• Journal of Yeungnam Medical Science
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• 제5권2호
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• pp.31-36
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• 1988

회전조사시 회전각도에 따른 계산치와 측정치를 비교, 검토하여 마음과 같은 결과를 얻었다. $90^{\circ}$ 회전시에는 계산치와 측정치와는 4.5%의 차이를 나타내었고 $120^{\circ}$ 회전시에는 4.4%, $180^{\circ}$ 회전시에는 3.9%, $240^{\circ}$ 회전시에는 2.9%, $360^{\circ}$ 회전시에는 2.1%의 차이를 나타내어 회전각도가 클수록 계산치와 측정치와의 차이는 적은 것으로 나타났다. 또한 회전각도에 따라 최고선량지점이 상부로 이동하는 정도는 $90^{\circ}$에서 $240^{\circ}$까지 회전할 때 tumor depth가 4.5cm일 경우에 는 1.67cm에서 1.10cm 정도 상부로 이동하였으며, tumor depth가 8cm일 경우에는 2.45cm에서 1.40cm 정도 상부로 이동하는 것으로 나타났다.

• 대한방사선치료학회지
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• 제12권1호
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• pp.91-104
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• 2000

Recently linear accelerator in radiation therapy in asymmetric field has been easily used since the improvement and capability of asymmetrical field adjustment attached to the machine. It has been thought there have been some significant errors in dose calculation when asymmetrical radiation fields have been utilized in practice of radiation treatments if the fundamental data for dose calculation have been measured in symmetrical standard fields. This study investigated how much the measured data of dose distributions and their isodose curves are different between in asymmetrical and symmetrical standard fields, and how much there difference affect the error in dose calculation in conventional method measured in symmetrical standard field. The distributions of radiation dose were measured by photon diode detector in the water phantom (RFA-300P, Scanditronix, Sweden) as tissue equivalent material on utilization of 6 MV linear accelerator with source surface distance (SSD) 1000 mm. The photon diode detector has the velocity of 1 mm per second from water surface to 250 mm depth in the field size of $40mm{\times}40mm\;to\;250mm{\times}250mm\;symmetric\;field\;and\;40mm{\times}20mm\;to\;250mm{\times}125mm$ asymmetrical fields. The measurements of percent depth dose (PDD) and subsequent plotting of their isodose curves were performed from water surface to 250mm dmm from Y-center axis in $100mm{\times}50mm$ field in order to absence the variability of depth dose according to increasing field sizes and their affects to plotted isodose curves. The difference of PDD between symmetric and asymmetric field was maximum $4.1\%\;decrease\;in\;40mm{\times}20mm\;field,\;maximum\;6.6\%\;decrease\;in\;100mm{\times}50mm\;and\;maximum\;10.2\%\;decrease\;200mm{\times}100mm$, the larger decrease difference of PDD as the greater field size and as greater the depth, The difference of PDD between asymmetrical field and equivalent square field showed maximum $2.4\%\;decrease\;in\;60mm{\times}30mm\;field,\;maximum\;4.8\%\;decrease\;in\;150mm{\times}75mm\;and\;maximum\;6.1\%\;decrease\;in\;250mm{\times}125mm$, and the larger decreased differenced PDD as the greater field size and as greater the depth, these differences of PDD were out of $5\%$ of dose calculation as defined by international Commission on radiation unit and Measurements(ICRU). In the dose distribution of asymmetrical field (half beam) the plotted isodose curves were observed to have deviations by decreased PDD as greater as the blocking of the beam moved closer to the central axis, and as the asymmetrical field increased by moving the block 10 mm keeping away from the central axis, the PDD increased and plotted isodose curves were gradually more flattened, due to reduced amount of the primary beam and the fraction of low energy soft radiations by passing thougepth in asymmetrical field by moving independent jaw each 10 h beam flattening filter. As asymmetrical radiation field as half beam radiation technique is used, the radiation dosimetry calculated in utilizing the fundamental data which measured in standard symmetrical field should be converted on bases of nearly measured data in asymmetrical field, measured beam data flies of various asymmetrical field in various energy and be necessary in each institution.

• 대한방사선기술학회지:방사선기술과학
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• 제22권2호
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• pp.53-56
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• 1999

A Gaussian distribution was parametrized for the initial distribution of the electron beam emitted from a 6MeV medical linear accelerator. A percent depth dose was measured in a water phantom and the corresponding Monte Carlo calculations were performed starting from a Gaussian distribution for a range of standard deviations, ${\sigma}=0.1$, 0.15, 0.2, 0.25, and 0.3 with being the mean value for the Incident beam energy. When measurement and calculation were compared, the calculation with the Gaussian distribution for ${\sigma}=0.25$ turned out to agree best with the measurement. The results from the present work can be utilized as input energy data in planning an electron beam therapy with a Monte Carlo calculation.

• 한국의학물리학회지:의학물리
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• 제1권1호
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• pp.69-73
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• 1990

Dosimetric measurement of an asymmetric collimator system was performed, using water phantom system for 4MV X-ray linear accelerator. We have studied the system of dose calculation with those measured result. We compared the field size factor and the percent depth dose for asymmetric collimator to those factor for symmetric fields. The results show that we can use symmetric field data directly within 1% error, if we consider the off axis ratio(OAR).

