• Nuclear Engineering and Technology
• /
• 제55권1호
• /
• pp.248-253
• /
• 2023

Directly, it is not possible to measure the absorbed dose of radiopharmaceuticals in the organs of the human body. Therefore, simulation methods are utilized to estimate the dose in distinct organs. In this study, individual organs were separately considered as the source organ or target organ to calculate the mean absorption dose, which SAF and S factors were then calculated according to the target uptake via MIRD method. Here, ^99mTc activity distribution within the target was analyzed using the definition and simulation of ideal organs by summing the fraction of cumulative activities of the heart as source organ. Thus, GATE code was utilized to simulate the Zubal humanoid phantom. To validate the outcomes in comparison to the similar results reported, the accumulation of activity in the main organs of the body was calculated at the moment of injection and cardiac rest condition after 60 min of injection. The results showed the highest dose absorbed into pancreas was about 21%, then gallbladder 18%, kidney 16%, spleen 15%, heart 8%, liver 8%, thyroid 7%, lungs 5% and brain 2%, respectively, after 1 h of injection. This distinct simulation model may also be used for different periods after injection and modifying the prescribed dose.

• 대한방사성의약품학회지
• /
• 제3권1호
• /
• pp.18-24
• /
• 2017

Patient-specific image-based internal dosimetry involves using the patient's individual anatomy and spatial distribution of radioactivity over time to obtain an absorbed dose calculation. Individual absorbed dose was calculated by accumulated activity multiply S-value of each organs. The aim of this study was to calculate the S-values using Monte Carlo simulation in monkey and mouse and evaluation of absorbed dose in each organ. Self-irradiation S-value of monkey heart self-irradiation was 3.15E-03 mGy-g/MBq-s, lung self-irradiation was 8.94E-04 mGy-g/MBq-s and liver self-irradiation S-value was 2.23E-03 mGy-g/MBq-s. Mouse heart self-irradiation S-value was 1.95E-01 mGy-g/MBq-s, lung was 9.59E-02 mGy-g/MBq-s, and liver was 1.40E-03 mGy-g/MBq-s. The results of this study show that the calculation protocol of image based individual absorbed dose of each organ using Monte Carlo simulation. Therefore, this study may be applied to calculate human specific absorbed dose.

• 대한방사선기술학회지:방사선기술과학
• /
• 제47권3호
• /
• pp.213-218
• /
• 2024

The myocardial nuclear medicine examination is widely performed to diagnose myocardium disease using various radionuclides. Although image quality according to radionuclides has improved, the radiation exposure for target organ as well as peripheral organs should be considered. Here, the aim of this study was to evaluate absorbed dose (Gy) for peripheral organs in myocardial nuclear medicine scan from myocardium according to various scan environments based on Monte Carlo simulation. The simulation environment was modeled 5 cases, which were considered by radionuclides, number of injections, and radiodosage. In addition, the each radionuclide simulation such as distribution fraction was considered by recommended standard protocol, and the mesh computational female phantom, which is provided by International Commission on Radiological Protection (ICRP) 145, was used using the particle and heavy ion transport code system (PHITS) version 3.33. Based on the results, the closer to the myocardium, the higher the absorbed dose values. In addition, application for dual injection for radionuclides leaded to high absorbed dose compared with single injection for radionuclide. Consequently, there is difference for absorbed dose according to radionuclides, number of injections, and radiodosage. To detect the accurate diseased area, acquisition for improved image quality is crucial process by injecting radionuclides, however, we need to consider absorbed dose both target and peripheral inner organs from radionuclides in terms radiation protection for patient.

• 한국의학물리학회지:의학물리
• /
• 제18권4호
• /
• pp.187-193
• /
• 2007

한국인의 생리적 특성에 맞는 방사성핵종의 체내 흡수선량 평가를 위한 일환으로 한국 성인 남성 28명을 대상으로 $^{131}|$을 경구투여 후 갑상선섭취율 및 소변 일일배설률을 산정하고 각 장기별 흘수선량을 평가하였다 그 결과, 첫째, 투여 24시간 후 갑상선이 평균 19.70%의 섭취율과 71.12%의 소변 일일배설률을 나타냈다. 둘째 본 연구에서 산출한 갑상선섭취율과 기존 ICRP에서 제시하는 갑상선섭취율 30%에 따른 전신유효선량은 각각 1.464E-08 Sv, 2.189E-08 Sv로 약 1.5배의 차이를 나타났다. 정량적인 방사성 옥소의 흡수선량 평가를 위해서는 기존 ICRP에서 제시하는 자료에 의존하기 보다는 인종별 새로운 측정을 통해 각 핵종별 자료의 확보만이 체내피폭평가시 오류를 최소화 할 수 있다.

