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A micro-pattern gaseous detector based on gas electron multiplier technology (GEM detector) was developed as a new transmission beam monitor for charged-particle therapy to obtain real-time information about the parameters of a therapeutic beam. Feasibility tests for the GEM detector were performed using an 80-MeV proton beam to evaluate the lateral intensity distributions of a pencil beam and the dose delivered to a target. The beam intensity distributions measured with the GEM detector were in good agreement with those measured with an imaging plate while the charge output from the GEM detector was in proportion to that of a reference dose monitor of an ionization chamber design. These experimental results showed that the GEM detector can be used not only as a beam monitor for the position and two-dimensional intensity distribution but also as a dose monitor. Thus, it is possible to simultaneously measure these beam parameters for beam control in charged-particle therapy using a single GEM-based transmission monitor.

In the frame of a systematic study of activation cross sections of deuteron induced nuclear reactions on rare earths, the reactions on neodymium for production of therapeutic radionuclides were measured for the first time. The excitation functions of the Nd-nat(d,x) Pm-151.150,Pm-149,Pm-148m,Pm-148g,Pm-146,Pm-144,Pm-143, Nd-149.147,Nd-139m, Pr-142 and Ce-139g nuclear reactions were assessed by using the stacked foil activation technique and high resolution gamma-spectrometry. The experimental excitation functions were compared to the theoretical predictions calculated with the modified model codes ALICE-IPPE-D and EMPIRE-II-D and with the data in the TENDL-2012 library based on latest version of the TALYS code. The application of the data in the field of medical isotope production and nuclear reaction theory is discussed. (C) 2014 Elsevier B.V. All rights reserved.

We present an updated assessment of soil contamination due to the nuclear accident at the Fukushima No. 1 nuclear power plant on 11 March 2011. A safe limit for the spatial dose rate (micro-Sv/h) of gamma rays from 134,137 Cs has been established in this work. Based on this value, the highly contaminated region within Fukushima Prefecture that must be decontaminated could be defined. Moreover, a conceptual model for the chemical speciation that occurred during the accident has been delineated. The compound model Cs 2 CO 3 was found to be meaningful and practical (non-radioactive) to simulate contamination in our decontamination experiments. Finally, we explain the mechanism of action of our soil remediation technique, which effectively reduces the total volume of contaminated soil by isolating the highly Cs-adsorptive clay fraction. The adsorption of non-radioactive Cs atoms on clay particles with diameters

In the frame of a systematic study of the activation cross-sections of deuteron induced nuclear reactions, excitation functions of the 103 Rh(d,x) 100,101,103 Pd, 100g,101m,101g,102m,102g Rh and 103g Ru reactions were determined up to 40 MeV. Cross-sections were measured with the activation method using a stacked foil irradiation technique. Excitation functions of the contributing reactions were calculated using the ALICE-IPPE, EMPIRE-II and TALYS codes. From the measured cross-section data integral production yields were calculated and compared with experimental integral yield data reported in the literature. From the measured cross-sections and previous data, activation curves were deduced to support thin layer activation (TLA) on rhodium and Rh containing alloys.

In the frame of a systematic study on activation cross-sections of deuteron induced reactions experimental excitation functions on 55 Mn were measured with the activation method using the stacked foil irradiation technique up to 40 MeV. By using high resolution γ-ray spectrometry, cross-section data for the production of 56,54,52 Mn and 51 Cr were determined. Comparison with the earlier published data and with the results predicted by the ALICE-IPPE and EMPIRE-II theoretical codes – improved for more reliable calculations for d-induced reactions – and with data in the TENDL 2010 libraries are also included. Thick target yields were calculated from a fit to our experimental excitation curves and implications for practical applications in industrial (Thin Layer Activation) accelerator technology are discussed.

Cross-sections of deuteron induced nuclear reactions on gold were measured up to 40 MeV by using the standard stacked foil irradiation technique and high resolution gamma-ray spectroscopy. Experimental cross-sections and derived integral yields are reported for the 197 Au(d,xn) 197m,197g,195m,195g Hg and 197 Au(d,x) 198g,196m,196g,195,194 Au nuclear reactions. The experimental data are analyzed and compared to literature and predictions of the ALICE-IPPE, EMPIRE and TALYS theoretical model codes. The application of the new cross-sections for accelerator technology, medical radioisotope production, thin layer activation and dose calculation is discussed.