• Journal of Radiation Protection and Research
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• 제32권1호
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• pp.15-20
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• 2007

An empirical formula fur the neutron dose equivalent at the maze entrance of medical accelerator treatment rooms was derived on the basis of a Monte Carlo simulation. The simulated neutron dose equivalents around the Varian medical accelerator by the MCNPX code were employed. Two cases of target rotational planes were considered: parallel and perpendicular to maze walls. Most of the maximum neutron dose equivalents at the doorway were found when the target rotational planes were parallel to maze walls and the beams were directed to the inner maze entrances. The neutron dose equivalents at the outer maze entrances were calculated for about 698 medical accelerator facilities which were generated from the geometry configurations of running treatment rooms, based on such gantry rotation that produces the maximum neutron dose at the doorway. The results calculated with the empirical formula in this study were compared with those calculated by the Kersey method for 7 operating facilities. It was found that the maximum disagreement between the calculation of this study and that of the Kersey method was a factor of 8.54 with the value calculated by the Kersey method exceeding that of this study. It was concluded that the kersey method estimated the neutron dose equivalent at the doorway computed by MCNPX more conservatively than this study technique.

• Journal of Radiation Protection and Research
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• 제15권2호
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• pp.75-85
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• 1990

Kalsruhe원자력 연구소(KfK) 주변의 방사능 측정자료로부터 피폭선량을 계산하였다. 식물성 식품의 섭취가 가장 중요한 피폭 경로였고, 식품중의 자연방사성 동위원소인 K-40 과 Pb-210이 주요 피폭원이었다. 인공방사능에의한 피폭은 대부분 지표에 침척된 Cs-134 와 Cs-137으로부터 방출되는 감마선 때문이었다. KfK주변환경에서의 유효선량당량은 ICRP의 권고제한치보다 훨씬 적은 값이었다.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2002년도 Proceedings
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• pp.106-108
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• 2002

Recent advances in radiation transport algorithms, computer hardware performance, and parallel computing make the clinical use of Monte Carlo based dose calculations possible. Monte Carlo treatment planning requires accurate beam information as input to generate accurate dose distributions. The procedures to obtain this accurate beam information are called "commissioning", which includes accelerator head modeling. In this study, we would like to investigate how much accurately Monte Carlo based dose calculations can predict the measured beam data in various conditions. The Siemens 6MV photon beam and the BEAM Monte Carlo code were used. The comparisons including the percentage depth doses and off-axis profiles of open fields and wedges, output factors will be presented.

• Nuclear Engineering and Technology
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• 제40권7호
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• pp.527-532
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• 2008

As therapeutic uses of radionuclides in nuclear medicine increases, the use of patient-specific methods for calculation of radiation dose becomes more important. In this manuscript basic methods and resources for internal dose calculations are outlined, with a focus on how current changes and advances are making more accurate and detailed, patient-individualized dose calculations possible. Most current resources make use of standardized models of the human body representing median individuals, but the use of image-based and more realistic models will soon take their place, and will permit adjustments to represent individual patients and tailor therapy planning uniquely for each subject.

• Journal of Astronomy and Space Sciences
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• 제19권2호
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• pp.151-162
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• 2002

인공위성에서의 우주방사선 차폐계산을 위한 근사계산 방법으로 sectoring method를 적용하는 방법과 chord-length 분포를 이용하는 방법을 상세 계산 결과와 비교하였다. 저 궤도 위성인 우리별 1호를 대상으로 양성자의 차폐계산을 수행하였다. 이때 방사선환경은 AP-8 model을 이용하여 구한 SAA(South Atlantic Anomaly)지역으로 가정하였다. Sectoring method와 chord-length 분포를 이용하는 방법은 양성자가 물질내에서 직진한다는 기본적인 가정을 사용하므로 3차원 상세계산 결과와 비교하여 어느 정도의 오차를 갖는다. 그러나 우리별 1호를 대상으로 수행된 계산 결과에서 두 계측기 위치에서의 피폭량 예측은 2가지 근사모델이 모두 상세계산 결과와 근사하게 일치하였다.

• 대한한의학회지
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• 제31권3호
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• pp.1-7
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• 2010

Objectives: To introduce to TKM scientific dose conversion methods of human to animal or animal to human for new drug investigations. Methods: We searched guidelines of the FDA and KFDA, and compared them with references for drug-dose conversion from various databases such as PubMed and Google. Then, we analyzed the potential issues and problems related to dose conversion in safety documentation of new herbal drugs based on our experiences during Investigational New Drug (IND) applications of TKM. Results: Dose conversion from human to animal or animal to human must be appropriately translated during new drug development. From time to time, investigators have some difficulty in determining the appropriate dose, because of misunderstandings of dose conversion, especially when they estimate starting dose in clinical or animal studies to investigate efficacy, toxicology and mechanisms. Therefore, education of appropriate dose calculation is crucial for investigators. The animal dose should not be extrapolated to humans by a simple conversion method based only on body weight, because many studies suggest the normalization method is based mainly on body surface area (BSA). In general, the body surface area seems to have good correlation among species with several parameters including oxygen utilization, caloric expenditure, basal metabolism, blood volume and circulating plasma protein. Likewise, a safety factor should be taken into consideration when deciding high dose in animal toxicology study. Conclusion: Herein, we explain the significance of dose conversion based on body surface area and starting dose estimation for clinical trials with safety factor.