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Aylward JD, Henthorn N, Manger S, Warmenhoven JW, Merchant MJ, Taylor MJ, Mackay RI, Kirkby KJ. Characterisation of the UK high energy proton research beamline for high and ultra-high dose rate (FLASH) irradiation. Biomed Phys Eng Express 2023; 9:055032. [PMID: 37567152 DOI: 10.1088/2057-1976/acef25] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Accepted: 08/11/2023] [Indexed: 08/13/2023]
Abstract
Objective. This work sets out the capabilities of the high energy proton research beamline developed in the Christie proton therapy centre for Ultra-High Dose Rate (UHDR) irradiation and FLASH experiments. It also characterises the lower limits of UHDR operation for this Pencil Beam Scanning (PBS) proton hardware.Approach. Energy dependent nozzle transmission was measured using a Faraday Cup beam collector. Spot size was measured at the reference plane using a 2D scintillation detector. Integrated depth doses (IDDs) were measured. EBT3 Gafchromic film was used to compare UHDR and conventional dose rate spots. Our beam monitor calibration methodolgy for UHDR is described. A microDiamond detector was used to determine dose rates at zref. Instantaneous depth dose rates were calculated for 70-245 MeV. PBS dose rate distributions were calculated using Folkerts and Van der Water definitions.Main results. Transmission of 7.05 ± 0.1% is achieveable corresponding to a peak instantaneous dose rate of 112.7 Gy s-1. Beam parameters are comparable in conventional and UHDR mode with a spot size ofσx= 4.6 mm,σy= 6.6 mm. Dead time in the beam monitoring electonics warrants a beam current dependent MU correction in the present configuration. Fast beam scanning of 26.4 m s-1(X) and 12.1 m s-1(Y) allows PBS dose rates of the order tens of Grays per second.Significance. UHDR delivery is possible for small field sizes and high energies enabling research into the FLASH effect with PBS protons at our facility. To our knowledge this is also the first thorough characterisation of UHDR irradiation using the hardware of this clinical accelerator at energies less than 250 MeV. The data set out in this publication can be used for designing experiments at this UK research facility and inform the possible future clinical translation of UHDR PBS proton therapy.
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Affiliation(s)
- J D Aylward
- Division of Cancer Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom
- Christie Medical Physics and Engineering, The Christie NHS Foundation Trust, Manchester, United Kingdom
- Cockcroft Institute, Daresbury Laboratory, Keckwick Ln, Daresbury, Warrington WA4 4AD, United Kingdom
| | - N Henthorn
- Division of Cancer Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom
- The Christie NHS Foundation Trust, Manchester, United Kingdom
| | - S Manger
- Division of Cancer Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom
- The Christie NHS Foundation Trust, Manchester, United Kingdom
| | - J W Warmenhoven
- Division of Cancer Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom
- The Christie NHS Foundation Trust, Manchester, United Kingdom
| | - M J Merchant
- Division of Cancer Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom
- The Christie NHS Foundation Trust, Manchester, United Kingdom
| | - M J Taylor
- Division of Cancer Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom
- Cockcroft Institute, Daresbury Laboratory, Keckwick Ln, Daresbury, Warrington WA4 4AD, United Kingdom
- The Christie NHS Foundation Trust, Manchester, United Kingdom
| | - R I Mackay
- Division of Cancer Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom
- Christie Medical Physics and Engineering, The Christie NHS Foundation Trust, Manchester, United Kingdom
| | - K J Kirkby
- Division of Cancer Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom
- Cockcroft Institute, Daresbury Laboratory, Keckwick Ln, Daresbury, Warrington WA4 4AD, United Kingdom
- The Christie NHS Foundation Trust, Manchester, United Kingdom
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2
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Smith EAK, Henthorn NT, Warmenhoven JW, Ingram SP, Aitkenhead AH, Richardson JC, Sitch P, Chadwick AL, Underwood TSA, Merchant MJ, Burnet NG, Kirkby NF, Kirkby KJ, Mackay RI. In Silico Models of DNA Damage and Repair in Proton Treatment Planning: A Proof of Concept. Sci Rep 2019; 9:19870. [PMID: 31882690 PMCID: PMC6934522 DOI: 10.1038/s41598-019-56258-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Accepted: 11/29/2019] [Indexed: 01/29/2023] Open
Abstract
There is strong in vitro cell survival evidence that the relative biological effectiveness (RBE) of protons is variable, with dependence on factors such as linear energy transfer (LET) and dose. This is coupled with the growing in vivo evidence, from post-treatment image change analysis, of a variable RBE. Despite this, a constant RBE of 1.1 is still applied as a standard in proton therapy. However, there is a building clinical interest in incorporating a variable RBE. Recently, correlations summarising Monte Carlo-based mechanistic models of DNA damage and repair with absorbed dose and LET have been published as the Manchester mechanistic (MM) model. These correlations offer an alternative path to variable RBE compared to the more standard phenomenological models. In this proof of concept work, these correlations have been extended to acquire RBE-weighted dose distributions and calculated, along with other RBE models, on a treatment plan. The phenomenological and mechanistic models for RBE have been shown to produce comparable results with some differences in magnitude and relative distribution. The mechanistic model found a large RBE for misrepair, which phenomenological models are unable to do. The potential of the MM model to predict multiple endpoints presents a clear advantage over phenomenological models.
