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Fira AMR, Keta OD, Petković VD, Đorđević M, Petringa G, Fattori S, Catalano R, Cirrone GP, Cuttone G, Sakata D, Tran NH, Chatzipapas K, Incerti S, Petrović IM. In vitro validation of helium ion irradiations as a function of linear energy transfer in radioresistant human malignant cells. Int J Radiat Biol 2024:1-12. [PMID: 39058324 DOI: 10.1080/09553002.2024.2373752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Revised: 06/11/2024] [Accepted: 06/17/2024] [Indexed: 07/28/2024]
Abstract
PURPOSE Based on considerable interest to enlarge the experimental database of radioresistant cells after their irradiation with helium ions, HTB140, MCF-7 and HTB177 human malignant cells are exposed to helium ion beams having different linear energy transfer (LET). MATERIALS AND METHODS The cells are irradiated along the widened 62 MeV/u helium ion Bragg peak, providing LET of 4.9, 9.8, 23.4 and 36.8 keV/µm. Numerical simulations with the Geant4 toolkit are used for the experimental design. Cell survival is evaluated and compared with reference γ-rays. DNA double strand breaks are assessed via γ-H2AX foci. RESULTS With the increase of LET, surviving fractions at 2 Gy decrease, while RBE (2 Gy, γ) gradually increase. For HTB140 cells, above the dose of 4 Gy, a slight saturation of survival is observed while the increase of RBE (2 Gy, γ) remains unaffected. With the increase of LET the increase of γ-H2AX foci is revealed at 0.5 h after irradiation. There is no significant difference in the number of foci between the cell lines for the same LET. From 0.5 to 24 h, the number of foci drops reaching its residual level. For each time point, there are small differences in DNA DSB among the three cell lines. CONCLUSION Analyses of data acquired for the three cell lines irradiated by helium ions, having different LET, reveal high elimination capacity and creation of a large number of DNA DSB with respect to γ-rays, and are between those reported for protons and carbon ions.
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Affiliation(s)
| | - Otilija D Keta
- Vinča Institute of Nuclear Sciences, University of Belgrade, Belgrade, Serbia
| | - Vladana D Petković
- Vinča Institute of Nuclear Sciences, University of Belgrade, Belgrade, Serbia
| | - Miloš Đorđević
- Vinča Institute of Nuclear Sciences, University of Belgrade, Belgrade, Serbia
| | - Giada Petringa
- Istituto Nazionale di Fisica Nucleare, LNS, Catania, Italy
| | - Serena Fattori
- Istituto Nazionale di Fisica Nucleare, LNS, Catania, Italy
| | | | | | | | | | - Ngoc Hoang Tran
- University of Bordeaux, CNRS, LP2I, UMR 5797, F-33170 Gradignan, France
| | | | - Sebastien Incerti
- University of Bordeaux, CNRS, LP2I, UMR 5797, F-33170 Gradignan, France
| | - Ivan M Petrović
- Vinča Institute of Nuclear Sciences, University of Belgrade, Belgrade, Serbia
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Wang D, Luo H, Chen Y, Ou Y, Dong M, Chen J, Liu R, Wang X, Zhang Q. 14-3-3σ downregulation sensitizes pancreatic cancer to carbon ions by suppressing the homologous recombination repair pathway. Aging (Albany NY) 2024; 16:9727-9752. [PMID: 38843383 PMCID: PMC11210243 DOI: 10.18632/aging.205896] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Accepted: 04/15/2024] [Indexed: 06/22/2024]
Abstract
This study explored the role of 14-3-3σ in carbon ion-irradiated pancreatic adenocarcinoma (PAAD) cells and xenografts and clarified the underlying mechanism. The clinical significance of 14-3-3σ in patients with PAAD was explored using publicly available databases. 14-3-3σ was silenced or overexpressed and combined with carbon ions to measure cell proliferation, cell cycle, and DNA damage repair. Immunoblotting and immunofluorescence (IF) assays were used to determine the underlying mechanisms of 14-3-3σ toward carbon ion radioresistance. We used the BALB/c mice to evaluate the biological behavior of 14-3-3σ in combination with carbon ions. Bioinformatic analysis revealed that PAAD expressed higher 14-3-3σ than normal pancreatic tissues; its overexpression was related to invasive clinicopathological features and a worse prognosis. Knockdown or overexpression of 14-3-3σ demonstrated that 14-3-3σ promoted the survival of PAAD cells after carbon ion irradiation. And 14-3-3σ was upregulated in PAAD cells during DNA damage (carbon ion irradiation, DNA damaging agent) and promotes cell recovery. We found that 14-3-3σ resulted in carbon ion radioresistance by promoting RPA2 and RAD51 accumulation in the nucleus in PAAD cells, thereby increasing homologous recombination repair (HRR) efficiency. Blocking the HR pathway consistently reduced 14-3-3σ overexpression-induced carbon ion radioresistance in PAAD cells. The enhanced radiosensitivity of 14-3-3σ depletion on carbon ion irradiation was also demonstrated in vivo. Altogether, 14-3-3σ functions in tumor progression and can be a potential target for developing biomarkers and treatment strategies for PAAD along with incorporating carbon ion irradiation.
