Microbeam System Research Articles

Characteristics of focusing high-energy heavy ion microbeam system at the JAEA AVF cyclotron

Ion optical analysis was made for a new focusing high-energy heavy ion microbeam system connected to the AVF cyclotron ( K=110) at the accelerator facility, TIARA of JAEA Takasaki. The focusing performance of the microbeam system was estimated from both the calculation up to third-order term using TRANSPORT code and the measurement of beam resolution with the secondary electron imaging. As a result, a minimum beam size was evaluated at 0.56 and 0.62 μm in FWHM for the X and Y directions, respectively. The high-energy heavy ion microbeam system seemed to have been established as designed by the calculation with the TRANSPORT code, because it was confirmed that the calculation results was fairly reproduced by the measurement result.

Development of micromachining technology in ion microbeam system at TIARA, JAEA

An ion-beam-lithography technique has been progressed in the microbeam systems at Japan Atomic Energy Agency (JAEA) Takasaki. In order to obtain a high-precision measure for microbeam size estimation with a high precision, we applied this technique combined with the electroplating process to make a Ni relief pattern as a resolution standard used in secondary electron imaging. As a result, the smallest beam size could be recorded. The scattering of ions in the materials influenced the spatial resolution and this is also discussed.

Conceptual Design for Real Time Monitoring of Electron Microbeam

It is recognized that the microbeam is powerful system to understand the interaction of ionizing radiation with cells. Especially, electron microbeam system is useful to investigate the effect of low-LET radiation for cells. Electron microbeam has been developed in KIRAMS. It can irradiate the small volume in cell level by collimator and electromagnetic field and give local dose to individual cell by controlling the number of electrons. When the electron microbeam irradiates the individual cell, however, there is a possibility to change the current and intended trajectory of electron beam. Because this possibility introduces the uncertainty of dose, it is necessary to monitor the trajectory and current of electron beam. This study deals with development of real time monitoring device to confirm beam quality and to control if necessary during experiment. Consequently we designed dual monitoring device to solve various factors. And we optimize the design by simulation.

A compact micro-beam system using a tapered glass capillary for proton-induced X-ray radiography

A compact micro-beam system, containing a tapered glass capillary tube with a tip diameter on the order of 10μm, was constructed to examine the applicability of capillary-generated micro-beams to high-contrast radiography based on proton-induced quasi-monochromatic X-rays. The transport efficiency of swift protons (2–3MeV) through the capillary was examined as a function of the capillary tilt angle and the capillary tip diameter. We obtained transport efficiencies of approximately three times larger than would be expected from the geometrical shape of the capillary. This enhancement indicates that a focusing effect occurred in the capillary. A metallic thin foil was irradiated with the micro-beam and quasi-monochromatic X-rays were produced. By calculating the X-ray yields induced by proton bombardment in the foil and comparing them with the X-ray counts observed at the detector, the throughput efficiency of the X-ray imaging system was evaluated. We demonstrated magnification radiography of a small object to show that a spatial resolution on the order of 10μm was achievable in our system.

Microbeam analysis of yellow sand dust particles

AbstractA microbeam system was applied to analyses of yellow sand dust particles. Such particles from the Asian continent sometimes cause turbid conditions in Japan, especially in spring, and are sometimes changed by mixing with anthropogenic and marine aerosols. For better understanding of their formation mechanism, analysis of single particles is indispensable. For this purpose, we developed a microbeam analysis system at Tohoku University with a spatial resolution of better than 1 µm. The system comprises two x‐ray Si(Li) detectors for particle‐induced x‐ray emission (PIXE), an annular ion‐implanted Si detector for Rutherford backscattering (RBS), an ion‐implanted Si detector for off‐axis scanning transmission ion microscopy (STIM), and a Si‐PIN photodiode for direct STIM analyses. The combination of PIXE, RBS and off‐axis STIM methods enabled simultaneous analyses of hydrogen to metal elements and revealed the chemical compositions of these particles. Yellow sand dust particles were impacted on a thin polycarbonate film and analyzed using the microbeam analysis system. After quantification of the elemental components of these particles, the chemical composition of each particle was obtained. Silicon, calcium, oxygen, carbon, and hydrogen are the main composing elements of the particles originating mainly from soil dust from the Asian continent. The particles contain sulfur and heavier elements too, originating from mixing with anthropogenic aerosols. Sodium, magnesium, and chlorine, which come from marine aerosols, are also included in these particles and might be adsorbed during transport from the Asian continent. Single particle analysis of yellow sand dust will engender a better understanding of their formation process during transport. Copyright © 2008 John Wiley & Sons, Ltd.

