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Tang W, Tang B, Li X, Wang Y, Li Z, Gao Y, Gao H, Yan C, Sun L. Cellular S-value evaluation based on real human cell models using the GATE MC package. Appl Radiat Isot 2020; 168:109509. [PMID: 33214023 DOI: 10.1016/j.apradiso.2020.109509] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 10/28/2020] [Accepted: 11/06/2020] [Indexed: 11/25/2022]
Abstract
Exploring the spatial distribution of the energy loss of ionising radiation at the subcellular level is indispensable for evaluating the radiobiological effects of targeted radionuclide therapy accurately. Believing that S-values are important for obtaining the target dose, the Committee on Medical Internal Radiation Dose (MIRD) proposed a method to obtain the cellular dosimetric parameter. However, most available data on cellular S-values were calculated based on simple geometric models, such as ellipsoids or spheres, which do not accurately reflect biological reality. To investigate the influence of the cellular model on S-values, calculations were performed for two kinds of polygon-surface phantom models of realistic, individual human cells, the lung epithelial cell model (the B2B Phantom model) and the hepatocyte model (the Liver Phantom model), using the Monte Carlo (MC) software package GATE. To analyse the influence of cell geometry on the final S-value, the differences in the S-values between the realistic cell models and simple geometric sphere and ellipsoid models with similar volumes were calculated and compared for six different combinations of source and target regions. The irradiation conditions were 0.01-1.10 MeV monoenergetic electron sources and the Auger electronic therapy nuclides Ga-67, Tc-99m, In-111, I-125 and Tl-201, which are commonly used in nuclear medicine. The S-values calculated in this study are different from the results of the simple geometry models proposed by previous researchers. Two more precise polygon-surface phantom models of realistic, individual human cells were used, which provided more accurate information about the cell dose and will be very useful for the diagnostic application of radiotherapy in the future.
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Affiliation(s)
- Wei Tang
- State Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection, Soochow University, Suzhou, 215123, China; Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions, China
| | - Bo Tang
- State Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection, Soochow University, Suzhou, 215123, China; Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions, China; Department of Radiation Protection Safety, Shandong Center for Disease Control and Prevention, Jinan, 250014, China
| | - Xiang Li
- State Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection, Soochow University, Suzhou, 215123, China; Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions, China
| | - Yidi Wang
- State Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection, Soochow University, Suzhou, 215123, China; Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions, China
| | - Zhanpeng Li
- State Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection, Soochow University, Suzhou, 215123, China; Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions, China
| | - Yunan Gao
- State Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection, Soochow University, Suzhou, 215123, China; Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions, China
| | - Han Gao
- State Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection, Soochow University, Suzhou, 215123, China; Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions, China
| | - Congchong Yan
- State Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection, Soochow University, Suzhou, 215123, China; Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions, China
| | - Liang Sun
- State Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection, Soochow University, Suzhou, 215123, China; Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions, China.
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Das S, Joshi MB, Parashiva GK, Rao SBS. Stimulation of cytoprotective autophagy and components of mitochondrial biogenesis / proteostasis in response to ionizing radiation as a credible pro-survival strategy. Free Radic Biol Med 2020; 152:715-727. [PMID: 31968231 DOI: 10.1016/j.freeradbiomed.2020.01.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Revised: 01/14/2020] [Accepted: 01/14/2020] [Indexed: 12/11/2022]
Abstract
The present study illustrates mitochondria-mediated impact of ionizing radiation which is paralleled by activation of several pro-adaptive responses in normal human dermal fibroblast cells. Irradiation of cells with X-rays (5 Gy) led to an increase in fragmentation and mitochondrial mass. Distinct temporal changes in cytosolic and mitochondrial reactive oxygen species (ROS) were noted in response to radiation, which was associated with depletion in mitochondrial membrane potential followed by decrease in ATP levels. Long Amplicon-Polymerase Chain Reaction (LA-PCR) analysis showed time-dependent increase in mitochondrial DNA damage that preceded mitochondrial ROS generation. Irradiation of cells led to an initial G2/M arrest at 8 h that persisted till 16 h, with subsequent block at G0/G1 measured at 48 and 72 h time points. Interestingly, cells activated autophagy as a countermeasure against radiation-mediated cellular insults and aided in removal of damaged mitochondria. Blocking autophagy using 3-methyladenine led to cell death via activation of enhanced ROS, PARP-1 and caspase 3 cleavage. Upregulation of mitochondrial biogenesis factors Nrf1/PGC-1α, following irradiation was observed. Irradiated cells exhibited an increase in the phosphorylation of GCN2, PERK and eIF2α that might be responsible for the up-regulation of ATF4 and CHOP thereby regulating autophagy and components of integrated stress response. Apart from this, we measured accumulation of mitochondrial chaperones (HSP60/HSP10) and ATF5 which is a major molecule involved in mitochondrial stress. Taken together, mitochondria are one of the major cytoplasmic targets for ionizing radiation and possibly act as an early indicator of cellular insult. The findings also show that stressed mitochondria might influence endoplasmic reticulum (ER)-related signalling leading to the activation of adaptive mechanisms like cytoprotective autophagy, and molecules responsible for mitochondrial biogenesis and protein quality control in order to replenish mitochondrial pool and maintain cellular homeostasis.
