Journal of Radiation Protection and Research

The Korean Association for Radiation Protection (대한방사선방어학회)
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Simulation of Counting Efficiencies of Portable NaI Detector for Rapid Screening of Internal Exposure in Radiation Emergencies

방사선비상시 내부피폭 신속 분류를 위한 휴대용 NaI 검출기의 계측효율 전산모사

  • Ha, Wi-Ho (National Radiation Emergency Medical Center, Korea Institute of Radiological and Medical Sciences) ;
  • Yoo, Jaeryong (National Radiation Emergency Medical Center, Korea Institute of Radiological and Medical Sciences) ;
  • Yoon, Seokwon (National Radiation Emergency Medical Center, Korea Institute of Radiological and Medical Sciences) ;
  • Pak, Min Jung (National Radiation Emergency Medical Center, Korea Institute of Radiological and Medical Sciences) ;
  • Kim, Jong Kyoung (Department of Nuclear Engineering, Hanyang University)
  • 하위호 (한국원자력의학원 국가방사선비상진료센터) ;
  • 유재룡 (한국원자력의학원 국가방사선비상진료센터) ;
  • 윤석원 (한국원자력의학원 국가방사선비상진료센터) ;
  • 박민정 (한국원자력의학원 국가방사선비상진료센터) ;
  • 김종경 (한양대학교 원자력공학과)
  • Received : 2015.08.28
  • Accepted : 2015.11.16
  • Published : 2015.12.31
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Abstract

In case of radiation emergencies, radioactive materials released into environments can cause internal exposure of members of the public. Even though whole body counters are widely used for direct measurement of internally deposited radionuclides, those are not likely to be used at the field to rapidly screen internal exposure. In this study, we estimated the counting efficiencies of portable NaI detector for different size BOMAB phantoms using Monte Carlo transport code to apply handheld gamma spectrometers for rapid screening of internal exposure following radiological accidents. As a result of comparison for two counting geometries, counting efficiencies for sitting model were about 1.1 times higher than those for standing model. We found, however, that differences of counting efficiencies according to different size are higher than those according to counting geometry. Therefore, we concluded that when we assess internal exposure of small size people compared to the reference male, the body size should be considered to estimate more accurate radioactivity in the human body because counting efficiencies of 4-year old BOMAB phantom were about 2.4~3.1 times higher than those of reference male BOMAB phantom.

원자력사고 등의 방사선비상시 환경으로 누출된 방사성물질은 일반인의 내부피폭을 야기할 수 있다. 특히 감마선 방출핵종의 내부피폭의 경우 전신계수기가 널리 사용되지만 현장에서 신속히 내부피폭을 분류하는 용도로는 부적합하다. 본 연구에서는 휴대용 감마스펙트로메터를 비상시 내부피폭 신속분류에 적용하기 위하여 몬테카를로 전산모사 방법을 이용하여 NaI 검출기의 계측효율을 BOMAB 팬텀의 크기별로 평가하였다. 두 가지 측정 지오메트리에서 계측효율을 비교한 결과 앉은 모델에서의 계측효율이 서 있는 모델에 비해 약 1.1배 높은 계측효율을 나타내었다. 하지만 측정 지오메트리에 의한 계측효율 차이보다 신체크기에 따른 계측효율 차이가 크게 발생하는 것을 확인하였다. 특히 신체크기가 작은 4세 팬텀의 경우 표준남성과 비교하면 약 2.4~3.1배의 높은 계측효율을 나타내어 신체크기가 상이한 일반인을 대상으로 내부피폭을 모니터링할 경우 반드시 계측효율에 대한 고려가 필요한 것으로 확인되었다.

Keywords

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