螺旋断层治疗计划系统升级前后验证结果及叶片打开时间对比研究

Comparison of validation results and leaf open time before and after upgrading of helix tomotherapy planning system

目的比较4.0.4、4.2.3版本螺旋断层治疗计划系统叶片打开时间参数和γ通过率差别及改进状况。方法用4.0.4、4.2.3版本治疗计划系统各选择345例计划进行回顾性比较。从患者备份计划文件提取出Sinogram并计算叶片打开时间参数进行评估分析,包含最大叶片打开时间、叶片平均打开时间、打开时间<100 ms的叶片数比例、打开时间在最大时间5ms范围内叶片数比例及出束总时间。对升级前后计划的γ通过率(分析标准为3mm/3%、10%Threshold和全局误差)及叶片打开时间参数对比采用独立t检验分析,采用多元线性回归评估叶片打开时间参数与γ通过率之间相关性。结果4.0.4版本的γ通过率低于4.2.3版本(97.86%∶98.6%,P<0.001),4.2.3版本的最大时间与投影时间的间隔低于4.0.4版本(1 ms∶11ms,P<0.001)。多元线性回归显示4.0.4版本最大打开时间附近5ms范围内的叶片数比例和出束总时间与γ通过率呈显著负相关(P<0.001),而4.2.3版本仅出束总时间与γ通过率呈显著负相关(P<0.001)。结论螺旋断层治疗系统升级到4.2.3版本后提高了计划验证的γ通过率,且有效修复了旧版系统在最大叶片打开时间附近的叶片可能会导致γ通过率下降的问题。

Objective To compare the leaf open time(LOT)parameters andγpassing rates between the 4.0.4 and 4.2.3 helix Tomotherapy planning systems and evaluate the improvement.Methods Retrospective comparison of the treatment plans of 345 cases selected by 4.0.4 and 4.2.3 versions was performed.The Machine Specific Sinogram of each plan was extracted from the archived plan file to calculate the LOT.The evaluated LOT parameters included the projection time,the maximum LOT,the mean non-zeros time,the time difference between the projection time and the maximum LOT,the relative count of leaves with LOT greater than maximum LOT minus 5ms,the relative count of leaves with LOT lower than 100ms and the beam on time.Theγpassing rate(criteria:3mm/3%,10%threshold and global error)and the LOT parameters between two version systems were evaluated with the independent t-test.The relationship between the LOT parameters andγpassing rate was analyzed by the multiple linear regression method.Results Theγpassing rate of the Ver 4.0.4 system was 97.86%,significantly lower than 98.6%of the Ver 4.2.3 system(P<0.001).The time gap between the projection time and the maximum LOT of the Ver 4.2.3 system was significantly less than that of the Ver 4.0.4 system(1 ms vs.11 ms,P<0.001).For the Ver 4.0.4 system,the multiple linear regression method showed that the maximum LOT ratio and the beam on time were negatively correlated with theγpassing rate(both P<0.001).However,for the Ver 4.2.3 system,only the beam on time showed a negative correlation with theγpassing rate(P<0.001).Conclusion Theγpassing rate of the Ver 4.2.3 system is significantly higher than that of the Ver 4.0.4 system.The decrease ofγpassing rate caused by the leaves near the maximum LOT is properly resolved in the new version system.