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Affiliation(s)
- Shubhankar Das
- Department of Radiation Biology & Toxicology, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal, 576104, Karnataka, India
| | - Manjunath B Joshi
- Department of Aging Research, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal, 576104, Karnataka, India
| | - Guruprasad K Parashiva
- Department of Aging Research, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal, 576104, Karnataka, India
| | - Satish B S Rao
- Department of Radiation Biology & Toxicology, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal, 576104, Karnataka, India.
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Qi Tan H, Yang Calvin Koh W, Kuan Rui Tan L, Hao Phua J, Wei Ang K, Yong Park S, Siang Lew W, Cheow Lei Lee J. Dependence of LET on material and its impact on current RBE model. ACTA ACUST UNITED AC 2019; 64:135022. [DOI: 10.1088/1361-6560/ab1c90] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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4
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Oliver PAK, Thomson RM. Investigating energy deposition within cell populations using Monte Carlo simulations. ACTA ACUST UNITED AC 2018; 63:155018. [DOI: 10.1088/1361-6560/aacf7b] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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5
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Lazarakis P, Incerti S, Ivanchenko V, Kyriakou I, Emfietzoglou D, Corde S, Rosenfeld AB, Lerch M, Tehei M, Guatelli S. Investigation of track structure and condensed history physics models for applications in radiation dosimetry on a micro and nano scale in Geant4. Biomed Phys Eng Express 2018. [DOI: 10.1088/2057-1976/aaa6aa] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Kuncic Z, Lacombe S. Nanoparticle radio-enhancement: principles, progress and application to cancer treatment. Phys Med Biol 2018; 63:02TR01. [PMID: 29125831 DOI: 10.1088/1361-6560/aa99ce] [Citation(s) in RCA: 138] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Enhancement of radiation effects by high-atomic number nanoparticles (NPs) has been increasingly studied for its potential to improve radiotherapeutic efficacy. The underlying principle of NP radio-enhancement is the potential to release copious electrons into a nanoscale volume, thereby amplifying radiation-induced biological damage. While the vast majority of studies to date have focused on gold nanoparticles with photon radiation, an increasing number of experimental, theoretical and simulation studies have explored opportunities offered by other NPs (e.g. gadolinium, platinum, iron oxide, hafnium) and other therapeutic radiation sources such as ion beams. It is thus of interest to the research community to consolidate findings from the different studies and summarise progress to date, as well as to identify strategies that offer promising opportunities for clinical translation. This is the purpose of this Topical Review.
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Affiliation(s)
- Zdenka Kuncic
- School of Physics and Sydney Nano Institute, University of Sydney, Sydney, NSW 2006, Australia
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7
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Mazza A, Newhauser W, Pittman S, Halloran A, Maggi P, Tran L, Gila B, Rosenfeld A, Ziegler J. Cell-shaped silicon-on-insulator microdosimeters: characterization and response to 239PuBe irradiations. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2017; 40:667-673. [PMID: 28887797 DOI: 10.1007/s13246-017-0576-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Accepted: 07/31/2017] [Indexed: 11/30/2022]
Abstract
This work tested the feasibility of a silicon-on-insulator microdosimeter, which mimics the size and shape of specific cells within the human body, to determine dose equivalent from neutron irradiation. The microdosimeters were analyzed in terms of their basic diode characteristics, i.e., leakage current as a function of bias voltage. Lineal energy spectra were acquired using two different converter layers placed atop the microdosimeter: a tissue-substitute converter made from high-density polyethylene, and a boron converter consisting of epoxy coated with boron powder. The spectra were then converted into absorbed dose and dose equivalent. Experimental results were compared to Monte Carlo simulations of the neutron irradiations, revealing good agreement. Uncertainty in the dose equivalent determinations was 7.5% when using the cell-shaped microdosimeter with the tissue-substitute converter and 13.1% when using the boron converter. This work confirmed that the SOI approach to cell-mimicking microdosimetry is feasible.