VR collaborative and interactive design over the web: a MEMS case study

It is important to simulate the MEMS's working performance to make design effective. A collaborative and interactive design framework and implementation of a MEMS design system is presented based on the web manufacturing concept. Technologies used in dynamic web Java Server Pages (JSP) and computer graphics Virtual Reality Modelling Language (VRML) have been integrated. By comparing two approaches to controlling the VRML object, the advantages and limitations between them are discussed. A better interactive performance can be obtained by combining them. So a micro-beam virtual manufacturing system for the web has been developed based on the framework proposed.

Involvement of Oxidative Metabolism and Membrane Signaling in Bystander Response: A Microbeam Study.

Charged particles microbeam facilities are a unique tool that allows targeting of single cells and analysis of the induced damage on a cell-by-cell basis. The ability of these tools to discriminate between hit and non-hit cells, and to deliver a precise dose is of particular interest in the investigation of various phenomena related to low dose radiation responses and more particularly in bystander effects. Since spring 2004, the choice was made to develop a device specifically designed and dedicated to radiobiology studies, with for imperative to adapt the device to the ideal conditions for cell culture. Today the single-cell microbeam system is operational: it can deliver 10 individual alpha particles (3 MeV) to selected cell nuclei in a precisely known proportion of cells in a population. The investigated endpoint in radiobiology studies is the identification of signaling pathways implicated in the appearance of non targeted effects. Here, the induction of bystander effect was studied by assessing DNA double-strand breaks (DSB) formation with the γH2AX and 53BP1 foci formation assay. Then, a comparative kinetics was established between these foci formation assay and reactive oxygen species (ROS) generation. This kinetics was accomplished in a range of time going from 30 minutes till 24 hours post-irradiation. By this way, we showed the presence of ROS in the hit cells as well as in the bystander cells. This was noticed till 2 hours post irradiation and correlated in observation of foci in both populations of cells. Moreover, alpha particles induced generation of ROS in the hit cells by a mitochondria-dependent way. This ROS generation was partly involved in a process of radio-induced apoptosis (24h post-irradiation) in the hit cells. However, no apoptosis was detected in bystander cells. On the other hand, the cell membrane seemed to play a decisive role in the signaling leading to the generation of ROS in the hit and bystander cells. Indeed, the use of filipine, which destabilized the rafts of cholesterol in the membrane, annihilated the ROS generation in these two populations of cells. We thus support the hypothesis that ROS, generated by mitochondria as well as cell membrane, belongs to signaling pathways directly involved in bystander effect.

Heavy-Ion Microbeam System at JAEA-Takasaki for Microbeam Biology

Research concerning cellular responses to low dose irradiation, radiation-induced bystander effects, and the biological track structure of charged particles has recently received particular attention in the field of radiation biology. Target irradiation employing a microbeam represents a useful means of advancing this research by obviating some of the disadvantages associated with the conventional irradiation strategies. The heavy-ion microbeam system at JAEA-Takasaki, which was planned in 1987 and started in the early 1990's, can provide target irradiation of heavy charged particles to biological material at atmospheric pressure using a minimum beam size 5 mum in diameter. A variety of biological material has been irradiated using this microbeam system including cultured mammalian and higher plant cells, isolated fibers of mouse skeletal muscle, silkworm (Bombyx mori) embryos and larvae, Arabidopsis thaliana roots, and the nematode Caenorhabditis elegans. The system can be applied to the investigation of mechanisms within biological organisms not only in the context of radiation biology, but also in the fields of general biology such as physiology, developmental biology and neurobiology, and should help to establish and contribute to the field of "microbeam biology".

