Wang Su-zhen, Li Jian-bin, Wang Wei, Zhang Ying-jie, Li Feng-xiang, Fan Ting-yong, Shang Dong-ping
Department of Radiation Oncology, Shandong Cancer Hospital & Institute, Jinan 250117, China.
Zhonghua Zhong Liu Za Zhi. 2012 Mar;34(3):201-4. doi: 10.3760/cma.j.issn.0253-3766.2012.03.009.
To explore the displacement of the selected clips and the center of the geometry consisted of all the clips in the surgical cavity measured on the basis of four-dimensional computed tomography (4D-CT) simulation images.
Fourteen breast cancer patients after breast-conserving surgery were recruited for external beam partial-breast irradiation (EB-PBI), and received large aperture CT simulation. The 4D-CT image data sets were collected when the patient was in the free breathing state. Using the Varian Eclipse treatment planning system, the selected four clips in the cavity were separately delineated on the CT images from 10 phases of the breath cycle, and all of the clips in the cavity were marked to obtain the geometry. Then the displacement of the four selected clips and the center of the geometry in the left-right (LR), anterior-posterior (AP), and superior-inferior (SI) directions were measured. The differences of the displacement were compared.
The displacements in the AP and SI directions were always greater than the displacement in LR direction for the same selected clip. The difference of the displacements in the same direction of the different selected clips was not statistically significant (P>0.05). The displacements of the geometry center consisted of all of the clips in the LR, AP, SI directions were (1.34±0.39) mm, (2.01±1.02) mm and (1.89±1.03) mm, respectively, and the difference of the displacements between LR and AP, LR and SI were all statistically significant (P<0.05). In the same directions (LR, AP and SI), the displacement of geometry center was always greater than the displacement of the selected clips, and the difference except SI direction was all statistically significant (P<0.05). In the SI direction, the association between the displacement of geometry center and the upper clip, geometry center and the lower clip was statistically significant (P<0.05).
When the target for EB-PBI is defined on the basis of 4D-CT simulation images, the displacement of the selected clips at the border of the surgical cavity is not qualified to substitute the displacement of the target defined basing on all of the clips in the surgical cavity.
探讨基于四维计算机断层扫描（4D-CT）模拟图像测量手术腔隙中所选金属夹及由所有金属夹构成的几何体中心的位移情况。
招募14例行保乳手术的乳腺癌患者接受外照射部分乳腺放疗（EB-PBI），并进行大孔径CT模拟。在患者自由呼吸状态下采集4D-CT图像数据集。使用瓦里安Eclipse治疗计划系统，在呼吸周期的10个时相的CT图像上分别勾画出腔隙内所选的4个金属夹，并标记出腔隙内所有金属夹以获得几何体。然后测量所选4个金属夹以及几何体中心在左右（LR）、前后（AP）和上下（SI）方向上的位移。比较位移的差异。
对于同一所选金属夹，AP和SI方向上的位移始终大于LR方向上的位移。不同所选金属夹在同一方向上的位移差异无统计学意义（P>0.05）。由所有金属夹构成的几何体中心在LR、AP、SI方向上的位移分别为（1.34±0.39）mm、（2.01±1.02）mm和（1.89±1.03）mm，LR与AP、LR与SI之间的位移差异均有统计学意义（P<0.05）。在相同方向（LR、AP和SI）上，几何体中心的位移始终大于所选金属夹的位移，除SI方向外差异均有统计学意义（P<0.05）。在SI方向上，几何体中心与上方金属夹、几何体中心与下方金属夹的位移之间的相关性有统计学意义（P<0.05）。
当基于4D-CT模拟图像定义EB-PBI的靶区时，手术腔隙边界处所选金属夹的位移不足以替代基于手术腔隙内所有金属夹定义的靶区的位移。
