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A new method of image reconstruction for the time-of-flight positron emission tomograph (TOF-PET) has been developed. A construction function was found to reconstruct a positron image by directly convoluting three-dimensional sinograms. This construction function consists of the product of the well-known function for a conventional PET and the response function of time-of-flight measurement system for annihilation γ rays. [ABSTRACT FROM AUTHOR]

The accident at the Fukushima Daiichi Nuclear Power Plant caused widespread contamination in Fukushima Prefecture. The area was mainly contaminated with radioisotopes of iodine 131, cesium 134, and cesium 137. The surface soil has been removed in an attempt to decontaminate the evacuated area (1,150 km2). Rainfall erosion is believed to decontaminate mountains, so the surface soil has not been removed there. We thus investigated whether the mountains had been decontaminated by analyzing soil from the sedimentary layers found at the mouth of a stream that passes through these mountains. The volume and radioactivity distributions of the sedimentary layers showed that the heavy rainfall right after the earthquake contained a large amount of radioactive cesium. We confirmed that most small soil particles, those with diameters less than 210 μm, were not deposited at intermediate positions as they were transported downstream. Hence, rainfall erosion is a very effective means of decontaminating the mountains. [ABSTRACT FROM AUTHOR]

More than 22,000,000 m3 of soil was contaminated with cesium (Cs) radioisotopes following the accident at the Fukushima Daiichi Nuclear Power Plant. For site remediation, it is necessary to reduce this huge volume of contaminated soil. To achieve this, we investigated the distribution of contamination within soil particles. We measured the radioactivity distribution in soil particles using an autoradiogram (ARG) method, with a resolution of 50 × 50 μm, and also determined the elemental distributions with energy-dispersive X-ray spectroscopy. The ARG showed that almost all particles were uniformly contaminated with Cs radioisotopes, while the elemental distributions indicated that the particles were clay aggregates. These results suggest that, by impacting contaminated particles with each other and classifying them, we can reduce the volume of contaminated soil. [ABSTRACT FROM AUTHOR]

The article traces the history of particle-induced X-ray emission (PIXE) analysis. Biology and medicine are cited as some of the industrial applications for PIXE. Particular focus is given to the development of micro-PIXE analysis at the Japan Atomic Energy Agency's Takasaki Ion Accelerators for Advanced Radiation Application, as well as the 1997 and 2015 symposiums on PIXE. Also mentioned is the development of micro-PIXE analysis for micron-computed tomography.

Information about several papers presented at the Seventh International Symposium on Bio-Particle induced X-Ray Emission (PIXE), held from October 30 to November 4, 2011, at the Katahira Sakura Hall and the Center Hall, Graduate School of Engineering, Tohoku University, Sendai, Japan, is presented. Topics discussed include the fundaments of PIXE, techniques of PIXE analysis and experimental developments. It featured 122 participants from 17 countries.

In this study, we developed a three-dimensional (3D) computed tomography (CT) in vivo imaging system for imaging small insects with micrometer resolution. The 3D CT imaging system, referred to as 3D PIXE-micron-CT (PIXEμCT), uses characteristic X-rays produced by ion microbeam bombardment of a metal target. PIXEμCT was used to observe the body organs and internal structure of a living Drosophila melanogaster . Although the organs of the thorax were clearly imaged, the digestive organs in the abdominal cavity could not be clearly discerned initially, with the exception of the rectum and the Malpighian tubule. To enhance the abdominal images, a barium sulfate powder radiocontrast agent was added. For the first time, 3D images of the ventriculus of a living D. melanogaster were obtained. Our results showed that PIXEμCT can provide in vivo 3D-CT images that reflect correctly the structure of individual living organs, which is expected to be very useful in biological research. [ABSTRACT FROM AUTHOR]

Purpose The effect of alginate-hyaluronate microcapsules that release carboplatin in response to radiation was improved by adding ascorbic acid (AA). Materials and Methods Four measures of the effectiveness of the microcapsules were evaluated: 1) release of carboplatin in response to radiation in vitro and in vivo; 2) detectability of their accumulation by computed tomography (CT) in vivo; 3) enhancement of antitumor effects in vivo; and 4) reduction of adverse effects in vivo. Results There were significant increases in the rupture of microcapsules by adding AA in vitro. Subcutaneously injected microcapsules around the tumor could be detected by using CT and the alteration of CT-values correlated with the accumulation of the microcapsules. Those microcapsules released carboplatin and resulted in synergistic antitumor effect with concomitant radiation. With the encapsulation of carboplatin, chemotherapeutic effects were still observed two weeks after treatment. However, addition of AA did not result in increased antitumor effect in vivo. A reduction in adverse effects was observed with the encapsulation of carboplatin, through localization of carboplatin around the tumor. Conclusion Addition of AA to the materials of microcapsules did not result in increasing antitumor effect. However encapsulation of carboplatin will be useful as a clinical cancer-therapy option. [ABSTRACT FROM AUTHOR]

