• Nuclear Engineering and Technology
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• 제55권6호
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• pp.1994-1998
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• 2023

This study quantitatively evaluated the source term of a linear accelerator according to target thickness for a 6-20 MeV electron beam using MCNP6. The elements of the target were tungsten and copper, and a composite target and single target were simulated by setting different thickness parameters depending on energy. The accumulation of energy generated through interaction with the collided target was evaluated at 0.1-mm intervals, and F6 tally was used. The results indicated that less than 3% reference error was maintained according to the MCNP recommendations. At 6, 8, 10, 15, 18, and 20 MeV, the energy accumulation peaks identified for each target were 0.3 mm in tungsten, 1.3 mm in copper, 1.5 mm in copper, 0.5 mm in tungsten, 0.5 mm in tungsten, and 0.5 mm in tungsten. For 8 and 10 MeV in a single target consisting only of copper, the movement of electrons was confirmed at the end of the target, and the proportion of escaped electrons was 0.00011% and 0.00181%, respectively.

• 한국의학물리학회지:의학물리
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• 제32권4호
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• pp.83-91
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• 2021

Various types of high-precision radiotherapy, such as intensity-modulated radiation therapy (IMRT), tomotherapy (Tomo), and stereotactic body radiation therapy have been available since 1997. After being covered by insurance in 2015, the number of IMRT cases rapidly increased 18-fold from 2011 to 2018 in Korea. IMRT, which uses a high-beam irradiation monitor unit, requires higher shielding conditions than conventional radiation treatments. However, to date, research on the shielding of facilities using IMRT and the current understanding of its status are insufficient, and detailed safety regulation procedures have not been established. This study investigated the recommended criteria for the shielding evaluation of facilities using medical linear accelerators (LINACs), including 1) the current status of safety management regulations and systems in domestic and international facilities using medical LINACs and 2) the current status of the recommended standards for safety management in domestic and international facilities using medical LINACs. It is necessary to develop and introduce a safety management system for facilities using LINACs for clinical applications that is suitable for the domestic medical environment and corresponds to the safety management systems for LINACs used overseas.

• 한국의학물리학회지:의학물리
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• 제31권2호
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• pp.9-19
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• 2020

Purpose: This study aims to develop a multi-purpose electron beam irradiation device for preclinical research and material testing using the research electron linear accelerator installed at the Dongnam Institute of Radiological and Medical Sciences. Methods: The fabricated irradiation device comprises a dual scattering foil and collimator. The correct scattering foil thickness, in terms of the energy loss and beam profile uniformity, was determined using Monte Carlo calculations. The ion-chamber and radiochromic films were used to determine the reference dose-rate (Gy/s) and beam profiles as functions of the source to surface distance (SSD) and pulse frequency. Results: The dose-rates for the electron beams were evaluated for the range from 59.16 Gy/s to 5.22 cGy/s at SSDs of 40-120 cm, by controlling the pulse frequency. Furthermore, uniform dose distributions in the electron fields were achieved up to approximately 10 cm in diameter. An empirical formula for the systematic dose-rate calculation for the irradiation system was established using the measured data. Conclusions: A wide dose-rate range electron beam irradiation device was successfully developed in this study. The pre-clinical studies relating to FLASH radiotherapy to the conventional level were made available. Additionally, material studies were made available using a quantified irradiation system. Future studies are required to improve the energy, dose-rate, and field uniformity of the irradiation system.

• 한국의학물리학회지:의학물리
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• 제8권2호
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• pp.59-65
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• 1997

전자포탈영상장치 (EPID)를 이용하여 의료용 선형가속기의 기하학적인 요소를 성능 평가할 수 있도록 고안하였다. light field와 radiation field 의 일치, 콜리메이터 회전축, 갠트리 회전축 크기 등을 측정하였다. EPID에서 수집한 영상정보를 이용하여 radiation-light field 일치여 부를 1mm 이내의 정밀도를 갖고 평가하였으며, 콜리메이터, 갠트리 회전축 역시 4개의 방사선 방향에 대한 영상을 중첩시켜서 중첩된 영상이 이루는 교점을 분석하여 구할 수 있었다. 이 방법으로 선형가속기의 기하학적인 QC/QA를 객관적이고 정량적으로 시행할 수 있었다.

• 한국의학물리학회지:의학물리
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• 제31권4호
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• pp.194-204
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• 2020

This study investigated and analyzed the Korean and international status of radioactive waste management for medical linear accelerators (linacs) and proceed prior research to suggest radiation safety regulations and guidelines for the safe use of radiation. We analyzed the number of linacs installed in the radiation oncology departments of 103 institutions. In addition, we analyzed the procedures and standards for disposal in Korea and foreign countries. For foreign countries, we analyzed the status based on reports from the United States, Japan, Europe, and Canada. A total of 182 linacs are installed in Korea and 95% of them use more than 10 MV of energy. In Korea, standards for managing radioactive waste from a linac, disposal procedures, and clearance criteria have yet to be established. Therefore, radioactive waste is disposed of in different ways depending on the hospitals where they originate. Japan, the US, and Canada have recommended clearance levels and procedures for linacs. Other countries have provided management guidelines for research or large-scale accelerators, but not for medical purposes. In this study, we investigated the management of radioactive waste from medical linacs in Korea and abroad. Several foreign countries have suggested a clearance level and criteria for disposing of waste storage drums. For the safe management of medical linacs, it is necessary to establish safety management regulations. In Korea, standards for disposal, such as radiation or dose limits, are required for medical linacs. A system for clearance when disposing at a medical institution should be created.

