中文摘要：

目的应用数字技术探讨胸椎椎弓根进钉通道不同外偏角方向的变化规律。方法健康成人胸椎CT连续扫描数据集,应用Mimics 10.01三维重建胸椎数字解剖模型,将模型导入UG Imageware12.0,确定椎骨正中矢状切面和经椎弓根中部水平面为0°正交平面,0°水平面为头尾偏角参考平面,正中矢状切面为水平面角参考平面,确定左右椎弓根各个方向进钉通道的正投影,获得椎弓根进钉通道的正投影内边界和内边界内切圆,以及内切圆在正投影方向经椎板、椎弓根与椎体的进钉通道长度和各内切圆半径,对获取的相关数据进行统计学分析和可视化显示。结果 （1）T2～T12内切圆半径：在节段之间T7最小,内切圆半径2.3～4.5mm;在角度之间,内切圆半径2.3～3.5mm,其中0°～20°内切圆半径分别为：左3.4～3.5mm,右3.3～3.5mm,相差0.1～0.2mm。进钉通道长度：在节段之间,通道长度26.9～47.8mm,T2最小,T9最大;在角度之间,通道长度23.1～53.2mm,其中0°～20°通道长度分别为：左23.1～39.7mm,右24.8～41.6mm。（2）胸椎椎弓根通道长度随着角度的增大而增大,内切圆半径的大小随着角度的增大先逐渐增大而后又逐渐减小。胸椎不同节段、不同水平面角的内切圆半径和通道长度各不相同,部分节段的内切圆半径和通道长度在左右侧别之间存在差异。结论 （1）椎弓根进钉通道是任意方向椎弓根内部三维空间正投影内边界在椎体与椎板之间的通道。它是一个动态的变化空间,一定范围内任意一个三维空间方向对应着一个椎弓根进钉通道,该椎弓根进钉通道对应着一个最大螺钉通道,该最大螺钉通道对应着最佳轴线和进钉点。（2）T2～T12左右侧0°～20°水平面角之间是内切圆半径相对较大而通道长度相对较短的区域,25°～40°则相反。

英文摘要：

Objectives To investigate the changing regularity of thoracic pedicle screw channel （PSC） in different transverse screw angle （TSA）. Methods CT scan images of thoracic vertebrae of a healthy adult were digitally analyzed by Mimics 10.01 software to establish three-dimensional models which were saved as .stl format and then imported into Image ware 12.0 software. Cross section planes were located in the vertebral middle sagittal section and the pedicle central transverse plane. Thoracic PSC were projected along in a vertical direction, inner borderline of each direction project and the following inscribed circle of each inner borderline were obtained. The radius of inscribed circle of each inner borderline was recorded, PSC length was measured. Results In different segments, radius of inscribed circle of T2-T12 was 2.3-4.5 mm, the smallest of was T7. In different angles, that of T2-T12 was 2.3-3.5mm.Radius of left and right inscribed circle of T2-T12 from 0° to 20° was 3.4-3.5 mm and 3.3-3.5 mm respectively, while the difference between both sides was 0.1-0.2 mm. In different segments, PSC length of T2-T12 was 26.9-47.8 mm which that of T2 was the shortest and that of T9 was the longest.In different angles, PSC length of T2-T12 was 23.1-53.2 mm while that of left and right side from 0o to 20o was respectively 23.1-39.7 mm and 24.8-41.6 mm. With the increased TSA, thoracic PSC length also lengthened while radius of inscribed circle increased gradually at first, and subsequently decreased.Radius of inscribed circle and PSC length were different in different thoracic segment and different TSA, and those in partial segments between left and right side containing differences. Conclusions 1. PSC is the channel of interior boundary of positive projection of pedicle three-dimensional space corresponding to the centrum and lamina in any random orientation.In certain scope, a three-dimensional direction is corresponding to a PSC while this PSC corresponds to the biggest screw channel, and the biggest channel corre