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Affiliation(s)
- Dandan Wang
- The First School of Clinical Medicine, Lanzhou University, Lanzhou, People’s Republic of China
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, People’s Republic of China
| | - Hongtao Luo
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, People’s Republic of China
- Graduate School, University of Chinese Academy of Sciences, Beijing, People’s Republic of China
| | - Yanliang Chen
- The First School of Clinical Medicine, Lanzhou University, Lanzhou, People’s Republic of China
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, People’s Republic of China
| | - Yuhong Ou
- The First School of Clinical Medicine, Lanzhou University, Lanzhou, People’s Republic of China
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, People’s Republic of China
| | - Meng Dong
- The First School of Clinical Medicine, Lanzhou University, Lanzhou, People’s Republic of China
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, People’s Republic of China
| | - Junru Chen
- The First School of Clinical Medicine, Lanzhou University, Lanzhou, People’s Republic of China
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, People’s Republic of China
| | - Ruifeng Liu
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, People’s Republic of China
- Graduate School, University of Chinese Academy of Sciences, Beijing, People’s Republic of China
| | - Xiaohu Wang
- The First School of Clinical Medicine, Lanzhou University, Lanzhou, People’s Republic of China
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, People’s Republic of China
- Graduate School, University of Chinese Academy of Sciences, Beijing, People’s Republic of China
| | - Qiuning Zhang
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, People’s Republic of China
- Graduate School, University of Chinese Academy of Sciences, Beijing, People’s Republic of China
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Kong X, Wang Y, Huang J, Zhang W, Du C, Yin Y, Xue H, Gao H, Liu K, Wu T, Sun L. Microdosimetric assessment about proton spread-out Bragg peak at different depths based on the normal human mesh-type cell population model. Phys Med Biol 2023; 68:175010. [PMID: 37578025 DOI: 10.1088/1361-6560/acec2b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Accepted: 07/31/2023] [Indexed: 08/15/2023]
Abstract
Objective.In clinical proton therapy, the spread-out Bragg peak (SOBP) is commonly used to fit the target shape. Dose depositions at microscopic sites vary, even with a consistent absorbed dose (D) in SOBP. In the present study, monolayer mesh-type cell population models were developed for microdosimetric assessment at different SOBP depths.Approach.Normal human bronchial epithelial (BEAS-2B) and hepatocytes (L-O2) mesh-type cell models were constructed based on fluorescence tomography images of normal human cells. Particle transport simulation in cell populations was performed coupled with Monte Carlo software PHITS. The relationship between microdosimetry and macrodosimetry of SOBP at different depths was described by analyzing the microdosimetric indicators such as specific energyz,specific energy distributionfz,D,and relative standard deviationσz/z¯within cells. Additionally, the microdosimetric distributions characteristics and their contributing factors were also discussed.Main results.The microscopic dose distribution is strongly influenced by cellular size, shape, and material. The mean specific energyz¯of nucleus and cytoplasm in the cell population is greater than the overall absorbed dose of the cell population model (Dp), with a maximumz¯/Dpof 1.1. The cellular dose distribution is different between the BEAS-2B mesh-type model and its concentric ellipsoid geometry-type model, which difference inz¯is about 10.3% for the nucleus and about 7.5% for the cytoplasm with the SOBP depth of 15 cm. WhenD= 2 Gy, the maximumzof L-O2 nucleus reaches 2.8 Gy andσz/z¯is 5.1% at the mid-depth SOBP (16-18 cm); while the maximumzof the BEAS-2B nucleus reaches 2.2 Gy with only 2.7% ofσz/z¯.Significance.The significant variation of microdosimetric distributions of SOBP different depths indicates the necessity to use mesh-type cell population models, which have the potential to be compared with biological results and build the bio-physical model.
