Abstract

Info

Title:: Lung phantom-based study on the effect of prescription isodose line on CyberKnife plan quality

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

Keywords:: ; Keywords: lung phantom; CyberKnife plan; prescription isodose line; Monte Carlo algorithm

Abstract:: Abstract: Objective To study the effects of prescription isodose line (PIDL) on the quality of CyberKnife plans designed on anthropomorphic lung phantom. Methods The spherical center sphere in anthropomorphic lung phantom was expanded 3 mm and selected as the target area, with a volume of 13.46 cc. Three dose-limit shells were set to be 2, 15 and 25 mm from the target surface, respectively. The plans were optimized according to predesigned strategy, and the plans of different PIDL were obtained under the condition that the prescription coverage of target area was above 98%. Results Monte Carlo algorithm for dose calculation was used to obtain the plans of 40% to 73% PIDL, in which the correlation coefficients of dose gradient index, homogeneity index and V25 with PIDL were 0.960 (P<0.01), -1.000 (P<0.01) and 0.673 (P=0.033), respectively. There was no statistically significant correlation between other parameters and PIDL. Conclusion Among the parameters of CyberKnife plans designed on lung phantom, dose gradient index, homogeneity index and V25 were significantly correlated with PIDL. The plan of about 50% PIDL has a sharper dose falloff gradient, and the plan of higher or lower PIDL may lead to a decreased dose conformity in target areas.