Cross sections of proton induced nuclear reactions on ytterbium were measured up to 70 MeV by using the standard stacked foil irradiation technique and high-resolution gamma-ray spectroscopy. Experimental cross sections and derived integral yields are reported for the first time for the natYb(p,xn)173,172mg,171mg,170,167Lu, natYb(p,x)175cum,166cumYb and natYb(p,x)173ind,172ind,168,167cum,165cumTm reactions. No earlier experimental cross section data were found in the literature. The experimental data were compared to and analyzed with the results of the theoretical model code ALICE-IPPE. Production routes of medical radioisotope 167Tm are discussed.

Activation cross sections of the natYb(p,xn)169Lu reaction have been measured for the first time up to 70 MeV to investigate the production possibility of the radionuclide 169Yb through decay of its parent 169Lu. The cross sections were measured using the stacked foil irradiation technique and gamma spectrometry. The experimental data were compared with the results of the ALICE-IPPE theoretical model code. Different production routes were compared for the internal radiotherapy related radioisotope 169Yb. Above 30 MeV proton energy the integral yield of the natYb(p,xn)169Lu reaction is higher than that of the earlier investigated 169Tm(p,n)169Yb, 169Tm(d,2n)169Yb, natEr(α,xn)169Yb, natYb(α,x)169Lu and natHf(p,x)169Lu reactions at the equivalent particle energies.

To improve the beam brightness and the stability of the accelerator for nanobeam and microbeam applications, the Dynamitron accelerator was upgraded. Although the microbeam system at Tohoku University can focus the beam to several hundred square micrometers, its beam currents were insufficient for analyses of sub-micrometer resolution because of the lack of the accelerator brightness. For this upgrade, an ion source, with lenses in the terminal, and an acceleration tube were replaced with new ones. A control system for the ion source and lens system was also newly developed. Beam brightness of 2.6 and 0.44 pA μm−2 mrad−2 MeV−1 is currently obtained for H 2 + and H 1 + beams at half divergence of 0.07 mrad. The voltage stability of the accelerator was improved by adjusting the voltage stabilizing system, thereby improving the beam current stability. The Dynamitron accelerator has been operated routinely for various experiments without a serious problem.

Microcapsules consisting of alginate and hyaluronic acid that can be decomposed by radiation are currently under development. In this study, the composition of the microcapsule material was optimized by changing the amounts of alginate and hyaluronic acid. Solutions of 0.025%, 0.05%, 0.1%, 0.2%, or 0.4% (wt./vol.) hyaluronic acid were mixed into a 0.2% alginate solution. To these mixtures, carboplatin (0.2 mmol) was added and the resulting material was used for the capsule preparation. The capsules were prepared by spraying the material into a CaCl 2 solution (0.34 mol/l) using a microatomizer. These capsules were irradiated by a single dose of 2, 5, or 10 Gy 60 Co γ-ray radiation. Immediately after irradiation, the releasing of core content of microcapsule was determined, using a micro particle induced X-ray emission (PIXE) camera. The average diameter of the microcapsules was 22.3 ± 3.3 μm, and that of the liquid core was 10.2 ± 4.3 μm. The maximum radiation-induced content release was observed with liquid-core microcapsules containing 0.1% hyaluronic acid and 0.2% alginate. Our liquid-core microcapsules suggest a new potential use for radiation: the targeted delivery of the chemotherapeutic agents or radiosensitizers. This offers the prospect of increased combined effectiveness of radiation with chemotherapy or radiosensitization and decreased adverse side effects.

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.

We improved the spatial resolution of a 3D-CT imaging system consisting of a micro-beam and an X-ray CCD camera of 1 mega pixels (Hamamatsu photonics C8800X), whose element size is 8 μm × 8 μm providing an image size of 8 mm × 8 mm. A small ant of ∼6 mm body length was placed in a small tube, rotated by a stepping motor, and a spatial resolution of 4 μm for X-ray micron-CT using characteristic Ti-K-X-rays (4.558 keV) produced by 3 MeV proton micro-beams was obtained. We applied the X-ray micron-CT to a small ant’s head and obtained the fine structures of the head’s interior. Because the CCD is sensitive to visible light, we also examined the capability of light micron-CT using visible red light from an Al 2 O 3 (Cr) ruby scintillator and applied the micron-CT to a small red tick. Though the red tick is highly transparent to Ti-K-X-rays, visible red light does not penetrate through the red tick. The most serious problem was dispersion of lights due to Thomson scattering resulting in obscure projection images.