Abstract: In this study, two types of microcapsules were designed: (1) computed tomography (CT)-detectable anti-αvβ3 (E[c(RGDfK)]2) microcapsules, containing P-selectin and P-selectin glycoprotein ligand-1 (PSGL-1), for the observation of metastases through αvβ3-antigen–antibody accumulation; and (2) metastasis-targeting microcapsules that upon irradiation release anticancer drugs with high affinity for P-selectin. These microcapsules were tested on C3He/N mice with MM48 tumors undergoing two radiotherapy sessions. The injected anti-αvβ3 microcapsules accumulated in the vascular endothelium of metastatic tissues and could be detected by CT. These microcapsules released P-selectin in response to the first irradiation, which was also induced in the endothelium of vessels in the case of metastasis. The microcapsules used for radiosensitizing metastases were injected 6h after the first radiotherapy session. Their accumulation reached a maximum at 3h after injection. After the second radiotherapy session, the microcapsules released carboplatin, which reduced the number of metastases; however, this reduction was not significant. [Copyright &y& Elsevier]

Abstract: Thallium bromide (TlBr) is a promising compound semiconductor for fabrication of gamma-ray detectors. The attractive physical properties of TlBr lie in its high photon stopping power, high resistivity and good charge transport properties. Gamma-ray detectors fabricated from TlBr crystals have exhibited excellent spectroscopic performance. In this paper, advances in TlBr radiation detector development are reviewed with emphasis on crystal growth, detector fabrication, physical properties and detector performance. [Copyright &y& Elsevier]

Purpose: Radiation-sensitive microcapsules composed of alginate and hyaluronic acid are being developed. We report the development of improved microcapsules that were prepared using calcium- and yttrium-induced polymerization. We previously reported on the combined antitumor effect of carboplatin-containing microcapsules and radiotherapy. Methods and Materials: We mixed a 0.1% (wt/vol) solution of hyaluronic acid with a 0.2% alginate solution. Carboplatin (l mg) and indocyanine green (12.5 μg) were added to this mixture, and the resultant material was used for capsule preparation. The capsules were prepared by spraying the material into a mixture containing a 4.34% CaCl2 solution supplemented with 0–0.01% yttrium. These capsules were irradiated with single doses of 0.5, 1.0, 1.5, or 2 Gy 60Co γ-rays. Immediately after irradiation, the frequency of microcapsule decomposition was determined using a microparticle-induced X-ray emission camera. The amount of core content released was estimated by particle-induced X-ray emission and colorimetric analysis with 0.25% indocyanine green. The antitumor effect of the combined therapy was determined by monitoring its effects on the diameter of an inoculated Meth A fibrosarcoma. Results: Microcapsules that had been polymerized using a 4.34% CaCl2 solution supplemented with 5.0 × 10−3% (10−3% meant or 10%−3) yttrium exhibited the maximal decomposition, and the optimal release of core content occurred after 2-Gy irradiation. The microcapsules exhibited a synergistic antitumor effect combined with 2-Gy irradiation and were associated with reduced adverse effects. Conclusion: The results of our study have shown that our liquid core microcapsules can be used in radiotherapy for targeted delivery of chemotherapeutic agents. [Copyright &y& Elsevier]

Semiconductor detectors for PIXE applications were fabricated using TlBr crystals. The TlBr detectors had a multiple-electrode detector design to minimize the pulse-height loss due to hole trapping. Electrodes containing thallium metal were employed for the TlBr detectors to suppress the polarization phenomena. Energy resolutions of 2.4, 3.3, and 3.8 keV FWHM for 5.9, 22.1, and 59.5 keV photons, respectively, were obtained for a TlBr detector operating at −50 °C. [ABSTRACT FROM AUTHOR]

Double-sided strip detectors were fabricated from thallium bromide (TlBr) crystals grown by the traveling-molten zone method using zone-purified materials. The detectors had three 3.4-mm-long strips with 1-mm widths and a surrounding electrode placed orthogonally on opposite surfaces of the crystals at approximately 6.5×6.5 mm 2 in area and 5 mm in thickness. Excellent charge transport properties for both electrons and holes were observed from the TlBr crystals. The mobility-lifetime products for electrons and holes in the detector were measured to be ~3×10 −3 cm 2 /V and ~1×10 −3 cm 2 /V, respectively. The 137 Cs spectra corresponding to the gamma-ray interaction position were obtained from the detector. An energy resolution of 3.4% of full width at half maximum for 662-keV gamma rays was obtained from one “pixel” (an intersection of the strips) of the detector at room temperature. [ABSTRACT FROM AUTHOR]

The average ionization energy required to excite an electron-hole pair in TlBr was estimated to be 5.50 \pm 0.05~\eV by comparing the peak position of 59.5-keV gamma rays obtained from four pixels of a pixelated TlBr detector to the peak position obtained from a Si PIN photodiode at room temperature. [ABSTRACT FROM PUBLISHER]

