Rapid detection of heavy elements in blood extracted from wounds using x-ray fluorescence analysis.

In radiation emergency situations involving persons having plutonium (Pu)-contaminated wounds, rapid assessment of the degree of Pu contamination is required to determine the appropriate course of treatment. Currently, rapid on-site detection of Pu is usually performed by analysis of α-particles emitted from the adhesive tape peeled off the wound. However, the detection of α-particles is difficult, especially in traumatic skin lesions with oozing blood, because of the low permeability of α-particles in blood. Therefore, we focused on x-ray fluorescence (XRF) analysis because x-rays easily pass through several millimetres of blood. In this study, we developed a new methodology for the rapid detection of heavy elements in wounds based on XRF analysis of the contaminated blood collected by gauze patch and filter paper, using stable lead (Pb) as a model contaminant substitute for Pu. Mouse blood samples contaminated with Pb were dropped on gauze patches or absorbed by filter papers and were subjected to XRF measurement. Small pieces of filter paper served as more suitable extraction materials than gauze patches because the entire amount of blood absorbed could be measured. When we used filter paper, the signal intensity of the Pb Lα peak was proportional to the Pb concentration in the blood. With a measurement time of 30 s, the minimum detection limit of Pb in blood collected by filter paper was 2.4 ppm.

Low 134Cs/137Cs ratio anomaly in the north-northwest direction from the Fukushima Dai-ichi Nuclear Power Station.

A low 134Cs/137Cs ratio anomaly in the north-northwest (NNW) direction from the Fukushima Dai-ichi Nuclear Power Station (FDNPS) is identified by a new analysis of the 134Cs/137Cs ratio dataset which we had obtained in 2011-2015 by a series of car-borne surveys that employed a germanium gamma-ray spectrometer. We found that the 134Cs/137Cs ratio is slightly lower (0.95, decay-corrected to March 11, 2011) in an area with a length of about 15 km and a width of about 3 km in the NNW direction from the FDNPS than in other directions from the station. Furthermore, the area of this lower 134Cs/137Cs ratio anomaly corresponds to a narrow contamination band that runs NNW from the FDNPS and it is nearly parallel with the major and heaviest contamination band in the west-northwest. The plume trace with a low 134Cs/137Cs ratio previously found by other researchers within the 3-km radius of the FDNPS is in a part of the area with the lower 134Cs/137Cs ratio anomaly that we found. Our result suggests that this lower 134Cs/137Cs ratio anomaly is the area which was contaminated before March 13, 2011 (UTC) in association with the hydrogen explosion of Unit 1 on March 12, 2011 at 06:36 (UTC) and it was less influenced by later subsequent plumes.

Radioactive contamination mapping of northeastern and eastern Japan by a car-borne survey system, Radi-Probe.

We constructed a new car-borne survey system called Radi-Probe with a portable germanium gamma-ray spectrometer onboard a cargo truck, to identify radionuclides and quantify surface contamination from the accident at Fukushima Dai-ichi Nuclear Power Station. The system can quickly survey a large area and obtain ambient dose equivalent rates and gamma-ray energy spectra with good energy resolution. We also developed a new calibration method for the system to deal with an actual nuclear disaster, and quantitative surface deposition densities of radionuclides, such as (134)Cs and (137)Cs, and kerma rates of each radionuclide can be calculated. We carried out car-borne survey over northeastern and eastern Japan (Tohoku and Kanto regions of Honshu) from 25 September through 7 October 2012. We discuss results of the distribution of ambient dose equivalent rate H(∗)(10), (134)Cs and (137)Cs surface deposition densities, spatial variation of (134)Cs/(137)Cs ratio, and the relationship between surface deposition densities of (134)Cs/(137)Cs and H(∗)(10). The ratio of (134)Cs/(137)Cs was nearly constant within our measurement precision, with average 1.06 ± 0.04 in northeastern and eastern Japan (decay-corrected to 11 March, 2011), although small variations from the average were observed.

Methodology using a portable X-ray fluorescence device for on-site and rapid evaluation of heavy-atom contamination in wounds: a model study for application to plutonium contamination.

