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40 Irradiation in molecular nanodroplets
Abstracts / Physica Medica 56 (2018) 1–39
6. Selvam TP, Bhola S. Technical Note: EGSnrc-based dosimetric study of the BEBIG C60o HDR brachytherapy sources. Med Phys 2010;37:1365–70. https://doi.org/10.1016/j.ejmp.2018.09.052
40 Irradiation in molecular nanodroplets T. Salbaing a, L. Feketeová a, H. Abdoul-Carime a, B. Farizon a, M. Farizon a, F. Calvo b, T.D. Märk c a
Institut de Physique Nucléaire de Lyon, Villeurbanne, France LiPhy, Grenoble, France c Institut für Ionenphysik und Angewandte Physik, Innsbruck, Austria b
Introduction. One of the specificities of ionizing radiations is that they interact with the electrons of the irradiated matter. In a molecular system the electrons are localized in molecules and the energy is initially deposited in the form of electronic excitation of one of the molecules. The description of the radiation of such initially deposited energy on the nanometer scale in the nearby molecules is challenging, in particular in the context of the therapies combining irradiation and radiosensitizers. Methods. The originality of the work consists of the study of ‘‘model” molecular nanosystems by both, the experiment and the theory. The nanodroplets are initially prepared with a given number of molecules. After a single ultrafast energy deposition located in one of the molecules, the nanodroplet is analyzed after a given relaxation time. The method combining mass spectrometry and imaging techniques allows the analysis of each nanodroplet and this is done for a large number of nanodroplets [1]. The results are compared with statistical molecular dynamics calculations [2]. Results. Thermalisation in nanodroplets following the sudden electronic excitation of one of the molecules [3] is observed with respect to the number of molecules (2–10 typically) in the nanodroplet and for several different types of nanodroplets: protonated water nanodroplets, water nanodroplets including an hydrophobic impurity, protonated methanol nanodroplets. The results show that the evaporation of a molecule takes place also before the full thermalisation of the nanodroplet through the ejection of a molecule with a speed clearly higher than that observed after full thermalisation. The measurements on the methanol nanodroplets evidence a competition between the evaporation of a molecule of methanol and a reaction between the molecules leading to the elimination of a water molecule. Conclusions. The quantitative comparison between the experimental results and the theoretical calculations for molecular nanosystems irradiated in the gas-phase paves the way to robust modelling of the irradiation mechanisms on the nanometer scale.
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41 Simulation of the biological effectiveness caused by 65 MeV protons (clinical beam) and carbon-ions Y. Ali a, M. Beuve e, A. Carnicer b, E. Débiton c,d, F. Degoul c,d, J. Hérault b, F. Smekens a, L. Maigne a a Université Clermont Auvergne, CNRS/IN2P3, LPC, Clermont-Ferrand, France b Centre Antoine Lacassagne, Cyclotron Biomédical, Nice, France c INSERM, 1240 Clermont-Ferrand, France d Imagerie Moléculaire et Stratégies Théranostiques, Université Clermont Auvergne, Clermont-Ferrand, France e Institut de Physique Nucléaire de Lyon (IPNL), Université Lyon 1, Villeurbanne, France
Introduction. In order to optimize hadron therapy treatments, not only the absorbed dose will be taken in account but the biological consequences on the irradiated cell structures will be considered as well. To achieve that, the relative biological effectiveness (RBE) is estimated to provide the information we need on how cells respond to irradiation. Here we are focusing on a 65 MeV clinical proton beam from the Antoine Lacassagne clinical center in Nice and a 4 MV carbon-ion beam from the Heavy-Ion Medical Accelerator in Chiba (Japan). To predict the said RBE, there are several biophysical models implemented by Monte Carlo codes, some of them already are in use for treatment planifications. Among them, the microkinetic model (MKM) [1,2] and the nanOx model are tested in this study. To address this issue, we use the GATE Monte Carlo platform to estimate the biological effectiveness. Methods. Are collected survival curves from the cell lines samples according to the linear quadratic model. The cells are irradiated by a reference 250 kVp X-ray beam (delivered by the X-rad 320 X-ray system) a 65 MeV proton beam and a 4MV carbon-ion beam (passive mode), the dose being in a 0 to 10 Gy range. All the beams used to conduct the cell irradiations are entirely emulated with the version 8.0 of the GATE Monte Carlo plateform. The microdosimetric spectrums (or linear energy distribution) are then estimated and implemented to the biophysical models. Results. The emulated depth dose distributions and Bragg peaks are verified and consistent with the experimental ionization chamber measurements. The MKM and the NanOx models then predict the biological effectiveness as the said predictions are compared from one model to the other. Conclusions. This work lead to the implementation and the validation of the two studied biological models on the GATE simulation plateform. The same methodology will be applicated to more energetic clinical proton and carbon-ion beams.
