• Journal of Radiation Protection and Research
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• 제46권1호
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• pp.14-23
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• 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
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• 제46권2호
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• pp.107-114
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• 2023

The purpose of this study was to compare the basic radiological characteristics of in-house polymer gel and commercially-available gel (BANG^TM) gel dosimeters with a spectro-photometer to use a optical computed tomography (CT) scanner. We investigated the radiological characteristics including dose linearity, absorbance spectrum, dose rate dependency and inter-and intra-reproducibility at wavelengths of 590, 600 and 630 nm. The optimal dose linearities of two gel dosimeters showed R² value of 0.939 and 0.948 at wavelengths of 590 nm and 600 nm, respectively. For two polymer gel dosimeters, there is no peak sensitivity within the range of all wavelengths in absorbance spectrum. For in-house gel dosimeter, the dose rate dependency were within 5% for all wavelengths except for the dose rate of 100 MU/min. For BANG^TM gel dosimeter, the dose rate dependency showed an error range of ±5% for all wavelengths. The inter-and intra-reproducibility of two gel dosimeters were within the range of 2.5%. We have confirmed that the two gel dosimeters was appropriate for use with a optical CT scanner.

• Applied Microscopy
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• 제39권1호
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• pp.79-83
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• 2009

We report a useful method to estimate the electron dose rate which may be a decisive factor to characterize sample properties. Even though most mircoscopes have their own exposure meters, there are several practical concerns when such exposure meters are used to measure the electron dose rate: 1) Specimen should be avoided within the entire area of exposure meter; 2) beam current has to be always recorded whenever the operation mode is changed; 3) the electron dose rate can not be calculated for the beam current beyond the detectable range. To overcome these limitations, we suggest a useful method which utilize a CCD (charge coupled device) camera which is now a popular detector to obtain the final electron micrographs. We have evaluated the CCD sensitivity using the linear relationship between electron current on the exposure meter and counter ratio on the CCD camera which are built in KBSI-HVEM (high voltage electron microscope). Applying the new method, we obtained the CCD sensitivity which are approximately 0.039 counts/$e^-$ and 1.37 counts/$e^-$ for the Top-TV and the HV-GIF CCD cameras, respectively.

• 대한방사선기술학회지:방사선기술과학
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• 제43권2호
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• pp.97-103
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• 2020

This study was conducted by SPECT test at the Department of Nuclear Medicine at Daegu P Hospital from June 1 to October 31, 2019. A 3-way injection material was mounted among inpatients, and a syringe that was administered with radiopharmaceuticals using a ^99mTc labeled compound was secured. We tried to find a way to calculate the dose rate of each radiopharmaceutical and increase the dose rate. As a result of measuring the radioactivity of radio-pharmaceuticals using ^99mTc, the average dose rate of 60 syringes of all 6 radiopharmaceuticals was 93.26±7.34%, and the average dose rate of ^99mTc-DMSA was 77.72%, 15.54% lower than the total. As a way to increase the dosing rate, the average dose rate diluted twice with the remaining amount of syringe after administration using normal saline increased to 95.37±6.99%, and the average dose rate diluted three times increased to 96.32±6.86%. The corresponding sample t-test to compare the pre- and post-dose rates at 1 dilution and 2 and 3 dilutions. As a result of the dilution and 2 dilutions, the probability of significance was 0.013, which was significantly higher than the dilution(p<0.05). The probability of significance for dilution 1 and dilution 3 was 0.016, which was significantly higher than in one dilution(p<0.05). The sum of the average dose rate using the experimental 3-way line was the highest with 98.85±1.42% of ^99mTc, ^99mTc-ECD 98.82±1.26%, ^99mTc-Mebrofenin 98.82 ± 1.16%, ^99mTc-HDP 98.74 ± 1.91%, ^99mTc -MIBI was 98.69 ± 1.48%, and ^99mTc-DMSA was the lowest with 86.47 ± 4.74%. When the number of dilutions was 5 times using 0.5 cc of normal saline and when the number of dilutions was 5 times using 1 cc of normal saline, when the number of dilutions was 5 times using 0.5 cc of normal saline and 1 cc of nomal saline When the number of dilutions was 5 times and the syringe volume was 0.5 cc, there was a statistically significant difference (p<0.05). There was a statistically significant difference when the number of dilutions was 5 times using 1 cc of nomal saline and the number of dilutions was 5 times using 1 cc of normal saline, and the syringe volume was 0.5 cc (p<0.05).

• 한국방사선학회논문지
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• 제11권3호
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• pp.117-122
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• 2017

레저생활의 급증으로 인하여 스키장 사용 인구가 급격히 증가하고 있다. 스키장은 직접적으로 자연광이나 우주선을 받을 확률이 높다. 왜냐하면 고도가 존재하는 산에 위치하기 때문이다. 일반적으로 고도가 높아질수록 자연방사선량이 증가한다는 사실은 널리 알려져 있다. 하지만 아직까지 스키장 고도에 관한 자연방사선량은 보고되지 않았다. 국내에는 다양한 스키장이 존재를 하지만 이번논문에서는 경기도 지역의 스키장4곳을 선정하여 고도에 따른 자연방사선량을 측정하였다. 결과적으로 스키장은 고도가 낮은 일반생활 지역에서보다는 방사선량보다 조금 많은 방사선량이 측정되었다. 우려할 수준은 아니지만 스키장 이용 시에는 반드시 스키 장비인 고글이나 다양한 스키 웨어(고글, 마스크, 헬멧)를 착용하여 자연방사선량을 보호한다면 환경방사선으로부터 안전하게 스키를 즐길 수 있을 것이다.

