摘要
目的 通过硅橡胶模型模拟实验探讨置入软组织内金标数目对射波刀系统影像定位精度的影响.方法 模型内层为刚体结构,使用Accuray公司设计的球方模型;实验中用5个金标进行摆位以确定参考位置.模型外层为模拟人体软组织的非刚体性结构,使用双组分加成型硅橡胶;实验中用8个金标按不同数目的 排列组合获取影像定位数据,比较其与参考位置在平移参量和旋转参量方面差值以此探讨追踪不同数目金标对影像定位精度的影响.结果 追踪4个金标时平均每个金标对平移和旋转参量误差下降的贡献最大,分别为0.086 mm和0.033°.1～4个金标的平移参量误差下降了0.343 mm,4～8个金标的下降了0.077 mm.3～4个金标旋转参量误差下降了0.131°,4～8个金标的下降了0.090°.结论 追踪4个金标时平均每个金标对误差降低的贡献最大.金标置入4个以下时每多置1个金标对影像定位精度明显增加,置入4个以上时再增加置入金标数目对定位精度无明显改善.置入4个金标是同时兼顾降低患者痛苦和增加定位精度的一个适宜选择.
Objective To find a proper number of implanted fiducials in order to reconcile both more accurate image tacking and less pain for the patients.Methods The phantom was made of two parts of different materials.The inner part was a ball-cube phantom developed by Accuray Corporation, which could be regarded as a rigid body, with 5 fiducials inside using as the reference to align the whole phantom in the experiment.The outer part was made of additional silicone rubber with two components to simulate soft tissue as a non-rigid body, which was implanted with 8 fiducials inside.All combinations of different number of fiducials were tracked to aquire the target location information, which were then compared with the reference position that was set by the inner 5 fiducials to obtain the deviations of the translation and the rotation parameters.Thus the impact of the number of fiducials on image target localization accuracy could be analyzed easily.Results When 4 fiducials are used for tracking, the decline of translation and rotation errors for every fiducial is largest （0.086 mm and 0.033°）.The translation error was decreased by 0.343 mm from 1 to 4 fiducials, while by only 0.077 mm from 4 to 8 fiducials;the same decline was observed for rotation errors （0.131° for 3 to 4 fiducials , and 0.09° for 4 to 8 fiducials , respectively） .Conclusions When 4 fiducials are used for tracking, the decline of errors for every fiducial is maximum.When one more fiducial is adding, the image target localization accuracy can be enhanced obviously from 1 to 4 fiducials, but not as obvious for more than 4 fiducials.
出处
《中华放射肿瘤学杂志》
CSCD
北大核心
2010年第5期465-467,共3页
Chinese Journal of Radiation Oncology
关键词
放射疗法
射波刀
金标数目
靶位置精度
Radiotherapy,cyberknife
Number of fiducials
Target localization accuracy
