• Communications for Statistical Applications and Methods
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• 제9권3호
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• pp.693-701
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• 2002

When the lowest dose level compared with zero-dose control has significant difference in effect, it is referred as minimum effective dose (MED). In this paper, we discuss several nonparametric methods for finding MED using updated rank at each sequential test step in small sample size and suggest new nonparametric procedures based on placement. Monte Carlo Simulation is adapted to compare power and Familywise Error Rate(FWE) of the new procedures with those of discussed nonparametric tests for finding MED.

• Communications for Statistical Applications and Methods
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• 제11권3호
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• pp.597-607
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• 2004

The primary interest of drug development studies is identifying the lowest dose level producing a desirable effect over that of the zero-dose control, which is referred as the minimum effective dose (MED). In this paper, we suggest a nonparametric procedure for identifying the MED with binary or ordered categorical response data. Proposed test and Williams' test are compared by Monte Carlo simulation study and discussed.

• Imaging Science in Dentistry
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• 제42권2호
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• pp.65-70
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• 2012

Purpose : The aim of this study was to compare the effective dose for imaging of mandible between multi-detector computed tomography (MDCT) and cone-beam computed tomography (CBCT). An MDCT with low dose technique was also compared with them. Materials and Methods : Thermoluminescent dosimeter (TLD) chips were placed at 25 organ sites of an anthropomorphic phantom. The mandible of the phantom was exposed using 2 different types of MDCT units (Somatom Sensation 10 for standard-dose MDCT, Somatom Emotion 6 for low-dose MDCT) and 3 different CBCT units (AZ3000CT, Implagraphy, and Kavo 3D eXaM). The radiation absorbed dose was measured and the effective dose was calculated according to the ICRP 2007 report. Results : The effective dose was the highest for Somatom Sensation 10 (425.84 ${\mu}Sv$), followed by AZ3000CT (332.4 ${\mu}Sv$), Somatom Emotion 6 (199.38 ${\mu}Sv$), and 3D eXaM (111.6 ${\mu}Sv$); it was the lowest for Implagraphy (83.09 ${\mu}Sv$). The CBCT showed significant variation in dose level with different device. Conclusion : The effective doses of MDCTs were not significantly different from those of CBCTs for imaging of mandible. The effective dose of MDCT could be markedly decreased by using the low-dose technique.

• Imaging Science in Dentistry
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• 제37권3호
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• pp.149-156
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• 2007

Purpose: The purpose of this study was to measure the absorbed dose and to calculate the effective dose for periapical radiography done by portable intraoral x-ray machines. Materials and Methods: 14 full mouth, upper posterior and lower posterior periapical radiographs were taken by wall-type 1 and portable type 3 intraoral x-ray machines. Thermoluminescent dosemeters were placed at 23 sites at the layers of the tissue-equivalent ART woman phantom for dosimetry. Average tissue absorbed dose and radiation weighted dose were calculated for each major anatomical site. Effective dose was calculated using 2005 ICRP tissue weighted factors. Results: On 14 full mouth periapical radiographs, the effective dose for wall-type x-ray machine was 30 Sv; for portable x-ray machines were 30 Sv, 22 Sv, 36 Sv. On upper posterior radiograph, the effective dose for wall-type x-ray machine was 4 Sv; for portable x-ray machines doses were 4 Sv, 3 Sv, 5 Sv. On lower posterior radiograph, the effective dose for wall type x-ray machine was 5 Sv; for portable x-ray machines doses were 4 Sv, 4 Sv, 5 Sv. Conclusion: Effective doses for periapical radiographs performed by portable intraoral x-ray machines were similar to doses for periapical radiographs taken by wall type intraoral x-ray machines.

• 대한방사선기술학회지:방사선기술과학
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• 제47권2호
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• pp.107-116
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• 2024

In this study, we analyzed the use of general radiography imaging and effective dose in inpatients. Our aim is to help reduce national medical radiation exposure doses and develop rational health-care financial policies. The effective dose for each general radiography was calculated using the ALARA-GR program for 53 types (total: 260 codes) general radiography codes selected from 'National Health Insurance Care Benefit Cost'. The usage of general radiography was analyzed in the 2018 inpatient patient data of the Health Insurance Review and Assessment Service, and the effective dose for each general radiography was analyzed. 89.00% of inpatients undergo general radiography imaging at least once, with an average of 12.63 scans per person and an effective dose of 1.00 mSv. Those who received support from Medical Aid showed a higher value compared to those who were insured by National Health Insurance, with 17.39 cases and 1.43 mSv (p<.001). Chest had the highest usage rate at 23.12% for general radiography imaging, while L-spine had the highest effective dose at 24.53%. It is estimated that 420 inpatients patients undergo 121 to 820 general radiography imaging procedures per year, and 233 inpatients are estimated to have an annual effective dose of >20.00~58.25 mSv. Rational use of health-care finances and the practice of medical radiation safety management are essential for the well-being of individuals, the enhancement of quality of life, and the improvement of health-care quality.

