• 대한방사선기술학회지:방사선기술과학
• /
• 제44권2호
• /
• pp.109-115
• /
• 2021

In this study, a physical evaluation of internal radiation exposure in children was conducted using nuclear medicine test(Renal DTPA Dynamic Study) to simulate the distribution and effects of the radiation throughout the tracer kinetics over time. Monte Carlo simulations were performed to determine the internal medical radiation exposure during the tests and to provide basic data for medical radiation exposure management. Specifically, dose variability based on changes in the tracer kinetic was simulated over time. The internal exposure to the target organ (kidney) and other surrounding organs was then quantitatively evaluated and presented. When kidney function was normal, the dose to the target organ(kidney) was approximately 0.433 mGy/mCi, and the dose to the surrounding organs was approximately 0.138-0.266 mGy/mCi. When kidney function was abnormal, the dose to the surrounding organs was 0.228-0.419 mGy/mCi. This study achieved detailed radiation dose measurements in highly sensitive pediatric patients and enabled the prediction of radiation doses according to kidney function values. The proposed method can provide useful insights for medical radiation exposure management, which is particularly important and necessary for pediatric patients.

• 한국의학물리학회지:의학물리
• /
• 제24권3호
• /
• pp.140-144
• /
• 2013

본 연구에서는 방사선생물 분야에서는 사용하는 세슘-137 조사기에 대한 기준 흡수선량을 측정하고 시료의 방사선량 평가에 활용하기 위하여 유리선량계를 교정하였다. 세슘-137 감마선에 대하여 IAEA TRS-277 프로토콜을 적용하여 정밀하게 물흡수선량을 결정하였다. 기준 흡수선량 측정에는 PTW-TM300013 전리함과 PTW-TM41023 물팬텀을 사용하였으며, 유리선량계는 DoseAce사의 GD-302M 모델을 사용하였다. 교정된 유리선량계의 불확도(1 SD)는 약 2.7%로 평가되며, 본 결과는 연구용 시료의 방사선량 측정에 이용될 예정이다.

• 대한방사선기술학회지:방사선기술과학
• /
• 제45권4호
• /
• pp.305-312
• /
• 2022

The proportion and testing of portable radiation tests, which are limited at the request of the doctor, are gradually increasing only for patients in emergency situations and difficulties in moving. However, as there are many limiting factors compared to fixed devices, this study intends to measure and analyze the distortion of images according to the angle of the detector and the change in dose according to the position of the subject. For distortion experiments using a mobile radiation generator used in Hospital A, the SID was tilted by 110 cm, 14"×17" wireless FPD detector to 0°, -5°, -10°, -15°, -20°, and -35° to measure the change in area. The dose according to the location of the detector was analyzed on average by measuring the central dose at 110 cm of the SID and measuring the dose of 9 locations three times each. The analysis result of distortion by location according to the angle of the detector showed a statistically significant difference (f=58.74, p<0.000). Therefore, it can be seen that the angle of the detector and the tube is closely related to the distortion of the image. The difference in dose by location of the detector increased with respect to the center - pole, and decreased with the + pole. Tests using mobile radiation generators will require careful efforts by clinicians to position patients in the center of the detector for accurate diagnosis, and efforts will be made to level the angle between the mobile radiation generators and the detector.

• Journal of Radiation Protection and Research
• /
• 제46권1호
• /
• pp.14-23
• /
• 2021

Background: For radiological protection and control, the International Commission on Radiological Protection (ICRP) provides the nominal risk coefficients related to radiation exposure, which can be extrapolated using the excess relative risk and excess absolute risk obtained from the Life Span Study of atomic bomb survivors in Hiroshima and Nagasaki with the dose and dose-rate effectiveness factor (DDREF). Materials and Methods: Since it is impossible to directly estimate the radiation risk at doses less than approximately 100 mSv only from epidemiological knowledge and data, support from radiation biology is absolutely imperative, and thus, several national and international bodies have advocated the importance of bridging knowledge between biology and epidemiology. Because of the accident at the Tokyo Electric Power Company (TEPCO)'s Fukushima Daiichi Nuclear Power Station in 2011, the exposure of the public to radiation has become a major concern and it was considered that the estimation of radiation risk should be more realistic to cope with the prevailing radiation exposure situation. Results and Discussion: To discuss the issues from wide aspects related to radiological protection, and to realize bridging knowledge between biology and epidemiology, we have established a research group to develop low-dose and low-dose-rate radiation risk estimation methodology, with the permission of the Japan Health Physics Society. Conclusion: The aim of the research group was to clarify the current situation and issues related to the risk estimation of low-dose and low-dose-rate radiation exposure from the viewpoints of different research fields, such as epidemiology, biology, modeling, and dosimetry, to identify a future strategy and roadmap to elucidate a more realistic estimation of risk against low-dose and low-dose-rate radiation exposure.

