An accurate model for the computation of the dose of protons in water

Embriaco, Alessia; Bellinzona, Valentina Elettra; Fontana, A.; Rotondi, A.

doi:10.1016/j.ejmp.2017.05.049

Cited by 10 publications

(2 citation statements)

References 23 publications

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“…Generally speaking, the biophysical properties of He ions are intermediate between those of protons and C-ions (Tessonnier et al 2018), which at the moment are the only two species used in clinical practice. From a physical point of view, He-ion beams show a reduced range straggling and lateral scattering with respect to protons (Kempe et al 2007, Embriaco et al 2017 and a reduced fragmentation tail when compared to C-ions (Ströbele et al 2012), which results in a particularly favorable distribution of physical dose. Furthermore, the He-ion beam biological effectiveness is higher than that of protons, although not as high as that of C-ions.…”

Section: Introductionmentioning

confidence: 99%

Biological effectiveness of He-3 and He-4 ion beams for cancer hadrontherapy: a study based on the BIANCA biophysical model

et al. 2021

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While cancer therapy with protons and C-ions is continuously spreading, in the near future patients will be also treated with He-ions which, in comparison to photons, combine the higher precision of protons with the higher relative biological effectiveness (RBE) of C-ions. Similarly to C-ions, also for He-ions the RBE variation along the beam must be known as precisely as possible, especially for active beam delivery systems. In this framework the BIANCA biophysical model, which has already been applied to calculate the RBE along proton and C-ion beams, was extended to 4He-ions and, following interface with the FLUKA code, was benchmarked against cell survival data on CHO normal cells and Renca tumour cells irradiated at different positions along therapeutic-like 4He-ion beams at the Heidelberg Ion-beam Therapy centre, where the first He-ion patient will be treated soon. Very good agreement between simulations and data was obtained, showing that BIANCA can now be used to predict RBE following irradiation with all ion types that are currently used, or will be used soon, for hadrontherapy. Thanks to the development of a reference simulation database describing V79 cell survival for ion and photon irradiation, these predictions can be cell-type specific because analogous databases can be produced, in principle, for any cell line. Furthermore, survival data on CHO cells irradiated by a He-3 beam were reproduced to compare the biophysical properties of He-4 and He-3 beams, which is currently an open question. This comparison showed that, at the same depth, He-4 beams tend to have a higher RBE with respect to He-3 beams, and that this difference is also modulated by the considered physical dose, as well as the cell radiosensitivity. However, at least for the considered cases, no significant difference was found for the ratio between the RBE-weighted dose in the SOBP and that in the entrance plateau.

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Section: Introductionmentioning

confidence: 99%

Biological effectiveness of He-3 and He-4 ion beams for cancer hadrontherapy: a study based on the BIANCA biophysical model

et al. 2021

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“…In proton treatments, the physical fluence attenuation of the primary beam due to nuclear interactions is included in the planning software programs, and the contribution to the physical dose from secondary protons is taken into account with different parameterizations [ 23 , 24 , 25 ]. On the contrary, heavier target fragments are usually neglected.…”

Section: Introductionmentioning

confidence: 99%

Biological Impact of Target Fragments on Proton Treatment Plans: An Analysis Based on the Current Cross-Section Data and a Full Mixed Field Approach

Bellinzona

Grzanka

Attili

et al. 2021

Cancers

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Clinical routine in proton therapy currently neglects the radiobiological impact of nuclear target fragments generated by proton beams. This is partially due to the difficult characterization of the irradiation field. The detection of low energetic fragments, secondary protons and fragments, is in fact challenging due to their very short range. However, considering their low residual energy and therefore high LET, the possible contribution of such heavy particles to the overall biological effect could be not negligible. In this context, we performed a systematic analysis aimed at an explicit assessment of the RBE (relative biological effectiveness, i.e., the ratio of photon to proton physical dose needed to achieve the same biological effect) contribution of target fragments in the biological dose calculations of proton fields. The TOPAS Monte Carlo code has been used to characterize the radiation field, i.e., for the scoring of primary protons and fragments in an exemplary water target. TRiP98, in combination with LEM IV RBE tables, was then employed to evaluate the RBE with a mixed field approach accounting for fragments’ contributions. The results were compared with that obtained by considering only primary protons for the pristine beam and spread out Bragg peak (SOBP) irradiations, in order to estimate the relative weight of target fragments to the overall RBE. A sensitivity analysis of the secondary particles production cross-sections to the biological dose has been also carried out in this study. Finally, our modeling approach was applied to the analysis of a selection of cell survival and RBE data extracted from published in vitro studies. Our results indicate that, for high energy proton beams, the main contribution to the biological effect due to the secondary particles can be attributed to secondary protons, while the contribution of heavier fragments is mainly due to helium. The impact of target fragments on the biological dose is maximized in the entrance channels and for small α/β values. When applied to the description of survival data, model predictions including all fragments allowed better agreement to experimental data at high energies, while a minor effect was observed in the peak region. An improved description was also obtained when including the fragments’ contribution to describe RBE data. Overall, this analysis indicates that a minor contribution can be expected to the overall RBE resulting from target fragments. However, considering the fragmentation effects can improve the agreement with experimental data for high energy proton beams.

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