Workers decommissioning the Fukushima-Daiichi nuclear power plant damaged from the Great East Japan Earthquake and resulting tsunami are at risk of injury with possible contamination from radioactive heavy atoms including actinides, such as plutonium. We propose a new methodology for on-site and rapid evaluation of heavy-atom contamination in wounds using a portable X-ray fluorescence (XRF) device. In the present study, stable lead was used as the model contaminant substitute for radioactive heavy atoms. First, the wound model was developed by placing a liquid blood phantom on an epoxy resin wound phantom contaminated with lead. Next, the correlation between the concentration of contaminant and the XRF peak intensity was formulated considering the thickness of blood exiting the wound. Methods to determine the minimum detection limit (MDL) of contaminants at any maximal equivalent dose to the wound by XRF measurement were also established. For example, in this system, at a maximal equivalent dose of 16.5 mSv to the wound and blood thickness of 0.5 mm, the MDL value for lead was 1.2 ppm (3.1 nmol). The radioactivity of 239Pu corresponding to 3.1 nmol is 1.7 kBq, which is lower than the radioactivity of 239Pu contaminating puncture wounds in previous severe accidents. In conclusion, the established methodology could be beneficial for future development of a method to evaluate plutonium contamination in wounds. Highlights: Methodology for evaluation of heavy-atom contamination in a wound was established. A portable X-ray fluorescence device enables on-site, rapid and direct evaluation. This method is expected to be used for evaluation of plutonium contamination in wounds.

Development of target system for intense neutron source of p-Li reaction.

A target cooling system was developed for an intense neutron source of p-Li reaction. The system consists of target cooling devices and protection devices for lithium evaporation. A pin-structure cooling device was developed to enhance cooling power. Functional graded material was utilized for the evaporation of lithium. Test experiments were performed by using the neutron exposure accelerator system for biological effect experiments (NASBEE) at the National Institute of Radiological Sciences (NIRS) in Japan. The target system was confirmed to be applicable for accelerator-based boron neutron capture therapy.

Uptake of CDDP-containing polymeric micelles by cells using particle induced X-ray emission.

Polymeric micelles loaded with cis-diamminedichloroplatinum(II), CDDP, (cisplatin micelles) enable higher accumulation in solid tumors and lower toxicities compared with CDDP alone. The combined use of cisplatin micelles with radiation is expected to enhance therapeutic effects and reduce side effects. The kinetics of cisplatin micelle uptake, however, have not been fully understood. Particle Induced X-Ray Emission has been employed in this study to measure the time transients of platinum in Chinese Hamster ovary cells. The results show that the platinum content of cells treated with cisplatin micelles increased more slowly than with CDDP alone, suggesting that cellular uptake could be controlled using micelles. The CDDP released from micelles was predominantly incorporated into the cells by diffusion. The uptake characteristics were further analyzed using micelles with different collapse rates. The results and techniques used in this study will be useful for designing an optimum treatment plan combining platinum-containing polymeric micelles and radiation in clinical applications.

Microbeam irradiation facilities for radiobiology in Japan and China.

In order to study the radiobiological effects of low dose radiation, microbeam irradiation facilities have been developed in the world. This type of facilities now becomes an essential tool for studying bystander effects and relating signaling phenomena in cells or tissues. This review introduces you available microbeam facilities in Japan and in China, to promote radiobiology using microbeam probe and to encourage collaborative research between radiobiologists interested in using microbeam in Japan and in China.

Use of rubidium, manganese, and zinc as tracers to measure intestinal permeability by PIXE analysis: basal study in an experimental enteritis model.

Intestinal permeability has been suggested to be closely linked with the etiology or activity of Crohn's disease. However, current methods for measurement of intestinal permeability are too laborious for routine examination, as they require urine collection and/or use of radioisotopes. The present study was performed to develop a more convenient and safer method for assessing intestinal permeability using blood samples rather than urine. Rats with indomethacin-induced enteritis were orally administered Rb, Mn, and Zn as tracers. Intestinal permeability was determined by assaying the levels of Rb, Mn, and Zn in blood samples by particle-induced X-ray emission (PIXE). The distributions of Rb, Mn, and Zn in the small intestine after administration were analyzed by micro-PIXE. The conventional PIXE analysis showed that the levels of Rb and Zn in the blood in the enteritis group were correlated with the grade of enteritis. The micro-PIXE analysis showed that Rb, Mn, and Zn were translocated into the wall of the proximal small intestine 5 min after administration, and this effect was more conspicuous in the enteritis group than in controls. Analysis of blood or small intestine tissue samples using the PIXE allows determination of both intestinal permeability and the route of permeation.