The Singapore high resolution single cell imaging facility

The Centre for Ion Beam Applications, National University of Singapore has recently expanded from three state-of-the-art beam lines to five. Two new beam lines have been constructed: A second generation proton beam writing line, and a high resolution single cell imaging facility. Both systems feature high demagnification lens systems based on compact Oxford Microbeams OM52 lenses, coupled with reduced lens/image distances.The single cell imaging facility is designed around OM52 compact lenses capable of operating in a variety of high demagnification configurations including the spaced Oxford triplet and the double crossover Russian quadruplet. The new facility has design specifications aimed at spatial resolutions below 50 nm, with a variety of techniques including STIM, secondary electron and fluorescence imaging, and an in-built optical and fluorescence microscope for sample imaging, identification and positioning.Preliminary tests using the single space Oxford triplet configuration have indicated a beam spot size of 31 × 39 nm in the horizontal and vertical directions respectively, at beam currents of ∼10,000 protons per second. However, a weakness in the specifications of the electrostatic scanning system has been identified, and a more stable scanning system needs to be implemented before we can fully realize the optimum performance. A single whole fibroblast cell has been scanned using 1.5 MeV protons, and a median fit to the proton transmission energy loss data has shown that proton STIM gives excellent details of the cell structure despite the relatively poor contrast of proton STIM compared with alpha STIM.     

Application of heavy-ion microbeam system at Kyoto University: Energy response for imaging plate by single ion irradiation

A heavy-ion microbeam system for cell irradiation has been developed using an accelerator at Kyoto University. We have successfully developed proton-, carbon-, fluorine- and silicon-beams in order to irradiate a micro-meter sized area with ion counting, especially single ion irradiation. In the heavy-ion microbeam system, an imaging plate (IP) was utilized for beam diagnostics on the irradiation. The IP is widely used for radiography studies in biology. However, there are a few studies on the low linear energy transfer (LET) by single ions, i.e., low-intensity exposure. Thus we have investigated the energy response for the IP, which can be utilized for microbeam diagnostics.     

MgSO4对大鼠急性放射性脑损伤后脑细胞内Ca2+及脑组织NO含量的影响

为探讨硫酸镁(MgSO4)对电离辐射诱发脑损伤的保护作用,将成熟的SD大鼠36只随机分为空白对照组、实验对照组和硫酸镁实验用药组,用6 MeV电子束对实验组大鼠进行20 Gy全脑单次垂直照射,吸收剂量率为200 cGy/min;实验用药组大鼠于照射前1 d、照射后即刻和照射后连续5 d分别给予10%的MgSO4腹腔注射,分别于照后第3、10、17和24 d解剖大鼠,取其脑组织,用激光扫描共聚焦显微镜测定脑细胞内ca2+的含量,硝酸还原酶法测定脑组织一氧化氮(NO)含量.结果显示,与空白对照组相比,实验对照组大鼠脑细胞内Ca2+平均荧光强度及脑组织中NO含量明显升高(P＜0.05);与实验对照组相比,实验用药组大鼠脑细胞内Ca2+平均荧光强度及脑组织NO含量有所降低(P＜0.05).表明早期使用硫酸镁可抑制辐射引起的脑细胞内钙离子的超载及脑组织中NO含量的升高,硫酸镁对放射性脑损伤有保护作用.     

Development of Compton imaging system for nuclear material monitoring at pyroprocessing test-bed facility

The Korea Atomic Energy Research Institute (KAERI) has constructed a test-bed facility, named PRIDE (PyRoprocess Integrated inactive DEmonstration), for demonstration of pyroprocessing technology. Even though the PRIDE facility utilizes depleted uranium, instead of actual spent fuel, as process material, it will play an important role not only from the process perspective, but also from the safeguards standpoint. In the present study, a Compton imaging system based on pixelated GAGG:Ce scintillation detectors was constructed and tested to determine its utility for accurate imaging of nuclear material locations and, thus, its applicability as a safeguards monitoring system at the PRIDE facility. In a lab-scale performance evaluation, when the dose rate induced by a ¹³⁷Cs point-like source was ～0.1 μSv/h, the source location was imaged within 5 min. The image resolutions were 22° and 7.6° for real-time monitoring using a back-projection algorithm and for near-real-time monitoring using a statistical iterative algorithm, respectively. The developed Compton imaging system was finally applied to low-enriched uranium and also to depleted uranium, which latter is the process material of the PRIDE facility, and it was indicated that the Compton imaging system can localize nuclear materials within a few minutes under conditions similar to those prevailing at the PRIDE facility. The results of this study show that the Compton imaging system, and Compton imaging technology in general, has a great potential for utilization as a nuclear material monitoring tool at the PRIDE facility.     

