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Chappuis F, Tran HN, Zein SA, Bailat C, Incerti S, Bochud F, Desorgher L. The general-purpose Geant4 Monte Carlo toolkit and its Geant4-DNA extension to investigate mechanisms underlying the FLASH effect in radiotherapy: Current status and challenges. Phys Med 2023; 110:102601. [PMID: 37201453 DOI: 10.1016/j.ejmp.2023.102601] [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] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 04/06/2023] [Accepted: 05/01/2023] [Indexed: 05/20/2023] Open
Abstract
FLASH radiotherapy is a promising approach to cancer treatment that offers several advantages over conventional radiotherapy. With this novel technique, high doses of radiation are delivered in a short period of time, inducing the so-called FLASH effect - a phenomenon characterized by healthy tissue sparing without alteration of tumor control. The mechanisms behind the FLASH effect remain unknown. One way to approach this problem is to gain insight into the initial parameters that can distinguish FLASH from conventional irradiation by simulating particle transport in aqueous media using the general-purpose Geant4 Monte Carlo toolkit and its Geant4-DNA extension. This review article discusses the current status of Geant4 and Geant4-DNA simulations to investigate mechanisms underlying the FLASH effect, as well as the challenges faced in this research field. One of the primary challenges is to accurately simulate the experimental irradiation parameters. Another challenge is the temporal extension of the simulations. This review also focuses on two hypotheses to explain the FLASH effect - namely the oxygen depletion hypothesis and the inter-track interactions hypothesis - and discusses how the Geant4 toolkit can be used to investigate them. The aim of this review is to provide an overview of Geant4 and Geant4-DNA simulations for FLASH radiotherapy and to highlight the challenges that need to be overcome in order to better study the FLASH effect.
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Affiliation(s)
- Flore Chappuis
- Institute of Radiation Physics (IRA), Lausanne University Hospital and University of Lausanne, CH-1007 Lausanne, Switzerland
| | - Hoang Ngoc Tran
- Univ. Bordeaux, CNRS, LP2I Bordeaux, UMR 5797, F-33170 Gradignan, France
| | - Sara A Zein
- Univ. Bordeaux, CNRS, LP2I Bordeaux, UMR 5797, F-33170 Gradignan, France
| | - Claude Bailat
- Institute of Radiation Physics (IRA), Lausanne University Hospital and University of Lausanne, CH-1007 Lausanne, Switzerland
| | - Sébastien Incerti
- Univ. Bordeaux, CNRS, LP2I Bordeaux, UMR 5797, F-33170 Gradignan, France
| | - François Bochud
- Institute of Radiation Physics (IRA), Lausanne University Hospital and University of Lausanne, CH-1007 Lausanne, Switzerland
| | - Laurent Desorgher
- Institute of Radiation Physics (IRA), Lausanne University Hospital and University of Lausanne, CH-1007 Lausanne, Switzerland.
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Chappuis F, Grilj V, Tran HN, Zein SA, Bochud F, Bailat C, Incerti S, Desorgher L. Modeling of scavenging systems in water radiolysis with Geant4-DNA. Phys Med 2023; 108:102549. [PMID: 36921424 DOI: 10.1016/j.ejmp.2023.102549] [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] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 01/11/2023] [Accepted: 02/13/2023] [Indexed: 03/16/2023] Open
Abstract
PURPOSE This paper presents the capabilities of the Geant4-DNA Monte Carlo toolkit to simulate water radiolysis with scavengers using the step-by-step (SBS) or the independent reaction times (IRT) methods. It features two examples of application areas: (1) computing the escape yield of H2O2 following a 60Co γ-irradiation and (2) computing the oxygen depletion in water irradiated with 1 MeV electrons. METHODS To ease the implementation of the chemical stage in Geant4-DNA, we developed a user interface that helps define the chemical reactions and set the concentration of scavengers. The first application area example required two computational steps to perform water radiolysis using NO2- and NO3- as scavengers and a 60Co irradiation. The oxygen depletion computation technique for the second application area example consisted of simulating track segments of 1 MeV electrons and determining the radio-induced loss and gain of oxygen molecules. RESULTS The production of H2O2 under variable scavenging levels is consistent with the literature; the mean relative difference between the SBS and IRT methods is 7.2 % ± 0.5 %. For the oxygen depletion 1 µs post-irradiation, the mean relative difference between both methods is equal to 9.8 % ± 0.3 %. The results in the microsecond scale depend on the initial partial pressure of oxygen in water. In addition, the computed oxygen depletions agree well with the literature. CONCLUSIONS The Geant4-DNA toolkit makes it possible to simulate water radiolysis in the presence of scavengers. This feature offers perspectives in radiobiology, with the possibility of simulating cell-relevant scavenging mechanisms.