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Affiliation(s)
- Edward A K Smith
- Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK. .,Christie Medical Physics and Engineering, The Christie NHS Foundation Trust, Manchester, UK.
| | - N T Henthorn
- Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK.,The Christie NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, UK
| | - J W Warmenhoven
- Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK.,The Christie NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, UK
| | - S P Ingram
- Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK.,Christie Medical Physics and Engineering, The Christie NHS Foundation Trust, Manchester, UK
| | - A H Aitkenhead
- Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK.,Christie Medical Physics and Engineering, The Christie NHS Foundation Trust, Manchester, UK
| | - J C Richardson
- Christie Medical Physics and Engineering, The Christie NHS Foundation Trust, Manchester, UK
| | - P Sitch
- Christie Medical Physics and Engineering, The Christie NHS Foundation Trust, Manchester, UK
| | - A L Chadwick
- Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK.,The Christie NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, UK
| | - T S A Underwood
- Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK.,The Christie NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, UK
| | - M J Merchant
- Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK.,The Christie NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, UK
| | - N G Burnet
- Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK.,The Christie NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, UK
| | - N F Kirkby
- Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK.,The Christie NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, UK
| | - K J Kirkby
- Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK.,The Christie NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, UK
| | - R I Mackay
- Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK.,Christie Medical Physics and Engineering, The Christie NHS Foundation Trust, Manchester, UK
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3
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Henthorn NT, Warmenhoven JW, Sotiropoulos M, Aitkenhead AH, Smith EAK, Ingram SP, Kirkby NF, Chadwick A, Burnet NG, Mackay RI, Kirkby KJ, Merchant MJ. Clinically relevant nanodosimetric simulation of DNA damage complexity from photons and protons. RSC Adv 2019; 9:6845-6858. [PMID: 35518487 PMCID: PMC9061037 DOI: 10.1039/c8ra10168j] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Accepted: 02/21/2019] [Indexed: 12/16/2022] Open
Abstract
Relative Biological Effectiveness (RBE), the ratio of doses between radiation modalities to produce the same biological endpoint, is a controversial and important topic in proton therapy. A number of phenomenological models incorporate variable RBE as a function of Linear Energy Transfer (LET), though a lack of mechanistic description limits their applicability. In this work we take a different approach, using a track structure model employing fundamental physics and chemistry to make predictions of proton and photon induced DNA damage, the first step in the mechanism of radiation-induced cell death. We apply this model to a proton therapy clinical case showing, for the first time, predictions of DNA damage on a patient treatment plan. Our model predictions are for an idealised cell and are applied to an ependymoma case, at this stage without any cell specific parameters. By comparing to similar predictions for photons, we present a voxel-wise RBE of DNA damage complexity. This RBE of damage complexity shows similar trends to the expected RBE for cell kill, implying that damage complexity is an important factor in DNA repair and therefore biological effect. Relative Biological Effectiveness (RBE) is a controversial and important topic in proton therapy. This work uses Monte Carlo simulations of DNA damage for protons and photons to probe this phenomenon, providing a plausible mechanistic understanding.![]()
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Affiliation(s)
- N. T. Henthorn
- Division of Cancer Sciences
- School of Medical Sciences
- Faculty of Biology, Medicine and Health
- The University of Manchester
- UK
| | - J. W. Warmenhoven
- Division of Cancer Sciences
- School of Medical Sciences
- Faculty of Biology, Medicine and Health
- The University of Manchester
- UK
| | - M. Sotiropoulos
- Division of Cancer Sciences
- School of Medical Sciences
