• Journal of Radiation Protection and Research
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• 제42권1호
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• pp.69-76
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• 2017

Background: Time-resolved optically stimulated luminescence (TR-OSL) is a very useful method for calculating the lifetimes of crystalline quartz and feldspar. Materials and Methods: A compact TR-OSL system was developed, comprising a heater assembly manufactured using Kanthal wire, 2 powerful blue light-emitting diodes (LED, LXHL-PB02) for optical stimulation equipped with VIS liquid light guides, and a photomultiplier tube combined with an optical filter for luminescence detection. A pulse generated from the data acquisition board (NI PCI 6250) was used to initiate on/off signals in LED and TR-OSL measurements. Results and Discussion: The TR-OSL and background signals measured using this TR-OSL system using quartz samples were very similar to those reported in a previous study. Additionally, the lifetimes of the build-up and TR-OSL signals were calculated as $27.4{\pm}2.2{\mu}s$ and $30.3{\pm}0.6{\mu}s$, respectively, in good agreement with the findings of a previous study. Conclusion: It was concluded that the developed TR-OSL system was very reliable for TR-OSL signal measurements and lifetime calculations.

• 대한방사선기술학회지:방사선기술과학
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• 제47권4호
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• pp.271-278
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• 2024

This study aimed to evaluate the impact of changes in beam arrangement and arc counts on dosimetric factors in volumetric modulated arc therapy (VMAT) inverse radiation therapy planning for hippocampal-avoidance whole brain radiation therapy (HA-WBRT) by using the Elekta Monaco radiation therapy planning system (RTPs). For coplanar VMAT, both the arc per beam (APB) method and the beam determined arc(BDA) method, which is determined by the number of beams, were applied. For non-coplanar VMAT, the BDA method was utilized, and a total of 9 treatment plans were established by varying the arc counts. All radiation therapy plans met the radiation oncology group (RTOG) 0933 protocol standards, and 14 dosimetric factors were compared and analyzed. The results showed that the BDA-NC VMAT method demonstrated superior performance in terms of planning target volume (PTV) coverage and protection of normal organs, while APB-VMAT was advantageous in terms of hippocampal protection, monitor unit and delivery time. This study is expected to contribute to the efficient establishment of HA-WBRT plans considering the changes in beam arrangement and rotation arc numbers in Monaco RTPs.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.8-10
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• 1997

In recent years, the metal industry has become increasingly aware of an unwanted component in metal scrap-radioactive material. Worldwide, there have 38 instances where radioactive sources were unintentionally smelted in the course of recycling metal scrap. In some cases contaminated metal consumer products were distributed internationally. U.S. mill that have smelted a radioactive source face costs resulting from decontamination, waste disposal, and lost profits that range from 7 to 23 million U.S. dollars for each case. Despite radiation monitoring system does not provide 100% protection, POSCO has developed the system for the first time in the steel industry of KOREA.

• Journal of Radiation Protection and Research
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• 제42권4호
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• pp.212-221
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• 2017

Background: This study aims to calculate detector positions as a design of a radioactive source localizing radiation portal monitor (RPM) system using an improved genetic algorithm. Materials and Methods: To calculate of detector positions for a source localizing RPM system optimization problem is defined. To solve the problem, a modified iterative genetic algorithm (MIGA) is developed. In general, a genetic algorithm (GA) finds a globally optimal solution with a high probability, but it is not perfect at all times. To increase the probability to find globally optimal solution rather, a MIGA is designed by supplementing the iteration, competition, and verification with GA. For an optimization problem that is defined to find detector positions that maximizes differences of detector signals, a localization method is derived by modifying the inverse radiation transport model, and realistic parameter information is suggested. Results and Discussion: To compare the MIGA and GA, both algorithms are implemented in a MATLAB environment. The performance of the GA and MIGA and that of the procedures supplemented in the MIGA are analyzed by computer simulations. The results show that the iteration, competition, and verification procedures help to search for globally optimal solutions. Further, the MIGA is more robust against falling into local minima and finds a more reliably optimal result than the GA. Conclusion: The positions of the detectors on an RPM for radioactive source localization are optimized using the MIGA. To increase the contrast of the measurements from each detector, a relationship between the source and the detectors is derived by modifying the inverse transport model. Realistic parameters are utilized for accurate simulations. Furthermore, the MIGA is developed to achieve a reliable solution. By utilizing results of this study, an RPM for radioactive source localization has been designed and will be fabricated soon.

