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Harken AD, Deoli NT, Perez Campos C, Ponnaiya B, Garty G, Lee GS, Casper MJ, Dhingra S, Li W, Johnson GW, Amundson SA, Grabham PW, Hillman EMC, Brenner DJ. Combined ion beam irradiation platform and 3D fluorescence microscope for cellular cancer research. BIOMEDICAL OPTICS EXPRESS 2024; 15:2561-2577. [PMID: 38633084 PMCID: PMC11019671 DOI: 10.1364/boe.522969] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Accepted: 03/06/2024] [Indexed: 04/19/2024]
Abstract
To improve particle radiotherapy, we need a better understanding of the biology of radiation effects, particularly in heavy ion radiation therapy, where global responses are observed despite energy deposition in only a subset of cells. Here, we integrated a high-speed swept confocally-aligned planar excitation (SCAPE) microscope into a focused ion beam irradiation platform to allow real-time 3D structural and functional imaging of living biological samples during and after irradiation. We demonstrate dynamic imaging of the acute effects of irradiation on 3D cultures of U87 human glioblastoma cells, revealing characteristic changes in cellular movement and intracellular calcium signaling following ionizing irradiation.
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Affiliation(s)
- Andrew D Harken
- Radiological Research Accelerator Facility, Columbia University Irving Medical Center, 136 S. Broadway, P.O. Box 21, Irvington, New York 10533, USA
- Center for Radiological Research, Columbia University Irving Medical Center, 630 W. 168th Street, New York, NY 10032, USA
| | - Naresh T Deoli
- Radiological Research Accelerator Facility, Columbia University Irving Medical Center, 136 S. Broadway, P.O. Box 21, Irvington, New York 10533, USA
- Center for Radiological Research, Columbia University Irving Medical Center, 630 W. 168th Street, New York, NY 10032, USA
| | - Citlali Perez Campos
- Laboratory for Functional Optical Imaging, Departments of Biomedical Engineering and Radiology, Zuckerman Mind Brain Behavior Institute and Kavli Institute for Brain Sciences, Columbia University, New York, NY, 10027, USA
| | - Brian Ponnaiya
- Radiological Research Accelerator Facility, Columbia University Irving Medical Center, 136 S. Broadway, P.O. Box 21, Irvington, New York 10533, USA
- Center for Radiological Research, Columbia University Irving Medical Center, 630 W. 168th Street, New York, NY 10032, USA
| | - Guy Garty
- Radiological Research Accelerator Facility, Columbia University Irving Medical Center, 136 S. Broadway, P.O. Box 21, Irvington, New York 10533, USA
- Center for Radiological Research, Columbia University Irving Medical Center, 630 W. 168th Street, New York, NY 10032, USA
| | - Grace S Lee
- Laboratory for Functional Optical Imaging, Departments of Biomedical Engineering and Radiology, Zuckerman Mind Brain Behavior Institute and Kavli Institute for Brain Sciences, Columbia University, New York, NY, 10027, USA
| | - Malte J Casper
- Laboratory for Functional Optical Imaging, Departments of Biomedical Engineering and Radiology, Zuckerman Mind Brain Behavior Institute and Kavli Institute for Brain Sciences, Columbia University, New York, NY, 10027, USA
| | - Shikhar Dhingra
- Laboratory for Functional Optical Imaging, Departments of Biomedical Engineering and Radiology, Zuckerman Mind Brain Behavior Institute and Kavli Institute for Brain Sciences, Columbia University, New York, NY, 10027, USA
| | - Wenze Li
- Laboratory for Functional Optical Imaging, Departments of Biomedical Engineering and Radiology, Zuckerman Mind Brain Behavior Institute and Kavli Institute for Brain Sciences, Columbia University, New York, NY, 10027, USA
| | - Gary W Johnson
- Center for Radiological Research, Columbia University Irving Medical Center, 630 W. 168th Street, New York, NY 10032, USA
| | - Sally A Amundson
- Center for Radiological Research, Columbia University Irving Medical Center, 630 W. 168th Street, New York, NY 10032, USA
| | - Peter W Grabham
- Center for Radiological Research, Columbia University Irving Medical Center, 630 W. 168th Street, New York, NY 10032, USA
| | - Elizabeth M C Hillman
- Laboratory for Functional Optical Imaging, Departments of Biomedical Engineering and Radiology, Zuckerman Mind Brain Behavior Institute and Kavli Institute for Brain Sciences, Columbia University, New York, NY, 10027, USA
| | - David J Brenner
