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Original Article

Korean Journal of Medical Physics 2010; 21(2): 192-200

Published online June 25, 2010

Copyright © Korean Society of Medical Physics.

Monte Carlo Study Using GEANT4 of Cyberknife Stereotactic Radiosurgery System

GEANT4를 이용한 정위적 사이버나이프 선량분포의 계산과 측정에 관한 연구

Chung Il Lee*†‡, Jae Won Shin§, Hun Joo Shin, Jae Yong Jung*, Yon Lae Kim*, Jeong Hwan Min*#, Seung Woo Hong§, Su-Mi Chung, Won Gyun Jung*, Tae Suk Suh*

이충일*†‡ㆍ신재원§ㆍ신헌주ㆍ정재용*ㆍ김연래*ㆍ민정환*#ㆍ홍승우§ㆍ정수미ㆍ정원균*ㆍ서태석*

*Department of Biomedical Engineering, School of Medicine, Research Institute of Biomedical Engineering, Department of Radiation Oncology, St. Mary's Hospital, The Catholic University of Korea, §Department of Physics, Sungkyunkwan University, Seoul Wooridul Spine Hospital, Cyberknife Clinic, Seoul,Department of Radiologic Technology, Choonhae College of Health Sciences, Ulsan, #Department of Radiologic Technology, Shingu University, Seongnam, Korea

*가톨릭대학교 의과대학 의공학교실, 가톨릭대학교 생체의공학연구소, 가톨릭대학교 여의도성모병원 방사선종양학과, §성균관대학교 자연과학부 물리학과, 서울우리들병원 사이버나이프 클리닉, 춘해보건대학 방사선과, #신구대학 방사선과

Abstract

Cyberknife with small field size is more difficult and complex for dosimetry compared with conventional radiotherapy due to electronic disequilibrium, steep dose gradients and spectrum change of photons and electrons. The purpose of this study demonstrate the usefulness of Geant4 as verification tool of measurement dose for delivering accurate dose by comparing measurement data using the diode detector with results by Geant4 simulation. The development of Monte Carlo Model for Cyberknife was done through the two-step process. In the first step, the treatment head was simulated and Bremsstrahlung spectrum was calculated. Secondly, percent depth dose (PDD) was calculated for six cones with different size, i.e., 5 mm, 10 mm, 20 mm, 30 mm, 50 mm and 60 mm in the model of water phantom. The relative output factor was calculated about 12 fields from 5 mm to 60 mm and then it compared with measurement data by the diode detector. The beam profiles and depth profiles were calculated about different six cones and about each depth of 1.5 cm, 10 cm and 20 cm, respectively. The results about PDD were shown the error the less than 2% which means acceptable in clinical setting. For comparison of relative output factors, the difference was less than 3% in the cones lager than 7.5 mm. However, there was the difference of 6.91% in the 5 mm cone. Although beam profiles were shown the difference less than 2% in the cones larger than 20 mm, there was the error less than 3.5% in the cones smaller than 20 mm. From results, we could demonstrate the usefulness of Geant4 as dose verification tool.

KeywordsCyberknife, Small field, GEANT4, Electron disequilibrium

Korean Society of Medical Physics

Vol.35 No.2
June 2024

pISSN 2508-4445
eISSN 2508-4453
Formerly ISSN 1226-5829

Frequency: Quarterly

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