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Affiliation(s)
- Xianghui Kong
- State Key Laboratory of Radiation Medicine and Protection, Suzhou 215123, People's Republic of China
- School of Radiation Medicine and Protection, Soochow University, Suzhou 215123, People's Republic of China
- Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions, Suzhou 215123, People's Republic of China
| | - Yidi Wang
- State Key Laboratory of Radiation Medicine and Protection, Suzhou 215123, People's Republic of China
- School of Radiation Medicine and Protection, Soochow University, Suzhou 215123, People's Republic of China
- Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions, Suzhou 215123, People's Republic of China
| | - Jiachen Huang
- State Key Laboratory of Radiation Medicine and Protection, Suzhou 215123, People's Republic of China
- School of Radiation Medicine and Protection, Soochow University, Suzhou 215123, People's Republic of China
- Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions, Suzhou 215123, People's Republic of China
| | - Wenyue Zhang
- State Key Laboratory of Radiation Medicine and Protection, Suzhou 215123, People's Republic of China
- School of Radiation Medicine and Protection, Soochow University, Suzhou 215123, People's Republic of China
- Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions, Suzhou 215123, People's Republic of China
| | - Chuansheng Du
- State Key Laboratory of Radiation Medicine and Protection, Suzhou 215123, People's Republic of China
- School of Radiation Medicine and Protection, Soochow University, Suzhou 215123, People's Republic of China
- Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions, Suzhou 215123, People's Republic of China
| | - Yuchen Yin
- State Key Laboratory of Radiation Medicine and Protection, Suzhou 215123, People's Republic of China
- School of Radiation Medicine and Protection, Soochow University, Suzhou 215123, People's Republic of China
- Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions, Suzhou 215123, People's Republic of China
| | - Huiyuan Xue
- State Key Laboratory of Radiation Medicine and Protection, Suzhou 215123, People's Republic of China
- School of Radiation Medicine and Protection, Soochow University, Suzhou 215123, People's Republic of China
- Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions, Suzhou 215123, People's Republic of China
| | - Han Gao
- State Key Laboratory of Radiation Medicine and Protection, Suzhou 215123, People's Republic of China
- School of Radiation Medicine and Protection, Soochow University, Suzhou 215123, People's Republic of China
- Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions, Suzhou 215123, People's Republic of China
| | - Kun Liu
- State Key Laboratory of Radiation Medicine and Protection, Suzhou 215123, People's Republic of China
- School of Radiation Medicine and Protection, Soochow University, Suzhou 215123, People's Republic of China
- Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions, Suzhou 215123, People's Republic of China
| | - Tao Wu
- State Key Laboratory of Radiation Medicine and Protection, Suzhou 215123, People's Republic of China
- School of Radiation Medicine and Protection, Soochow University, Suzhou 215123, People's Republic of China
- Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions, Suzhou 215123, People's Republic of China
| | - Liang Sun
- State Key Laboratory of Radiation Medicine and Protection, Suzhou 215123, People's Republic of China
- School of Radiation Medicine and Protection, Soochow University, Suzhou 215123, People's Republic of China
- Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions, Suzhou 215123, People's Republic of China
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Chatzipapas K, Dordevic M, Zivkovic S, Tran NH, Lampe N, Sakata D, Petrovic I, Ristic-Fira A, Shin WG, Zein S, Brown JMC, Kyriakou I, Emfietzoglou D, Guatelli S, Incerti S. Geant4-DNA simulation of human cancer cells irradiation with helium ion beams. Phys Med 2023; 112:102613. [PMID: 37356419 DOI: 10.1016/j.ejmp.2023.102613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Revised: 05/03/2023] [Accepted: 05/30/2023] [Indexed: 06/27/2023] Open
Abstract
PURPOSE This study aimed to develop a computational environment for the accurate simulation of human cancer cell irradiation using Geant4-DNA. New cell geometrical models were developed and irradiated by alpha particle beams to induce DNA damage. The proposed approach may help further investigation of the benefits of external alpha irradiation therapy. METHODS The Geant4-DNA Monte Carlo (MC) toolkit allows the simulation of cancer cell geometries that can be combined with accurate modelling of physical, physicochemical and chemical stages of liquid water irradiation, including radiolytic processes. Geant4-DNA is used to calculate direct and non-direct DNA damage yields, such as single and double strand breaks, produced by the deposition of energy or by the interaction of DNA with free radicals. RESULTS In this study, the "molecularDNA" example application of Geant4-DNA was used to quantify early DNA damage in human cancer cells upon irradiation with alpha particle beams, as a function of linear energy transfer (LET). The MC simulation results are compared to experimental data, as well as previously published simulation data. The simulation results agree well with the experimental data on DSB yields in the lower LET range, while the experimental data on DSB yields are lower than the results obtained with the "molecularDNA" example in the higher LET range. CONCLUSION This study explored and demonstrated the possibilities of the Geant4-DNA toolkit together with the "molecularDNA" example to simulate the helium beam irradiation of cancer cell lines, to quantify the early DNA damage, or even the following DNA damage response.