- Radiological Research Accelerator Facility, Columbia University Irving Medical Center, 136 S. Broadway, P.O. Box 21, Irvington, New York 10533, USA
- Center for Radiological Research, Columbia University Irving Medical Center, 630 W. 168th Street, New York, NY 10032, USA
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2
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Dou Y, Osipowicz T, van Kan JA. Breaking the 10 nm barrier using molecular ions in nuclear microprobes. Ultramicroscopy 2023; 253:113812. [PMID: 37515932 DOI: 10.1016/j.ultramic.2023.113812] [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: 11/15/2022] [Revised: 06/25/2023] [Accepted: 07/12/2023] [Indexed: 07/31/2023]
Abstract
The spatial resolution plays a crucial role in determining the performance of a nuclear microprobe. However, the formation of spatial resolutions below 10 nm remains a challenge in nuclear microprobes. Here, we propose novel technologies (near-axis scanning transmission ion microscopy and double-fragment scattering) utilizing molecular ions to address this challenge and demonstrate a H2+ molecular beam with 6.0 × 10 nm2 lateral resolution and monolayer thickness resolution respectively. Using the improved nuclear microprobe, we directly demonstrate that the ionization of a H2+ can be efficiently achieved using one single layer graphene, and also that single and few layers of freestanding graphene can be clearly differentiated and identified. The precise control of fast molecular ions at sub-10 nm scales has the potential to unlock new avenues of applications.
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Affiliation(s)
- Yanxin Dou
- Centre for Ion Beam Applications, Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542; Singapore Nuclear Research and Safety Initiative, National University of Singapore, Singapore 138602.
| | - Thomas Osipowicz
- Centre for Ion Beam Applications, Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542
| | - Jeroen Anton van Kan
- Centre for Ion Beam Applications, Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542
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Zhang Z, Li K, Hong M. Radiation-Induced Bystander Effect and Cytoplasmic Irradiation Studies with Microbeams. BIOLOGY 2022; 11:biology11070945. [PMID: 36101326 PMCID: PMC9312136 DOI: 10.3390/biology11070945] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Revised: 06/17/2022] [Accepted: 06/18/2022] [Indexed: 12/02/2022]
Abstract
Simple Summary Microbeams are useful tools in studies on non-target effects, such as the radiation-induced bystander effect, and responses related to cytoplasmic irradiation. A micrometer or even sub-micrometer-level beam size enables the precise delivery of radiation energy to a specific target. Here we summarize the observations of the bystander effect and the cytoplasmic irradiation-related effect using different kinds of microbeam irradiators as well as discuss the cellular and molecular mechanisms that are involved in these responses. Non-target effects may increase the detrimental effect caused by radiation, so a more comprehensive knowledge of the process will enable better evaluation of the damage resulting from irradiation. Abstract Although direct damage to nuclear DNA is considered as the major contributing event that leads to radiation-induced effects, accumulating evidence in the past two decades has shown that non-target events, in which cells are not directly irradiated but receive signals from the irradiated cells, or cells irradiated at extranuclear targets, may also contribute to the biological consequences of exposure to ionizing radiation. With a beam diameter at the micrometer or sub-micrometer level, microbeams can precisely deliver radiation, without damaging the surrounding area, or deposit the radiation energy at specific sub-cellular locations within a cell. Such unique features cannot be achieved by other kinds of radiation settings, hence making a microbeam irradiator useful in studies of a radiation-induced bystander effect (RIBE) and cytoplasmic irradiation. Here, studies on RIBE and different responses to cytoplasmic irradiation using microbeams are summarized. Possible mechanisms related to the bystander effect, which include gap-junction intercellular communications and soluble signal molecules as well as factors involved in cytoplasmic irradiation-induced events, are also discussed.