• 방사성폐기물학회지
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• 제19권2호
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• pp.243-253
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• 2021

In the dismantling process of a reactor coolant system (RCS) piping, a radiation protection plan should be established to minimize the radiation exposure doses of dismantling workers. Hence, it is necessary to estimate the individual effective dose in the RCS piping dismantling process when decommissioning a nuclear power plant. In this study, the radiation exposure doses of the dismantling workers at different positions was estimated using the MicroShield dose assessment program based on the NUREG/CR-1595 report. The individual effective dose, which is the sum of the effective dose to each tissue considering the working time, was used to estimate the radiation exposure dose. The estimations of the simulation results for all RCS piping dismantling tasks satisfied the dose limits prescribed by the ICRP-60 report. In dismantling the RCS piping of the Kori-1 or Wolsong-1 units in South Korea, the estimation and reduction method for the radiation exposure dose, and the simulated results of this study can be used to implement the radiation safety for optimal dismantling by providing information on the radiation exposure doses of the dismantling workers.

• Nuclear Engineering and Technology
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• 제49권4호
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• pp.801-809
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• 2017

The purpose of this study is to assess the additional neutron effective dose during passive scattering proton therapy. Monte Carlo code (Monte Carlo N-Particle 6) simulation was conducted based on a precise modeling of the National Cancer Center's proton therapy facility. A three-dimensional neutron effective dose profile of the interior of the treatment room was acquired via a computer simulation of the 217.8-MeV proton beam. Measurements were taken with a $^3He$ neutron detector to support the simulation results, which were lower than the simulation results by 16% on average. The secondary photon dose was about 0.8% of the neutron dose. The dominant neutron source was deduced based on flux calculation. The secondary neutron effective dose per proton absorbed dose ranged from $4.942{\pm}0.031mSv/Gy$ at the end of the field to $0.324{\pm}0.006mSv/Gy$ at 150 cm in axial distance.

• Nuclear Engineering and Technology
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• 제49권7호
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• pp.1505-1512
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• 2017

Because accelerator-based boron neutron capture therapy (BNCT) systems are planned for use in hospitals, entry into the medical room should be controlled as hospitals are generally assumed to be public and safe places. In this paper, computational investigation of the medical staff effective dose during BNCT has been performed in different situations using Monte Carlo N-Particle (MCNP4C) code and two voxel based male phantoms. The results show that the medical staff effective dose is highly dependent on the position of the medical staff. The results also show that the maximum medical staff effective dose in an emergency situation in the presence of a patient is ${\sim}25.5{\mu}Sv/s$.

• 한국융합학회논문지
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• 제8권8호
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• pp.147-154
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• 2017

본 연구는 소아핵의학검사에 사용하는 다양한 소아투여량 공식의 투여량(MBq)과 유효선량(mSv)을 산출 비교하여 적정투여량의 기준을 위한 기초자료를 제공하고자 한다. 연구는 2가지 방사성의약품($^{99m}Tc$-MDP와 $^{99m}Tc$-Pertechnetate)의 성인투여량을 기준으로 5가지 소아투여량공식(Clark법, Area법, Webster법, Young법, Solomon(Fried)법) 간 투여량과 유효선량을 비교하였다. 소아투여량 산출에 기준이 되는 성인투여량은 정준기, 이명철 '핵의학'에 수록된 값을 사용하였으며, 유효선량 산출을 위한 방사성의약품의 방사능당 유효선량(mSv/MBq)은 ICRP 80과 UNSCEAR 2008 보고서에 수록된 값을 사용하였다. 연구결과 Young법이 산출량이 가장 적으며 다른 공식과의 차이는 최소 1.7배-최대 3.4배였다. $^{99m}Tc$-MDP의 공식 간 투여량 차이는 최대 309.9MBq, 유효선량은 3.76mSv, $^{99m}Tc$-Pertechnetate는 최대 154.9MBq, 유효선량은 5.50mSv였다. 소아투여량 공식 간 투여량뿐만 아니라 유효선량도 차이가 크기 때문에 의료방사선의 최적화를 위한 적정투여량 소아산출법이 개발되어야 한다.

• 한국방사선학회논문지
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• 제12권2호
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• pp.149-157
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• 2018

방사선 방호의 목적 중 하나는 확률적 영향을 최소화 하는 것이다. PCXMC 2.0은 몬테카를로 시뮬레이션 기반의 프로그램으로 입사표면선량을 통해 유효선량과 암의 발병확률을 예측가능하게 해준다. 그렇기 때문에 선량계에 따른 입사표면선량 측정이 특히 중요하다. 본 연구는 반도체 선량계, 일반 선량계, 유리선량계를 통해 입사표면선량을 측정하고 그에 따른 결정 장기의 유효선량과 발병 확률을 비교분석 하는 것에 목적을 두었다. 실험방법은 두개부, 흉부, 복부의 선량계 별 입사표면선량을 측정하고 PCXMC 2.0을 통해 부위 별 결정 장기의 유효선량과 암의 발병 확률을 평가하였다. 그 결과 부위 별 입사표면선량은 동일한 조건임에도 일반 선량계, 반도체 선량계, 유리 선량계 순으로 차이가 났다. 이를 토대로 유효선량과 결정 장기의 암 발병 확률을 분석한 결과 또한 일반 선량계, 반도체 선량계, 유리 선량계 순으로 차이가 났다. 결론적으로 동일한 조건임에도 사용한 선량계에 따라 유효선량과 발병 위험도는 다르게 나타났음을 알 수 있었고, 본 연구를 통해 각각의 선량계에 따른 정확한 입사표면선량 모델을 제시하는 것이 중요하다는 것을 알 수 있었다.