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Affiliation(s)
- Anthony Mazza
- Medical Physics and Health Physics Program, Department of Physics and Astronomy, Louisiana State University, 439 Nicholson Hall, Tower Dr., Baton Rouge, LA, 70803-4001, USA. .,Department of Physics, Mary Bird Perkins Cancer Center, Baton Rouge, LA, USA.
| | - Wayne Newhauser
- Medical Physics and Health Physics Program, Department of Physics and Astronomy, Louisiana State University, 439 Nicholson Hall, Tower Dr., Baton Rouge, LA, 70803-4001, USA.,Department of Physics, Mary Bird Perkins Cancer Center, Baton Rouge, LA, USA
| | - Stephen Pittman
- Medical Physics and Health Physics Program, Department of Physics and Astronomy, Louisiana State University, 439 Nicholson Hall, Tower Dr., Baton Rouge, LA, 70803-4001, USA
| | - Andrew Halloran
- Medical Physics and Health Physics Program, Department of Physics and Astronomy, Louisiana State University, 439 Nicholson Hall, Tower Dr., Baton Rouge, LA, 70803-4001, USA
| | - Paul Maggi
- Medical Physics and Health Physics Program, Department of Physics and Astronomy, Louisiana State University, 439 Nicholson Hall, Tower Dr., Baton Rouge, LA, 70803-4001, USA
| | - Linh Tran
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, Australia
| | - Brent Gila
- Nanoscale Research Facility, University of Florida, Gainesville, FL, USA
| | - Anatoly Rosenfeld
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, Australia
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Decrock E, Hoorelbeke D, Ramadan R, Delvaeye T, De Bock M, Wang N, Krysko DV, Baatout S, Bultynck G, Aerts A, Vinken M, Leybaert L. Calcium, oxidative stress and connexin channels, a harmonious orchestra directing the response to radiotherapy treatment? BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2017; 1864:1099-1120. [DOI: 10.1016/j.bbamcr.2017.02.007] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 02/02/2017] [Accepted: 02/04/2017] [Indexed: 02/07/2023]
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Oliver PAK, Thomson RM. A Monte Carlo study of macroscopic and microscopic dose descriptors for kilovoltage cellular dosimetry. Phys Med Biol 2017; 62:1417-1436. [PMID: 28114113 DOI: 10.1088/1361-6560/aa5136] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
This work investigates how doses to cellular targets depend on cell morphology, as well as relations between cellular doses and doses to bulk tissues and water. Multicellular models of five healthy and cancerous soft tissues are developed based on typical values of cell compartment sizes, elemental compositions and number densities found in the literature. Cells are modelled as two concentric spheres with nucleus and cytoplasm compartments. Monte Carlo simulations are used to calculate the absorbed dose to the nucleus and cytoplasm for incident photon energies of 20-370 keV, relevant for brachytherapy, diagnostic radiology, and out-of-field radiation in higher-energy external beam radiotherapy. Simulations involving cell clusters, single cells and single nuclear cavities are carried out for cell radii between 5 and [Formula: see text]m, and nuclear radii between 2 and [Formula: see text]m. Seven nucleus and cytoplasm elemental compositions representative of animal cells are considered. The presence of a cytoplasm, extracellular matrix and surrounding cells can affect the nuclear dose by up to [Formula: see text]. Differences in cell and nucleus size can affect dose to the nucleus (cytoplasm) of the central cell in a cluster of 13 cells by up to [Formula: see text] ([Formula: see text]). Furthermore, the results of this study demonstrate that neither water nor bulk tissue are reliable substitutes for subcellular targets for incident photon energies <50 keV: nuclear (cytoplasm) doses differ from dose-to-medium by up to [Formula: see text] ([Formula: see text]), and from dose-to-water by up to [Formula: see text] ([Formula: see text]). The largest differences between dose descriptors are seen for the lowest incident photon energies; differences are less than [Formula: see text] for energies [Formula: see text]90 keV. The sensitivity of results with regard to the parameters of the microscopic tissue structure model and cell model geometry, and the importance of the nucleus and cytoplasm as targets for radiation-induced cell death emphasize the importance of accurate models for cellular dosimetry studies.
