Value Of Magnetic Resonance Diffusion Weighted Imaging In Re-course Intensity Modulated Radiation Therapy For Locally Recurrent Esophageal Cancer After Radiotherapy

ObjectiveTo explore the effect of target area delineated according to DWI and CT fusion images on target volume and dose of normal lung tissue,heart and spinal cord in local recurrence of esophageal squamous cell carcinoma after radical radiotherapy patients with re-course Intensity Modulated Radiation Therapy.MethodsTwenty patients with recurrent esophageal cancer received radiotherapy in our hospital since 2016 were randomly selected as the research objects.The recurrent esophageal cancers were conformed by endoscopic pathological results,All the enrolled patients were excluded from the contraindications of re-radiotherapy and voluntarily joined the study,the KPS score was > 70,.CT and MRI images were acquisited under the same fixed position,the upper bound of the scanning range was the cricothyroid membrane level,and the lower bound was the edge of the liver.CT,MRI image data of the same patient was transmitted to the United States VARIAN treatment planning system through the network,tthe CT and DWI images were fused and three dimensionally econstructed to ensure the quality of image fusion.According to tumor size shape,organ movement and positioning error,Gross tumor volume(CTV)and Planning target volume(PTV)were respectively plotted on enhanced CT images and CT/MR fusion images.Three physicians in the radiotherapy department participated in the delineation of the target area to reduce the bias caused by subjective factors.Gross tumor target(GTV)includes esophageal lesions and regional metastatic lymph nodes demonstrated by imaging results.The clinical target area(CTV)was O.5-1.Ocm,left and right,before and after GTV,and 2.Ocm,left and right,respectively.The planned target area(PTV)is O.The lungs,heart and spinal cord were delineated as organs at risk(OAR).The volumes of GTV and PTV in the two target areas of the same patient group were calculated respectively,and statistical differences were compared between the two groups.To apply the same patients of two groups of target Monaco plan design system,by experienced physical teacher radiotherapy planning respectively,95% isodose curve contains PTV prescription dose for a 50.4 Gy/28 times,1.8 Gy/times,five times per week,statistics of two groups plan GTV size,double lung by according to the volume of 5 Gy(V5),the volume of 20 Gy(V20),the volume of 30 Gy(V30)and the average dose(MLD),The heart was exposed to 30 Gy volume(V30),40 Gy volume(V40)and the maximum dose of spinal cord(Dmax),and there was no statistical difference between them.ResultsThe volume of GTV and PTV in CT/DWI fusion group was smaller than that in CT group;the difference was statistically significant(P<0.05).When the prescription dose reached 50.4Gy/28 times,the two lungs V5,V20,V30 and MLD in the CT/DWI fusion group were lower than those in the CT group,the difference was statistically significant(P<0.05).Spinal cord Dmax in CT/DWI fusion group was lower than that in CT group,the difference was statistically significant(P<0.05).The heart V30 and V40 in the CT/DWI fusion group were lower than those in the CT group,the difference was statistically significant(P<0.05).ConclusionDWI and CT fusion images were used to delineate the target area of esophageal cancer in patients with recurrent esophageal cancer after radiotherapy,and the accuracy of the target area was improved compared with the traditional CT method,and it is beneficial to reduce the irradiation dose of normal tissue.It is worthy of further research and application in clinical practice.