A detailed ray-tracing simulation of the high resolution microbeam at the AIFIRA facility

The AIFIRA (Applications Interdisciplinaires des Faisceaux d’Ions en Région Aquitaine) ion beam facility at the CENBG (Centre d’Etudes Nucléaires de Bordeaux-Gradignan) is being equipped with a high demagnification focused microbeam line. This beam line, which is under its final stage of development, should allow focusing of protons and alpha particles down to a sub-micrometer resolution, and is therefore referred to as a “nanobeam line” in the following paper.We present the complete beam transport simulation along the chosen configuration for the nanobeam line, which consists of a long working distance doublet–triplet of Oxford Microbeam Ltd. OM-50® quadrupoles. These simulations have been performed using the Geant4 Monte Carlo simulation toolkit, which has been previously validated for ray-tracing studies in the design of quadrupole microbeam systems. They include a fine modelling of the quadupole magnetic field, based on the analytical Enge’s model, which is compared to a classical square field model and to a high granularity tri-dimensional field map computed with the OPERA3D® software. The beam emittance model is parameterized from experimental measurements performed directly on the HVEE Singletron® at the AIFIRA facility, allowing the computation of the beam transmitted current along the nanobeam line. Grid shadow images, acquired from simulations, for system alignment purposes and beam deflection studies on target are presented as well.

Fabrication of three-dimensional structures of resist by proton beam writing

The fabrication of three-dimensional (3D) structures was demonstrated by proton beam writing (PBW) using a MeV light-ion microbeam system at Japan Atomic Energy Agency. The fabrication of the 3D structures was performed using PBW in a thick SU-8 layer with a thickness of up to 50μm, which is a typical negative resist. The authors exposed the negative resist on a silicon substrate to focused MeV proton beams within 1μm in diameter, using two different beam energies to obtain two different depths in the resist aiming at fabrication of 3D structures. The two different beam energies were obtained using a 75μm Kapton film as a beam energy degrader to generate 1.6MeV proton beam from 3.0MeV, or using the accelerator voltage control in order to produce beam energy of 1.2MeV. The 3D lines and space structures with the same shape were fabricated using the two different methods. An Arc de Triomphe shape was also manufactured to demonstrate the superior and unique features of the PBW as a versatile tool for deep micromachining for 3D structures with high aspect ratio.

Gene expression profile of Limbal Epithelial Stem Cell niche

Abstract Purpose: It is established by laboratory and clinical evidence that corneal stem cells are localised at limbus but are not isolated as yet due to the lack of stem cell markers. Recently we had discovered a novel anatomical structure at limbus, termed as the Limbal epithelial crypt (LEC), which have the potential of a stem cell niche as determined from previous anatomical and immunohistological studies. We aim to characterise the differential gene expression of the LEC by comparing with other regions of the ocular surface epithelium by 30,000 genes human oligonucleotide microarray analysis with the view to find putative stem cell marker. Methods: On the frozen cryostat sections of the corneoscleral epithelium from cadaver donor tissue, Laser Capture Microdissection (LCM) by PALM® Microbeam systems was done. From the LMD tissue the RNA was extracted, amplified and hybridised to human oligonucleotide array chip. Raw data was obtained with Genepix Pro 6 software and uploaded on BASE where filtration and normalisation was done. Further analysis was done on TMev software by SAM and T Test. Results: Microarray analysis was performed on BASE and with Significance Analysis of Microarray (SAM) on TMev. The analysis showed significant gene expression indicative of stem cells such as specific and differentiation markers.Transcription factors, cell adhesion molecules, genes involved in cell metabolism and respiration showed up regulation in the LEC. Conclusions: The microarray analysis data supports our hypothesis that LEC harbours stem cells along with neighbouring niche cells and hence represents a Limbal Stem Cell niche.This is being confirmed with real time PCR.

