CT值-电子密度转换曲线对VMAT计划剂量计算的影响  

Influence of CT Value-Electron Density Conversion Curve on VMAT Planning Dose Calculation

作　　者：周军[1] 卢爱琼 何水 柯珍奇 王海屹 ZHOU Jun;LU Aiqiong;HE Shui;KE Zhenqi;WANG Haiyi(Department of Oncology and Hematology,Meishan Hospital Affiliated to Chengdu University of Traditional Chinese Medicine/Meishan Traditional Chinese Medicine Hospital,Meishan Sichuan 620010,China)

机构地区：[1]成都中医药大学附属眉山医院/眉山市中医医院肿瘤血液科,四川眉山620010

出　　处：《中国医疗设备》2023年第8期26-31,共6页China Medical Devices

基　　金：吴阶平医学基金(320.6750.2021-22-29)。

摘　　要：目的分析CT值-电子密度转换曲线对容积旋转调强放疗(Volumetric Modulated Arc Therapy,VMAT)计划剂量计算的影响。方法采集、建立不同管电压、管电流、扫描部位的9条CT值-电子密度转换曲线(H_100、H_120、H_140、C_100、C_120、C_140、A_100、A_120、A_140),并以头部扫描序列H_120条件为标准扫描条件,分别对同一鼻咽癌VMAT放疗计划进行剂量计算,将VMAT计划移植到验证模体,行剂量计算,创建验证计划,分析标准条件与非标准条件下的剂量差异。结果VMAT计划标准条件与非标准条件剂量对比,脑干剂量误差最大,Dmax误差为26.90 cGy,相对误差为0.52%;腹部条件A_140(腹部140 kV 300 mA)下与标准条件剂量学差异无统计学意义(P>0.05);其他条件下均与标准条件剂量学差异有统计学意义(P<0.05)。模体验证计划标准条件与非标准条件剂量对比,密质骨Dmean误差最大,为0.30 cGy,相对误差为0.56%;统计分析结果显示,模体验证放疗计划非标准条件与标准条件剂量比较,差异均有统计学意义(P<0.05)。结论不同CT值-电子密度转换曲线对VMAT计划剂量计算均有一定程度的影响;在临床工作中,必须针对不同的管电压、管电流、扫描部位等,建立标准的CT值-电子密度转换曲线;CT模拟定位和剂量计算时,应选择相应的扫描参数条件和CT值-电子密度转换曲线,以提高剂量计算的准确性。Objective To analyze the influence of CT value-electron density conversion curve on volumetric modulated arc therapy(VMAT)plan dose calculation.Methods A total of nine CT value-electron density conversion curves(H_100,H_120,H_140,C_100,C_120,C_140,A_100,A_120,A_140)of different tube voltages,tube currents and scanning sites were collected and established.Taking H_120 condition of head scan sequence as standard scanning condition,dose calculation was performed on the same VMAT radiotherapy plan for nasopharyngeal carcinoma,respectively.The VMAT plan was transplanted to the verification phantom,the dose calculation was performed,the verification plan was created,and the dose difference between standard and non-standard conditions was analyzed.Results The dose comparison between the standard condition and the non-standard condition of the VMAT plan showed that the dose error of brainstem was the largest,Dmax error was 26.90 cGy,and the relative error was 0.52%.There was no statistically significant difference in dosimetry between the abdominal condition A_140(abdominal 140 kV 300 mA)and the standard condition(P>0.05).There were statistically significant differences in dosimetry between other conditions and standard conditions(P<0.05).Compared with the standard condition and non-standard condition dose of the phantom verification plan,the Dmean error of the dense bone was the largest,which was 0.30 cGy,and the relative error was 0.56%.The statistical analysis results showed that there were statistically significant differences between the non-standard condition and the standard condition dose of the phantom verification radiotherapy plan(P<0.05).Conclusion Different CT value-electron density conversion curves have a certain influence on the dose calculation of VMAT plan.In clinical work,it is necessary to establish a standard CT value-electron density conversion curve for different tube voltages,tube currents,scanning sites,etc.During CT simulation and dose calculation,CT simulation localization and dose calculation,

关 键 词：CT值 电子密度 容积旋转调强放疗计划 剂量计算 

分 类 号：R144[医药卫生—公共卫生与预防医学] R811