CADPLAN(helios)调强放疗计划的绝对剂量验证

Absolute dose verification of intensity modulated radiation therapy on CADPLAN(helios)

目的:验证CADPLAN(helios)设计的病人调强放射治疗(IMRT)计划的绝对剂量准确性,保证IMRT治疗计划临床实施的正确性。方法:利用美国Varian 23-EX医用直线加速器6MV-X射线,根据经国家计量院校准过的0.6 cc电离室在体部模体中校准0.01 cc电离室;根据病人的CT图像资料,使用CADPLAN(helios)三维治疗计划系统设计出病人IMRT计划,并移置到模体中,重新计算出体模中过等中心点横截面上的剂量分布。将模体移放到加速器治疗床上,调用模体IMRT计划对模体进行照射。使用0.01 cc电离室测量出体模中等中心点及其周围两个感兴趣点上的吸收剂量,然后与模体计划中的计算值相比较。结果:空间三点绝对吸收剂量的测量值与计划值的偏差小于5%。结论:在准确、合理配置CADPLAN(helios)计划系统基础数据的情况下,利用它设计出的IMRT计划是可信的。

Objective： To ensure the accuracy of radiation therapy plan throughout the absolute dose verification of intensity modiulated radiation therapy on CADPLAN（helios）. Methods： Here we describe the procedure developed in the our hospital, and present the verification detailed steps and results of the patient. The procedure is composed of four steps that are the calibration for 0.01 cc ionization chamber, the design IMRT plan with Helios inverse planning system, the phantom plan, the dose distrbution in a transverse plane. We irradiated the phantom with 6-MV X ray generated by VARIAN 23EX accelerator. We measured the absolute absorbed doses at three reference points with 0.01 cc ionization and a FARMER 2570B dosimeter. Results： The dos error was within the preset tolerance （5%）. Conclusion： The IMRT plan designed with our CADPLAN（helios） is dependable.