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Affiliation(s)
| | - Milos Dordevic
- Vinca Institute of Nuclear Sciences, National Institute of the Republic of Serbia, University of Belgrade, Mike Petrovica Alasa 12-14, 11351 Vinca, Belgrade, Serbia.
| | - Sara Zivkovic
- Vinca Institute of Nuclear Sciences, National Institute of the Republic of Serbia, University of Belgrade, Mike Petrovica Alasa 12-14, 11351 Vinca, Belgrade, Serbia
| | - Ngoc Hoang Tran
- University of Bordeaux, CNRS, LP2i, UMR5797, F-33170 Gradignan, France
| | | | - Dousatsu Sakata
- Division of Health Sciences, Osaka University, Osaka 565-0871, Japan
| | - Ivan Petrovic
- Vinca Institute of Nuclear Sciences, National Institute of the Republic of Serbia, University of Belgrade, Mike Petrovica Alasa 12-14, 11351 Vinca, Belgrade, Serbia
| | - Aleksandra Ristic-Fira
- Vinca Institute of Nuclear Sciences, National Institute of the Republic of Serbia, University of Belgrade, Mike Petrovica Alasa 12-14, 11351 Vinca, Belgrade, Serbia
| | - Wook-Geun Shin
- Physics Division, Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, 02114 MA, USA
| | - Sara Zein
- University of Bordeaux, CNRS, LP2i, UMR5797, F-33170 Gradignan, France
| | - Jeremy M C Brown
- Optical Sciences Centre, Department of Physics and Astronomy, Swinburne University of Technology, Hawthorn 3122, Australia
| | - Ioanna Kyriakou
- Medical Physics Laboratory, Department of Medicine, University of Ioannina, 45110 Ioannina, Greece
| | - Dimitris Emfietzoglou
- Medical Physics Laboratory, Department of Medicine, University of Ioannina, 45110 Ioannina, Greece
| | - Susanna Guatelli
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Sebastien Incerti
- University of Bordeaux, CNRS, LP2i, UMR5797, F-33170 Gradignan, France
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Chatzipapas KP, Tran NH, Dordevic M, Zivkovic S, Zein S, Shin W, Sakata D, Lampe N, Brown JMC, Ristic‐Fira A, Petrovic I, Kyriakou I, Emfietzoglou D, Guatelli S, Incerti S. Simulation of DNA damage using Geant4‐DNA: an overview of the “molecularDNA” example application. PRECISION RADIATION ONCOLOGY 2023. [DOI: 10.1002/pro6.1186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023] Open
Affiliation(s)
| | - Ngoc Hoang Tran
- University of Bordeaux, CNRS, LP2I Bordeaux, UMR 5797 Gradignan France
| | - Milos Dordevic
- Vinca Institute of Nuclear Sciences, National Institute of the Republic of Serbia University of Belgrade, Vinca Belgrade Serbia
| | - Sara Zivkovic
- Vinca Institute of Nuclear Sciences, National Institute of the Republic of Serbia University of Belgrade, Vinca Belgrade Serbia
| | - Sara Zein
- University of Bordeaux, CNRS, LP2I Bordeaux, UMR 5797 Gradignan France
| | - Wook‐Geun Shin
- Physics Division, Department of Radiation Oncology Massachusetts General Hospital & Harvard Medical School Boston Massachusetts USA
| | | | | | - Jeremy M. C. Brown
- Department of Physics and Astronomy Swinburne University of Technology Melbourne Australia
| | - Aleksandra Ristic‐Fira
- Vinca Institute of Nuclear Sciences, National Institute of the Republic of Serbia University of Belgrade, Vinca Belgrade Serbia
| | - Ivan Petrovic
- Vinca Institute of Nuclear Sciences, National Institute of the Republic of Serbia University of Belgrade, Vinca Belgrade Serbia
| | - Ioanna Kyriakou
- Medical Physics Laboratory Department of Medicine University of Ioannina Ioannina Greece
| | - Dimitris Emfietzoglou
- Medical Physics Laboratory Department of Medicine University of Ioannina Ioannina Greece
| | - Susanna Guatelli
- Centre for Medical Radiation Physics University of Wollongong Wollongong New South Wales Australia
| | - Sébastien Incerti
- University of Bordeaux, CNRS, LP2I Bordeaux, UMR 5797 Gradignan France
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Frame CM, Chen Y, Gagnon J, Yuan Y, Ma T, Dritschilo A, Pang D. Proton induced DNA double strand breaks at the Bragg peak: Evidence of enhanced LET effect. Front Oncol 2022; 12:930393. [PMID: 35992825 PMCID: PMC9388940 DOI: 10.3389/fonc.2022.930393] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Accepted: 07/18/2022] [Indexed: 11/13/2022] Open
Abstract
PurposeTo investigate DNA double strand breaks (DSBs) induced by therapeutic proton beams in plateau and Bragg peak to demonstrate DSB induction due to the higher LET in the Bragg peak.Materials and MethodspUC19 plasmid DNA samples were irradiated to doses of 1000 and 3000 Gy on a Mevion S250i proton system with a monoenergetic, 110 MeV, proton beam at depths of 2 and 9.4 cm, corresponding to a position on the plateau and distal Bragg peak of the beam, respectively. The irradiated DNA samples were imaged by atomic force microscopy for visualization of individual DNA molecules, either broken or intact, and quantification of the DNA fragment length distributions for each of the irradiated samples. Percentage of the broken DNA and average number of DSBs per DNA molecule were obtained.ResultsCompared to irradiation effects in the plateau region, DNA irradiated at the Bragg peak sustained more breakage at the same dose, yielding more short DNA fragments and higher numbers of DSB per DNA molecule.ConclusionThe higher LET of proton beams at the Bragg peak results in more densely distributed DNA DSBs, which supports an underlying mechanism for the increased cell killing by protons at the Bragg peak.