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Affiliation(s)
- Flore Chappuis
- Institute of Radiation Physics (IRA), Lausanne University Hospital and University of Lausanne, CH-1007 Lausanne, Switzerland
| | - Veljko Grilj
- Institute of Radiation Physics (IRA), Lausanne University Hospital and University of Lausanne, CH-1007 Lausanne, Switzerland
| | - Hoang Ngoc Tran
- Univ. Bordeaux, CNRS, LP2I Bordeaux, UMR 5797, F-33170 Gradignan, France
| | - Sara A Zein
- Univ. Bordeaux, CNRS, LP2I Bordeaux, UMR 5797, F-33170 Gradignan, France
| | - François Bochud
- Institute of Radiation Physics (IRA), Lausanne University Hospital and University of Lausanne, CH-1007 Lausanne, Switzerland
| | - Claude Bailat
- Institute of Radiation Physics (IRA), Lausanne University Hospital and University of Lausanne, CH-1007 Lausanne, Switzerland
| | - Sébastien Incerti
- Univ. Bordeaux, CNRS, LP2I Bordeaux, UMR 5797, F-33170 Gradignan, France
| | - Laurent Desorgher
- Institute of Radiation Physics (IRA), Lausanne University Hospital and University of Lausanne, CH-1007 Lausanne, Switzerland.
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Akerele MI, Zein SA, Pandya S, Nikolopoulou A, Gauthier SA, Raj A, Henchcliffe C, Mozley PD, Karakatsanis NA, Gupta A, Babich J, Nehmeh SA. Population-based input function for TSPO quantification and kinetic modeling with [ 11C]-DPA-713. EJNMMI Phys 2021; 8:39. [PMID: 33914185 PMCID: PMC8085191 DOI: 10.1186/s40658-021-00381-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 03/29/2021] [Indexed: 11/23/2022] Open
Abstract
INTRODUCTION Quantitative positron emission tomography (PET) studies of neurodegenerative diseases typically require the measurement of arterial input functions (AIF), an invasive and risky procedure. This study aims to assess the reproducibility of [11C]DPA-713 PET kinetic analysis using population-based input function (PBIF). The final goal is to possibly eliminate the need for AIF. MATERIALS AND METHODS Eighteen subjects including six healthy volunteers (HV) and twelve Parkinson disease (PD) subjects from two [11C]-DPA-713 PET studies were included. Each subject underwent 90 min of dynamic PET imaging. Five healthy volunteers underwent a test-retest scan within the same day to assess the repeatability of the kinetic parameters. Kinetic modeling was carried out using the Logan total volume of distribution (VT) model. For each data set, kinetic analysis was performed using a patient-specific AIF (PSAIF, ground-truth standard) and then repeated using the PBIF. PBIF was generated using the leave-one-out method for each subject from the remaining 17 subjects and after normalizing the PSAIFs by 3 techniques: (a) Weightsubject×DoseInjected, (b) area under AIF curve (AUC), and (c) Weightsubject×AUC. The variability in the VT measured with PSAIF, in the test-retest study, was determined for selected brain regions (white matter, cerebellum, thalamus, caudate, putamen, pallidum, brainstem, hippocampus, and amygdala) using the Bland-Altman analysis and for each of the 3 normalization techniques. Similarly, for all subjects, the variabilities due to the use of PBIF were assessed. RESULTS Bland-Altman analysis showed systematic bias between test and retest studies. The corresponding mean bias and 95% limits of agreement (LOA) for the studied brain regions were 30% and ± 70%. Comparing PBIF- and PSAIF-based VT estimate for all subjects and all brain regions, a significant difference between the results generated by the three normalization techniques existed for all brain structures except for the brainstem (P-value = 0.095). The mean % difference and 95% LOA is -10% and ±45% for Weightsubject×DoseInjected; +8% and ±50% for AUC; and +2% and ± 38% for Weightsubject×AUC. In all cases, normalizing by Weightsubject×AUC yielded the smallest % bias and variability (% bias = ±2%; LOA = ±38% for all brain regions). Estimating the reproducibility of PBIF-kinetics to PSAIF based on disease groups (HV/PD) and genotype (MAB/HAB), the average VT values for all regions obtained from PBIF is insignificantly higher than PSAIF (%difference = 4.53%, P-value = 0.73 for HAB; and %difference = 0.73%, P-value = 0.96 for MAB). PBIF also tends to overestimate the difference between PD and HV for HAB (% difference = 32.33% versus 13.28%) and underestimate it in MAB (%difference = 6.84% versus 20.92%). CONCLUSIONS PSAIF kinetic results are reproducible with PBIF, with variability in VT within that obtained for the test-retest studies. Therefore, VT assessed using PBIF-based kinetic modeling is clinically feasible and can be an alternative to PSAIF.
