Quantification of the uncertainties of a biological model and their impact on variable RBE proton treatment plan optimization

Resch, Andreas; Landry, Guillaume; Kamp, Florian; Cabal, Gonzalo; Belka, Claus; Wilkens, Jan J.; Parodi, Katia; Dedes, Georgios

doi:10.1016/j.ejmp.2017.03.013

Cited by 29 publications

(39 citation statements)

References 45 publications

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“…Due to the uncertainties in RBE, treatment plan optimization based on RBE models is currently not feasible with clinically acceptable accuracy [57, 83]. RBE variations are thus only taken into account intuitively (for instance by avoiding certain beam angles), but not quantitatively, during the planning process.…”

Section: Biological Optimizationmentioning

confidence: 99%

Proton Relative Biological Effectiveness – Uncertainties and Opportunities

Paganetti

2018

International Journal of Particle Therapy

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Proton therapy treatments are prescribed using a biological effectiveness relative to photon therapy of 1.1, that is, proton beams are considered to be 10% more biologically effective. Debate is ongoing as to whether this practice needs to be revised. This short review summarizes current knowledge on relative biological effectiveness variations and uncertainties in vitro and in vivo. Clinical relevance is discussed and strategies toward biologically guided treatment planning are presented.

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Section: Biological Optimizationmentioning

confidence: 99%

Proton Relative Biological Effectiveness – Uncertainties and Opportunities

Paganetti

2018

International Journal of Particle Therapy

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“…The dose-averaged LET was extracted from the LET-Actor in GATE/Geant4 using the default scoring routine and the LET to water option, 49 which uses "method C" form Cortes-Giraldo and Carabe and is, hence, independent of step limiting events. 50…”

Section: C3 Let Quenching Correctionmentioning

confidence: 99%

Benchmarking a GATE/Geant4 Monte Carlo model for proton beams in magnetic fields

et al. 2019

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Purpose: Magnetic resonance guidance in proton therapy (MRPT) is expected to improve its current performance. The combination of magnetic fields with clinical proton beam lines poses several challenges for dosimetry, treatment planning and dose delivery. Proton beams are deflected by magnetic fields causing considerable changes in beam trajectories and also a retraction of the Bragg peak positions. A proper prediction and compensation of these effects is essential to ensure accurate dose calculations. This work aims to develop and benchmark a Monte Carlo (MC) beam model for dose calculation of MRPT for static magnetic fields up to 1 T. Methods: Proton beam interactions with magnetic fields were simulated using the GATE/Geant4 toolkit. The transport of charged particle in custom 3D magnetic field maps was implemented for the first time in GATE. Validation experiments were done using a horizontal proton pencil beam scanning system with energies between 62.4 and 252.7 MeV and a large gap dipole magnet (B = 0-1 T), positioned at the isocenter and creating magnetic fields transverse to the beam direction. Dose was measured with Gafchromic EBT3 films within a homogeneous PMMA phantom without and with bone and tissue equivalent material slab inserts. Linear energy transfer (LET) quenching of EBT3 films was corrected using a linear model on dose-averaged LET method to ensure a realistic dosimetric comparison between simulations and experiments. Planar dose distributions were measured with the films in two different configurations: parallel and transverse to the beam direction using single energy fields and spread-out Bragg peaks. The MC model was benchmarked against lateral deflections and spot sizes in air of single beams measured with a Lynx PT detector, as well as dose distributions using EBT3 films. Experimental and calculated dose distributions were compared to test the accuracy of the model. Results: Measured proton beam deflections in air at distances of 465, 665, and 1155 mm behind the isocenter after passing the magnetic field region agreed with MC-predicted values within 4 mm. Differences between calculated and measured beam full width at half maximum (FWHM) were lower than 2 mm. For the homogeneous phantom, measured and simulated in-depth dose profiles showed range and average dose differences below 0.2 mm and 1.2%, respectively. Simulated central beam positions and widths differed <1 mm to the measurements with films. For both heterogenous phantoms, differences within 1 mm between measured and simulated central beam positions and widths were obtained, confirming a good agreement of the MC model. Conclusions: A GATE/Geant4 beam model for protons interacting with magnetic fields up to 1 T was developed and benchmarked to experimental data. For the first time, the GATE/Geant4 model was successfully validated not only for single energy beams, but for SOBP, in homogeneous and heterogeneous phantoms. EBT3 film dosimetry demonstrated to be a powerful dosimetric tool, once the film response function is LET corrected,...

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“…The scarcity of the current evidence might come, as Dr. DeLuca hinted in his opening statement, from avoiding the detrimental impact of the end‐of‐range high LET through careful beam arrangements, thus, from indirectly accounting for the variability in the RBE. Nevertheless, instead of avoiding the issue under the false assumption that IMPT inherently eliminates all high‐LET components, biological optimization strategies, including LET optimization and variable RBE considerations, could mitigate RBE effects and maximize the potential of proton therapy, while prospectively collecting clinical data …”

Section: Against the Proposition: Paul M Deluca Jr Phdmentioning

confidence: 99%