• Nuclear Engineering and Technology
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• 제53권6호
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• pp.1991-1999
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• 2021

The response changes of the specific growth rate of Lemna minor duckweed was modeled using the logarithms of frond numbers on tritium activity concentration and gamma radiation dose from cobalt 60. The concept of average specific growth rate depends on the general exponential growth pattern, where toxicity is estimated based on the effect on the growth rate. One of the main questions of the effect of the radiation dose on duckweed is how to correlate the effect of beta radiation with the effect of any other radiation for modeling radiation on Lemna minor. Experimental data were extrapolated by utilizing the OECD guidelines. A linear relationship of absorbed dose and activity concentration was obtained for the average dependency growth rate of Lemna minor as D = (0.1257)·A^0.585. The dose rate of gamma irradiation from ⁶⁰Co increases with tritium activity dependence, on the specific growth rate of the Lemna minor duckweed. An increase in the tritium activity causes a decrease in the specific growth rate of the Lemna minor duckweed. It indicates that as the quantity of the beta radiation dose increase in Lemna minor duckweed, a higher quantity of gamma radiation will be required to cause the same effect in the specific growth rate of Lemna minor duckweed. The relation between the inhibition of the Lemna minor seedling growth and gamma and beta radiation dosage agrees roughly with that between the decrease of survival rate or fertility and dosage.

• Radiation Oncology Journal
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• 제14권2호
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• pp.123-128
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• 1996

목적 : 악성 종양으로 인해 기도 폐쇄가 온 환자들을 저선량 및 고선량으로 내기관지 근접 치료하였을 경우의 대중치료 효과, 생존율 및 병발증을 비교 검토한다. 대상 및 방법 : 1988년 10월부터 1992년 6월까지 저선량 방법으로 21명, 1992년 8월부터 1994년 4월까지 고선량 방법으로 22명, 총 43명의 환자들에게 내기관지 근접치료를 시행하였다. 총 91회의 치료시, 모두 Fluorocopy하에서 굴절성 Fiberoptlc 내시경을 이용하였으며, 저선량 방법의 21회는 15-30 Gy를 0.75 cm 원경에, 고선량 방법의 64회는 5-7.5 Gy를 Ir-192 선원으로부터 1 Cm 원경에 각각 투사하였다. 결과 : 주관적 및 객관적 치료효과의 분석은 임상재진시 나타난 환자의 증상, 흥부 방사선 사진 및 흥부 단층촬영의 결과로 이루어졌다. 저산량으로 치료한 21명 중 15명의 환자와 고선량으로 치료한 22명 중 19명의 환자들이 주관적 치료효과가 있었음을 보였고, 8명의 저선량 환자와 10명의 고선량 환자가 흥부 방사선 사진과 단층 촬영상에서 객관적 효과가 있었음을 나타냈다. 결론 : 저선량 및 고선량 방사선에 의해 근접치료의 기술은 비교적 간단하며 환자가 별다른 후유증 없이 치료를 잘 받아 드리는 편이다. 이 치료 방법은 여생이 얼마 남지 않은 말기 폐암환자에게 내기관지 협착 내지는 폐쇄가 왔을 때 기관지의 공기소통을 원활히 증진시켜주는 대증치료 방법 이다.

• Radiation Oncology Journal
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• 제13권1호
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• pp.101-104
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• 1995

High Dose Rate Remote Afterloading system was installed at Wonkwang University Hospital in January 1994. In this report, the calibration of a Gammamed 12-i High Dose Rate Remote Afterloading system and the radiation survey around the facility after design and construct a shieding room are discussed. The radiation survey of the facility indicates that the use of ordinary concrete shielding of existing room will provide adequate shielding. Also, the methodologies for performing source calibration are presented.

• 전기학회논문지
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• 제61권8호
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• pp.1172-1178
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• 2012

In this paper, the gamma ray irradiation test results of the CCD cameras are described. From the low dose-rate (2.11 Gy/h) to the high dose-rate (150 Gy/h) level, which is the same level when the hydrogen explosion was occurred in the 1~3 reactor unit of the Fukushima nuclear power plant, the monitoring performance of the cameras owing to the speckles are evaluated. The numbers of speckles, generated by gamma ray irradiation, in the image of cameras are calculated by image processing technique. And the legibility of the sensor indicator (dosimeter) owing to the numbers of the speckles is presented.

• Nuclear Engineering and Technology
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• 제51권5호
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• pp.1436-1443
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• 2019

A fast gamma-ray dose rate assessment method for complex geometries based on stylized model reconstruction and point-kernel method is proposed in this paper. The complex three-dimensional (3D) geometries are imported as a 3DS format file from 3dsMax software with material and radiometric attributes. Based on 3D stylized model reconstruction of solid mesh, the 3D-geometrical solids are automatically converted into stylized models. In point-kernel calculation, the stylized source models are divided into point kernels and the mean free paths (mfp) are calculated by the intersections between shield stylized models and tracing ray. Compared with MCNP, the proposed method can implement complex 3D geometries visually, and the dose rate calculation is accurate and fast.