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Affiliation(s)
- P A K Oliver
- Department of Physics, Carleton Laboratory for Radiotherapy Physics, Carleton University, Ottawa, K1S 5B6, Canada
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10
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McNamara AL, Kam WWY, Scales N, McMahon SJ, Bennett JW, Byrne HL, Schuemann J, Paganetti H, Banati R, Kuncic Z. Dose enhancement effects to the nucleus and mitochondria from gold nanoparticles in the cytosol. Phys Med Biol 2016; 61:5993-6010. [PMID: 27435339 DOI: 10.1088/0031-9155/61/16/5993] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Gold nanoparticles (GNPs) have shown potential as dose enhancers for radiation therapy. Since damage to the genome affects the viability of a cell, it is generally assumed that GNPs have to localise within the cell nucleus. In practice, however, GNPs tend to localise in the cytoplasm yet still appear to have a dose enhancing effect on the cell. Whether this effect can be attributed to stress-induced biological mechanisms or to physical damage to extra-nuclear cellular targets is still unclear. There is however growing evidence to suggest that the cellular response to radiation can also be influenced by indirect processes induced when the nucleus is not directly targeted by radiation. The mitochondrion in particular may be an effective extra-nuclear radiation target given its many important functional roles in the cell. To more accurately predict the physical effect of radiation within different cell organelles, we measured the full chemical composition of a whole human lymphocytic JURKAT cell as well as two separate organelles; the cell nucleus and the mitochondrion. The experimental measurements found that all three biological materials had similar ionisation energies ∼70 eV, substantially lower than that of liquid water ∼78 eV. Monte Carlo simulations for 10-50 keV incident photons showed higher energy deposition and ionisation numbers in the cell and organelle materials compared to liquid water. Adding a 1% mass fraction of gold to each material increased the energy deposition by a factor of ∼1.8 when averaged over all incident photon energies. Simulations of a realistic compartmentalised cell show that the presence of gold in the cytosol increases the energy deposition in the mitochondrial volume more than within the nuclear volume. We find this is due to sub-micron delocalisation of energy by photoelectrons, making the mitochondria a potentially viable indirect radiation target for GNPs that localise to the cytosol.
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Affiliation(s)
- A L McNamara
- Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, 30 Fruit St, Boston, MA 02114, USA. School of Physics, University of Sydney, NSW 2006, Australia
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11
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Cunha M, Testa E, Komova OV, Nasonova EA, Mel'nikova LA, Shmakova NL, Beuve M. Modeling cell response to low doses of photon irradiation--Part 1: on the origin of fluctuations. RADIATION AND ENVIRONMENTAL BIOPHYSICS 2016; 55:19-30. [PMID: 26590033 DOI: 10.1007/s00411-015-0621-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Accepted: 10/11/2015] [Indexed: 06/05/2023]
Abstract
Intra- and inter-individual variability is a well-known aspect of biological responses of cells observed at low doses of radiation, whichever the phenomenon considered (adaptive response, bystander effects, genomic instability, etc.). There is growing evidence that low-dose phenomena are related to cell mechanisms other than DNA damage and misrepair, meaning that other cellular structures may play a crucial role. Therefore, in this study, a series of calculations at low doses was carried out to study the distribution of specific energies from different irradiation doses (3, 10 and 30 cGy) in targets of different sizes (0.1, 1 and 10 μm) corresponding to the dimensions of different cell structures. The results obtained show a strong dependence of the probability distributions of specific energies on the target size: targets with dimensions comparable to those of the cell show a Gaussian-like distribution, whereas very small targets are very likely to not be hit. A statistical analysis showed that the level of fluctuations in the fraction of aberrant cells is only related to the fraction of aberrant cells and the number of irradiated cells, regardless of, for instance, the heterogeneity in cell response.
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Affiliation(s)
- Micaela Cunha
- Université de Lyon, 69622, Lyon, France
- Université de Lyon 1, Villeurbanne, France
- CNRS/IN2P3, Institut de Physique Nucléaire de Lyon, Villeurbanne, France
| | - Etienne Testa
- Université de Lyon, 69622, Lyon, France
- Université de Lyon 1, Villeurbanne, France
- CNRS/IN2P3, Institut de Physique Nucléaire de Lyon, Villeurbanne, France
| | - Olga V Komova
- Laboratory of Radiation Biology, Joint Institute for Nuclear Research, Dubna, Moscow Region, Russia
| | - Elena A Nasonova
- Laboratory of Radiation Biology, Joint Institute for Nuclear Research, Dubna, Moscow Region, Russia
| | - Larisa A Mel'nikova
- Laboratory of Radiation Biology, Joint Institute for Nuclear Research, Dubna, Moscow Region, Russia
| | - Nina L Shmakova
- Laboratory of Radiation Biology, Joint Institute for Nuclear Research, Dubna, Moscow Region, Russia
| | - Michaël Beuve
- Université de Lyon, 69622, Lyon, France.
- Université de Lyon 1, Villeurbanne, France.
- CNRS/IN2P3, Institut de Physique Nucléaire de Lyon, Villeurbanne, France.
