目的：研究在椎体追踪和肺追踪模式下，定位中心的改变对靶区剂量分布的影响。方法：选取3例肺癌患者，对椎体追踪靶区2例和肺追踪靶区1例进行计划设计，椎体追踪靶区分为靠近椎体病变和远离椎体病变。选择与靶区中心对应的定位中心进行计划设计，逐渐改变定位中心，每移动一个椎体设计一个计划，计划命名为T1-T5。结果：采用椎体追踪的靶区剂量分布参数均有所变化，其中覆盖靶区体积改变较大，如靠近椎体靶区的覆盖靶区体积由95.73%改变为93.08%，而远离椎体靶区的覆盖靶区体积由98.52%改变为90.42%。采用肺追踪的靶区剂量分布不随定位中心的改变而改变。结论：采用椎体追踪的靶区，定位中心的改变对靶区分布有一定影响，当定位中心改变较小时，剂量分布变化不大，而当定位中心改变较大时，剂量分布有较大的变化，其中远离椎体的靶区剂量分布改变较靠近椎体的稍大；采用肺追踪模式的靶区，定位中心的改变对靶区剂量分布无影响。%Objective:To investigate the influence of target dose distribution with the changes of align center in both Xsignt_spine and Xsight_lung tracking methods.Methods: Two cases using Xsight spine method and one case using Xsight_lung method were selected, one case was close to the spine and another was far away from the spine in Xsight_spine tracking targets, designed the treatment planning of all targets with the Cyberknife treatment planning system. First select the align center corresponding to target center to design the planning, then changed the align center gradually and designed a treatment plan when moving a spine, planning named as T1-T5.Results: The target dose distributions were changed of five planning in each target using Xsight_spine tracking methods, the change of coverage target volume was a little bigger than other parameters, the coverage target volume was from 95.73% to 93.08% in the target close to spine, and the coverage target volume was from 98.52% to 96.57% in the target away from spine. The dose distribution using Xsight_lung methods didn’t change with the align center.Conclusion: The influence of target dose distribution is definite with the change of align center with the targets using Xsight_spine methods. The change of dose distribution was not big when the change of align center was small, but when the change of align center was bigger, the dose distribution had great changes, the change of dose distribution with away from the spine was bigger than which close to the spine. The target dose distribution was constant with the change of align center under using Xsight_lung method.
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