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Affiliation(s)
- Ziqi Zhang
- College of Life Sciences, South China Agricultural University, Guangzhou 510642, China; (Z.Z.); (K.L.)
| | - Kui Li
- College of Life Sciences, South China Agricultural University, Guangzhou 510642, China; (Z.Z.); (K.L.)
| | - Mei Hong
- College of Life Sciences, South China Agricultural University, Guangzhou 510642, China; (Z.Z.); (K.L.)
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, South China Agricultural University, Guangzhou 510642, China
- Correspondence: ; Tel.: +86-20-85280901
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Guo Z, Buonanno M, Harken A, Zhou G, Hei TK. Mitochondrial Damage Response and Fate of Normal Cells Exposed to FLASH Irradiation with Protons. Radiat Res 2022; 197:569-582. [PMID: 35290449 DOI: 10.1667/rade-21-00181.1] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 02/24/2022] [Indexed: 11/03/2022]
Abstract
Radiation therapy (RT) plays an important role in cancer treatment. The clinical efficacy of radiation therapy is, however, limited by normal tissue toxicity in areas surrounding the irradiated tumor. Compared to conventional radiation therapy (CONV-RT) in which doses are typically delivered at dose rates between 0.03-0.05 Gy/s, there is evidence that radiation delivered at dose rates of orders of magnitude higher (known as FLASH-RT), dramatically reduces the adverse side effects in normal tissues while achieving similar tumor control. The present study focused on normal cell response and tested the hypothesis that proton-FLASH irradiation preserves mitochondria function of normal cells through the induction of phosphorylated Drp1. Normal human lung fibroblasts (IMR90) were irradiated under ambient oxygen concentration (21%) with protons (LET = 10 keV/μm) delivered at dose rates of either 0.33 Gy/s or 100 Gy/s. Mitochondrial dynamics, functions, cell growth and changes in protein expression levels were investigated. Compared to lower dose-rate proton irradiation, FLASH-RT prevented mitochondria damage characterized by morphological changes, functional changes (membrane potential, mtDNA copy number and oxidative enzyme levels) and oxyradical production. After CONV-RT, the phosphorylated form of Dynamin-1-like protein (p-Drp1) underwent dephosphorylation and aggregated into the mitochondria resulting in mitochondria fission and subsequent cell death. In contrast, p-Drp1 protein level did not significantly change after delivery of similar FLASH doses. Compared with CONV irradiation, FLASH irradiation using protons induces minimal mitochondria damage; our results highlight a possible contribution of Drp1-mediated mitochondrial homeostasis in this potential novel cancer treatment modality.
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Affiliation(s)
- Ziyang Guo
- Center for Radiological Research, College of Physician and Surgeons, Columbia University Medical Center, New York, New York.,State Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection, Institute of Space Life Sciences, Medical College of Soochow University, Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions, Suzhou 215123, China.,Department of Ultrasound Medicine, Peking University First Hospital, Beijing, China
| | - Manuela Buonanno
- Center for Radiological Research, College of Physician and Surgeons, Columbia University Medical Center, New York, New York
| | - Andrew Harken
- Center for Radiological Research, College of Physician and Surgeons, Columbia University Medical Center, New York, New York
| | - Guangming Zhou
- State Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection, Institute of Space Life Sciences, Medical College of Soochow University, Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions, Suzhou 215123, China
| | - Tom K Hei
- Center for Radiological Research, College of Physician and Surgeons, Columbia University Medical Center, New York, New York
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Garty G, Harken A, Brenner D. Traceable dosimetry for MeV ion beams. JOURNAL OF INSTRUMENTATION : AN IOP AND SISSA JOURNAL 2022; 17:T02002. [PMID: 35497570 PMCID: PMC9052763 DOI: 10.1088/1748-0221/17/02/t02002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Standard dosimetry protocols exist for highly penetrating photon and particle beams used in the clinic and in research. However, these protocols cannot be directly applied to shallow penetration MeV-range ion beams. The Radiological Research Accelerator Facility has been using such beams for almost 50 years to irradiate cell monolayers, using self-developed dosimetry, based on tissue equivalent ionization chambers. To better align with the internationally accepted standards, we describe implementation of a commercial, NIST-traceable, air-filled ionization chamber for measurement of absorbed dose to water from low energy ions, using radiation quality correction factors calculated using TRS-398 recommendations. The reported dose does not depend on the ionization density in the range of 10-150 keV/μm.