• 한국방사선학회논문지
• /
• 제14권5호
• /
• pp.523-528
• /
• 2020

반려견의 사망원인 1위인 암 중 암컷에게서 가장 높은 발생률을 보이는 유방암을 대상으로 근접방사선치료 수행 시 모의모사를 이용한 흡수선량 측정을 바탕으로 적용성을 평가하고자 하였다. 모의모사를 위해 MCNPX 프로그램을 이용하였으며, 흡수선량 측정을 위해 소형견 크기의 수학적 팬텀을 제작 하였다. 흡수선량 측정결과 종양의 경우 ¹⁹²Ir에서 1.02E-12 Gy/#으로 흡수선량이 가장 높은 것으로 나타났으며, 내·외부 흡수선량에서도 동일한 경향성으로 나타났다. 따라서 반려견 유방암의 근접방사선치료 시 견종과 피폭을 고려한 적절한 선원의 선택이 고려되어야 될 것이다.

• Nuclear Engineering and Technology
• /
• 제42권1호
• /
• pp.89-96
• /
• 2010

This paper describes the methodology of calculating the internal dose conversion coefficient in order to assess the radiological impact on non-human species. This paper also presents the internal dose conversion coefficients of 25 radionuclides ($^3H,\;^7Be,\;^{14}C,\;^{40}K,\;^{51}Cr,\;^{54}Mn,\;^{59}Fe,\;^{58}Co,\;^{60}Co,\;^{65}Zn,\;^{90}Sr,\;^{95}Nb,\;^{99}Tc,\;^{106}Ru,\;^{129}I,\;^{131}I,\;^{136}Cs,\;^{137}Cs,\;^{140}Ba,\;^{140}La,\;^{144}Ce,\;^{238}U,\;^{239}Pu,\;^{240}Pu$) for domestic seven reference animals (roe deer, rat, frog, snake, Chinese minnow, bee, and earthworm) and one reference plant (pine tree). The uniform isotropic model was applied in order to calculate the internal dose conversion coefficients. The calculated internal dose conversion coefficient (${\mu}Gyd^{-1}$ per $Bqkg^{-1}$) ranged from $10^{-6}$ to $10^{-2}$ according to the type of radionuclides and organisms studied. It turns out that the internal does conversion coefficient was higher for alpha radionuclides, such as $^{238}U,\;^{239}Pu$, and $^{240}Pu$, and for large organisms, such as roe deer and pine tree. The internal dose conversion coefficients of $^{239}U,\;^{240}Pu,\;^{238}U,\;^{14}C,\;^3H$, and $^{99}Tc$ were independent of the organism.

• 한국의학물리학회지:의학물리
• /
• 제24권1호
• /
• pp.48-53
• /
• 2013

몬테카를로 방식은 지금까지 인체 내 흡수선량을 계산하는 가장 정확한 방법으로 알려져 왔고. 이러한 계산 방법을 이용하기 위한 인체 내부의 장기 묘사는 인체 모형 팬텀이 주로 사용되어 왔다. 그러나 최근 Geant4 코드를 사용한 몬테카를로 계산에서는 CT의 DICOM 파일에서 인체의 여러 장기에 대한 자료를 직접 추출하고 시뮬레이션에 필요한 geometry로 변환하여 사용하려는 다양한 노력이 시도되고 있다. 이와 같은 기능은 실제 인체의 해부학적 구조를 그대로 재현하면서 인체 내부의 흡수선량을 정확히 계산 할 수 있도록 한다. 따라서 본 연구에서는 DICOM 파일을 연동한 Geant4을 이용하여 인체 내 흡수선량을 계산하였고, 이를 Gafchromic EBT2 필름을 이용한 측정 선량과 비교함으로써 그 유용성을 확인하고자 하였다. 본 연구에서 시뮬레이션을 이용하여 계산한 선량과 EBT2 필름을 이용한 선속 중심축에서의 측정선량을 비교한 결과 피부표면에서부터 최대선량 깊이까지 선량이 급격하게 변화하는 build up 영역을 제외하고는 오차(difference) 범위가 평균 3.75% 임을 알 수 있었다. 또한 선량의 계산 값을 각 CT slice 별로 출력되도록 하였고, 또 각 slice에서도 복셀 하나하나의 선량 값이 출력되도록 하여 측정하고자 하는 장기별, 기관별 흡수선량을 쉽게 확인 할 수 있도록 하였다. 이처럼 인체 모형 팬텀이 아닌 실제 인체의 image data인 CT DICOM 파일을 이용한 선량계산을 각 slice, voxel 별로 선량 값을 출력하는 방식은 다양한 부위의 정확한 선량계산을 가능하게 하므로 향후 방사선 치료계획 시스템의 선량 계산에 유용할 것이라 생각한다. 또한 현재 사용 중인 여러 에너지 영역에도 적용이 가능하므로 인체 내 방사선의 흡수선량 확인을 위해 유용하게 활용되어질 수 있을 것으로 생각된다.

