摘要
目的 通过蒙特卡罗方法模拟瓦里安IX 6 MV直线加速器治疗机头，得到不同射野下的最适电子线能量，研究径向强度分布对百分深度剂量的影响。方法 首先对所研究的每个射野，保持径向强度大小不变，改变电子线能量，将得到的百分深度剂量与测量值进行对比，得到该射野下的最适电子线能量。随后将电子线能量设置为得到的最适值，改变径向强度分布大小，研究其对百分深度剂量的影响。结果 对于4 cm×4 cm、10 cm×10 cm、20 cm×20 cm和30 cm×30 cm的射野，最适能量分别为5.9、6.0、6.3和6.4 MeV；改变径向强度分布对4 cm×4 cm、10 cm×10 cm射野下的百分深度剂量没有影响，对20 cm×20 cm和30 cm×30 cm的射野则有明显影响。结论 适用于不同射野的最佳能量略有不同，径向强度的改变对大野下的深度剂量有较明显影响。为提高模拟精度，电子线能量和径向强度分布的选取需要考虑射野大小的因素。
Objective To determine the optimal electron beam energy at different field size through a Monte Carlo-based simulation of the therapy head of Varian IX 6 MV linear accelerator so as to study the influence of radial intensity on depth dose. Methods Firstly, keeping the radial intensity unchanged for the field of interest while changing electron beam energy, compassion was carried out of calculated percentage depth doses between measured values. Thus, the optimal energy was identified for this field size. Then, the obtained energy was set the optimal value to study the radial intensity influence on the depth doses. Results The optimal electron energy for 4 cm×4 cm, 10 cm×10 cm, 20 cm×20 cm and 30 cm×30 cm field sizes was 5.9, 6.0, 6.3 and 6.4 MeV respectively. Changes in radial intensities resulted in negligible changes in percentage depth doses for 4 cm×4 cm and 10 cm×10 cm fields, but led to observable discrepancy for 20 cm×20 cm and 30 cm×30 cm fields. Conclusions The optimal electron energies for different field sizes are slightly different. Change in radial intensity distribution has significant influence on the depth dose for large field. To improve simulation accuracy, the field size needs to be taken into consideration in determining the electron beam energy and radial intensity distribution.
出处
《中华放射医学与防护杂志》
CAS
CSCD
北大核心
2018年第2期145-149,共5页
Chinese Journal of Radiological Medicine and Protection
基金
湖南省自然科学基金（2016JJ3108）
湖南省重点研发计划项目（2015SK2022）
关键词
蒙特卡罗
电子线能量
径向强度分布
百分深度剂量
Monte Carlo
Electron energy
Radial intensity distribution
Percentage depth dose