• 대한방사선기술학회지:방사선기술과학
• /
• 제46권6호
• /
• pp.509-517
• /
• 2023

This study analyzed imaging conditions and exposure index through clinical information collection and dose calculation programs in coronary angiography examinations. Through this, we aim to analyze the effective dose according to examination conditions and provide basic data for dose optimization. In this study, ALARA(As Low As Reasonably Achievable)-F(Fluoroscopy), a program for evaluating the radiation dose of patients and the collected clinical data, was used. First, analysis of imaging conditions and exposure index was performed based on the data of the dose report generated after coronary angiography. Second, after evaluating organ dose according to 9 imaging directions during coronary angiography, with the LAO fixed at 30°, dose evaluation was performed according to tube voltage, tube current, number of frames, focus-skin distance, and field size. Third, the effective dose for each organ was calculated according to the tissue weighting factors presented in ICRP(International Commission on Radiological Protection) recommendations. As a result, the average sum of air kerma during coronary angiography was evaluated as 234.0±112.1 mGy, the dose-area product was 25.9±13.0 Gy·cm², and the total fluoroscopy time was 2.5±2.0 min. Also, the organ dose tended to increase as the tube voltage, milliampere-second, number of frames, and irradiation range increased, whereas the organ dose decreased as the FSD increased. Therefore, medical radiation exposure to patients can be reduced by selecting the optimal tube voltage and field size during coronary angiography, maximizing the focal-skin distance, using the lowest tube current possible, and reducing the number of frames.

• 대한방사선기술학회지:방사선기술과학
• /
• 제40권1호
• /
• pp.49-55
• /
• 2017

의료기관 내 핵의학 종사자는 방사성동위원소 취급 시 사용하는 선원의 종류, 방사능량, 차폐기구의 사용 여부에 따라 종사자 개인별로 광범위한 피폭선량을 나타낼 수 있다. 이에 본 연구에서는 몬테카를로 기법을 기반으로 한 모의실험을 통해 진단용 방사선원 취급 시 종사자의 장기별 선량평가와 L-block 차폐기구 사용에 따른 선량감소효과를 분석하였다. 그 결과, 방사선원의 취급 위치에 근접할수록 높은 장기선량 분포를 나타내었고, ICRP 조직가중치에 따라 유효선량 분포가 상이한 양상을 보였다. 또한 L-block 두께에 따른 선량감소효과는 차폐두께 증가에 따라 지수함수 분포로 감소되는 경향을 나타내었으며, 방사선원별 선량감소효과는 방출하는 감마선 에너지에 비례하여 낮은 차폐효과를 보였다.

• Journal of Radiation Protection and Research
• /
• 제47권3호
• /
• pp.143-151
• /
• 2022