Maize Tissue Preparation and Extraction of RNA from Target Cells for Genotyping

INTRODUCTIONThe use of RNA for genotyping analysis can be advantageous because transcriptomes are significantly smaller than genomes and typically contain far fewer repetitive sequences. Laser capture microdissection (LCM) has been used successfully to isolate sequences (especially rare transcripts) that accumulate in specific tissues. Where the quantity of isolated material is limiting, amplification can be used to increase the amount of product. Upon conversion to cDNA, the product serves as template for 454 sequencing to produce expressed sequence tags for subsequent SNP analysis and detection.This protocol describes the preparation of acetone-fixed and paraffin-embedded maize seedling tissue sections. Once the sections are prepared, the PALM MicroBeam System, with its Laser Microdissection and Pressure Catapulting (LMPC) technology, is used to cut out cells of interest and "catapult" isolated tissues into collection caps. This tissue can then be used for RNA extraction.

Tissue preparation for laser capture microdissection and RNA extraction from fresh frozen breast tissue

Tissue preparation for laser capture microdissection and RNA extraction from fresh frozen breast tissue

SU‐FF‐T‐232: Feasibility Study of a Carbon Nanotube Field Emission Microbeam System for Cellular Irradiation

Purpose: Tissue‐level radiobiological effects that influence tumor control or normal tissue complications stem from processes initiated at the cellular and sub‐cellular levels immediately following radiation energy deposition. The exact mechanisms of these processes at the critical moments are still poorly understood. We proposed to develop a nanotechnology based microbeam pixel array cellular irradiation system that promises to enable researchers to study the micro‐processes at the spatial and temporal scale of the events. This presentation reports the feasibility study results. Method and Materials: A multi‐pixel microbeam cellular irradiation system is proposed to selectively irradiate chosen target cells in a Petri dish under microscope observation. The microbeam system uses carbon nanotube (CNT) field emission technology. Each of the CNT pixels emits an electron beam and a silicon nitride window collimates the electron beam to a specific microbeam size. The electron microbeam has a tunable energy of 20–60 keV. Each of the pixel beams in the multi‐pixel microbeam can be controlled individually. The initial phase of the research is design and development of a prototype single pixel microbeam device and cell irradiation demonstration. Results: We have designed and fabricated a prototype single pixel CNT field emission microbeam system and performed dose calibration. GAFCHROMIC film is used to measure absolute dose and dose distribution. Microbeam radiation dose is calibrated as dose per radiation pulse. We performed cell irradiation using the prototype microbeam device on Rat‐1 cells. H2AX is phosphorylated at DNA damage sites and the microbeam irradiation pattern is confirmed by the pattern of DNA damage. Conclusion: We have demonstrated the feasibility of a single pixel CNT field emission microbeam for cellular irradiation. The next research step is study the feasibility of the multi‐pixel microbeam array.This work is funded by NCI (R21 CA118351) and North Carolina Biotechnology Center (2005 MRG‐111).

Progress and application of the Tohoku microbeam system

A microbeam system was constructed at the Tohoku University Dynamitron laboratory and optimization of the system was performed. Parasitic field contamination from tungsten carbide slit chips and an annular Si surface barrier detector limited the beam spot size to 2 × 2 μm 2. By replacing these components, the parasitic field contamination of the system was reduced and the performance of the microbeam system was remarkably improved. A measured beam spot size of 0.4 × 0.4 μm 2 at a beam current of several tens of pA has been accomplished. The results obtained using the grid shadow method show that a beam spot size of less than 0.4 μm is obtainable in the low-current regime. For easy tuning and operation of the microbeam system, a human–machine interface (HMI) was developed based on the user participatory design concept. The HMI has been accepted favorably by users and is used in routine operations. The analysis system has been re-developed and is applicable to simultaneous in-air/in-vacuum PIXE, RBS, SEM, and STIM analyses and 3D μ-CT. The system is now applied for studies in biological, environmental, and other fields.