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Affiliation(s)
- G. Garty
- Radiological Research Accelerator Facility, Columbia University, 136 S. Broadway, Irvington, NY 10533, U.S.A
| | - A.D. Harken
- Radiological Research Accelerator Facility, Columbia University, 136 S. Broadway, Irvington, NY 10533, U.S.A
| | - D.J. Brenner
- Radiological Research Accelerator Facility, Columbia University, 136 S. Broadway, Irvington, NY 10533, U.S.A
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Grilj V, Buonanno M, Welch D, Brenner DJ. Proton Irradiation Platforms for Preclinical Studies of High-Dose-Rate (FLASH) Effects at RARAF. Radiat Res 2020; 194:646-655. [PMID: 32926735 DOI: 10.1667/rade-20-00062.1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 07/31/2020] [Indexed: 11/03/2022]
Abstract
Limited availability of proton irradiators optimized for high-dose-rate studies makes the preclinical research of proton FLASH therapy challenging. We assembled two proton irradiation platforms that are capable of delivering therapeutic doses to thin biological samples at dose rates equal to and above 100 Gy/s. We optimized and tested dosimetry protocols to assure accurate dose delivery regardless of the instantaneous dose rate. The simplicity of the experimental setups and availability of custom-designed sample holders allows these irradiation platforms to be easily adjusted to accommodate different types of samples, including cell monolayers, 3D tissue models and small animals. We have also fabricated a microfluidic flow-through device for irradiations of biological samples in suspension. We present one example of a measurement with accompanying preliminary results for each of the irradiation platforms. One irradiator was used to study the role of proton dose rate on cell survival for three cancer cell lines, while the other was used to investigate the depletion of oxygen from an aqueous solution by water radiolysis using short intense proton pulses. No dose-rate-dependent variation was observed between the survival fractions of cancer cells irradiated at dose rates of 0.1, 10 and 100 Gy/s up to 10 Gy. On the other hand, irradiations of Fricke solution at 1,000 Gy/s indicated full depletion of oxygen after proton doses of 107 Gy and 56 Gy for samples equilibrated with 21% and 4% oxygen, respectively.
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Affiliation(s)
- V Grilj
- Center for Radiological Research, Columbia University Irving Medical Center, New York, New York
| | - M Buonanno
- Center for Radiological Research, Columbia University Irving Medical Center, New York, New York
| | - D Welch
- Center for Radiological Research, Columbia University Irving Medical Center, New York, New York
| | - D J Brenner
- Center for Radiological Research, Columbia University Irving Medical Center, New York, New York
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Tan HQ, Koh WYC, Yeo ELL, Ang KW, Poon DJJ, Lim CP, Vajandar SK, Chen CB, Ren M, Osipowicz T, Soo KC, Chua MLK, Park SY. Dosimetric uncertainties impact on cell survival curve with low energy proton. Phys Med 2020; 76:277-284. [PMID: 32738775 DOI: 10.1016/j.ejmp.2020.07.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 07/01/2020] [Accepted: 07/03/2020] [Indexed: 10/23/2022] Open
Abstract
There is an increasing number of radiobiological experiments being conducted with low energy protons (less than 5 MeV) for radiobiological studies due to availability of sub-millimetre focused beam. However, low energy proton has broad microdosimetric spectra which can introduce dosimetric uncertainty. In this work, we quantify the impact of this dosimetric uncertainties on the cell survival curve and how it affects the estimation of the alpha and beta parameters in the LQ formalism. Monte Carlo simulation is used to generate the microdosimetric spectra in a micrometer-sized water sphere under proton irradiation. This is modelled using radiobiological experiment set-up at the Centre of Ion Beam Application (CIBA) in National University of Singapore. Our results show that the microdosimetric spectra can introduce both systematic and random shifts in dose and cell survival; this effect is most pronounced with low energy protons. The alpha and beta uncertainties can be up to 10% and above 30%, respectively for low energy protons passing through thin cell target (about 10 microns). These uncertainties are non-negligible and show that care must be taken in using the cell survival curve and its derived parameters for radiobiological models.
