Carlo simulations (refer to equation (5) the BIC model (Folger et al 2004) in Geant4. Böhlen et al (2010) and Robert et al (2013) compared FLUKA and Geant4 nuclear models for carbon-ion beams and for proton and carbon-ion beams, respectively, and both studies reported substantial deviations between codes. Moreover, ICRU Report 63 (2000) estimated uncertainties of the order of 5%-10% on the total nonelastic cross sections and 20%-30% on the angle-integrated production cross sections for secondary particles in proton beams.…”

Nuclear physics and particle therapy

“…The relevance of existing discrepancies in numerical models (see for example ref. [6,7]) should be discussed in the context of clinical applications. The detailed quantitative evaluation of biological dose distributions would require the simulation of a carbon ion treatment field including radiobiological modeling.…”

Hadron accelerators for radiotherapy

“…This is managed in treatment by prescribing a margin around the target volume as is commonly done in radiotherapy for other reasons, and by trying to ensure that the optimised treatment plan is robust against density uncertainties [145]. Because of this limitation a number of techniques -some to be used in combination with each other -are being studied to improve the prediction of proton stopping, and include techniques such as magnet resonance imaging (MRI), and monitoring of secondary particles produced during treatment [146][147][148].…”