[1]李洁,汪晖,汪冬,等. 小野照射不同密度肺模体横向电子不平衡现象的蒙特卡罗模拟研究[J].中国医学物理学杂志,2019,36(4):379-383.[doi:DOI:10.3969/j.issn.1005-202X.2019.04.002]
　LI Jie,WANG Hui,et al. Monte Carlo simulation of lateral electron disequilibrium in different lung density phantoms after small-field radiation[J].Chinese Journal of Medical Physics,2019,36(4):379-383.[doi:DOI:10.3969/j.issn.1005-202X.2019.04.002]
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 小野照射不同密度肺模体横向电子不平衡现象的蒙特卡罗模拟研究
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《中国医学物理学杂志》[ISSN:1005-202X/CN:44-1351/R]

卷:
36卷
期数:
2019年第4期
页码:
379-383
栏目:
医学放射物理
出版日期:
2019-04-25

文章信息/Info

Title:
 Monte Carlo simulation of lateral electron disequilibrium in different lung density phantoms after small-field radiation
文章编号:
1005-202X（2019）04-0379-05
作者:
 李洁1; 2; 汪晖1; 汪冬1; 郑华庆1; 吴宜灿1
 1.中国科学院核能安全技术研究所/中子输运理论与辐射安全重点实验室， 安徽 合肥 230031； 2.中国科学技术大学科学岛分院， 安徽 合肥 230026
Author(s):
 LI Jie1;  2;  WANG Hui1;  WANG Dong1;  ZHENG Huaqing1;  WU Yican1
 1. Key Laboratory of Neutronics and Radiation Safety, Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei 230031, China; 2. Science Island Branch, University of Science and Technology of China, Hefei 230026, China
关键词:
 ; 小野; 肺密度; 放射治疗; 电子不平衡; 蒙特卡罗模拟
Keywords:
 ; Keywords: small field;  lung density;  radiotherapy;  electron disequilibrium;  Monte Carlo simulation
分类号:
R811.1；R312
DOI:
DOI:10.3969/j.issn.1005-202X.2019.04.002
文献标志码:
A
摘要:
 目的：研究小野对不同密度肺模体横向电子不平衡程度的影响，为肺部小野放射治疗提供参考。方法：利用蒙特卡罗程序EGSnrc/DOSXYZnrc对不同射野照射包含不同密度肺组织的模体进行模拟，选择6和15 MV两种能量、8种射野大小[（0.2×0.2） cm2~（3.0×3.0） cm2]、7种肺密度（0.001~1.000 g/cm3）的不同组合，利用剂量衰减百分比（DRP）衡量横向电子不平衡的严重程度。结果：当肺密度小于0.4 g/cm3时，DRP非常大且随密度剧烈变化，电子不平衡现象比较严重；当肺密度大于0.4 g/cm3时，DRP随密度变化幅度减缓。肺内剂量衰减程度随射野的增加而减小，肺组织后方相对更小的野会有较大程度的剂量升高。结论：低密度范围内，密度的改变会引起肺部剂量的剧烈变化，在使用小野对肺部肿瘤进行治疗时，应更加注意CT-电子密度转换曲线的准确性，谨慎选择放射治疗参数以保护肺周围重要危及器官。针对低密度肺的剂量计算，应选用考虑电子不平衡的更精确的剂量计算方法。
Abstract:
 Abstract: Objective To study the effects of small-field radiation on lateral electron disequilibrium in different lung density phantoms and provide references for small-field radiotherapy for lung cancers. Methods Monte Carlo code EGSnrc/DOSXYZnrc was used to simulate different densities of lung tissues after radiation with different field sizes. The combinations of 2 kinds of energies (6 MV and 15 MV), 8 kinds of field sizes (from 0.2 cm×0.2 cm to 3.0 cm×3.0 cm) and 7 kinds of lung densities (from 0.001 g/cm3 to 1.000 g/cm3) were selected in the simulation. The lateral electron disequilibrium was evaluated by dose reduction percentage. Results The dose reduction percentage was very large and changed remarkably with the density when the lung density was less than 0.4 g/cm3. However, when the lung density was greater than 0.4 g/cm3, the change of dose reduction percentage was mitigated with the density. The attenuation of lung dose decreased with the increase of radiation field, and the doses in the small fields behind the lung tissues were significantly increased. Conclusion In a range of low density, the change of density might cause dramatic changes in the lung dose. During the treatment for lung cancer, medical physicists should pay more attention to the accuracy of the CT- electron density conversion curves and select the optimal radiotherapy parameters to protect the organs-at-risk around the lungs. A more accurate dose calculation method considering the electron disequilibrium is recommended in the low-density lung dose calculation.

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备注/Memo

备注/Memo:
 【收稿日期】2018-11-28
【基金项目】国家自然科学基金（11605233）；中国科学院合肥物质科学研究院院长基金（YZJJ201618）
【作者简介】李洁，在读硕士研究生，研究方向：精准放射治疗中的剂量计算方法，E-mail: jie.li@fds.org.cn
【通信作者】汪晖，助理研究员，研究方向：精准放射治疗中的剂量计算方法，E-mail: hui.wang@fds.org.cn
更新日期/Last Update: 2019-04-22