• Nuclear Engineering and Technology
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• 제55권1호
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• pp.1-11
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• 2023

To protect people and the environment from environmental radiation, the Act on Protective Action Guidelines against Radiation in the Natural Environment was formulated in Korea in 2011. This law regulates matters related to radiation safety that can be encountered in life. In accordance with this law, radiation monitoring equipment is operated at major airports and ports across the country, ensuring radiation monitoring of imported cargo. Currently, six ministries conduct radiation monitoring of imported cargo: the Nuclear Safety and Security Commission; the Korea Customs Service; the Ministry of Food and Drug Safety; the Ministry of Environment; the Ministry of Agriculture, Food and Rural Affairs; and the Korea Forest Service. Each ministry designates the relevant cargo items for radiation monitoring. The objective of this study was to comprehensively review the Korean radiation monitoring system for imported cargo and identify the areas and scopes of improvement. This paper also proposes a new law and an integrated supervision plan, which involves establishing a dedicated department to enhance the efficiency and professionalism of the national radiation monitoring system for imported cargo. The review will contribute to the development of a more sophisticated national radiation monitoring system for imported cargo.

• Journal of Radiation Protection and Research
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• 제31권2호
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• pp.53-63
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• 2006

원전 종사자를 대상으로 경시적인 코호트 연구를 통하여 저준위 방사선 노출과 암 발생 위해도를 규명하고자 하였다. 방사선 노출에 관한 정보는 한국수력원자력(주)의 방사선 관리 DB에서 수집하였고, 암 발생에 관한 정보는 한국인 중앙 암 등록 자료를, 암 사망에 관한 정보는 통계청 사망원인 자료를 이용하여 수집하였다. 방사선 노출과 암 발생 위해도는 표준화 암 사망비(SMR)와 표준화 암 발생 비(SIR)로 평가하였다. 노출 군에서 암 발생에 대한 상대위험도는 1.08로 평가되었으나 전체 암에 대한 SIR은 0.81로 유의성이 관찰되지 않았다. 암 사망에 대한 상대위험도는 1.21 이었으나 전체 암에 대한 SMR도 0.86으로 역시 유의성은 관찰되지 않았다. 암 유형별 양상은 우리나라 일반인과 유사한 결과를 보였으며, 방사선량 증가에 따른 양-반응 관계 또한 확인되지 않았다.

• 대한수의학회지
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• 제54권3호
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• pp.151-157
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• 2014

A nationwide survey on radiation safety management in Korean animal hospitals was conducted. By 2013, 53 radiation generators were registered as veterinary medical devices (41 X-ray generators and 12 computed tomography scanners). Additionally there were six approved laboratories for radiation equipment and protection facility, and five approved laboratories for radiation exposure of employees, respectively. By March 2013, 2,030 out of 3,829 animal hospitals operated radiation-generating devices. Among these devices, 389 (19.2%) out of 2,030 were not labeled with the model name and 746 (36.7%) were not labeled with production dates. Thus, most veterinary X-ray generators were outdated (42.6%) and needed replacements. When periodic inspections of 2,018 animal hospitals were performed after revision of the Veterinarians Act in 2011, the hospitals were found to be equipped with appropriate radiation generators and protection facilities. Among 2,545 employees exposed to radiation at the hospitals, 93.9% were veterinarians, 4.3% were animal nurse technicians, and 18% held other positions. Among 169 employees supervised by administrators, none of those had a weekly maximum operating load that exceeded $10mA{\cdot}min$. This study suggests that the radiation safety management system of animal hospitals was general good.