Characterisation of a pre-cell hit detector to be used in single cell irradiation experiments at the Lund Nuclear Microprobe

This paper describes the characterisation of an ultra-thin silicon semiconductor ΔE detector to be used as a pre-cell ion hit detector in single ion experiments on individual, living cells. The characteristics of interest for this specific application are the hit detection efficiency, which has to be close to 100% to enable bombardment with either a single ion or a counted number of ions, the beam spreading, which should be as small as possible to maintain the targeting accuracy, and the vacuum tightness, since the detector is intended, if possible, to be used simultaneously as vacuum window. The hit detection efficiency was shown to be above 99% when detecting alpha particles or 2 MeV protons, the increase in beam size was about 1 μm and the vacuum tightness was comparable to that of the Si₃N₄ wafer which is normally used as vacuum window, thus the ΔE detector fulfils the main criteria to function properly as a single ion hit detector.     

一台用于IMP重离子治癌线上的电离室

介绍一种用于中国科学院近代物理研究所(IMP)重离子肿瘤治疗线上、于纵向场常压下工作的气体电离室,其灵敏面积为250 mm×250 mm,极间距离为10 mm,电离室工作气体为P10,在85kPa下流气式工作.用75 MeV/u 12C离子入射,测量了电离室的坪曲线.发现电离室工作坪区900-3000 V,12C的Bragg峰位于13.73 mm,峰的极大值半高宽(FWHM)为0.19 mm.     

The role of autophagy in cell survival from heavy ion irradiation in the plateau region

To study cytotoxic effect of heavy ion irradiation in the plateau region, and investigate whether autophagy in- duced by heavy ion irradiation is cytoprotective, HeLa cells were irradiated with 350 MeV/u carbon ions beams, and the clonogenic survival was analyzed. The results showed that cell survival decreased with increasing doses. It was also found that G2/M-phase cells increased, and the autophagy-related activity was significantly higher than the control. When autophagy was blocked by 3-methyladenine in carbon-ion irradiated cells, G2/M phase arrest and the percentage of apoptosis cells were further elevated, and cell survival decreased significantly, in- dicating the induction of cytoprotective autophagy by carbon-ion irradiation. Our results demonstrated that autophagy induced by carbon ion irradiation provided a self-protective mechanism in HeLa ceils, short-time inhibition of autophagy before carbon-ion irradiation could enhance radiation cytotoxicity in HeLa cells.     

~(99m)Tc热变性红细胞的制备及其在脾显像中的应用

近年来由于介入放射学的发展,使晚期肝硬变伴牌机能亢进者由于不能耐受脾切除术,有可能作脾栓塞治疗,为配合临床判断脾栓塞的疗效及脾显像在其它方面的临床应用,我们于1982年6月起开展~(99m)Tc-热变性红细胞脾显像的研究,今将结果报道如下。     

Recent developments of ion beam induced luminescence at the external scanning microbeam facility of the LABEC laboratory in Florence

A new ionoluminescence (IL) apparatus has been successfully installed at the external scanning microbeam facility of the 3 MV Tandetron accelerator of the INFN LABEC in Firenze; the apparatus for photon detection has been fully integrated in the existing ion beam analysis (IBA) set-up, for the simultaneous acquisition of IL and PIXE/PIGE/BS spectra and maps.The potential of the new set-up is illustrated in this paper by some results extracted by the analysis of art objects and advanced semiconductor materials. In particular, the adequacy of the new IBA set-up in the field of cultural heritage is pointed out by the coupled PIXE/IL micro-analysis of a lapis lazuli stone; concerning applications in material science, IL spectra from a N doped diamond sample were acquired and compared with CL analyses to evaluate the relevant sensitivities and the effect of ion damage.