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Key biological mechanisms involved in high-LET radiation therapies with a focus on DNA damage and repair. Expert Rev Mol Med 2022; 24:e15. [PMID: 35357290 DOI: 10.1017/erm.2022.6] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
DNA damage and repair studies are at the core of the radiation biology field and represent also the fundamental principles informing radiation therapy (RT). DNA damage levels are a function of radiation dose, whereas the type of damage and biological effects such as DNA damage complexity, depend on radiation quality that is linear energy transfer (LET). Both levels and types of DNA damage determine cell fate, which can include necrosis, apoptosis, senescence or autophagy. Herein, we present an overview of current RT modalities in the light of DNA damage and repair with emphasis on medium to high-LET radiation. Proton radiation is discussed along with its new adaptation of FLASH RT. RT based on α-particles includes brachytherapy and nuclear-RT, that is proton-boron capture therapy (PBCT) and boron-neutron capture therapy (BNCT). We also discuss carbon ion therapy along with combinatorial immune-based therapies and high-LET RT. For each RT modality, we summarise relevant DNA damage studies. Finally, we provide an update of the role of DNA repair in high-LET RT and we explore the biological responses triggered by differential LET and dose.
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A Geant4-DNA Evaluation of Radiation-Induced DNA Damage on a Human Fibroblast. Cancers (Basel) 2021; 13:cancers13194940. [PMID: 34638425 PMCID: PMC8508455 DOI: 10.3390/cancers13194940] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2021] [Revised: 09/21/2021] [Accepted: 09/26/2021] [Indexed: 11/17/2022] Open
Abstract
Simple Summary DNA damage caused by ionizing radiation in a human fibroblast cell evaluated by the Geant4-DNA Monte Carlo toolkit is presented. A validation study using a computational geometric human DNA model was then carried out, and the calculated DNA damage as a function of particle type and energy is presented. The results of this work showed a significant improvement on past work and were consistent with recent radiobiological experimental data, such as damage yields. This work and the developed methodology could impact a broad number of research fields in which the understanding of radiation effects is crucial, such as cancer radiotherapy, space science, and medical physics. Abstract Accurately modeling the radiobiological mechanisms responsible for the induction of DNA damage remains a major scientific challenge, particularly for understanding the effects of low doses of ionizing radiation on living beings, such as the induction of carcinogenesis. A computational approach based on the Monte Carlo technique to simulate track structures in a biological medium is currently the most reliable method for calculating the early effects induced by ionizing radiation on DNA, the primary cellular target of such effects. The Geant4-DNA Monte Carlo toolkit can simulate not only the physical, but also the physico-chemical and chemical stages of water radiolysis. These stages can be combined with simplified geometric models of biological targets, such as DNA, to assess direct and indirect early DNA damage. In this study, DNA damage induced in a human fibroblast cell was evaluated using Geant4-DNA as a function of incident particle type (gammas, protons, and alphas) and energy. The resulting double-strand break yields as a function of linear energy transfer closely reproduced recent experimental data. Other quantities, such as fragment length distribution, scavengeable damage fraction, and time evolution of damage within an analytical repair model also supported the plausibility of predicting DNA damage using Geant4-DNA.The complete simulation chain application “molecularDNA”, an example for users of Geant4-DNA, will soon be distributed through Geant4.
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