Abstract

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Title:: Effect of prescription isodose line on the quality of CyberKnife plan designed on anthropomorphic head and neck phantom

Author(s):: YANG Jing; LIU Gang; NIE Xin; LIU Hongyuan; LIANG Zhiwen; HAN Jun; LI Qin; Cancer Center, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China

Keywords:: ; Keywords: intracranial tumor; anthropomorphic head and neck phantom; CyberKnife; prescription isodose line; plan quality

Abstract:: Abstract: Objective To study the effects of different prescription isodose lines (PIDL) on the quality of CyberKnife plans designed on anthropomorphic head and neck phantom. Methods The spherical center sphere in anthropomorphic head and neck phantom was selected as the target area. The volume of the target area was 16.9 cc. Four dose-limit shells were set to be 2, 20, 40, and 60 mm from the target surface, respectively. The dose limit of the innermost shell was the main optimization parameter. By changing the limit parameters, the plans of different PIDL were obtained under the condition that the prescription coverage of target area approached 100%. Results Plans of 39%, 44%, 49%, 57%, 61% and 65% PIDL were obtained. The dose gradient index, conformity index, V5, V9, and V12 of plan of 49% PIDL were reduced by 17.5%, 9.8%, 12.9%, 16.1%, and 21.3% compared with the maximum values of the other plans. However, the plan of 49% PIDL had the largest number of beams and the longest planning time. Conclusion The research of CyberKnife plan designed on anthropomorphic head and neck phantom shows that multiple factors should be considered in the selection of PIDL for intracranial tumor plan. Increasing the radiation dose to the tumor and reducing the irradiation volume of normal brain tissues can improve the tumor control probability and reduce radiation damage, but meanwhile increase treatment time which requires better tolerance in patients.