- Faculty of Biology, Medicine and Health
- The University of Manchester
- UK
| | - A. H. Aitkenhead
- Division of Cancer Sciences
- School of Medical Sciences
- Faculty of Biology, Medicine and Health
- The University of Manchester
- UK
| | - E. A. K. Smith
- Division of Cancer Sciences
- School of Medical Sciences
- Faculty of Biology, Medicine and Health
- The University of Manchester
- UK
| | - S. P. Ingram
- Division of Cancer Sciences
- School of Medical Sciences
- Faculty of Biology, Medicine and Health
- The University of Manchester
- UK
| | - N. F. Kirkby
- Division of Cancer Sciences
- School of Medical Sciences
- Faculty of Biology, Medicine and Health
- The University of Manchester
- UK
| | - A. L. Chadwick
- Division of Cancer Sciences
- School of Medical Sciences
- Faculty of Biology, Medicine and Health
- The University of Manchester
- UK
| | - N. G. Burnet
- Division of Cancer Sciences
- School of Medical Sciences
- Faculty of Biology, Medicine and Health
- The University of Manchester
- UK
| | - R. I. Mackay
- Division of Cancer Sciences
- School of Medical Sciences
- Faculty of Biology, Medicine and Health
- The University of Manchester
- UK
| | - K. J. Kirkby
- Division of Cancer Sciences
- School of Medical Sciences
- Faculty of Biology, Medicine and Health
- The University of Manchester
- UK
| | - M. J. Merchant
- Division of Cancer Sciences
- School of Medical Sciences
- Faculty of Biology, Medicine and Health
- The University of Manchester
- UK
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4
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Schuemann J, McNamara AL, Warmenhoven JW, Henthorn NT, Kirkby KJ, Merchant MJ, Ingram S, Paganetti H, Held KD, Ramos-Mendez J, Faddegon B, Perl J, Goodhead DT, Plante I, Rabus H, Nettelbeck H, Friedland W, Kundrát P, Ottolenghi A, Baiocco G, Barbieri S, Dingfelder M, Incerti S, Villagrasa C, Bueno M, Bernal MA, Guatelli S, Sakata D, Brown JMC, Francis Z, Kyriakou I, Lampe N, Ballarini F, Carante MP, Davídková M, Štěpán V, Jia X, Cucinotta FA, Schulte R, Stewart RD, Carlson DJ, Galer S, Kuncic Z, Lacombe S, Milligan J, Cho SH, Sawakuchi G, Inaniwa T, Sato T, Li W, Solov'yov AV, Surdutovich E, Durante M, Prise KM, McMahon SJ. A New Standard DNA Damage (SDD) Data Format. Radiat Res 2018; 191:76-92. [PMID: 30407901 DOI: 10.1667/rr15209.1] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Our understanding of radiation-induced cellular damage has greatly improved over the past few decades. Despite this progress, there are still many obstacles to fully understand how radiation interacts with biologically relevant cellular components, such as DNA, to cause observable end points such as cell killing. Damage in DNA is identified as a major route of cell killing. One hurdle when modeling biological effects is the difficulty in directly comparing results generated by members of different research groups. Multiple Monte Carlo codes have been developed to simulate damage induction at the DNA scale, while at the same time various groups have developed models that describe DNA repair processes with varying levels of detail. These repair models are intrinsically linked to the damage model employed in their development, making it difficult to disentangle systematic effects in either part of the modeling chain. These modeling chains typically consist of track-structure Monte Carlo simulations of the physical interactions creating direct damages to DNA, followed by simulations of the production and initial reactions of chemical species causing so-called "indirect" damages. After the induction of DNA damage, DNA repair models combine the simulated damage patterns with biological models to determine the biological consequences of the damage. To date, the effect of the environment, such as molecular oxygen (normoxic vs. hypoxic), has been poorly considered. We propose a new standard DNA damage (SDD) data format to unify the interface between the simulation of damage induction in DNA and the biological modeling of DNA repair processes, and introduce the effect of the environment (molecular oxygen or other compounds) as a flexible parameter. Such a standard greatly facilitates inter-model comparisons, providing an ideal environment to tease out model assumptions and identify persistent, underlying mechanisms. Through inter-model comparisons, this unified standard has the potential to greatly advance our understanding of the underlying mechanisms of radiation-induced DNA damage and the resulting observable biological effects when radiation parameters and/or environmental conditions change.