References References 1. Abdoul-Carime H et al.. Velocity of a molecule evaporated from a water nanodrplet: Maxwell-Boltzmann statistic versus nonergodic events. Angew Chem Int Ed 2015;54:14685. 2. Calvo F et al.. Collision-induced evaporation of water clusters and contribution of momentum transfer. Eur Phys J D 2017;71:110. 3. Berthias F et al.. Measurement of the velocity of neutral fragments by the ‘‘correlated ion and neutral time of flight” method combined with ‘‘velocity-map imaging”. Rev Sci Instrum 2017;88.. 083101. https://doi.org/10.1016/j.ejmp.2018.09.053
1. Caterina Monini, Testa Étienne, Beuve Michael. NanOx Prediction of cell survival probabilities for three cell lines. Acta Physica Polonica B 2017;48(10). 2. Kase Y et al.. Microdosimetric calculation of relative biological effectiveness for design of therapeutic proton beams. J Radiat Res 2013;54:485–93.
https://doi.org/10.1016/j.ejmp.2018.09.054
6. Selvam TP, Bhola S. Technical Note: EGSnrc-based dosimetric study of the BEBIG C60o HDR brachytherapy sources. Med Phys 2010;37:1365–70. https://doi.org/10.1016/j.ejmp.2018.09.052
40 Irradiation in molecular nanodroplets T. Salbaing a, L. Feketeová a, H. Abdoul-Carime a, B. Farizon a, M. Farizon a, F. Calvo b, T.D. Märk c a
Institut de Physique Nucléaire de Lyon, Villeurbanne, France LiPhy, Grenoble, France c Institut für Ionenphysik und Angewandte Physik, Innsbruck, Austria b
Introduction. One of the specificities of ionizing radiations is that they interact with the electrons of the irradiated matter. In a molecular system the electrons are localized in molecules and the energy is initially deposited in the form of electronic excitation of one of the molecules. The description of the radiation of such initially deposited energy on the nanometer scale in the nearby molecules is challenging, in particular in the context of the therapies combining irradiation and radiosensitizers. Methods. The originality of the work consists of the study of ‘‘model” molecular nanosystems by both, the experiment and the theory. The nanodroplets are initially prepared with a given number of molecules. After a single ultrafast energy deposition located in one of the molecules, the nanodroplet is analyzed after a given relaxation time. The method combining mass spectrometry and imaging techniques allows the analysis of each nanodroplet and this is done for a large number of nanodroplets [1]. The results are compared with statistical molecular dynamics calculations [2]. Results. Thermalisation in nanodroplets following the sudden electronic excitation of one of the molecules [3] is observed with respect to the number of molecules (2–10 typically) in the nanodroplet and for several different types of nanodroplets: protonated water nanodroplets, water nanodroplets including an hydrophobic impurity, protonated methanol nanodroplets. The results show that the evaporation of a molecule takes place also before the full thermalisation of the nanodroplet through the ejection of a molecule with a speed clearly higher than that observed after full thermalisation. The measurements on the methanol nanodroplets evidence a competition between the evaporation of a molecule of methanol and a reaction between the molecules leading to the elimination of a water molecule. Conclusions. The quantitative comparison between the experimental results and the theoretical calculations for molecular nanosystems irradiated in the gas-phase paves the way to robust modelling of the irradiation mechanisms on the nanometer scale.
