宫颈癌调强计划Portal Dosimetry剂量验证中拼接野的应用分析

Application and Analysis of the Splicing Field in Portal Dosimetry Dose Verification for IMRT Plans of Cervical Carcinoma

目的提出一种生成Portal Dosimetry(以下简称PD)分野的拼接野(以下简称PD拼接野)方法,并对宫颈癌计划的PD拼接野进行分析研究。方法选取20例宫颈癌患者的七野调强治疗计划进行研究,治疗计划中每个大野分成1对分野。首先制作仅含分野的PD剂量验证计划,然后使用直线加速器出束执行。通过矩阵拼接和矩阵叠加,分别得到每对PD分野对应的PD拼接野和PD大野。使用PD软件模块,得到PD拼接野和PD大野的伽玛通过率,分别记为Gp和Gd。使用Gm表示每对PD分野的平均伽玛通过率值。对Gp、Gd和Gm进行统计分析和比较研究。结果所有140个射野的Gp、Gd和Gm的值分别为98.78%±0.70%、97.34%±1.25%和98.87%±0.51%。两两比较结果显示,Gp和Gd差异具有统计学意义(P<0.05);Gp和Gm的数据差异较小。对每个PD验证计划,计算所有同一类射野对应的计划验证通过率(Gplan)。对Gplan数据进行统计分析显示,PD拼接野和PD大野差异具有统计学意义(P<0.05),PD拼接野和PD分野的数据差异较小。结论本文提出的PD拼接野概念为评价PD剂量验证结果提供了有益的参考信息。

Objective To propose a method for obtaining the Portal Dosimetry(hereinafter referred to as PD)splicing field(hereinafter referred to as PD splicing field)through matrix concatenation for split fields,and to analyze data of PD splicing field for cervical cancer planning.Methods Seven fields of intensity modulated therapy were selected for 20 patients with cervical cancer.Each field was divided into one pair of fields.First,a PD dose verification plan containing only the separation field was prepared,and then the linear accelerator beam was used to execute it.By means of matrix splicing and matrix superposition,PD splicing field and PD large field corresponding to each pair of PD division field were obtained respectively.Using the PD software module,the gamma pass rates of the PD splicing field and the PD large field were obtained,which were denoted as Gp and Gd respectively.Gm was used to represent the average gamma pass rate value for each pair of PD divisions.The statistical analysis and comparative study of Gp,Gd and Gm were carried out.Results The values of Gp,Gd,and Gm for all 140 large fields were 98.78%±0.70%,97.34%±1.25%and 98.87%±0.51%,respectively.Pairwise comparison results showed that there was a significant statistical difference(P<0.05)between Gp and Gd.Overall the difference between Gp and Gm was relatively small.For each PD verification plan,the plan verification pass rate(Gplan)was calculated for all fields of the same type.Statistical analysis results of Gplan showed that there was a significant statistical difference between PD splicing field(P<0.05)and PD large field,the difference between PD splicing field and PD split field was relatively small.Conclusion The concept of PD splicing field proposed in this study provides useful reference information for evaluating the dose verification results of PD.