鼻咽癌调强计划分野和大野Portal Dosimetry剂量验证的分析比较

目的 对鼻咽癌(Nasopharyngeal Carcinoma,NPC)调强计划的Portal Dosimetry(PD)剂量验证计划进行研究,比较PD计划分野和大野的Gamma通过率值(G),为评估NPC调强计划的PD剂量验证结果提供参考.方法 选取11例NPC患者的调强治疗计划,首先使用Eclipse制作仅含分野...

Analysis and Comparison of Portal Dosimetry Dose Verification Results of Split Field and Large Field for IMRT Plans of Nasopharyngeal Carcinoma

Objective To study the portal dosimetry(PD)dose verification of intensity modulated radiotherapy(IMRT)plan for nasopharyngeal carcinoma(NPC),and compare the values of gamma passing rate(G)between split field and large field,so as to provide valuable reference for evaluating the PD dose verification results of IMRT plan for NPC.Methods The IMRT plans for 11 patients with NPC were chosen for this study.Firstly,the PD dose verification plans with only split fields were created by using the Eclipse treatment planning system.The PD plans were performed by Clinac iX linear accelerator.Then,the value of G for each split field was obtained by PD software module.The value of G for each large field was obtained by matrix addition.Finally,statistical analysis and comparison were applied to the data of G for split field and large field.Results For 11 cases of PD dose verification plans,the statistical values of G for all split fields and large fields were 98.08%±1.80% and 97.81%±1.96% respectively.The results of comparison between 198 split fields and corresponding large fields by paired t-test showed that,there was no statistical difference between the two groups(P>0.05).The symbolΔG represented the difference in values of G between split field and large field.The statistical value and absolute value ofΔG were 0.26%±2.21% and 1.38%±1.75%respectively.For each PD dose verification plan,the maximum,minimum,mean and standard deviation of G values for all the split fields and large fields were calculated respectively.The paired t-test was applied to the two types of field with the above four parameters.The results showed that,there was no significant difference for the three parameters of minimum,mean and standard deviation(P>0.05).Conclusion By and large,there is small difference in gamma passing rate between split field and large field for the PD verification plans of NPC.There is no statistical difference in values of mean and standard deviation of gamma passing rate of all the fields for each PD verification plan between split field and large field.