• 한국의학물리학회지:의학물리
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• 제14권1호
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• pp.20-27
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• 2003

컴퓨터에 의해 작동되는 선형가속기의 경우 모든 기기가 적절히 작동되는가를 확인하는 정도관리가 오작동으로 인한 환자 피해를 방지하기 위해 절대적으로 필요하다. 따라서 컴퓨터로직 및 마이크로 프로세서에 의해 작동되는 시스템의 안전을 고려하는 많은 보고서들이 발표되었다. 그 보고서에는 소프트웨어 및 하드웨어 고장으로 인해 발생하는 문제점들을 개선하기 위한 방법들이 제시하고 있다. 이와 관련하여 국내의 경우도 컴퓨터에 의해 작동되는 선형가속기의 수가 점차 적으로 증가하고 있는데 비해 체계적이고 일원화된 정도관리서가 없는 실정이다. 따라서 본 논문에서는 국내의 실정에 맞는 선형가속기 정도관리 기술을 개발하기 위한 기반으로 사용하기 위해 미국, 일본, 및 유럽에서 가장 일반적으로 사용되고 있는 정도관리서를 수집 및 요약하였다. 또한 각 나라간의 공통점 및 차이점이 비교분석 하였다. 국가별 정도관리를 비교한 결과 유럽의 경우 미국의 AAPM TG40을 참고자료로 주로 사용하였으며 중요한 정도관리의 항목은 점검주기에는 약간의 차이가 있으나 점검항목들은 거의 동일하다.

• 대한방사선치료학회지
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• 제6권1호
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• pp.123-126
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• 1994

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2002년도 Proceedings
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• pp.113-115
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• 2002

The Monte Carlo simulation method is a numerical solution to a problem that models objects interacting with other objects or their environment based upon simple object-object or object-environment relationships. In spite of its great accuracy, It was turned away because of long calculation time to simulate a model. But, it is used to simulate a linear accelerator frequently with the advance of computer technology. To simulate linear accelerator in Monte Carlo simulations, there are many parameters needed to input to Monte Carlo code. These data can be supported by a linear accelerator manufacturer. Although the model of a linear accelerator is the same, a different characteristic property can be found. Thus, we performed a commissioning process of 6MV photon beam in Varian 2300C/D model with BEAM/EGS4 Monte Carlo code. The head geometry data were put into BEAM/EGS4 data. The mean energy and energy spread of the electron beam incident on the target were varied to match Monte Carlo simulations to measurements. TLDs (thermoluminescent dosimeter) and radiochromic films were employed to measure the absorbed dose in a water phantom. Beam profile was obtained in 40cm${\times}$40cm field size and Depth dose was in 10cm${\times}$10cm. At first, we compared the depth dose between measurements and Monte Carlo simulations varying the mean energy of an incident electron beam. Then, we compared the beam profile with adjusting the beam radius of the incident electron beam in Monte Carlo simulation. The results were found that the optimal mean energy was 6MV and beam radius of 0.1mm was well matched to measurements.

• Radiation Oncology Journal
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• 제2권2호
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• pp.303-309
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• 1984

Radiation therapy(RT) has been used in the treatment of breast cancer for over 80years. Technically, it should include a part or all of such areas as chest wall or breast, axilla, internal mammary nodes (IM) and supraclavicular nodes (SCL). Authors tried three-field technique for the treatment of breast cancer using 6-MV linear accelerator, exclusively the department of radiology. Kang-Nam St. Mary's Hospital, at Catholic Medical College. The field junction was checked by a Phantom study and radiation doses measured by film densitometry and TLD. The 3 fields we used in this study were two isocentric opposing tangential fields encompassing the breast, chest wall and occasionally IM and one single anterior field encompassing the axilla and SCL. sing appropriate beam blocks and boluses, we were able to avoid unwanted intrinsic divergency of photon beam. Blocking also enabled us to set-up precise radiation field with ease.

• 한국의학물리학회지:의학물리
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• 제22권2호
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• pp.79-84
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• 2011

본 연구에서는 GEANT4 toolkit을 이용하여 의료용 선형가속기에 대한 몬테칼로(Monte Carlo) 전산모사를 하였다. Medical Linac2 예제를 수정해서 사용하였다. 에너지스펙트럼, 최빈에너지, 평균에너지를 EGS4 결과와 비교 하였고 선속의 중심에서부터 반경에 따른 단위면적당 광자수, 단위면적당 에너지, 평균에너지를 분석하였다. 그 결과 EGS4 결과와 큰 차이를 보이지 않기 때문에 Medical Linac2 예제의 선속특성에 관한 전산모사에 큰 문제점은 없는 것으로 판단된다. 같은 헤드구조에서도 Physics List의 모델에 따라서는 결과에 차이가 발생하므로 연구 환경에 알맞은 Physics List 모델을 선택하는 것이 중요하다고 판단된다. 본 연구는 처음 몬테칼로 전산모사를 접하는 사용자가 선속특성에 대한 전산모사를 수행하고 6 MV 광자선속의 특성을 분석하는 과정에 많은 도움이 될 것으로 사료된다.