Evaluation of electromagnetic and nuclear scattering models in GATE/Geant4 for proton therapy

Resch, Andreas; Elia, Alessio; Fuchs, H.; Carlino, A.; Palmans, Hugo; Stock, Markus; Georg, Dietmar; Grevillot, L.

doi:10.1002/mp.13472

Cited by 34 publications

(43 citation statements)

References 32 publications

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“…Some depth‐dose profile measurements were additionally reproduced: (a) at ISD0 with a Bragg peak chamber having a sensitive electrode diameter of 39.6 mm (PTW type 34073) to evaluate the energy loss from scattering, (b) at ISD0 with a MLIC to fasten constancy checks and (c) at ISD50 to acquire baseline data in non‐isocentric conditions with and without RS. Transverse dose profiles were acquired in water at ISD0 and at ISD50 with RS, using PinPoint ionization chambers (PTW type 31015) for the nuclear halo study; and a micro‐diamond (PTW type TM60019) for the core . Depending on the energy, up to five transverse dose profiles were acquired from entrance to Bragg peak depth.…”

Section: Methodsmentioning

confidence: 99%

“…The contributions of the different field sizes necessary to compute the FSF were then derived by summing‐up the dose contribution of different frames. Output factors acquired in 2D are complementary measurements to the transverse dose profiles acquired in 1D for the validation for electromagnetic and nuclear scattering models …”

Section: Methodsmentioning

confidence: 99%

“…Transverse dose profiles were acquired in water at ISD0 and at ISD50 with RS, using PinPoint ionization chambers (PTW type 31015) for the nuclear halo study; and a micro-diamond (PTW type TM60019) for the core. 5,23 Depending on the energy, up to five transverse dose profiles were acquired from entrance to Bragg peak depth. Acquisition of transverse dose profiles in the nuclear halo region has been performed with several detectors in the past, such as radiochromic films, scintillating screens, optically stimulated luminescent detectors, diamond, and small volume ionization chambers.…”

Section: D3 Acquisition Of Baseline Datamentioning

confidence: 99%

“…Output factors acquired in 2D are complementary measurements to the transverse dose profiles acquired in 1D for the validation for electromagnetic and nuclear scattering models. 23 Baseline data related to the 3D-delivery are summarized in Table V. Treatment plans were optimized in the TPS to deliver a uniform dose to cubic targets of various sizes and various treatment depths in water.…”

Section: D3 Acquisition Of Baseline Datamentioning

confidence: 99%

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Clinical implementation and commissioning of the MedAustron Particle Therapy Accelerator for non‐isocentric scanned proton beam treatments

et al. 2019

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Purpose This paper describes the clinical implementation and medical commissioning of the MedAustron Particle Therapy Accelerator (MAPTA) for non‐isocentric scanned proton beam treatments. Methods Medical physics involvement during technical commissioning work is presented. Acceptance testing procedures, including advanced measurement methods of intra‐spill beam variations, are defined. Beam monitor calibration using two independent methods based on a dose‐area product formalism is described. Emphasis is given to the medical commissioning work and the specificities related to non‐isocentric irradiation, since a key feature of MedAustron is the routine delivery of non‐isocentric scanned proton beam treatments. Results Key commissioning results and beam stability trend lines for more than 2 yr of clinical operation have been provided. Intra‐spill beam range, size, and position variations were within specifications of 0.3 mm, 15%, and 0.5 mm, respectively. The agreement between two independent beam monitor calibration methods was better than 1.0%. Non‐isocentric treatment delivery allowed lateral penumbra reduction of up to about 30%. Daily QA measurements of the beam range, size, position, and dose were always within 1 mm, 10%, 1 mm, and 2% from the baseline data, respectively. Conclusions Non‐isocentric treatments have been successfully implemented at MedAustron for routine scanned proton beam therapy using horizontal and vertical fixed beamlines. Up to now every patient was treated in non‐isocentric conditions. The presented methodology to implement a new Scanned Ion Beam Delivery (SIBD) system into clinical routine for proton therapy may serve as a guidance for other centers.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: D3 Acquisition Of Baseline Datamentioning

confidence: 99%

Section: D3 Acquisition Of Baseline Datamentioning

confidence: 99%

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Clinical implementation and commissioning of the MedAustron Particle Therapy Accelerator for non‐isocentric scanned proton beam treatments

et al. 2019

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“…The GATE/Geant4 package was demonstrated to be a powerful tool for beam modeling and dose calculation in ion beam therapy. [30][31][32][33] Likewise, Geant4 demonstrated high accuracy describing and propagating particle tracks in a variety of electromagnetic fields, regardless their homogeneity. 34 This work aims to develop and validate a GATE/Geant4 MC beam model for clinically relevant proton beams interacting with external heterogeneous magnetic fields up to 1 T. The performance of the model describing the beam optics and the energy spectrum were evaluated using in-depth and lateral dose profiles.…”

Section: Introductionmentioning

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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Technical Note: Simulation of dose buildup in proton pencil beams

et al. 2019

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Purpose The purpose of this study is to characterize the magnitude and depth of dose buildup in pencil beam scanning proton therapy. Methods We simulate the integrated depth–dose curve of realistic proton pencil beams in a water phantom using the Geant4 Monte Carlo toolkit. We independently characterize the electronic and protonic components of dose buildup as a function of proton beam energy from 40 to 400 MeV, both with and without an air gap. Results At clinical energies, electronic buildup over a distance of about 1 mm leads to a dose reduction at depth of the basal layer (0.07 mm) by up to 6% compared to if no buildup effect were present. Protonic buildup reduces the dose to the basal layer by up to 16% and has effects at depths of up to 150 mm. Secondary particles with a mass number A > 1 do not contribute to dose buildup. An air gap of 1 m has no significant effect on protonic buildup but reduces electronic buildup below 1%. Conclusions Protonic and electronic dose buildup are relevant for accurate dosimetry in proton therapy although a realistic air gap reduces the electronic buildup to levels where it can be safely neglected. We recommend including electrons and secondary protons in Monte Carlo‐based treatment planning systems down to a predicted range of 10–20 μ m in order to accurately model the dose at depths of the basal layer, no matter the size of the air gap between nozzle and patient.

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Evaluation of electromagnetic and nuclear scattering models in GATE/Geant4 for proton therapy

Cited by 34 publications

References 32 publications

Clinical implementation and commissioning of the MedAustron Particle Therapy Accelerator for non‐isocentric scanned proton beam treatments

Clinical implementation and commissioning of the MedAustron Particle Therapy Accelerator for non‐isocentric scanned proton beam treatments

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

Technical Note: Simulation of dose buildup in proton pencil beams

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