• Journal of Radiation Protection and Research
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• 제37권3호
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• pp.146-148
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• 2012

The use of GEANT4 simulation toolkit has increased in the radiation medical field for the design of treatment system and the calibration or validation of treatment plans. Moreover, it is used especially on calculating dose simulation using medical data for radiation therapy. However, using internal visualization tool of GEANT4 detector constructions on expressing dose result has deficiencies because it cannot display isodose line. No one has attempted to use this code to a real patient's data. Therefore, to complement this problem, using the result of gMocren that is a three-dimensional volume-visualizing tool, we tried to display a simulated dose distribution and isodose line on medical image. In addition, we have compared cross-validation on the result of gMocren and GEANT4 simulation with commercial radiation treatment planning system. We have extracted the analyzed data of dose distribution, using real patient's medical image data with a program based on Monte Carlo simulation and visualization tool for radiation isodose mapping.

• Journal of Radiation Protection and Research
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• 제12권1호
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• pp.54-60
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• 1987

The quasi-exposure rate and the quasi-effective energy of the natural radiation in the field at 47 monitoring points around nuclear power plants have been studied with the pair filter thermoluminescence dosimeter system. The results of the six years observation showed that the relationship between the quasi-exposure rate $X_q$, and quasi-effective energy $E_q$ can be represented as a hyperbolic function: $X_q=A+C/(E_q-B)$, where the constants A and B correspond to the quasi-exposure rate of cosmic-rays and the minimum quasi-effective energy of natural radiation, respectively. Furthermore, the constant A is in close agreement with the values obtained by using ionization chambers and scintillation detectors. The constant B is approximately 0.68 MeV, closely corresponding to the mean energy of the photons emitted from natural uranium.

• Journal of Radiation Protection and Research
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• 제48권3호
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• pp.117-123
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• 2023

Background: We investigated the impact of 0.35 T magnetic field on dose calculation for non-small cell lung cancer (NSCLC) stereotactic ablative radiotherapy (SABR) in the ViewRay system (ViewRay Inc.), which features a simultaneous use of magnetic resonance imaging (MRI) to guide radiotherapy for an improved targeting of tumors. Materials and Methods: Here, we present a comprehensive analysis of the effects induced by the 0.35 T magnetic field on various characteristics of SABR plans including the plan qualities and dose calculation for the planning target volume, organs at risk, and outer/inner shells. Therefore, two SABR plans were set up, one with a 0.35 T magnetic field applied during radiotherapy and another in the absence of the field. The dosimetric parameters were calculated in both cases, and the plan quality indices were evaluated using a Monte Carlo algorithm based on a treatment planning system. Results and Discussion: Our findings showed no significant impact on dose calculation under the 0.35 T magnetic field for all analyzed parameters. Nonetheless, a significant enhancement in the dose was calculated on the skin surrounding the tumor when the 0.35 T magnetic field was applied during the radiotherapy. This was attributed to the electron return effect, which results from the deviation of the electrons ejected from tissues upon radiation due to Lorentz forces. These returned electrons re-enter the tissues, causing a local dose increase in the calculated dose. Conclusion: The present study highlights the impact of the 0.35 T magnetic field used for MRI in the ViewRay system for NSCLC SABR treatment, especially on the skin surrounding the tumors.

• Journal of Radiation Protection and Research
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• 제26권3호
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• pp.305-309
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• 2001

Site-specific atmospheric dispersion characteristics have been analyzed. The northwest and the southwest wind prevail on nuclear sites of Korea. The annual isobaric surface averaged for twenty years around Korean peninsula shows that west wind prevails. The prevailing west wind is profitable in the viewpoint of radiation protection because three of four nuclear sites are located in the east side. Large scale field tracer experiments over nuclear sites have been conducted for the purpose of analyzing the atmospheric dispersion characteristics and validating a real-time atmospheric dispersion and dose assessment system FADAS. To analyze the site-specific atmospheric dispersion characteristics is essential for making effective countermeasures against a nuclear emergency.

• Journal of Radiation Protection and Research
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• 제14권2호
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• pp.45-50
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• 1989

원자력병원 싸이클로트른 중성자선(中性子線) 치료실의 방사선 준위(準位)를 측정함으로써 방사선 안전도를 검토하여 보았다. 중성자선 치료실내 방사선 노출은 주로 isocentric gantry에 내장된 중성자선 표적(標的)과 조사야(照射野)를 결정하는 collimator의 방사화(放射化)로 인한 잔류방사능(殘留放射能) (remanent radioactivity)에 의해 결정 된다. 측정결과 선량율(線量率)은 과다하지 않았고 개인 집적선량(集積線量)도 허용치 이내였다. 방사선 작업종사자로서의 의료기사는 환자치료 시 매 조사(照射) 완료 직후부터 5분간 멸살(滅殺)시간을 갖도록 조치하였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -1
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• pp.425-428
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• 2002

The technology of Computer Graphics (CG) has been in great progress for almost 20 years and has proven to be a valuable tool for a broad variety of fields, including nuclear engineering. To work in any hazardous environment for example radiation field is particularly challenging because the danger is not always visually apparent. In this study as the application of CG to nuclear engineering field, we proposed to develop a radiation risk recognition aided system in which various radiation information; radiation risks, radiation distribution, hazard information and so on, were visualized by CG. The system used the server and client system. In the server there were two parts; one (main-server) was the database part having various data and the other (sub-server) was the visualization part visualizing the human phantom by POV-Ray. In the client there was the input and output part. The outputs from the system were various radiation information represented by coloring, circle graph and line graph intuitionally. The system is useful for a broad range of activities including radiation protection, radiation management, dose minimization, and demonstration to the public.

