Radiation Environment and Medicine Vol.9, No.1
- Publisher : Hirosaki University Press
- Language : English
- ISSN : 2423-9097 (PRINT), 2432-163X (ONLINE)
- Release : February 2020
- Issue : Hirosaki University Press
- pp. 1-45
A Comparison of Radiobiological Response in Cells Exposed to Low LET Radiation with Different Beam Energies
There is conflicting evidence in the literature on biological effects between different low LET radiations. The aim of this study was to investigate the impact of different low LET radiations on radiobiological response.
Chromosomal radiosensitivity was measured in human lymphocytes from healthy donors using the G2 chromosomal radiosensitivity assay. Radiation induced mitotic inhibition was also measured.
Cells were irradiated to doses of 0.05 and 0.5 Gy using a Cobalt 60 teletherapy unit and a Linac operating at 6 MV (photons) and 12 MeV (electrons). As expected, a dose response was observed with increasing dose resulting in greater response. No statistically significant differences were observed, however, with different beam energies. Our study shows no statistically significant difference in radiobiological response with beam energy as measured using G2 chromosomal radiosensitivity and radiation induced mitotic inhibition as endpoints.
Activity Concentration and Soil to Plant Transfer Factor of Natural Radionuclides in Thai Lemongrass
The Activity concentration of three natural radionuclides (226Ra, 232Th, and 40K) in soil and lemongrass plant which are used in various Asia spices and traditional herb. The Lemongrass plant and their cultivated soils were collected from twelve locations in northern and northeastern Thailand under natural field conditions. The concentration of radionuclides was evaluated from gamma-ray spectrometry using HPGe detector. Soil-to-Plant transfer factors (TFs) for 226Ra, 232Th, and 40K were investigated in stalk portions. The mean activities of 226Ra, 232Th, and 40K in soil samples were 36±2, 55±3 and 477±10 Bq/kg, respectively, while the mean activities in lemongrass were 1.4±0.5, 3.2±0.8 and 860±14 Bq/kg, respectively. The mean TFs of 226Ra, 232Th, and 40K were 0.05, 0.15 and 10.30, respectively. These are valuable source of baseline data for activity concentrations and TFs of natural radionuclides in Thailand for environmental radiation check-up in the future.
External Radiation Exposure to the Public Using Car-borne Survey Method in the Uranium and Thorium Bearing Region of Lolodorf, Cameroon
This study deals with natural radiation exposure to the public caused by external sources in seven inhabited areas located in the uranium and thorium bearing region of Lolodorf, Cameroon. The activity concentrations of 238U, 232Th, and 40K were measured, the annual effective dose to the public assessed, and the distribution map of absorbed dose rate in air was performed. In-situ gamma spectrometry and car-borne survey method using the 3-in × 3-in NaI (Tl) scintillation spectrometer were used. The average absorbed dose rates in air, the external effective dose and the activity concentrations in soil of 238U, 232Th and 40K were 50.4 ± 7.2 nGy h-1, 0.33 ± 0.05 mSv y-1, and 33 ± 3 Bq kg-1, 53 ± 9 Bq kg-1, 182 ± 22 Bq kg-1 respectively. The ratios of the indoor dose rate to outdoor dose rate varied from 0.86 ± 0.04 to 1.12 ± 0.67 with a mean value of 1.02 ± 0.02. Compared to UNSCEAR limits, these radiological risk indicators are relatively high at certain points in the study area. Except for these points and their nearest neighborhood, soils can be used as building materials. In addition, high natural radiation areas are known and well located.
Lung Dose Estimation of 222Rn and 220Rn Progeny Based on IMBA Professional® Software
Radiation doses associated with exposures to 222Rn (radon) and 220Rn (thoron) are primarily due to inhalation of their short-lived progeny instead of the gas. The dosimetric data of radon are commonly used to assess the risk of radon-induced lung cancer derived from epidemiological studies of underground miners and from residential pooled analyzes. For estimation of the lung dose due to radon and thoron progeny, the dose conversion factor, which is the ratio of the activity concentration or PAEC of the decay products and dose is needed. There are three commonly used internal dosimetric software RADEP, LUDEP, and IMBA, which can be competent to implement to most of the biokinetic and dosimetric models recommended by ICRP to deduce the dose conversion factor and moreover to estimate the lung dose. Although all of the three internal dosimetric software use the same dosimetric model recommended by ICRP, due to the different data handling techniques, there are minor differences between the estimation results of the internal dose. There were several researchers who used the RADEP and LUDEP to conduct the dose calculation of lung dose of radon and thoron, but fewer researches gave the effective dose coefficient especially on IMBA. In this research, therefore, the dose conversion factor based on IMBA was calculated based on the reference parameters provided by the ICRP 66 and 137 and was compared with the published value of RADEP and LUDEP.
Rapid Tritium Analysis for Marine Products in the Coastal Area of Fukushima
The analysis of tritium in aquatic biota is one of the most important research areas in Fukushima. The conventional method for measuring the concentration of tritium consists of complicated pretreatment procedures and requires skillful techniques as well as a significant amount of time. Consequently, there are only a few reports on tritium monitoring data in marine products from the coast of Fukushima. In this study, we measured the Tissue Free Water Tritium (TFWT) and Organically Bound Tritium (OBT) in flounders collected from the coast of Fukushima to examine the impacts of the nuclear accident on aquatic biota. The study was done for a period of 4 years; from 2015 to 2018. The conventional method of analysis was firstly used, after which the method was modified by improving the freeze-drying and combustion water recovery processes. Results from both methods show that the most of the concentrations of the TFWT and OBT in
the flounder were below the detection or quantitative limit. The effect of the nuclear accident on humans, through internal exposure, was also examined and found to be negligible. Although some uncertainties exist due to the short cut of the processes, the modified version could be considered an effective and practical approximate method.
International Activities on Radiation Emergency Medical Personnel Training: Reports of Japan-Korea Joint Radiation Emergency Medicine Winter Training 2019
Hirosaki University and the Korea Institute of Radiological and Medical Sciences signed an agreement in 2013 regarding research and human resource development in radiation emergency medicine. The two institutions collaborated to hold the “2019 Radiation Emergency Medical Education and Training Winter Course” from February 11 to 22, 2019. This article describes the content of the training course and the results obtained. Doctors, nurses, and radiological technologists, among others, from radiation emergency institutions in Korea and Japan took the course, which ran a total of ten days. For the first eight days, participants learned a wide range of fundamentals in radiation emergency medicine and disaster medicine, including the use of personal protective equipment, portable radiation measurement instruments, communication tools, and various tents. During the last two days, the participants went to a campsite near a nuclear power plant and conducted the simulated operation of a nuclear disaster medical countermeasure headquarters. Through this activity, participants learned that information management is very important in disaster activities and also learn the difficulty to treat with contaminated patients in winter.
Current Situation of Triage Methods for Exposed Patients in the Acute Phase of a Nuclear Disaster
Patients with exposure to radiation are encountered in the event of a nuclear disaster and/or radiation accident. However, in Japan, there are no uniform rules or laws such as how to do triage for exposed patients. This study aimed to collect information for develop a triage method for exposure patients in the acute phase of a nuclear disaster. We surveyed research academic articles and collected information from radiation emergency medical institutions. In the academic articles survey, five triage-related articles were found that can be used in the acute phase of a nuclear disaster. Furthermore, on surveying radiation emergency medical institutions, the Radiation Emergency Medical Management in the United States of America provided useful information. Although situations involving radiological emergencies in a large number of people exposed to radiation are rare, it is necessary to establish on-site judgment criteria and triage methods in response to radiation disasters.