Radiation accidents, fortunately, are rare events. However, the potential consequences can be very serious and radiation accident medical management is of great importance. In terms of clinical treatment decisions, it is crucial to rapidly obtain an estimate of the exposure scenario to predict the expected severity of radiation-induced injuries and to manage medical treatment. Accident scenarios involving dispersion of radioactive materials or nuclear power plants can mount up to large-scale events, like the accidents at Chernobyl and Fukushima. Thus, preparatory planning of the medical management of radiation accident victims is very important. Different types of radiation exposure, sometimes combined with injuries are possible and the diagnostic and therapeutic measure as well as the outcomes will accordingly differ. The absorption of significant doses of ionizing radiation will lead to acute radiation syndrome (ARS) whose clinical course depends on the absorbed radiation dose and its distribution. Besides the hematopoietic system being the most vulnerable organ system to radiation exposure, the skin plays an important role in diagnostics and treatment of radiation accident victims. Multi-organ-involvement and multi-organ-failure also need to be taken into account. Basics and principles of radiation accident medical management and the most important therapeutic approaches will be addressed.

Large scale radiological emergencies pose a particular problem for emergency preparedness because of potentially large numbers of worried well and the necessity to carry out triage in a timely manner. Here, an indispensable tool is biological dosimetry. Although a number of biodosimetric tools exist, not many have been tested and adapted for a large scale emergency scenario. In the framework of an EU-funded project MULTIBIODOSE we tested a variety of biodosimetric tools and adapted them to different mass casualty scenarios. The assays were chosen because they complement each other with respect to sensitivity, specificity to radiation and the exposure scenario, as well as speed of performance. The project was completed in April 2013. Its major conclusions are presented.

This paper describes performance experiments of a humidity control system in a thoron ²²⁰Rn chamber which adjusts and controls the humidity inside the chamber. The easily constructed and used humidity control system has a perfluorosulfonic membrane (commercially known as Nafion®) tube as the air humidity conditioner. The tube includes tube moisture exchangers that allow the transfer of water vapor between a flowing sample gas stream and a flowing purge gas stream over the exterior surface of the tube. Thus the tube has an advantage of being able to adjust the sample air flow to the desired humidity conditions. We investigated the optimal operation of the air humidity conditioner, including such items as response time to humidity, ability to control the humidity in the air and the losses of ²²⁰Rn gas in passing through the air humidity conditioner. Our first experiment showed that the performance of the air humidity conditioner depended on the flow rate conditions of sample and purge air flows. Only small losses due to decay of ²²⁰Rn and adsorption of ²²⁰Rn gas onto the tube surfaces were also evident. In the second experiment with the ²²⁰Rn chamber, we were able to adjust and control the humidity in the chamber using the humidity control system with the air humidity conditioner.

This article describes our participation in a civil protection training exercise with a dirty bomb scenario that was held jointly by the Japanese government (Cabinet Secretariat), Aomori Prefecture and Hirosaki City on November 7, 2013. Our missions took place mainly in an evacuation area (safe shelter) and included a surface contamination survey, decontamination, risk communication, and interviews on participants’ symptom and history. In total, 40 members of our faculty played important roles in this exercise in cooperation with staff from other organizations. About 240 evacuees were transported to an evacuation area for surface contamination surveys, interviews, group risk communication and filling out registration forms. Decontamination or personal consultation was also performed if necessary. Despite some confusion caused by multiple staffs from different organizations working together and many casualties coming in one after another, we believe that most of our tasks were successfully implemented as a result of our faculty’s experience with the project for radiation emergency medicine (REM) professions. Although nuclear disaster is considered rare, its effects are serious, and we must prepare a system to enable an effective response. Our project which involves developing human resources for REM is considered essential for this purpose.

Exposure to radon occurs not only by inhaling radon but also by drinking water. When using the direct method, the radon concentration in water is measured with a conventional liquid scintillation counter (LSC), which can measure samples contained in vials up to 20 ml. The purpose of our research is to develop effective measures for lowering the minimum detectable radon concentration. For the present study, the radon concentration in water was determined using a high efficiency LSC, which can measure larger than usual samples and hence detect lower minimum radon concentrations. In this case, it is a problem that only a few institutes are equipped with the high efficiency LSC. Moreover, the samples are not designated as articles prohibited for mailing by the Japanese Postal Law if they have been prepared. But, by using a mineral oil scintillator with an ignition point higher than 30℃, the samples can be transported to measuring institute without being designated as articles prohibited for mailing by the Japanese Postal Law. We examined the conditions for that. The results suggest that radon leakage from samples contained in Teflon LSC 100 ml vials is negligible for 6 days after sampling. When samples can be mailed to an institute equipped with a counting system capable of measuring the 100 ml vials, results of the samples can be obtained at lower minimum detectable radon concentrations.

The radioactivity released from the Fukushima Daiichi Nuclear Power Plant (F1NPP) into the environment after an accident clearly decreased. The decrease in radiocesium on the surface of the ground directly results in a decrease in the ambient dose rate. The term ” terrestrial halflife” was used to describe the decrease of a radionuclide only from the surface of the ground due to weathering. Terrestrial half-lives of cesium on artificial pavement was determined to be 1.1-2.6 y using official monitoring dose-rate data measured in several areas of the Fukushima region.

The aim of this study was to measure two parameters concerning the severity of acute radiodermatitis and to investigate the clinical relevance of the measurement, considering the implication of preventive and protective skin-care for the radiodermatitis. The subjects were five patients with breast cancer who underwent postoperative radiotherapy after breast-conserving surgery. Skin surface temperature (SST) and erythema intensity (EI) within the irradiated fields were measured twice, during radiotherapy and one month after. The measurement during radiotherapy was performed in the last week of radiotherapy, and the irradiated dose ranged from 44 to 48 Gy. For the contralateral breast, measurement was also performed as a control. The SST during radiotherapy was 1.1±0.7 (average±standard deviation), and that after radiotherapy 1.0±0.3. The EI during radiotherapy was 101 ±44, and that after radiotherapy 85±55. No significant difference in the values during and after radiotherapy was observed for each of the parameters. Inflammation of the irradiated skin tissues appeared to continue even one month after radiotherapy. Therefore it was suggested that skin-care is needed for a certain period following radiotherapy as well as during the therapy in order to prevent the condition of irradiated skin becoming worse.