中文摘要：

目的探讨适度深吸气呼吸控制（mDIBH）状态下部分乳腺外照射（EB-PBI）时基于不同参照物配准对术腔中全部银夹构成几何体分次内位移的影响。方法选择拟行EB—PBI患者27例，采集2套mDIBH状态CT模拟定位扫描图像，标记术腔中全部银夹，获得全部银夹构成几何体中心，在2套mDIBH图像间自动配准的基础上，分别根据术腔中最上层银夹、术腔中心层面前界乳腺皮肤及离术腔最近的体表金属标记进行手动配准，分别测量3种配准方式所对应的银夹构成几何体中心在左右、前后和头脚方向上的位移。结果基于最上层银夹配准时，银夹构成几何体中心在左右、前后和头脚方向上的位移分别为（0．61±0．62）mm、（0．63±0．59）mm和（0．91±0．96）mm；基于选定区域皮肤配准时，在左右、前后和头脚方向上的位移分别为（1．11±1．21）mm、（0．92±0．93）mm和（2．13±2．12）mm；基于选定体表金属标记配准时，在左右、前后和头脚方向上的位移分别为（1．31±1．55）mm、（1．19±1．24）mm和（1．93±1．55）mm。3种配准方式所致银夹构成几何体中心在同一方向间的位移比较，仅在头脚方向上最上层银夹配准与皮肤配准间和体表金属标记配准间的差异有统计学意义（t值分别为5．045和7．210，P值分别为0．025和0．007）。3种配准方式所致银夹构成几何体中心在各自三维方向上的位移差异均无统计学意义（均P〉0．05）。结论mDIBH状态下实施EB—PBI时，基于术腔中选定银夹配准进行分次内靶区位移测量应当是合理的选择，而基于选定区域皮肤和基于体表金属标记配准均会导致计划靶区头脚方向边界的过度外扩。

英文摘要：

Objective To investigate the influence of registration based on different reference markers on the displacement of the geometry consisted of all clips in the cavity for external-beam partial breast irradiation at moderate deep inspiration breath holding assisted by active breathing control device. Methods Twenty-seven early stage breast cancer patients feasible for external beam partial breast irradiation （EB-PBI） were selected. The patients undertaken three-dimensional computed tomography （3DCT） simulation scan at moderate deep inspiration breath holding （mDIBH） assisted by active breathing control device, and two sets of mDIBH CT images were got and transferred to the Pinnacle 3 planning system. All of the silver clips were delineated and a geometry consisted of all clips were generated. On the account of automatic registration of mDIBH CT images, manual registration was carried out based separately on the topside clip in the cavity, the labeled skin at anterior surface of the cavity at central level and the metal mark on the body surface near the cavity, then the displacements of center of the geometry in left-right （LR）, anterior-posterior （AP） and superior-inferior （SI） directions based separately on the three registrations were measured. Results The displacements of center of the geometry in LR, AP and SI directions based on registration of the clips, the labeled skin and the metal mark were （0.61 ± 0.62） mm vs. （1.11±1. 21） mm vs. （1.31 ±1.55）mm, （0.63 ±0.59）mm vs. （ 0. 92 ±0. 93 ） mm vs. （1.19± 1.2g）mm and （0.91 ±0.96）mm vs. （2.13±2.12）mm vs. （1.93±1.55）mm, respectively. Compared the displacements of center of the geometry in the same direction between the three registrations, significant differences were found only in SI direction between chp registration and skin registration, clip registration and mark registration （ t = 5. 045,7. 210 and P = 0. 025, 0. 007） . Compared the displacements of center of the geometry between three dime