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Affiliation(s)
- Hong Qi Tan
- Division of Radiation Oncology, National Cancer Centre Singapore, Singapore.
| | - Wei Yang Calvin Koh
- Division of Physics and Applied Physics, Nanyang Technological University, Singapore
| | | | - Khong Wei Ang
- Division of Radiation Oncology, National Cancer Centre Singapore, Singapore
| | | | - Chu Pek Lim
- Division of Medical Sciences, National Cancer Centre Singapore, Singapore; Duke-NUS Medical School, Oncology Academic Clinical Programme, Singapore
| | - Saumitra K Vajandar
- Centre for Ion Beam Application, National University of Singapore, Singapore
| | - Ce-Belle Chen
- Centre for Ion Beam Application, National University of Singapore, Singapore
| | - Minqin Ren
- Centre for Ion Beam Application, National University of Singapore, Singapore
| | - Thomas Osipowicz
- Centre for Ion Beam Application, National University of Singapore, Singapore
| | - Khee Chee Soo
- Division of Medical Sciences, National Cancer Centre Singapore, Singapore
| | - Melvin Lee Kiang Chua
- Division of Radiation Oncology, National Cancer Centre Singapore, Singapore; Division of Medical Sciences, National Cancer Centre Singapore, Singapore; Duke-NUS Medical School, Oncology Academic Clinical Programme, Singapore
| | - Sung Yong Park
- Division of Radiation Oncology, National Cancer Centre Singapore, Singapore
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An Integrated Preprocessing Approach for Exploring Single-Cell Gene Expression in Rare Cells. Sci Rep 2019; 9:19758. [PMID: 31875032 PMCID: PMC6930255 DOI: 10.1038/s41598-019-55831-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 11/25/2019] [Indexed: 02/08/2023] Open
Abstract
Exploring the variability in gene expressions of rare cells at the single-cell level is critical for understanding mechanisms of differentiation in tissue function and development as well as for disease diagnostics and cancer treatment. Such studies, however, have been hindered by major difficulties in tracking the identity of individual cells. We present an approach that combines single-cell picking, lysing, reverse transcription and digital polymerase chain reaction to enable the isolation, tracking and gene expression analysis of rare cells. The approach utilizes a photocleavage bead-based microfluidic device to synthesize and deliver stable cDNA for downstream gene expression analysis, thereby allowing chip-based integration of multiple reactions and facilitating the minimization of sample loss or contamination. The utility of the approach was demonstrated with QuantStudio digital PCR by analyzing the radiation and bystander effect on individual IMR90 human lung fibroblasts. Expression levels of the Cyclin-dependent kinase inhibitor 1a (CDKN1A), Growth/differentiation factor 15 (GDF15), and Prostaglandin-endoperoxide synthase 2 (PTGS2) genes, previously shown to have different responses to direct and bystander irradiation, were measured across individual control, microbeam-irradiated or bystander IMR90 cells. In addition to the confirmation of accurate tracking of cell treatments through the system and efficient analysis of single-cell responses, the results enable comparison of activation levels of different genes and provide insight into signaling pathways within individual cells.
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Barbieri S, Babini G, Morini J, Friedland W, Buonanno M, Grilj V, Brenner DJ, Ottolenghi A, Baiocco G. Predicting DNA damage foci and their experimental readout with 2D microscopy: a unified approach applied to photon and neutron exposures. Sci Rep 2019; 9:14019. [PMID: 31570741 PMCID: PMC6769049 DOI: 10.1038/s41598-019-50408-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Accepted: 09/05/2019] [Indexed: 01/01/2023] Open
Abstract
The consideration of how a given technique affects results of experimental measurements is a must to achieve correct data interpretation. This might be challenging when it comes to measurements on biological systems, where it is unrealistic to have full control (e.g. through a software replica) of all steps in the measurement chain. In this work we address how the effectiveness of different radiation qualities in inducing biological damage can be assessed measuring DNA damage foci yields, only provided that artefacts related to the scoring technique are adequately considered. To this aim, we developed a unified stochastic modelling approach that, starting from radiation tracks, predicts both the induction, spatial distribution and complexity of DNA damage, and the experimental readout of foci when immunocytochemistry coupled to 2D fluorescence microscopy is used. The approach is used to interpret γ-H2AX data for photon and neutron exposures. When foci are reconstructed in the whole cell nucleus, we obtain information on damage characteristics "behind" experimental observations, as the average damage content of a focus. We reproduce how the detection technique affects experimental findings, e.g. contributing to the saturation of foci yields scored at 30 minutes after exposure with increasing dose and to the lack of dose dependence for yields at 24 hours.
