ABSTRACT
Objective To evaluate the optimized simultaneous integrated boost intensity-modulated radiotherapy (SIB-IMRT) plans in cervical esophageal carcinoma underwent prophylactic lymphatic irradiation.MethodsSix patients with cervical esophageal carcinoma were studied.The gross tumor volume (GTV) and clinical target volume (CTV) (including bilateral mid-lower neck and supraclavicular lymph drainage regions,upper mediastinal lymph drainage regions) were delineated on sim-CT images,GTV and CTV were uniformly expanded by 5 mm to create PGTV and PTV.Five fields(5F) ,7F and 9F SIB-IMRT plans were designed.The prescribed doses to PGTV and PTV were 66 Gy and 60 Gy in 30 fractions respectively.The parameters of dose-volume histograms in three groups planning were compared.Results The values of conformity index(CI) of PGTV were 0.56,0.62 and 0.69 (F =6.22,P ＜0.01 ),the V66 with 88.24% ,95.03% and 94.91% ( F = 4.39,P ＜ 0.05 ) and D95 with 6539.67,6601.83 and 6602.00 cGy (F=4.46,P ＜0.05) in 5F,7F and 9F SIB-IMRT plans.The values of CI,V66 and D95 of PTV were 0.80,0.85 and 0.87 (F=11.29,P＜0.01),with 91.64%,94.05% and 95.06% (F=4.10,P＜0.05) and with 5934.00,5987.17 and 6006.33 cGy (F =4.01,P ＜0.05).The values of maximal dose of spinal cord were 4707.17,4497.83 and 4357.00 cGy( F = 11.26 ,P ＜0.011 ) in 5F ,7F and 9F SIB-IMRT plans.The values of all dosimetic parameters about PGTV and PTV were same in 7F and 9F SIB-IMRT plans ( all P ＞ 0.05 ).Conclusion 7F-SIB-IMRT plan is best one scheme for cervical esophageal carcinoma underwent prophylactic lymphatic irradiation.