We are developing a PET camera using small semiconductor detectors, whose resolution is equivalent to the physical limit of spatial resolution. First, a coincidence system of 16 Schottky CdTe detectors of 0.5 mm width obtained a resolution of

A new detection apparatus for both low energy X-rays like 1 keV and back scattered protons of MeV energy was developed. The detection apparatus consists of a large-solid-angle multi-device Si detector and a data acquisition system. The detector has 45 detection devices which are arranged in the shape of a pentagonal pyramid and fully cover a sample. A micro-beam irradiates the sample through the center of the pentagonal pyramid and X-rays emitted from the sample are detected in a solid angle of about 1.0 sr. This novel detection setup has about five times higher sensitivity than a conventional micro-PIXE camera. In addition, not only X-rays but back scattered protons can be detected, since the counting rate of back scattered protons per detection device is small despite lack of a passive absorber.

We developed a novel technique to obtain 3D-imaging of elemental distribution based on multi-angle RBS measurement and micro-beam scanning. Since cross-sections of RBS are too small to obtain 3D-imaging, it is necessary to measure scattered particles with large solid angle detectors. Hence, the RBS profiles from each scattering angle are superposed and a true depth profile cannot be obtained. Recently, a large solid angle X-ray detector array consisting of 45 detector elements was installed at the TIARA facility of Japan Energy Research Institute. Each detector element measures X-rays as well as scattered particles. For this utilization, we introduced a technique to superpose RBS profiles and applied it to the surface analysis of an ant’s head.

A microbeam system is under construction in the Dynamitron laboratory at Tohoku University for the purpose of applying X-rays produced by a microproton beam as monochromatic X-ray point source to biological and materials research etc. The system consists of a dedicated beam line with a doublet quadrupole and a slit-system of microslits, divergence-defining slits and baffle slits connected to the 4.5 MV Dynamitron accelerator’s energy analyzing system, which was a newly installed second analyzing magnet. The demagnification factors are 8.0 and 27.5 for horizontal and vertical planes, respectively. Performance of the microbeam system was tested by beam scanning across the surface of a copper mesh sample (1000 lines/inch) and measuring the X-ray spectrum. A beam spot size of 2 × 2 μm 2 , which is larger than the design goal, is currently obtained. We are now adjusting the whole system to achieve a beam spot size of 1 × 1 μm 2 .

We developed a micro-PIXE system for the analysis of frozen cellular samples at atmospheric pressure under helium gas cooling. We analyzed bovine aortic endothelial (BAE) cells previously cultured in a medium containing bromodeoxyuridine (BrdU). It is known that these cells take BrdU into their nuclei at the S phase of their metabolic cycle. We examined the Br uptake for incubation times of 6, 12 and 24 h, respectively. The Br maps showed an accumulation in the nuclei and the Br concentration was found strongly dependent on the incubation time. We have demonstrated that in-air micro-PIXE analysis is a relevant technique for examining the molecular uptake in cells.

Continuous background appearing over the wide region of X-ray energy in the PIXE spectrum is very troublesome presence in the peak fitting. In the usual manner, the spectrum of continuous background is predicted as a function of polynomial and is subtracted from the X-ray spectrum. However, the parameters of the polynomial are determined with difficulty in the case that the continuous background exists under many peaks of characteristic X-rays. We calculated the production cross sections of continuous X-rays for several elements on the basis of the theories of quasi-free electron bremsstrahlung (QFEB), secondary electron bremsstrahlung (SEB) and atomic bremsstrahlung (AB), and obtained the continuous X-ray spectrum as a function of atomic number and X-ray energy. X-ray spectra of a standard sample and of a bovine liver sample were analyzed by a pattern analysis method assuming the reference spectra consisting of characteristic X-rays and continuous X-rays for each element. The results of analysis are quite satisfactory. By the present method, the PIXE spectra can be analyzed under little influence of the background subtraction, and it enables us a full auto-analysis of PIXE spectrum.