23
41 Simulation of the biological effectiveness caused by 65 MeV protons (clinical beam) and carbon-ions Y. Ali a, M. Beuve e, A. Carnicer b, E. Débiton c,d, F. Degoul c,d, J. Hérault b, F. Smekens a, L. Maigne a a Université Clermont Auvergne, CNRS/IN2P3, LPC, Clermont-Ferrand, France b Centre Antoine Lacassagne, Cyclotron Biomédical, Nice, France c INSERM, 1240 Clermont-Ferrand, France d Imagerie Moléculaire et Stratégies Théranostiques, Université Clermont Auvergne, Clermont-Ferrand, France e Institut de Physique Nucléaire de Lyon (IPNL), Université Lyon 1, Villeurbanne, France
Introduction. In order to optimize hadron therapy treatments, not only the absorbed dose will be taken in account but the biological consequences on the irradiated cell structures will be considered as well. To achieve that, the relative biological effectiveness (RBE) is estimated to provide the information we need on how cells respond to irradiation. Here we are focusing on a 65 MeV clinical proton beam from the Antoine Lacassagne clinical center in Nice and a 4 MV carbon-ion beam from the Heavy-Ion Medical Accelerator in Chiba (Japan). To predict the said RBE, there are several biophysical models implemented by Monte Carlo codes, some of them already are in use for treatment planifications. Among them, the microkinetic model (MKM) [1,2] and the nanOx model are tested in this study. To address this issue, we use the GATE Monte Carlo platform to estimate the biological effectiveness. Methods. Are collected survival curves from the cell lines samples according to the linear quadratic model. The cells are irradiated by a reference 250 kVp X-ray beam (delivered by the X-rad 320 X-ray system) a 65 MeV proton beam and a 4MV carbon-ion beam (passive mode), the dose being in a 0 to 10 Gy range. All the beams used to conduct the cell irradiations are entirely emulated with the version 8.0 of the GATE Monte Carlo plateform. The microdosimetric spectrums (or linear energy distribution) are then estimated and implemented to the biophysical models. Results. The emulated depth dose distributions and Bragg peaks are verified and consistent with the experimental ionization chamber measurements. The MKM and the NanOx models then predict the biological effectiveness as the said predictions are compared from one model to the other. Conclusions. This work lead to the implementation and the validation of the two studied biological models on the GATE simulation plateform. The same methodology will be applicated to more energetic clinical proton and carbon-ion beams.
References References 1. Abdoul-Carime H et al.. Velocity of a molecule evaporated from a water nanodrplet: Maxwell-Boltzmann statistic versus nonergodic events. Angew Chem Int Ed 2015;54:14685. 2. Calvo F et al.. Collision-induced evaporation of water clusters and contribution of momentum transfer. Eur Phys J D 2017;71:110. 3. Berthias F et al.. Measurement of the velocity of neutral fragments by the ‘‘correlated ion and neutral time of flight” method combined with ‘‘velocity-map imaging”. Rev Sci Instrum 2017;88.. 083101. https://doi.org/10.1016/j.ejmp.2018.09.053
1. Caterina Monini, Testa Étienne, Beuve Michael. NanOx Prediction of cell survival probabilities for three cell lines. Acta Physica Polonica B 2017;48(10). 2. Kase Y et al.. Microdosimetric calculation of relative biological effectiveness for design of therapeutic proton beams. J Radiat Res 2013;54:485–93.
https://doi.org/10.1016/j.ejmp.2018.09.054