• 한국임상수의학회지
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• 제40권6호
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• pp.429-437
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• 2023

In veterinary medicine, most radiographic images are obtained by restraining patients, inevitably exposing the restrainer to secondary scattered radiation. Radiation exposure can result in stochastic reactions such as cancer and genetic effects, as well as deterministic reactions such as skin burns, cataracts, and bone marrow suppression. Radiation-shielding equipment, including aprons, thyroid shields, eyewear, and gloves, can reduce radiation exposure. However, the risk of radiation exposure to the upper arms, face, and back remains, and lead aprons and thyroid shields are heavy, restricting movement. We designed a new radiation-shielding system and compared its shielding ability with those of conventional radiation-shielding systems. We hypothesized that the new shielding system would have a wider radiation-shielding range and similar shielding ability. The radiation exposure dose differed significantly between the conventional and new shielding systems in the forehead, chin, and bilateral upper arm areas (p < 0.001). When both systems were used together, the radiation-shielding ability was better than when only one system was used at all anatomical locations (p < 0.01). This study suggests that the new radiation-shielding system is essential and convenient for veterinary radiation workers because it is a step closer to radiation safety in veterinary radiography.

• Journal of Radiation Protection and Research
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• 제43권4호
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• pp.160-169
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• 2018

Background: This study aims to develop an integrated optical system that can simultaneously or selectively measure the signals obtained from radioluminescence (RL), thermoluminescence (TL), and optically stimulated luminescence (OSL), which are luminescence phenomena of materials stimulated by radioactivity, heat, and light, respectively. The luminescence mechanism of various materials could be investigated using the glow curves of the luminescence materials. Materials and Methods: RL/TL/OSL integrated measuring system was equipped with a X-ray tube (50 kV, $200{\mu}A$) as an ionizing radiation source to irradiate the sample. The sample substrate was used as a heating source and was also designed to optically stimulate the sample material using various light sources, such as high luminous blue light emitting diode (LED) or laser. The system measured the luminescence intensity versus the amount of irradiation/stimulation on the sample for the purpose of measuring RL, TL and OSL sequentially or by selectively combining them. Optical filters were combined to minimize the interference of the stimulation light in the OSL signal. A long-pass filter (420 nm) was used for 470 nm LED, an ultraviolet-pass filter (260-390 nm) was used for detecting the luminescence of the sample by PM tube. Results and Discussion: The reliability of the system was evaluated using the RL/OSL characteristics of $Al_2O_3:C$ and the RL/TL characteristics of LiF:Mg,Cu,Si, which were used as dosimetry materials. The RL/OSL characteristics of $Al_2O_3:C$ showed relatively linear dose-response characteristics. The glow curve of LiF:Mg,Cu,Si also showed typical RL/OSL characteristics. Conclusion: The reliability of the proposed system was verified by sequentially measuring the RL characteristics of radiation as well as the TL and OSL characteristics by concurrent thermal and optical stimulations. In this study, we developed an integrated measurement system that measures the glow curves of RL/TL/OSL using universal USB-DAQs and the control program.

• Journal of Radiation Protection and Research
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• 제10권1호
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• pp.64-66
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• 1985

Methylene blue-PVA필름을 만들어 krad 영역의 선량계(線量計)로서 사용할 수 있는지를 조사하였다. 선원(線源)으로서는 X-선을 사용하였고, 일정량의 X-선을 조사(照射)한 후 methylene blue의 흡수파장(吸收波長) 670 nm 에서 분광분석계(分光分析計)로써 optical density를 측정하여 조사선량(照射線量)에 대한 optical density 곡선을 얻었다. dose-optical density 곡선은 비교적 좋은 비례성(比例性)과 합리적인 재현성(再現性)을 보였다. 따라서 본 methylene blue-PVA 계(系)는 이 선량(線量)영역의 선량계(線量計)로서 적합함을 시사해준다.