Improvement in beam quality of the JAEA AVF cyclotron for focusing heavy-ion beams with energies of hundreds of MeV

In order to achieve a heavy-ion microbeam with an energy of hundreds of MeV applied to the research fields of biotechnology and materials science, the JAEA AVF cyclotron ( K = 110) has been upgraded to provide a high quality beam with a smaller energy spread and a higher current stability. A flat-top (FT) acceleration system of the cyclotron, designed to produce ion beams with an energy spread of Δ E/ E ⩽ 0.02%, has been developed to reduce chromatic aberrations in the lenses of the focusing microbeam system. The FT acceleration system provides uniform energy gain of the beam by superimposing a fifth-harmonic voltage on the fundamental one. In addition, stabilization of the acceleration rf voltage and the phase were achieved to accelerate the high quality beam and to provide it stably to the microbeam system connected to a cyclotron beam line. In the latest experiment, we have succeeded to accelerate 260 MeV 20Ne 7+ with an energy spread of 0.05% in FWHM using the FT acceleration system.

The Fudan nuclear microprobe set-up and performance

A new scanning nuclear microprobe has been constructed at the Institute of Modern Physics in Fudan University, to replace the old microbeam system which had been running for more than ten years. The key parts were purchased from Oxford Microbeams Ltd., including triplet quadrupole lens (model OM-150), collimator slits, scanning system, target chamber, and data acquisition system. Ion beams are provided from a NEC 9SDH-2 Tandem accelerator. Three CCD cameras and multiple monitors were installed to assist beam adjust. The design of beam line and beam monitors is described. Beam optics calculations were carried out based on the specific Fudan microprobe system geometry, and the results regarding beam line performance and limitations of the spacial resolution are presented and discussed here. A comparison with experimental results is given as well. About 1.5 μm beam spot size could be achieved with a 3 MeV proton beam at a current of around 10 pA. Recently, the new microprobe is applied to obtain information of fly ash particle, algae cell and otoliths.

Focusing high-energy heavy ion microbeam system at the JAEA AVF cyclotron

Performance of a focusing high-energy heavy ion microbeam system in TIARA facility of JAEA Takasaki was tested for the spatial resolution and for the hitting accuracy at a target. A 260 MeV 20Ne 7+ ion beam was successfully extracted from the JAEA AVF cyclotron ( K = 110) with the smallest momentum spread (Δ P/ P = δ) at present. The beam was focused by the microbeam lens system, and a spatial resolution of 260 MeV 20Ne 7+ microbeam was measured from a secondary electron image of a Cu grid which had sharp edges, and the hitting accuracy was estimated using single ion hitting onto a CR-39 film. From those two methods of measurement, both the spatial resolution and the hitting accuracy were evaluated at less than 1 μm.

New capabilities of the Zagreb ion microbeam system

The installation of a new 1.0 MV Tandetron accelerator and a recent upgrade of the 6.0 MV Tandem Van de Graaff accelerator increased the application possibilities of the Zagreb ion microbeam system. Several ion sources enable now the selection of a wide variety of ions. Most of them can be focused by the existing microprobe system. Sample positioning tools and new scanner control options are implemented in the new generation of SPECTOR data acquisition system. Details of the upgrades are presented.

Progress report of the single particle irradiation system to cell (SPICE)

At the National Institute of Radiological Sciences (NIRS), we constructed a microbeam system in 2003, the single particle irradiation to cell, SPICE. From the beginning of 2005, we redesigned it to improve the stability of the optical alignment of the system, and obtained an reduction of the beam size proportional to the vertical dimension of the object slits. As a result, SPICE is now capable of producing a beam size of approximately 10 μm diameter, and the particle numbers controllable to an intensity as low as single particles per second, and therefore a single particle irradiation facility has been successfully implemented. Moreover, these conditions can be easily reproduced with a employing a routine procedure. We describe in detail the modifications of the beam line and results, demonstrating the improvements. In addition, results from our first biological experiments are shown.