Progress in Medical Physics (한국의학물리학회지:의학물리)

Korean Society of Medical Physics (한국의학물리학회)
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Precision Validation of Electromagnetic Physics in Geant4 Simulation for Proton Therapy

양성자 치료 전산모사를 위한 Geant4 전자기 물리 모델 정확성 검증

  • Park, So-Hyun (Department of Biomedical Engineering, College of Medicine, The Catholic University of Korea) ;
  • Rah, Jeong-Eun (Proton Therapy Center, National Cancer Center of Korea) ;
  • Shin, Jung-Wook (Proton Therapy Center, National Cancer Center of Korea) ;
  • Park, Sung-Yong (Proton Therapy Center, National Cancer Center of Korea) ;
  • Yoon, Sei-Chul (Department of Oncology, Seoul St. Mary's Hospital) ;
  • Jung, Won-Gyun (Department of Biomedical Engineering, College of Medicine, The Catholic University of Korea) ;
  • Suh, Tae-Suk (Department of Biomedical Engineering, College of Medicine, The Catholic University of Korea)
  • 박소현 (가톨릭대학교 의과대학 의공학교실) ;
  • 라정은 (국립암센터 양성자치료센터) ;
  • 신정욱 (국립암센터 양성자치료센터) ;
  • 박성용 (국립암센터 양성자치료센터) ;
  • 윤세철 (서울성모병원 방사선종양학과) ;
  • 정원균 (가톨릭대학교 의과대학 의공학교실) ;
  • 서태석 (가톨릭대학교 의과대학 의공학교실)
  • Published : 2009.12.31
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Abstract

Geant4 (GEometry ANd Tracking) provides various packages specialized in modeling electromagnetic interactions. The validation of Geant4 physics models is a significant issue for the applications of Geant4 based simulation in medical physics. The purpose of this study is to evaluate accuracy of Geant4 electromagnetic physics for proton therapy. The validation was performed both the Continuous slowing down approximation (CSDA) range and the stopping power. In each test, the reliability of the electromagnetic models in a selected group of materials was evaluated such as water, bone, adipose tissue and various atomic elements. Results of Geant4 simulation were compared with the National Institute of Standards and Technology (NIST) reference data. As results of comparison about water, bone and adipose tissue, average percent difference of CSDA range were presented 1.0%, 1.4% and 1.4%, respectively. Average percent difference of stopping power were presented 0.7%, 1.0% and 1.3%, respectively. The data were analyzed through the kolmogorov-smirnov Goodness-of-Fit statistical analysis test. All the results from electromagnetic models showed a good agreement with the reference data, where all the corresponding p-values are higher than the confidence level $\alpha=0.05$ set.

Geant4 toolkit은 전자기적 상호작용(electromagnetic interactions)에 대한 다양한 물리적 모델을 제공한다. 이러한 물리적 모델들에 대한 검증은 신뢰성 있는 Geant4 응용을 위해서 중요한 역할을 한다. 그러므로, 본 연구의 목적은 양성자 치료 전산모사를 위해 Geant4가 제공하는 물리적 모델 중 전자기 물리 모델의 정확성을 검증하는 것이다. 검증은 물, 뼈, 지방 그리고 원자번호가 다른 물질에 대해 양성자의 CSDA 비정(continuous slowing down approximation range)과 저지능(stopping power) 데이터를 미국 국립기술표준원(National Institute of Standards and Technology, NIST)의 데이터를 각각 비교하는 방법으로 이루어졌다. 물, 뼈 그리고 지방에 대해 0.01 MeV에서 10 GeV 범위의 입사 에너지의 CSDA 비정과 저지능 전산모사 결과와 NIST값을 비교한 결과, CSDA 비정의 평균 차는 각각 1.0%, 1.4% 그리고 1.4%를 나타내었고, 저지능에 대한 평균 차는 각각 0.7%, 1.0% 그리고 1.3%를 나타내었다. 또한, 각 물질에 대한 NIST 값과의 유의성을 분석하기 위해 kolmogorov-smirnov Goodness-of-Fit 통계분석 방법을 이용한 결과, 전자기 물리 모델의 전산모사 결과 데이터와 NIST 데이터 사이의 유의성을 나타내는 p-value가 유의 수준 0.05 이상 값을 가진다는 것을 확인 하였으며, 이를 통해 Geant4 전자기 물리 모델의 정확성을 검증할 수 있었다.

Keywords

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