中上段食管癌调强放疗肺及心脏体积与吸收剂量数学模型建立与验证

Relationship between lung and heart volume and absorbed dose in intensity-modulated radiotherapy for middle and upper esophageal cancer

目的随着调强放疗(intensity modulated radiation therapy,IMRT)在食管癌中的广泛应用,肺与心脏的放射损伤也逐渐成为关注焦点。本研究探讨中上段食管癌IMRT中肺和心脏吸收剂量相关因素,并建立相关数学模型,为食管癌IMRT中肺与心脏吸收剂量提供预测。方法收集2013-07-01-2017-12-30西南医科大学附属医院肿瘤科收治的50例中上段食管癌IMRT患者资料,分析放疗计划中靶区肺及心脏体积与其吸收剂量的相关关系,并通过SPSS 17.0软件拟合出相关公式。结果肺体积(V肺)与肺的归一化平均剂量(Dnmean=Dmean/D处方)、Dn5%、Dn25%、Dn50%、Dn75%和Dn95%之间具有负相关性,均P<0.05;肺与计划靶区(planning target volume,PTV)的归一化相交体积(Vo-肺/V肺)与肺的Dnmean、Dn5%、Dn25%、Dn50%、Dn75%和Dn95%之间呈正相关性,均P<0.05。心脏体积(V心脏)与心脏的Dnmean、Dn5%、Dn25%、Dn50%、Dn75%和Dn95%之间无相关性,均P>0.05;心脏与PTV的相交体积(Vo-心脏)、心脏的Dnmean、Dn5%、Dn25%、Dn50%、Dn75%和Dn95%之间呈正相关性,均P<0.05。所有拟合公式均P<0.001。结论本研究成功建立中上段食管癌IMRT中肺和心脏吸收剂量预测数学模型,从拟合公式P值看,结果较为精确。不同治疗计划系统均可利用该方法建立适合各自系统的危及器官剂量预测模型,并不需要购买新的软件模块。

OBJECTIVE With the extensive application of intensity modulated radiation therapy(IMRT)in esophageal cancer,radiation injury to the lungs and heart has gradually become a focus of attention.This study explored the factors related to the absorbed dose of lungs and heart in IMRT of middle and upper esophageal cancer,and established a relevant mathematical model to provide predictions for the absorbed dose of lungs and heart in IMRT of esophageal cancer.METHODS Fifty patients with esophageal cancer treated in the Department of Oncology of the Affiliated Hospital of Southwest Medical University from July 2013 to December 2017 were selected randomly,the correlation between the target volume lung and heart volume and their absorbed doses in the radiotherapy plan was analyzed and relevant formula was fitted by using SPSS 17.0.RESULTS Lung volume(Vlung)was negatively related to normalized mean dose of the lung(Dnmean=Dmean/Dprescription),Dn5%,Dn25%,Dn50%,Dn75%and Dn95%,all P<0.05;the intersecting volume(Vo-lung/Vlung)between the normalized lung and planning target volumes(PTV)was positively related to Dnmean,Dn5%,Dn25%,Dn50%,Dn75%and Dn95%,P<0.05.There was no correlation between heart volume(Vheart)and normalized mean dose(Dnmean)of heart,normalized Dn5%,Dn25%,Dn50%,Dn75%and Dn95%,all P>0.05;PTV was positively related to the intersecting volume of heart(Vo-heart),Dnmean,Dn5%,Dn25%,Dn50%,Dn75%and Dn95%,all P<0.05.For all fitting formulas,all P<0.001.CONCLUSIONS In this study,a mathematical model for predicting the absorbed dose of lung and heart in IMRT of middle and upper esophageal cancer was successfully established,and according to the Pvalue of fitting formulas,the result was more accurate.Different treatment plan systems can use this method to build an OAR(organs-at-risk)predicted dose model suitable for their respective systems,eliminating the need to purchase new software modules.