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Affiliation(s)
- J Schuemann
- a Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - A L McNamara
- a Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - J W Warmenhoven
- b Division of Cancer Sciences, The University of Manchester, Manchester, United Kingdom
| | - N T Henthorn
- b Division of Cancer Sciences, The University of Manchester, Manchester, United Kingdom
| | - K J Kirkby
- b Division of Cancer Sciences, The University of Manchester, Manchester, United Kingdom
| | - M J Merchant
- b Division of Cancer Sciences, The University of Manchester, Manchester, United Kingdom
| | - S Ingram
- b Division of Cancer Sciences, The University of Manchester, Manchester, United Kingdom
| | - H Paganetti
- a Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - K D Held
- a Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - J Ramos-Mendez
- c Department of Radiation Oncology, University of California San Francisco, San Francisco, California
| | - B Faddegon
- c Department of Radiation Oncology, University of California San Francisco, San Francisco, California
| | - J Perl
- d SLAC National Accelerator Laboratory, Menlo Park, California
| | - D T Goodhead
- e Medical Research Council, Harwell, United Kingdom
| | | | - H Rabus
- g Physikalisch-Technische Bundesanstalt (PTB), Braunschweig, Germany.,h Task Group 6.2 "Computational Micro- and Nanodosimetry", European Radiation Dosimetry Group e.V., Neuherberg, Germany
| | - H Nettelbeck
- g Physikalisch-Technische Bundesanstalt (PTB), Braunschweig, Germany.,h Task Group 6.2 "Computational Micro- and Nanodosimetry", European Radiation Dosimetry Group e.V., Neuherberg, Germany
| | - W Friedland
- h Task Group 6.2 "Computational Micro- and Nanodosimetry", European Radiation Dosimetry Group e.V., Neuherberg, Germany.,i Institute of Radiation Protection, Helmholtz Zentrum München - German Research Center for Environmental Health, Neuherberg, Germany
| | - P Kundrát
- i Institute of Radiation Protection, Helmholtz Zentrum München - German Research Center for Environmental Health, Neuherberg, Germany
| | - A Ottolenghi
- j Physics Department, University of Pavia, Pavia, Italy
| | - G Baiocco
- h Task Group 6.2 "Computational Micro- and Nanodosimetry", European Radiation Dosimetry Group e.V., Neuherberg, Germany.,j Physics Department, University of Pavia, Pavia, Italy
| | - S Barbieri
- h Task Group 6.2 "Computational Micro- and Nanodosimetry", European Radiation Dosimetry Group e.V., Neuherberg, Germany.,j Physics Department, University of Pavia, Pavia, Italy
| | - M Dingfelder
- k Department of Physics, East Carolina University, Greenville, North Carolina
| | - S Incerti
- l CNRS, IN2P3, CENBG, UMR 5797, F-33170 Gradignan, France.,m University of Bordeaux, CENBG, UMR 5797, F-33170 Gradignan, France
| | - C Villagrasa
- h Task Group 6.2 "Computational Micro- and Nanodosimetry", European Radiation Dosimetry Group e.V., Neuherberg, Germany.,n Institut de Radioprotection et Sûreté Nucléaire, F-92262 Fontenay aux Roses Cedex, France
| | - M Bueno
- n Institut de Radioprotection et Sûreté Nucléaire, F-92262 Fontenay aux Roses Cedex, France
| | - M A Bernal
- o Applied Physics Department, Gleb Wataghin Institute of Physics, State University of Campinas, Campinas, SP, Brazil
| | - S Guatelli
- p Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, Australia
| | - D Sakata
- p Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, Australia
| | - J M C Brown
- q Department of Radiation Science and Technology, Delft University of Technology, Delft, The Netherlands
| | - Z Francis
- r Department of Physics, Faculty of Science, Saint Joseph University, Beirut, Lebanon
| | - I Kyriakou
- s Medical Physics Laboratory, University of Ioannina Medical School, Ioannina, Greece
| | - N Lampe
- l CNRS, IN2P3, CENBG, UMR 5797, F-33170 Gradignan, France
| | - F Ballarini
- j Physics Department, University of Pavia, Pavia, Italy.,t Italian National Institute of Nuclear Physics, Section of Pavia, I-27100 Pavia, Italy
| | - M P Carante
- j Physics Department, University of Pavia, Pavia, Italy.,t Italian National Institute of Nuclear Physics, Section of Pavia, I-27100 Pavia, Italy
| | - M Davídková
- u Department of Radiation Dosimetry, Nuclear Physics Institute of the CAS, Řež, Czech Republic
| | - V Štěpán
- u Department of Radiation Dosimetry, Nuclear Physics Institute of the CAS, Řež, Czech Republic
| | - X Jia
- v Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas
| | - F A Cucinotta
- w Health Physics and Diagnostic Sciences, University of Nevada Las Vegas, Las Vegas, Nevada
| | - R Schulte
- x Division of Biomedical Engineering Sciences, School of Medicine, Loma Linda University, Loma Linda, California
| | - R D Stewart