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Zygmanski P, Sajo E. Nanoscale radiation transport and clinical beam modeling for gold nanoparticle dose enhanced radiotherapy (GNPT) using X-rays. Br J Radiol 2015; 89:20150200. [PMID: 26642305 PMCID: PMC4986475 DOI: 10.1259/bjr.20150200] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Revised: 11/17/2015] [Accepted: 12/01/2015] [Indexed: 11/05/2022] Open
Abstract
We review radiation transport and clinical beam modelling for gold nanoparticle dose-enhanced radiotherapy using X-rays. We focus on the nanoscale radiation transport and its relation to macroscopic dosimetry for monoenergetic and clinical beams. Among other aspects, we discuss Monte Carlo and deterministic methods and their applications to predicting dose enhancement using various metrics.
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Affiliation(s)
- Piotr Zygmanski
- Department of Radiation Oncology, Brigham and Women's Hospital, Dana-Farber Cancer Institute, and Harvard Medical School, Boston, MA, USA
| | - Erno Sajo
- Department of Physics and Applied Physics, University of Massachusetts Lowell, Medical Physics Program, Lowell, MA, USA
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13
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Gholami Y, Zhu X, Fulton R, Meikle S, El-Fakhri G, Kuncic Z. Stochastic simulation of radium-223 dichloride therapy at the sub-cellular level. Phys Med Biol 2015. [DOI: 10.1088/0031-9155/60/15/6087] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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14
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Klein EE, Dong L, Paganetti H, Tanderup K. The far-reaching subject matter of medical physics in radiation oncology. Int J Radiat Oncol Biol Phys 2015; 91:697-700. [PMID: 25752380 DOI: 10.1016/j.ijrobp.2014.10.032] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Revised: 10/14/2014] [Accepted: 10/14/2014] [Indexed: 11/29/2022]
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15
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Byrne HL, Domanova W, McNamara AL, Incerti S, Kuncic Z. The cytoplasm as a radiation target: an in silico study of microbeam cell irradiation. Phys Med Biol 2015; 60:2325-37. [PMID: 25715947 DOI: 10.1088/0031-9155/60/6/2325] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
We performed in silico microbeam cell irradiation modelling to quantitatively investigate ionisations resulting from soft x-ray and alpha particle microbeams targeting the cytoplasm of a realistic cell model. Our results on the spatial distribution of ionisations show that as x-rays are susceptible to scatter within a cell that can lead to ionisations in the nucleus, soft x-ray microbeams may not be suitable for investigating the DNA damage response to radiation targeting the cytoplasm alone. In contrast, ionisations from an ideal alpha microbeam are tightly confined to the cytoplasm, but a realistic alpha microbeam degrades upon interaction with components upstream of the cellular target. Thus it is difficult to completely rule out a contribution from alpha particle hits to the nucleus when investigating DNA damage response to cytoplasmic irradiation. We find that although the cytoplasm targeting efficiency of an alpha microbeam is better than that of a soft x-ray microbeam (the probability of stray alphas hitting the nucleus is 0.2% compared to 3.6% for x-rays), stray alphas produce more ionisations in the nucleus and thus have greater potential for initiating damage responses therein. Our results suggest that observed biological responses to cytoplasmic irradiation include a small component that can be attributed to stray ionisations in the nucleus resulting from the stochastic nature of particle interactions that cause out-of-beam scatter. This contribution is difficult to isolate experimentally, thus demonstrating the value of the in silico approach.
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Affiliation(s)
- H L Byrne
- Institute of Medical Physics, School of Physics, University of Sydney, NSW 2006, Australia
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Szumiel I. Ionizing radiation-induced oxidative stress, epigenetic changes and genomic instability: The pivotal role of mitochondria. Int J Radiat Biol 2014; 91:1-12. [DOI: 10.3109/09553002.2014.934929] [Citation(s) in RCA: 117] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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17
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McNamara AL, Oelfke U, Kuncic Z. Revealing the underlying mechanism of microbeam radiation therapy with low energy Monte Carlo simulations. ACTA ACUST UNITED AC 2014. [DOI: 10.1088/1742-6596/489/1/012018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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18
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Gholami Y, Toghyani M, Champion C, Kuncic Z. In silico radiobiology: Have we reached the limit of Monte Carlo simulations? ACTA ACUST UNITED AC 2014. [DOI: 10.1088/1742-6596/489/1/012011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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19
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Hill R, Healy B, Holloway L, Kuncic Z, Thwaites D, Baldock C. Advances in kilovoltage x-ray beam dosimetry. Phys Med Biol 2014; 59:R183-231. [DOI: 10.1088/0031-9155/59/6/r183] [Citation(s) in RCA: 110] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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