방사선의학 웹진

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Abstract
In Korea, when replacing or discarding parts of a medical linear accelerator (linac), self-disposal is required in the consideration of the activity, but there is no standard regulation to manage radioactive waste. The aim of this study is to check the activity of each part to determine the disposal time according to the clearance level for self-disposal. The results of measuring the components of the linac head parts of the disposed Varian, Elekta, and Siemens equipment were reflected in the Monte Carlo simulation to confirm the radionuclide change according to the presence or absence of impurities. To confirm the degree of activation of the linac, the main radionuclides according to the time after the linac shutdown, considering the workloads of 40/80 Gy/day of 10/15 MV linac irradiated with beams for 10 years in the results of the simulation of the linac parts, and the radionuclide concentration was confirmed. As a result of applying the clearance level for self-disposal in the notice of the Korean Nuclear Safety (KINS) to each linac head part, most parts of the 10 MV linac could be dismantled after 1 month, and 15 MV target and primary collimators were stored after a long period of time before being dismantled. Although additional radionuclides were identified according to the presence or absence of impurities, the disposal timing for each part did not change significantly. In this study, the clearance level for self-disposal for each radionuclide was applied to activated parts by three manufacturers to confirm the self-disposal timing and predict the timing at which workers are not exposed to radiation during dismantling/disposal.
 

 대표그림1. 각 제조사별 치료용 선형가속기 모델링 결과 (a) Varian (b) Elekta (c) Siemens 

대표그림2. 80 Gy/day 가동하중을 고려한 제조사별 15 MV / 10 MV 에너지 선형가속기의 부품별 허용 농도 (그림 내 빨간색 선은 허용농도 1 기준 선이며, 1 미만이 되는 시점에서 자체처분이 가능하다.) (a) Varian 15 MV (b) Varian 10 MV (c) Elekta 15 MV (d) Elekta 10 MV (e) Siemens 15 MV (f) Siemens 10 MV

Affiliations

Young Jae Jang1,2,† , Na Hye Kwon3,4,† , Seong Hee Park2, Yona Choi2 , Kum Bae Kim1 , Dong Wook Kim3,4 , Suk Ho Bhang5,* and Sang Hyoun Choi1,* 
 
1
Research Team of Radiological Physics & Engineering, Korea Institute of Radiological & Medical Sciences, Seoul 01812, Republic of Korea
2
Department of Accelerator Science, Korea University, Sejong 30015, Republic of Korea
3
Department of Radiation Oncology, Yonsei Cancer Center, Heavy Ion Therapy Research Institute, Yonsei University College of Medicine, Seoul 03722, Republic of Korea
4
Medical Physics and Biomedical Engineering Lab (MPBEL), Yonsei University College of Medicine, Seoul 03722, Republic of Korea
5
School of Chemical Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea
*
Authors to whom correspondence should be addressed.
†
These authors contributed equally to this work.