锥形束CT引导自主呼吸控制保乳术后三维适形部分乳腺外照射术腔中银夹位移的研究  

Cone-beam computed tomography guided study on silver clips displacement in breast cancer patients treated by three-dimensional conformal partial breast irradiation assisted by active breathing control after breast-conserving surgery

作　　者：刘翠翠[1] 李建彬[1] 范廷勇[1] 白瞳[2] 孙涛[2] 余宁莎[3] 尹勇[2] 刘同海[2] 张英杰[1] 

机构地区：[1]山东省肿瘤医院放疗一科,济南250117 [2]山东省肿瘤医院物理室,济南250117 [3]山东省肿瘤医院IGRT技术组,济南250117

出　　处：《中华放射肿瘤学杂志》2008年第1期43-46,共4页Chinese Journal of Radiation Oncology

摘　　要：目的锥形束CT（CBCT）引导测定术腔中银夹位移以探讨保乳术后三维适形部分乳腺外照射（EB-PBI）临床靶体积（CTV）外扩到计划靶体积（PTV）的边界。方法自主呼吸控制（ABC）辅助行CT模拟定位扫描，获取适度深吸气呼吸控制（mDIBH）状态CT图像，分别勾画和标记术腔中4个选定银夹，并勾画所有银夹构成的术腔作为肉眼靶体积（GTV）。每次照射前获取ABC辅助mDIBH状态下2次CBCT扫描图像。每次获取CBCT图像后先与计划CT图像自动匹配，在自动匹配基础上对选定银夹进行手动匹配。获得选定银夹在左右、上下、前后各个方向的位移数据，依据获取的数据分别计算选定银夹放疗分次内和分次间群体系统误差的标准差和群体随机误差的标准差及总体系统误差和总体随机误差的标准差，依据公式M=2．5∑总＋0．7σ总计算各个选定银夹在各个方向上由CTV外扩到PTV所需要边界大小。结果最上层银夹LAT、LNG、VRT方向由CTV到PTV的外扩边界分别为9．2、6．4、12．0mm，最近胸壁层银夹为8．1、8．0、11．7mm，最外侧银夹为9．8、7．7、12．5mm，最下层银夹为9．8、7．7、12．5mm。结论ABC辅助mDIBH状态下CBCT图像与计划CT图像自动加手动配准可准确显示银夹位移，为EB-PBI的PTV边界确定提供了依据。Objective To study the displacement of silver clips guided by cone-beam computed tomography （CBCT） to explore the margin of clinical target volume （CTV） to planning target volume （PTV） for breast cancer patients treated by throe-dimensional conformal external-beam partial breast irradiation （EB-PBI） assisted by active breathing control （ABC） after breast-conserving surgery. Methods All patients received CT simulated positioning assisted by ABC to get CT imags based on the respiratory condition of moderate deep inspiration breath hold （ mDIBH）, and the images were transferred to Varian Eclipse treatment planning system. Four silver clips located at the cephal, pedal, lateral border and bottom of the cavity were delineated respectively and the cavity based on all of the clips were delineated as gross tumor volume （GTV）. The treatment planning for EB-PBI was performed in Varian 23 EX linear accelerator equipped with kilovohage（kV） CBCT image-guided system named On-Board Imager （OBI） system. Before each irradiation, kV-CBCT were carried out twice for patients on the respiratory condition of mDIBH assisted by ABC device with the same threshold as CT simulated positioning to get the CBCT images. 3D-3D automatic registration based on pixel between the CBCT image and the planning CT image was finished and the diplacement on EAT, LNG and VRT directions were recorded, and then the marked clips were registered by hand movement based on the automatic registration and the shifts and directions were also recorded. A total of eight groups data of displacement of each marked clip for each patient were got from four fractions with two groups data during each fraction. Based on the registration data of the marked clips, the intrafraction and interfraction group systematic errors （∑intra a vs ∑intra ） and group random errors （ σintra vs σintra ） were analysed. General group systematic error ∑general and general random error σgeneral were calculated based on combination of intrafr

关 键 词：部分乳腺/三维适形放射疗法 自主呼吸控制 锥形束CT 银夹位移 

分 类 号：R686[医药卫生—骨科学]