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Affiliation(s)
- Mercy I Akerele
- Department of Radiology, Weill Cornell Medical College, New York, NY, 10021, USA.
| | - Sara A Zein
- Department of Radiology, Weill Cornell Medical College, New York, NY, 10021, USA
| | - Sneha Pandya
- Department of Radiology, Weill Cornell Medical College, New York, NY, 10021, USA
| | | | - Susan A Gauthier
- Department of Radiology, Weill Cornell Medical College, New York, NY, 10021, USA
- Department of Neurology, Weill Cornell Medical College, New York, NY, 10021, USA
- Feil Family Brain and Mind Institute, Weill Cornell Medical College, New York, NY, 10021, USA
| | - Ashish Raj
- Department of Radiology, Weill Cornell Medical College, New York, NY, 10021, USA
| | - Claire Henchcliffe
- Department of Radiology, Weill Cornell Medical College, New York, NY, 10021, USA
- Department of Neurology, Weill Cornell Medical College, New York, NY, 10021, USA
| | - P David Mozley
- Department of Radiology, Weill Cornell Medical College, New York, NY, 10021, USA
| | | | - Ajay Gupta
- Department of Radiology, Weill Cornell Medical College, New York, NY, 10021, USA
| | - John Babich
- Department of Radiology, Weill Cornell Medical College, New York, NY, 10021, USA
| | - Sadek A Nehmeh
- Department of Radiology, Weill Cornell Medical College, New York, NY, 10021, USA
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Francis Z, Incerti S, Zein SA, Lampe N, Guzman CA, Durante M. Monte Carlo Simulation of SARS-CoV-2 Radiation-Induced Inactivation for Vaccine Development. Radiat Res 2021; 195:221-229. [PMID: 33411888 DOI: 10.1667/rade-20-00241.1] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Accepted: 12/16/2020] [Indexed: 11/03/2022]
Abstract
Immunization with an inactivated virus is one of the strategies currently being tested towards developing a SARS-CoV-2 vaccine. One of the methods used to inactivate viruses is exposure to high doses of ionizing radiation to damage their nucleic acids. While gamma (γ) rays effectively induce lesions in the RNA, envelope proteins are also highly damaged in the process. This in turn may alter their antigenic properties, affecting their capacity to induce an adaptive immune response able to confer effective protection. Here, we modeled the effect of sparsely and densely ionizing radiation on SARS-CoV-2 using the Monte Carlo toolkit Geant4-DNA. With a realistic 3D target virus model, we calculated the expected number of lesions in the spike and membrane proteins, as well as in the viral RNA. Our findings showed that γ rays produced significant spike protein damage, but densely ionizing charged particles induced less membrane damage for the same level of RNA lesions, because a single ion traversal through the nuclear envelope was sufficient to inactivate the virus. We propose that accelerated charged particles produce inactivated viruses with little structural damage to envelope proteins, thereby representing a new and effective tool for developing vaccines against SARS-CoV-2 and other enveloped viruses.
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Affiliation(s)
- Ziad Francis
- Saint Joseph University, U.R. Mathématiques et Modélisation, Beirut, Lebanon
| | - Sebastien Incerti
- Université de Bordeaux, CNRS/IN2P3, UMR5797, Centre d'Études Nucléaires de Bordeaux Gradignan, France
| | - Sara A Zein
- Université de Bordeaux, CNRS/IN2P3, UMR5797, Centre d'Études Nucléaires de Bordeaux Gradignan, France
| | - Nathanael Lampe
- Université de Bordeaux, CNRS/IN2P3, UMR5797, Centre d'Études Nucléaires de Bordeaux Gradignan, France
| | - Carlos A Guzman
- Helmholtz Zentrum für Infektionsforschung (HZI), Department of Vaccinology and Applied Microbiology, Braunschweig, Germany
| | - Marco Durante
- GSI Helmholtzzentrum für Schwerionenforschung, Biophysics Department, Darmstadt, Germany.,Technische Universität Darmstadt, Institute of Condensed Matter Physics, Darmstadt, Germany
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