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Affiliation(s)
| | | | - Jacopo Morini
- Physics Department, University of Pavia, Pavia, Italy
| | - Werner Friedland
- Institute of Radiation Medicine, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
| | - Manuela Buonanno
- Center for Radiological Research, Columbia University Medical Center, New York, USA
| | - Veljko Grilj
- Center for Radiological Research, Columbia University Medical Center, New York, USA
| | - David J Brenner
- Center for Radiological Research, Columbia University Medical Center, New York, USA
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Abstract
The change in optical properties of GafChromic films depends not only on the absorbed dose, but also on the linear energy transfer (LET) of the ionizing radiation. The influence of LET on the film dose-response relationship is especially important when films are applied for dosimetry of energetic charged particles. In the present study, we examined the response of the unlaminated EBT3 and MD-V3 films to proton, deuterium and helium beams with energies in the range of several megaelectronvolts (MeV). Films were exposed to doses up to 200 Gy and a model based on the bimolecular chemical reaction was chosen to fit the measured film signals. The LET in the active layers of the films and the dose correction factors were computed with Monte Carlo software TRIM. Signal quenching, observed for all ion beams in comparison to x-rays, was investigated as a function of the LET in the range of 10-100 keV µm-1. The response of the films got weaker with increasing the LET and showed no dependence on the ion species. The LET effect was quantified by introducing a modified expression for the relative effectiveness (RE) by which a unique RE value is assigned to a single LET. The RE defined in that way decreased from about 90% for LET of 10 keV µm-1 to less than 50% for LET of 100 keV µm-1. Similar behavior was observed for EBT3 and MD-V3 film models.
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Affiliation(s)
- V. Grilj
- Center for Radiological Research, Columbia University Irving Medical Center, New York, NY, USA
| | - D. J. Brenner
- Center for Radiological Research, Columbia University Irving Medical Center, New York, NY, USA
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Abstract
PURPOSE Even though the first ultraviolet microbeam was described by S. Tschachotin back in 1912, the development of sophisticated micro-irradiation facilities only began to flourish in the late 1980s. In this article, we highlight significant microbeam experiments, describe the latest microbeam irradiator configurations and critical discoveries made by using the microbeam apparatus. MATERIALS AND METHODS Modern radiological microbeams facilities are capable of producing a beam size of a few micrometers, or even tens of nanometers in size, and can deposit radiation with high precision within a cellular target. In the past three decades, a variety of microbeams has been developed to deliver a range of radiations including charged particles, X-rays, and electrons. Despite the original intention for their development to measure the effects of a single radiation track, the ability to target radiation with microbeams at sub-cellular targets has been extensively used to investigate radiation-induced biological responses within cells. RESULTS Studies conducted using microbeams to target specific cells in a tissue have elucidated bystander responses, and further studies have shown reactive oxygen species (ROS) and reactive nitrogen species (RNS) play critical roles in the process. The radiation-induced abscopal effect, which has a profound impact on cancer radiotherapy, further reaffirmed the importance of bystander effects. Finally, by targeting sub-cellular compartments with a microbeam, we have reported cytoplasmic-specific biological responses. Despite the common dogma that nuclear DNA is the primary target for radiation-induced cell death and carcinogenesis, studies conducted using microbeam suggested that targeted cytoplasmic irradiation induces mitochondrial dysfunction, cellular stress, and genomic instability. A more recent development in microbeam technology includes application of mouse models to visualize in vivo DNA double-strand breaks. CONCLUSIONS Microbeams are making important contributions towards our understanding of radiation responses in cells and tissue models.
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Affiliation(s)
- Jinhua Wu
- a Center for Radiological Research, College of Physicians and Surgeons, Columbia University , New York , NY , USA
| | - Tom K Hei
- a Center for Radiological Research, College of Physicians and Surgeons, Columbia University , New York , NY , USA.,b Department of Environmental Health Sciences, Mailman School of Public Health , Columbia University , New York , NY , USA
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