Pitfalls in the beam modelling process of Monte Carlo calculations for proton pencil beam scanning
Aitkenhead, Adam H
Mackay, Ranald I
AffiliationCentre for Proton Therapy, Paul Scherrer Institute, Villigen, Switzerland
MetadataShow full item record
AbstractOBJECTIVE: Monte Carlo (MC) simulations substantially improve the accuracy of predicted doses. This study aims to determine and quantify the uncertainties of setting up such a MC system. METHODS: Doses simulated with two Geant4-based MC calculation codes, but independently tuned to the same beam data, have been compared. Different methods of MC modelling of a pre-absorber have been employed, either modifying the beam source parameters (descriptive) or adding the pre-absorber as a physical component (physical). RESULTS: After the independent beam modelling of both systems in water (resulting in excellent range agreement) range differences of up to 3.6/4.8?mm (1.5% of total range) in bone/brain-like tissues were found, which resulted from the use of different mean water ionisation potentials during the energy tuning process. When repeating using a common definition of water, ranges in bone/brain agreed within 0.1?mm and gamma-analysis (global 1%,1mm) showed excellent agreement (>93%) for all patient fields. However, due to a lack of modelling of proton fluence loss in the descriptive pre-absorber, differences of 7% in absolute dose between the pre-absorber definitions were found. CONCLUSION: This study quantifies the influence of using different water ionisation potentials during the MC beam modelling process. Furthermore, when using a descriptive pre-absorber model, additional Faraday cup or ionisation chamber measurements with pre-absorber are necessary. ADVANCES IN KNOWLEDGE: This is the first study quantifying the uncertainties caused by the MC beam modelling process for proton pencil beam scanning, and a more detailed beam modelling process for MC simulations is proposed to minimise the influence of critical parameters.
CitationWinterhalter C, Aitkenhead A, Oxley D, Richardson J, Weber DC, MacKay RI, et al. Pitfalls in the beam modelling process of Monte Carlo calculations for proton pencil beam scanning. The British journal of radiology. 2020;93(1107):20190919.
JournalBritish Journal of Radiology
- Benchmarking a GATE/Geant4 Monte Carlo model for proton beams in magnetic fields.
- Authors: Padilla-Cabal F, Alejandro Fragoso J, Franz Resch A, Georg D, Fuchs H
- Issue date: 2020 Jan
- Experimental characterisation of a proton kernel model for pencil beam scanning techniques.
- Authors: De Marzi L, Da Fonseca A, Moignier C, Patriarca A, Goudjil F, Mazal A, Buvat I, Hérault J
- Issue date: 2019 Aug
- A pencil beam algorithm for magnetic resonance image-guided proton therapy.
- Authors: Padilla-Cabal F, Georg D, Fuchs H
- Issue date: 2018 May
- Automated Monte-Carlo re-calculation of proton therapy plans using Geant4/Gate: implementation and comparison to plan-specific quality assurance measurements.
- Authors: Aitkenhead AH, Sitch P, Richardson JC, Winterhalter C, Patel I, Mackay RI
- Issue date: 2020 Oct 1
- Improvements in pencil beam scanning proton therapy dose calculation accuracy in brain tumor cases with a commercial Monte Carlo algorithm.
- Authors: Widesott L, Lorentini S, Fracchiolla F, Farace P, Schwarz M
- Issue date: 2018 Jul 16