Comparison On Dosimetric Analysis And Risk Prediction Of Radiation-induced Heart Disease In Patients With Middle Esophageal Cancerradical Radiatherapy

Objective:Esophageal cancer is one of the most common tumors in China.Most patients with esophageal cancer need radiotherapy in the course of treatment.Cardiovascular complications caused by radiotherapy is the first non-tumor cause of death after radiotherapy for chest tumors.So,reducing radiation-induced heart disease is particularly important.By comparing dosimetric characteristics of three kinds of radiation techniques(helical tomotherapy(TOMO),intensity-modulated radiotherapy(IMRT)and Volumetric Modulated Arc Therapy(VMAT))for patients with middle esophageal carcinoma,and predicting the risk of Radiation-induced heart disease(RIHD),to provide reference for the choice of clinical treatment.Methods:A total of 10 patients with middle esophageal carcinoma diagnosed by pathology and imaging from May 11 th 2015 to April 5th 2017 in radiotherapy unit of Chongqing Cancer Hospital.The target volume and organs at risk(OARs)were contoured in CT image,moreover,IMRT,VMAT and TOMO plans were designed respectively.We evaluated the planning target volume(PTV)and OARs by the dosimetric parameters,and predicted the risk of RIHD by fitting dose response curve.SPSS 22.0 was used for statistical analysis of the dose data.Results:For PGTV,TOMO plan(Dmax=67.37Gy;Dmin=62.80Gy)showed statistical significance F=9.56 P<0.001;F=6.50 P=0.005)compared to IMRT(Dmax=67.58Gy;Dmin=62.02Gy)and VMAT(Dmax=67.71Gy;Dmin= 62.05 Gy).The homogeneity index(HI=0.06)and conformity index(CI95%=0.71)of TOMO showed statistical significance(FHI=12.32 PHI=0.001,FCI95%=7.40 PCI95%=0.003)compared to IMRT(HI=0.09;CI95%=0.64)and VMAT(HI=0.09;CI95%=0.59).The difference of V20 showed statistical significance(TOMO/IMRT/VMAT=24.76/31.46/31.44,F=9.79,P=0.001)of lungs in TOMO 、IMRT and VMAT plans.The risk of RIHD was lowest in VMAT plan(AER:VMAT/IMRT/TOMO=10.66/18.07/13.79,F=14.69,P<0.001).Conclusions: As VMAT reduced the risk of radiation-induced cardiac injury,the dose of dual lung was significantly increased.TOMO can reduce the risk of radiation induced heart injury and the radiation dose of dual lung.TOMO still has its advantage.