Background: After the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, biological alterations in the natural biota, including morphological changes of fir trees in forests surrounding the power plant, have been reported. Focusing on the terminal buds involved in the morphological formation of fir trees, this study developed a method for estimating the absorbed radiation dose rate using radionuclide distribution measurements from tree organs. Materials and Methods: A phantom composed of three-dimensional (3D) tree organs was constructed for the three upper whorls of the fir tree. A terminal bud was evaluated using Monte Carlo simulations for the absorbed dose rate of radionuclides in the tree organs of the whorls. Evaluation of the absorbed dose targeted ¹³¹I, ¹³⁴Cs, and ¹³⁷Cs, the main radionuclides subsequent to the FDNPP accident. The dose contribution from each tree organ was calculated separately using dose coefficients (DC), which express the ratio between the average activity concentration of a radionuclide in each tree organ and the dose rate at the terminal bud. Results and Discussion: The dose estimation indicated that the radionuclides in the terminal bud and bud scale contributed to the absorbed dose rate mainly by beta rays, whereas those in 1-year-old trunk/branches and leaves were contributed by gamma rays. However, the dose contribution from radionuclides in the lower trunk/branches and leaves was negligible. Conclusion: The fir tree model provides organ-specific DC values, which are satisfactory for the practical calculation of the absorbed dose rate of radiation from inside the tree. These calculations are based on the measurement of radionuclide concentrations in tree organs on the 1-year-old leader shoots of fir trees. With the addition of direct gamma ray measurements of the absorbed dose rate from the tree environment, the total absorbed dose rate was estimated in the terminal bud of fir trees in contaminated forests.

• 대한방사선기술학회지:방사선기술과학
• /
• 제19권2호
• /
• pp.59-65
• /
• 1996

We studied exposure techniques and exposure dose for simple abdomen A-P projection for 41 medical facilities that are located in Seoul area. 1. The range of tube voltage used was 60 to 84 kVp, the average tube voltage used was 74 kVp 2. Only 17% of added filter was used. 3. Tube current mostly used was 200 mA, some of them used 400 mA. 4. The grid ratio mostly was used 10 : 1, 54 % of the rare earth screen was used in most facilities. 5. The average skin entrance dose was 4.15 mSv and the dose range was 1.05 mSv to 11.0 mSv.

• Journal of Radiation Protection and Research
• /
• 제28권3호
• /
• pp.247-254
• /
• 2003

To prevent the potential health detriment to the public from radioactive effluents, radiological dose assessments due to the operation of nuclear facilities located at Korea Atomic Energy Research Institute (KAERI) site has been performed semiannually in compliance with the Minister of Science and Technology (MOST)'s Notice in Korea. Radiological dose assessment based on the new recommendation of the International Committee on Radiation Protection (ICRP-60) has been conducted since 1998. In this manuscript, a serial activities at KAERI site to meet the regulatory standards for routine releases of radioactive effluents are introduced and discussed including technical approaches. It is clear that each nuclear facility has been operated in compliance with regulatory standards. Furthermore, it is identified that the radiation induced health effects for residents around the site are neglectable.

• 전자공학회논문지
• /
• 제53권9호
• /
• pp.143-147
• /
• 2016

최근 디지털 단층영상합성 시스템 (digital tomosynthesis system, DTS)은 일반 X-ray의 영상 중첩현상과 전산화단층촬영장치 (computed tomography, CT)의 높은 선량의 문제점을 해결하기 위하여 개발되었다. 본 연구의 목적은 흉부 촬영용 디지털 단층영상합성 시스템 (chest digital tomosynthesis, CDT)의 재구성 알고리즘 개발 및 화질과 선량 평가를 수행하는 것이다. 영상의 재구성은 필터 후 역투영 (filtered back-projection, FBP)을 모델링하였고, 팬텀 영상을 획득하기 위한 X-선과 검출기 사이의 각도를 ${\pm}10^{\circ}$, ${\pm}15^{\circ}$, ${\pm}20^{\circ}$, 그리고 ${\pm}30^{\circ}$로 구성하였다. 영상의 화질 평가는 평균 제곱근 편차 (root mean square error, RMSE)와 신호대 잡음 변화율 (signal difference-to-noise ratio, SDNR)로 수행하였고, 선량 평가는 ${\pm}20^{\circ}$의 범위에서 유효선량으로 수행하였다. 결과적으로, 모든 각도에서 Slice thickness 필터를 적용한 팬텀영상이 가장 우수한 RMSE와 SDNR 결과를 나타내었고, 최종 유효 선량은 0.166 mSv로 측정되었다. 결론적으로, 개발한 CDT 재구성 알고리즘의 유용성을 증명하였고, 최종 유효 선량을 측정하여 CDT의 기초 실험 데이터를 구축할 수 있었다.