IMRT计划在不同加速器上互换执行的可行性

Research on the Feasibility of Exchanging IMRT Plans Between Two Accelerators with Different MLC Leaf Widths

目的探讨调强放疗(IMRT)计划在不同多叶光栅(MLC)叶片宽度配置的加速器上互换执行的可行性。方法将设计在EX加速器上执行的5例鼻咽癌IMRT(SW)计划,不进行重新优化和计算,直接移植到IX加速器上执行;以及通过治疗计划系统(TPS)模拟在IX加速器执行1、2、3、4、5、10次后再返回EX加速器继续执行,用剂量体积直方图(DVH)分析和评估靶区和危及器官的剂量体积参数的变化。结果将EX加速器的IMRT计划完全移植到IX加速器执行,以及在IX加速器执行1、2、3、4、5、10次后再返回至EX加速器继续执行时,靶区和危及器官的剂量体积参数发生了一定程度的变化,前者的变化更大。结论若两台加速器产自同一个厂家,且能量配置和治疗时的机械参数相同时,当一台加速器发生故障且短时间内无法修复时,可以将其治疗计划移植至另一台加速器上执行(5次以内),待故障加速器修复后再返回原计划加速器执行。

Objective To explore the feasibility of exchanging IMRT plans between two accelerators with different MLC leaf widths. Methods Five IMRT plans ofnasopharyngeal cancer which were designed for EX accelerator were directly executed through IX accelerator without reoptimization and recalculation （method 1）. The same IMRT plans were firstly executed through IX accelerator for 1, 2, 3, 4, 5, 10 times and then were executed through EX accelerator （method 2）. Then the dose volume parameters of target region and organs at risk were analyzed and evaluated with dose-volume histogram （DVH）. Results After the exchange of IMRT plans between two accelerators with different MLC leaf widths, the dose volume parameters of target region and organs at risk had changed. The rangeability of the dose volume parameters of method 1 is larger than that of method 2. Conclusion When an accelerator is out of order, its IMRT plans can be executed less than 5 times through another accelerator with the same energy configuration and mechanical parameters, which was produced by the same vendor. The IMRT plans should be executed by the original accelerator when it is repaired.