- y Department of Radiation Oncology, University of Washington, Seattle, Washington
| | - D J Carlson
- z Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, Connecticut
| | - S Galer
- aa Medical Radiation Science Group, National Physical Laboratory, Teddington, United Kingdom
| | - Z Kuncic
- bb School of Physics, University of Sydney, Sydney, NSW, Australia
| | - S Lacombe
- cc Institut des Sciences Moléculaires d'Orsay (UMR 8214) University Paris-Sud, CNRS, University Paris-Saclay, 91405 Orsay Cedex, France
| | | | - S H Cho
- ee Department of Radiation Physics and Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - G Sawakuchi
- ee Department of Radiation Physics and Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - T Inaniwa
- ff Department of Accelerator and Medical Physics, National Institute of Radiological Sciences, Chiba, Japan
| | - T Sato
- gg Japan Atomic Energy Agency, Nuclear Science and Engineering Center, Tokai 319-1196, Japan
| | - W Li
- i Institute of Radiation Protection, Helmholtz Zentrum München - German Research Center for Environmental Health, Neuherberg, Germany.,hh Task Group 7.7 "Internal Micro- and Nanodosimetry", European Radiation Dosimetry Group e.V., Neuherberg, Germany
| | - A V Solov'yov
- ii MBN Research Center, 60438 Frankfurt am Main, Germany
| | - E Surdutovich
- jj Department of Physics, Oakland University, Rochester, Michigan
| | - M Durante
- kk GSI Helmholtzzentrum für Schwerionenforschung, Biophysics Department, Darmstadt, Germany
| | - K M Prise
- ll Centre for Cancer Research and Cell Biology, Queens University Belfast, Belfast, United Kingdom
| | - S J McMahon
- ll Centre for Cancer Research and Cell Biology, Queens University Belfast, Belfast, United Kingdom
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5
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Henthorn NT, Warmenhoven JW, Sotiropoulos M, Mackay RI, Kirkby KJ, Merchant MJ. Nanodosimetric Simulation of Direct Ion-Induced DNA Damage Using Different Chromatin Geometry Models. Radiat Res 2017; 188:690-703. [PMID: 28792846 DOI: 10.1667/rr14755.1] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Monte Carlo based simulation has proven useful in investigating the effect of proton-induced DNA damage and the processes through which this damage occurs. Clustering of ionizations within a small volume can be related to DNA damage through the principles of nanodosimetry. For simulation, it is standard to construct a small volume of water and determine spatial clusters. More recently, realistic DNA geometries have been used, tracking energy depositions within DNA backbone volumes. Traditionally a chromatin fiber is built within the simulation and identically replicated throughout a cell nucleus, representing the cell in interphase. However, the in vivo geometry of the chromatin fiber is still unknown within the literature, with many proposed models. In this work, the Geant4-DNA toolkit was used to build three chromatin models: the solenoid, zig-zag and cross-linked geometries. All fibers were built to the same chromatin density of 4.2 nucleosomes/11 nm. The fibers were then irradiated with protons (LET 5-80 keV/μm) or alpha particles (LET 63-226 keV/μm). Nanodosimetric parameters were scored for each fiber after each LET and used as a comparator among the models. Statistically significant differences were observed in the double-strand break backbone size distributions among the models, although nonsignificant differences were noted among the nanodosimetric parameters. From the data presented in this article, we conclude that selection of the solenoid, zig-zag or cross-linked chromatin model does not significantly affect the calculated nanodosimetric parameters. This allows for a simulation-based cell model to make use of any of these chromatin models for the scoring of direct ion-induced DNA damage.
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Affiliation(s)
- N T Henthorn
- a Division of Molecular and Clinical Cancer Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom
| | - J W Warmenhoven
- a Division of Molecular and Clinical Cancer Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom
| | - M Sotiropoulos
- a Division of Molecular and Clinical Cancer Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom
| | - R I Mackay
- b Christie Medical Physics and Engineering, The Christie NHS Foundation Trust, Manchester, United Kingdom; and
| | - K J Kirkby
- a Division of Molecular and Clinical Cancer Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom.,c The Christie NHS Foundation Trust, Manchester, United Kingdom
| | - M J Merchant
- a Division of Molecular and Clinical Cancer Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom.,c The Christie NHS Foundation Trust, Manchester, United Kingdom
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