中文摘要：

目的：通过比较不同静态IMRT和VMAT计划靶区剂量分布与正常组织照射情况，以明确原发纵隔B细胞淋巴瘤（ PMBCL）患者最佳IMRT方式。方法共16例（男女各8例）首程放疗的Ann？ArborⅠ期PMBCL患者纳入研究。 PGTV与PTV分别给予45 Gy与40 Gy。每例患者均设计4种调强计划：静态IMRT （5F？IMRT、7F？IMRT、9F？IMRT）和VMAT计划，评估各计划靶区剂量分布、正常组织照射剂量与计划实施效率。单向方差分析剂量差异。结果5F？、7F？、9F？IMRT、VMAT 的PGTV平均CI值和HI值分别为1．01和1．10、1．01和1．10、1．01和1．10、1．01和1．11（ P＝0．963和0．843），PTV平均CI值和HI值分别为1．04和1．22、1．03和1．19、1．03和1．17、1．08和1．14（P＝0．964和0．969）。正常组织体积剂量参数均相近（ P＝0．192～1．000）。9F？IMRT计划治疗时间和机器跳数明显高于其他静态 IMRT 与 VMAT （ P＝0．000、0．000），其中 VMAT 机器跳数最少（13345．0 MU）、治疗时间最短（5．9 mins ）。结论7F？与9F？IMRT 靶区覆盖度比5F？IMRT 与 VMAT 更好。VMAT在早期PMBCL中较IMRT无剂量学优势，尤其是乳腺低剂量照射范围较大，但实施效率更佳。

英文摘要：

Objective To compare target dosimetric distribution and normal tissue radiation between different static intensity？modulated radiation therapy （ IMRT） plans and volumetric modulated arc therapy （ VMAT） and to identify the best IMRT plan for patients with primary mediastinal B？cell lymphoma （ PMBCL） . Methods A total of 16 patients （ 8 males and 8 females） with early？stage （ Ann？Arbor stageⅠ） PMBCL were enrolled in this study,with doses of 45 Gy for primary gross tumor volume （ PGTV） and 40 Gy for planning target volume （PTV）.Four plans were designed for each patient,consisting of static IMRT （5F？IMRT,7F？IMRT,9F？IMRT） and VMAT,and the target dosimetric distribution,normal tissue radiation dose,and efficiency of each plan were evaluated. The difference of dose was analyzed by analysis of variance. Results The mean conformity index （ CI） and homogeneity index （ HI） for PGTV in 5F？,7F？,9F？IMRT and VMAT were 1. 01 and 1. 10, 1. 01 and 1. 10, 1. 01 and 1. 10, and 1. 01 and 1. 11 （ P= 0. 963 and 0. 843） ,respectively,while these two indices for PTV were 1. 04 and 1. 22,1. 03 and 1. 19,1. 03 and 1. 17, and 1. 08 and 1. 14（ P=0. 964 and 0. 969） ,respectively. The parameters of volume and dose were similar on normal tissue （ P= 0. 192？1. 000 ） . The treatment time and number of monitor units in 9F？IMRT were significantly higher than those in other static IMRT plans and VMAT （ P=0. 000,0. 000） ,and among these plans,VMAT had the lowest number of monitor units （ 13 345. 0 MU） and the shortest treatment time （ 5. 9 min） . Conclusions The target volume coverage of 7F？and 9F？IMRT is better than that of 5F？IMRT and VMAT.For early？stage PMBCL,VMAT is not superior to IMRT in terms of dosimetry,especially with a larger area of low？dose radiation to the breast,but it is highly efficient in practice.