Abstract: A 4.36-mm-thick pixelated thallium bromide (TlBr) detector with Tl electrodes was fabricated from a crystal grown by the traveling molten zone method using zone-purified material. The detector had four 1×1mm2 pixelated anodes. The detector performance was characterized at room temperature. The mobility-lifetime products of electrons for each pixel of the TlBr detector were measured to be >2.8×10−3 cm2/V. The four pixelated anodes of the detector exhibited energy resolutions of 1.5–1.8% full width at half maximum (FWHM) for 662-keV gamma rays for single-pixel events with the depth correction method. An energy resolution of 4.5% FWHM for 662-keV gamma rays was obtained from a reconstructed energy spectrum using two-pixel events from the two pixelated anodes on the detector. [Copyright &y& Elsevier]

To separate minor actinides from high level liquid waste (HLLW) of PUREX reprocessing, a silica-based macroporous isobutyl-BTP/SiO-P adsorbent was synthesized by impregnating isobutyl-BTP (2,6-di(5,6-diisobutyl-1,2,4-triazin-3-yl)pyridine) extractant into the macroporous SiO-P support with a mean diameter of 60 μm. A partitioning process using extraction chromatography for the treatment of HLLW was designed consisting five separation columns. As a partly work focused on isobutyl-BTP/SiO-P separation column, adsorption behavior of Am and trivalent rare earth (RE) from simulated HLLW onto silica-based isobutyl-BTP/SiO-P adsorbent was investigated by batch method. Meanwhile, the chemical and radiolytic stabilities of isobutyl-BTP/SiO-P adsorbent against 0.01 M HNO solution and γ-ray irradiation were studied. It was found that isobutyl-BTP/SiO-P adsorbent exhibited good adsorption selectivity for Am over RE(III) in 0.01 M HNO solution and showed weak or no adsorption affinity to light and middle RE(III) groups. In addition, in stability experiments, isobutyl-BTP adsorbent showed excellent stability against 0.01 M HNO solution and γ-ray irradiation over 4 months contact time. [ABSTRACT FROM AUTHOR]

Highlights: [•] Three novel macroporous silica-based adsorbents are used in this study. [•] Chromatographic separation behavior of Ru, Rh and Pd were studied by column method. [•] Separation effects of every column experiment for aim elements were compared. [•] A relatively excellent chromatographic separation operating for PGMs was obtained. [ABSTRACT FROM AUTHOR]

To separate platinum group metals (PGMs) from high level liquid waste (HLLW), a novel silica-based (Crea + TOA)/SiO-P adsorbent was synthesized by impregnating Crea ( N′, N′-di- n-hexyl-thiodiglycolamide) and TOA (trioctylamine) two extractants into the macroporous SiO-P support with a mean diameter of 60 μm. Adsorption properties and behavior of PGMs from simulated HLLW onto the novel silica-based (Crea + TOA)/SiO-P adsorbent were investigated by batch method. It was found that (Crea + TOA)/SiO-P adsorbent exhibited good adsorption selectivity for PGMs over the other tested fission product element in a wide HNO concentration. This adsorbent showed strong affinity to Pd(II) but almost no adsorption for rare earth elements. Adsorption process of PGMs could be expressed by Langmuir monomolecular layer adsorption mode and be governed by the chemisorption process. In addition, the adsorption isotherms and thermodynamic parameters of tested elements were calculated by Langmuir equation, Freundlich equation and van't Hoff equation, respectively. [ABSTRACT FROM AUTHOR]

To understand the separation behavior of Zr(IV) in the partitioning process for high level liquid waste, a silica-based macroporous adsorbent (TODGA/SiO-P) was prepared by impregnating N, N, N′, N′-tetraoctyl-3-oxapentane-1,5-diamide (TODGA) into a macroporous silica/polymer composite particles support (SiO-P). Adsorption and desorption behavior of Zr(IV) from nitric acid solution onto silica-based TODGA/SiO-P adsorbent were investigated by batch experiment. It was found that TODGA/SiO-P showed strong adsorption affinity to Zr(IV) and this adsorption process reached equilibrium state around 6 h at 298 K. Meanwhile, HNO concentration had no significant effect on the adsorption of Zr(IV) above 1 M. From calculated thermodynamic parameters, this adsorption process could occur spontaneously at the given temperature and was confirmed to be an exothermic reaction. This adsorption process could be expressed by Langmuir monomolecular layer adsorption mode and the maximum adsorption capacity were determined to be 0.283 and 0.512 mmol/g for Zr(IV) at 298 and 323 K, respectively. In addition, more than 90 % of Zr(IV) adsorbed onto adsorbent could be desorbed with 0.01 M diethylenetriamine pentaacetic acid solution within 24 h at 298 K. [ABSTRACT FROM AUTHOR]