• Journal of Radiation Protection and Research
• /
• 제46권1호
• /
• pp.8-13
• /
• 2021

Background: Salmonella enteritidis (SE) was the main cause of the pandemic of foodborne salmonellosis. The surface of eggs' shells can be contaminated with this bacterium; however, washing them with sodium hypochlorite solution not only reduces their flavor but also heavily impacts the environment. An alternative to this is surface sterilization using low-energy electron beam. It is known that irradiation with 1 kGy resulted in a significant 3.9 log reduction (reduction factor of 10,000) in detectable SE on the shell. FAO/IAEA/WHO indicates irradiation of any food commodity up to an overall average dose of 10 kGy presents no toxicological hazard. On the other hand, the Food and Drug Administration has deemed a dose of up to 3 kGy is allowable for eggs. However, the maximum dose permitted to be absorbed by an edible part (i.e., internal dose) is 0.1 Gy in Japan and 0.5 Gy in European Union. Materials and Methods: The electron beam (EB) depth dose distribution in the eggshell was calculated by the Monte Carlo method. The internal dose was also estimated by Monte Carlo simulation and experimentation. Results and Discussion: The EB depth dose distribution for the eggshells indicated that acceleration voltages between 80 and 200 kV were optimal for eggshell sterilization. It was also found that acceleration voltages between 80 and 150 kV were suitable for reducing the internal dose to ≤ 0.10 Gy. Conclusion: The optimum irradiative conditions for sterilizing only eggshells with an EB were between 80 and 150 kV.

• 대한핵의학회지
• /
• 제29권1호
• /
• pp.54-60
• /
• 1995

방사성 핵종의 체내 투여 또는 체내 오염에 의한 내부피폭 흡수선량 측정을 위하여 개발된 MIRD 씨스템을 이용하여 175mCi $^{131}I$ 치료를 받는 8명의 분화된 갑상선암의 주변림프절 전이 환자에서 전신, 위, 신장, 방광 및 골수 등의 흡수선랑을 측정하였다. 전리함 검출기와 자료저장 장치가 부착된 Eberline Smart 200 씨스템을 이용하여 전신 $^{131}I$의 시간 방사능 곡선을 얻었고, 선형 회귀분석을 하여 곡선하면적을 구한 값을 투여 방사능량(Ao)으로 나누어 체류시간($\tau$)으로 하였다. MIRDose2의 S값을 이용하여 전신흡수선량을 구하였으며 ICRP publication 53의 표준인 신장, 방광, 위의 체류시간을 이용하여, 이들 장기의 흡수선량을 구하였다. 전신 및 골수의 흡수선량은 22.4 및 25.4rad로 ICRP 최대허용선량보다 훨씬 낮았으며, 방광에 375.1, 위에 285.1rad로 심각한 증상을 초래할 정도의 선량은 아니었다. 분화된 갑상선암의 폐 및 뼈전이 환자에서 200mCi 이상 투여방사능량을 증가시킬 경우 이 방법으로 전신 및 골수 등의 흡수 선량을 평가하여 안전성을 확인할 수 있을 것으로 생각된다.

• Environmental Analysis Health and Toxicology
• /
• 제16권2호
• /
• pp.43-50
• /
• 2001

A daily newspaper in Korea addressed an controversial issue recently that the concentration of radon measured from the groundwater in Taejon was found out a relatively high level. The cancer risk arising from ingestion of such radon should be derived from calculation of the dose absorbed by the tissues at risk. The study performed by the National Research Council in United States confirmed that the use of a PBPK model for the ingested radon could provide the useful information regarding the distribution of radon among the organs of the body. This study presents an approach for the internal dose assessment of ingested radon for this case. At first, the study develops a PBPK model for ingested radon. However, the important issue is how to simulate a more realistic situation using the model associated with repeated oral doses rather than a single oral dose. The simulations are performed for repeated oral exposures per 8-hour interval using the PBPK model for a male adult. The concentration and cumulative value of radon concentration are calculated and analyzed for lung tissue and adipose group, respectively. The results could be used for the realistic prediction of the internal dose of radon in the human body for repeated oral exposures.