摘要：提出一种树状体数据的骨架自动提取算法.通过适当地定义体素的间距,就可以借助区域生长技术在体数据中生成从给定根节点到所有体素的最短距离图.基于此距离图,骨架提取算法即可自动检测出所有体数据分支的结束节点及其到根节点的最短路径.然后,通过中心化算法删除冗余点,且保证剩余节点集中于树状体数据的中轴线上.该算法产生的骨架具有单体素宽度和26邻域连通性,可以用作虚拟内窥镜的自动漫游路径,实现所有分支的内表面浏览的自动导航.

摘要：A simple procedure to plan, verify and implement craniospinal irradiation（CSI） with patients supine is presented. Treatment is conducted with a single posterior spinal field abutting two lateral cranial fields. The opposed lateral fields are half-blocked and the inferior line is perpendicular. The posterior field uses some fixed field parameters so that the cephalad edge of the posterior field is coplanar with the caudal edges of the lateral fields and it is independent of the height of the couch. A steel-shot ball is used to measure the size of overlap or gap at the junction using portal images of an electron portal image device or portal films. The results of analyzing the portal images show that the errors of the junction are within ± 1 mm. The dose-volume histograms （DVHs）show that there are not unbearable hot or cold spots in the clinic target volumes （CTVs）. Supine craniospinal treatment is a reliable and convenient alternative to treatment in the prone position and avoids the technical difficulties of the latter. The use of fixed field geometry greatly facilitates treatment planning and effectively reduces the amount of time of setup, verification and treatment.