• Journal of Radiation Protection and Research
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• 제46권2호
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• pp.48-57
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• 2021

Background: In this study, the complexities of step-and-shoot intensity-modulated radiation therapy (IMRT) plans in magnetic resonance-guided radiation therapy systems were evaluated. Materials and Methods: Overall, 194 verification plans from the abdomen, prostate, and breast sites were collected using a ⁶⁰Co-based ViewRay radiotherapy system (ViewRay Inc., Cleveland, OH, USA). Various plan complexity metrics (PCMs) were calculated for each verification plan, including the modulation complexity score (MCS), plan-averaged beam area (PA), plan-averaged beam irregularity, plan-averaged edge (PE), plan-averaged beam modulation, number of segments, average area among all segments (AA/Seg), and total beam-on time (TBT). The plan deliverability was quantified in terms of gamma passing rates (GPRs) with a 1 mm/2% criterion, and the Pearson correlation coefficients between GPRs and various PCMs were analyzed. Results and Discussion: For the abdomen, prostate, and breast groups, the average GPRs with the 1 mm/2% criterion were 77.8 ± 6.0%, 79.8 ± 4.9%, and 84.7 ± 7.3%; PCMs were 0.263, 0.271, and 0.386; PAs were 15.001, 18.779, and 35.683; PEs were 1.575, 1.444, and 1.028; AA/Segs were 15.37, 19.89, and 36.64; and TBTs were 18.86, 19.33, and 5.91 minutes, respectively. The various PCMs, i.e., MCS, PA, PE, AA/Seg, and TBT, showed statistically significant Pearson correlation coefficients of 0.416, 0.627, -0.541, 0.635, and -0.397, respectively, with GPRs. Conclusion: The area-related metrics exhibited strong correlations with GPRs. Moreover, the AA/Seg metric can be used to estimate the IMRT plan accuracy without beam delivery in the ⁶⁰Co-based ViewRay radiotherapy system.

• Journal of Radiation Protection and Research
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• 제11권1호
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• pp.70-76
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• 1986

중성자 측정의 국가표준을 확립하기 위하여 국제원자력거주(IAEA)로 부터 기술지원을 받아서 $MnSO_4$용액조장치를 개발하였다. 본 용액조장치는 구형의 s.s. 316L $MnSO_4$용액조(두께 3.5mm, 내경 125cm), 용액의 순환계 및 5$^{56}Mn\;{\gamma}$-선 검출계동으로 구성되어 있다 .용액조 본체로부터 퍼내어진 용액은 2개의 $3.8cm{\phi}{\times}3.8cm$ NaI(T1) 검출기가 설치된 Marinelli 비이커형의 모니터 용기로 진입되어 순환된다. 본 장치의 성능검사는 $^{241}Am-Be$ 과 $^{252}Cf$ 중성자 선원 을 사용하여 수행하였다. $^{56}Mn$ 방사능의 붕괴 곡선을 분석한 결과, $^{252}Cf$의 중성자 방출율은 1985년 11월 15일 현재 $3.71{\times}10^7\;n/s\;per\;50{mu}g$ 으로 얻어졌다.

• Journal of Radiation Protection and Research
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• 제22권4호
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• pp.263-272
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• 1997

방사선 작업자의 과피폭을 방지하기 위해 방사선 작업 도중 이상 사태가 발생할 경우 광 음경보가 발생한 후 이상 사태 발생 90분, 발생 30분간의 방사선량과 방사선량율 변화를 저장하고 외부 PC로 데이터를 전송한 후 사고를 분석하여 차후에 같은 유형의 방사선 사고를 사전에 예방할 수 있도록 고안된 방사선 경보장치를 개발하였다. 이 방사선 경보장치의 특징은 넓은 방사선 측정 범위(10mR/h $\sim$ 100 R/h), 방사선 준위의 기록 및 기억, PC와의 data처리 기능, 휴대성, 교정 기능에 의한 높은 정밀도(${\pm}5%$), 인지도가 높은 강력한 경보기능 채택 등이다. 개발된 방사선 경보장치의 물리적 환경 적응시험을 가장 엄격한 ANSI N42.17A의 표준 시험조건에 의거하여 온도, 습도, 진동, 전자기파 간섭 등에 관해 한국표준과학연구원에서 수행하였으며 모든 시험항목을 통과하였다.

• Journal of Radiation Protection and Research
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• 제41권2호
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• pp.161-165
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• 2016

Background: Radiation accidents having occurred in recent containing the accident in Fukushima nuclear power plants of Japan were resulted to the increase in some public concern, anxiety and confusion for radiation or nuclear safety. The public anxiety for radiation is not being decreased though the announcements done in radiation research institutes in Korea. Therefore, this study aims at providing an effective system for radiation publicity to the public members by the clipping analysis for the radiation articles reported in the media. And, the relation between those radiation issues and the radiation perception to the public members is analyzed. Materials and Methods: The radiation articles reported by them in 2013 and 2014 have been collected, and they are then classified with the article characteristic, field and tendency. Classified articles have been reviewed by dividing as two year. The 210 articles have been compared for their tendencies, characteristics and fields by year reported, and their characteristic comparison by reported year are then reviewed. Results and Discussion: Though the frequency that the radiological accidents have occurred in worldwide is far low compared to the accidental frequencies occurred in the general industrial fields, the radiation perception is being still deteriorated because of its special problem, which is defined as exposure, contamination or radioactivity, about radiation. The basic principles for radiation communication were suggested for preventing some unnecessary misunderstanding due to the variation of understanding for radiation issues. Conclusion: It is necessary to perform a variety of strategies for the publicity in improving the radiation perception, to build a relationship with the press or the media and then to consistently interact with them. Radiation communication must be performed by radiation experts or complete charge department, and must be consistently performed and be taken predictable patterns.