Hao Chang, Can Liang, HongqiYu, Dongjie He, Suna Zhou,Qiming Wang, Zongyan Yu, Qiuju Shao

Department of Radiotherapy, TangDu Hospital, FourthMilitary Medical University

Objective:Proposed a new IMRT treatment planningtechnique with the potential of reducing low dose region of the lungs inesophageal cancer patients treated with definitive chemoradiotherapy. Method:Ten patients with middle and/or distal thoracic esophageal cancer wereenrolled. For fixed overlap field-IMRT plan (FOF-IMRT), beams were targeteddifferently to the higher portion and lower portion from the trachea level.5F-IMRT and 7F-IMRTplans were placed at equal angles. Result: Thehomogeneity index of the FOF-IMRT plans was significantly better comparedto5F-IMRT and 7F-IMRT plans (P=0.000, 0.003), but the conformity indexof the FOF-IMRT plans was lower than 5F-IMRT and 7F-IMRT plans (P=0.011,0.014). Total lung V5 of the FOF-IMRT was decreased significantly 20.12% [95%confidence intervals (CI) 12.94-27.30] and 20.88% (95%CI 13.69-28.06) comparedwith 5F-IMRT and 7F-IMRT. TheV10 decreased level was 10.39% (95%CI 5.17-15.60)and 10.20%(95%CI 4.98-15.42). For the heart, the mean dose,V30, V35, and V40values of the FOF-IMRT plans were higher than equispaced coplanar IMRT plansbut there was no significant difference (P>0.05). The Dmax values forthe spinal cord among the all plans was not more than 45Gy. Conclusion: FOF-IMRTplans was useful in clinical practice in terms of reducing the low-dose regionof the lungs in middle and/or distal thoracic esophageal cancer patients withcervical and upper media stinal lymph node metastasis.

Key Words: esophageal cancer  intensity modulated radiotherapy