Earticle

The contributions of nuclear science and technology in enhancing prosperity and quality of life all over the world and its potential to achieve many important Sustainable Developments Goals (SDGs) of the United Nations are well recognized. It also is now recognized that with fewer students getting attracted to Science, Technology, Engineering and Mathematics (STEM) in general and nuclear science and technology (NST) in particular; hence, there is a vital need to reach out to young students to provide the crucial human resources needed for these endeavours to continue in this highly specialized area. The success of a recently completed IAEA project related to introducing NST during 2012–2016 in secondary schools in the Asia-Pacific region countries encouraged the formulation of a new IAEA TC project RAS0079 entitled “Educating Secondary Students and Science Teachers on Nuclear Science and Technology” for 2018– 2021, focusing on enhancing existing educational approaches through training and development opportunities both for teachers and students. The project aims at reaching a million students during the project duration while keeping the depth of learning between teacher and student. The strategy of executing the project, implementation status and its impact so far is presented in this paper.

Background: Dose rate meters are the most widely used, and perhaps one of the most important tools for the measurement of ionising radiation. They are often the first, or only, device available to a user for an instant check of radiation dose at a certain location. Throughout the world, radiation safety practices rely strongly on the output of these dose rate meters. But how well do we know the quality of their output? Materials and Methods: This review is based on the measurements 1,158 commercially available dose rate meters of 116 different makes and models. Expected versus the displayed dose patterns and consistency was checked at various dose rates between 5 μGy∙ h–1 and 2 mGy∙ h–1. Samples of these meters were then selected for further investigation and were exposed to radiation sources covering photon energies from 50 keV to 1.5 MeV. The effect of detector orientation on its reading was also investigated. Rather than focusing on the angular response distribution that is often reported by the manufacturer of the device, this study focussed on the design ergonomics i.e. the angles that the operator will realistically use to measure a dose rate. Results and Discussion: This review shows the scope and boundaries of the ionising radiation dose rate estimations that are made using commonly available meters. Observations showed both inter and intra make and model variations, occasional cases of instrument failure, instrument walk away, and erroneous response. Conclusion: The results indicate the significance of selecting and maintaining suitable monitors for specific applications in radiation safety.

Background: Four-dimensional computed tomographic (4DCT) images are increasingly used in clinic with the growing need to account for the respiratory motion of the patient during radiation treatment. One of the reason s that makes the dose evaluation using 4DCT inaccurate is a change of the patient respiration during the treatment session, i.e., intrafractional uncertainty. Especially, when the amplitude of the patient respiration is greater than the respiration range during the 4DCT acquisition, such an organ motion from the larger respiration is difficult to be represented with the 4DCT. In this paper, the method to generate images expecting the organ motion from a respiration with extended amplitude was proposed and examined. Materials and Methods: We propose a method to generate extra-phase images from a given set of the 4DCT images using deformable image registration (DIR) and linear extrapolation. Deformation vector fields (DVF) are calculated from the given set of images, then extrapolated according to respiratory surrogate. The extra-phase images are generated by applying the extrapolated DVFs to the existing 4DCT images. The proposed method was tested with the 4DCT of a physical 4D phantom. Results and Discussion: The tumor position in the generated extra-phase image was in a good agreement with that in the gold-standard image which is separately acquired, using the same 4DCT machine, with a larger range of respiration. It was also found that we can generate the best quality extra-phase image by using the maximum inhalation phase (T0) and maximum exhalation phase (T50) images for extrapolation. Conclusion: In the present study, a method to construct extra-phase images that represent expanded respiratory motion of the patient has been proposed and tested. The movement of organs from a larger respiration amplitude can be predicted by the proposed method. We believe the method may be utilized for realistic simulation of radiation therapy.

Background: This study aimed to estimate occupational doses and patient peak skin doses (PSDs) during interventional radiology procedures. Materials and Methods: We examined data from brain embolization (n = 30), hepatic chemoembolization (n = 50), and uterine embolization (n = 12). The PSDs were measured using radiochromic film around the patient’s head (group 1) or abdominal/pelvic region (group 2). Acquisition technical data and kerma-area products (KAP) were also recorded. Occupational doses were measured using InstadoseTM dosimeters near the left eye region (LER), chest, and left ankle. Results and Discussion: The third quartile (median) KAP values were 408.1 (235.3) Gy∙cm2 for group 1 and 584.4 (449.4) Gy∙cm2 for group 2. The average PSDs were greatest during vascular procedures, reaching 1,004.4 (786.4) mGy, and the highest PSD was 2,352.6 mGy (during hepatic chemoembolization). The third quartile (median) occupational doses were 0.35 (0.21) mSv at the LER, 0.25 (0.15) mSv at the chest, and 1.47 (0.64) mSv at the left ankle. Occupational doses at the LER were higher than at the chest, which highlights the importance of protective glasses and suspended shields. The occupational doses at the ankle region were also high, which highlights the importance of using a lead-lined curtain attached to the table. Conclusion: The results indicate that physicians can reach, for eye region, the weekly occupational dose limit after around 15 procedures, even when using proper protection. The average PSD values were below the threshold for tissue reactions, although the complexity of these procedures emphasises the importance of considering related risks.

Background: Government conducts environmental radioactivity surveillance for verification purpose around nuclear facilities based on the Nuclear Safety Law and issues a surveillance report every year. This study aims to evaluate the short and the long-term fluctuation of radionuclides detected above MDC and their origins using concentration ratios between these radionuclides. Materials and Methods: Sample media for verification surveillance are air, rainwater, groundwater, soil, and milk for terrestrial samples, and seawater, marine sediment, fish, and seaweed for marine samples. Gamma-emitting radionuclides including 137Cs, 90Sr, Pu, 3H, and 14C are evaluated in these samples. Results and Discussion: According to the result of the environmental radioactivity verification surveillance in the vicinity of nuclear power facilities in 2017, the anthropogenic radionuclides were not detected in most of the environmental samples except for the detection of a trace level of 137Cs, 90Sr, Pu, and 131I in some samples. Radioactivity concentration ratios between the anthropogenic radionuclides (137Cs/90Sr, 137Cs/239+240Pu, 90Sr/239+240Pu) were similar to those reported in the environmental samples, which were affected by the global fallout of the past nuclear weapon test, and Pu atomic ratios (240Pu/239Pu) in the terrestrial sample and marine sample showed significant differences due to the different input pathway and the Pu source. Radioactive iodine (131I) was detected at the range of < 5.6–190 mBq∙ kg-fresh–1 in the gulfweed and sea trumpet collected from the area of Kori and Wolsong intake and discharge. A high level of 3H was observed in the air (Sangbong: 0.688±0.841 Bq∙m–3) and the precipitation (Meteorology Post: 199±126 Bq∙L–1) samples of the Wolsong nuclear power plant (NPP). 3H concentration in the precipitation and pine needle samples showed typical variation pattern with the distance and the wind direction from the stack due to the gaseous release of 3H in Wolsong NPP. Conclusion: Except for the detection of a trace level of 137Cs, 90Sr, Pu, and 131I in some samples, anthropogenic radionuclides were below MDC in most of the environmental samples. Overall, no unusual radionuclides and abnormal concentration were detected in the 2017’s surveillance result for verification. This research will be available in the assessment of environment around nuclear facilities in the event of radioactive material release.