Measurement of Growth Delay and the Oxygen Enhancement Ratio of Fast Neutron Beam Using Mouse Model System

마우스모델을 이용한 고속중성자선의 성장지연 및 산소증강비의 측정

  • Eom, Keun-Yong (Department of Radiation Oncology, Seoul National University College of Medicine) ;
  • Park, Hye-Jin (Department of Radiation Oncology, Seoul National University College of Medicine) ;
  • Kwon, Eun-Kyung (Department of Radiation Oncology, Seoul National University College of Medicine) ;
  • Ye, Sung-Joon (Department of Radiation Oncology, Seoul National University College of Medicine) ;
  • Lee, Dong-Han (Department of Radiation Oncology, the Korea Institute of Radiological and Medical Sciences) ;
  • Wu, Hong-Gyun (Department of Radiation Oncology, Seoul National University College of Medicine)
  • 엄근용 (서울대학교 의과대학 방사선종양학교실) ;
  • 박혜진 (서울대학교 의과대학 방사선종양학교실) ;
  • 권은경 (서울대학교 의과대학 방사선종양학교실) ;
  • 예성준 (서울대학교 의과대학 방사선종양학교실) ;
  • 이동한 (원자력의학원 방사선종양학과) ;
  • 우홍균 (서울대학교 의과대학 방사선종양학교실)
  • Published : 2007.12.30

Abstract

Neutrons are high LET (linear energy transfer) radiation and cause more damage to the target cells than x-rays or gamma rays. The damage from neutrons is generally considered fatal to a cell and neutrons have a greater tendency to cause cell death through direct interaction on DNA. We performed experiments to measure growth delay ratio and oxygen enhancement ratio (OER) in mouse model system. We inoculated EMT-6 cells to the right hind leg of BALB-c mouse and X-rays and neutron beams were given when the average volume of tumors reached $200-300mm^3$. We irradiated 0, 11, 15.4 Gy of X-ray and 0, 5, 7 Gy of fast neutron beam at normoxic and hypoxic condition. The volume of tumors was measured 3 times per week. In x-ray experiment, growth delay ratio was 1.34 with 11 Gy and 1.33 with 15.4 Gy in normoxic condition compared to in hypoxic condition, respectively. In neutron experiment, growth delay ratio was 0.94 with 5 Gy and 0.98 with 7 Gy, respectively. The OER of neutron beam was 0.97. The neutron beam was more effective than X-ray in the control of hypoxic tumors.

중성자선은 고 LET (linear energy transfer) 방사선으로 X선이나 감마선 등의 저 LET 방사선보다 세포에 더욱 큰 손상을 입힌다. 중성자에 의한 손상은 일반적으로 세포에 있어서 치명적이며, 중성자선은 X선이나 감마선에 비하여 직접작용을 통하여 세포사를 일으키는 경향이 있다. 본 연구에서는 고속중성자선의 성장지연비 및 산소증강비를 동물실험을 통하여 측정하고자 하였다. BALB-c 마우스의 우측 하지에 EMT-6 세포주를 이식한 후 종양의 평균용적이 $200-300mm^3$가 되었을 때 X선 및 고속중성자선을 조사하였다. 정상산소환경 및 저산소환경의 종양에 대하여 X선은 0, 11, 15.4 Gy를 조사하였고 고속중성자선은 0, 5, 7, Gy를 조사하였다. 방사선조사 후에는 종양의 용적을 주 3회 측정하였다. 정상산소환경 실험군의 경우 저산소환경 실험군에 비하여 X선 11 Gy를 조사하였을 때 성장지연비가 1.34였고, 15.4 Gy를 조사하였을 때 1.33였다. 고속중성자선을 조사한 경우정상산소환경 실험군이 저산소환경 실험군에 비하여 고속중성자선 5 Gy를 조사하였을 때 성장지연비는 0.94였고, 고속중성자선 7 Gy를 조사하였을 때 0.98였다. 고속중성자선의 산소증강비는 0.97이었다. 고속중성자선은 X선에 비하여 저산소환경에 있는 종양의 성장억제에 있어서 보다 효과적이었다.

Keywords

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