一种用于调强适形放疗剂量验证模型的研究

Dose Verification Model for Intensity Modulated Radiotherapy

目的:为了提高调强适形放疗治疗效率,保证调强适形放疗治疗计划临床实施的正确性,建立并应用两参数指数模型,以验证调强适形放疗的剂量准确性。方法:利用德国西门子公司Primus直线加速器6 MV X线,测定百分深度剂量及射野相对输出因子;根据患者的CT图像资料,设计患者治疗计划,并移植到模体中,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,调用模体调强适形放疗计划对模体进行照射;使用Capintec0.65 cc PR-06C Farmer型(AE帽)电离室测量出体模内等中心点的吸收剂量,然后与使用两参数指数模型预测的中心轴上的剂量值相比较。结果:空间绝对吸收剂量的测量值与模型预测值的偏差小于3%,符合ICRU第24号报告指出的原发灶根治剂量的精确性应好于5%的要求。结论:两参数指数模型用于验证调强适形放疗剂量是可行的。

Objective To establish one two-parameter exponential model to verify dose of intensity modulated radiotherapy（IMRT）,and ensure the accurateness IMRT treatment plan.Methods Percentage Depth Dose（PDD） and relative output factor of 6 MV X-ray were measured in Siemens Primus linear accelerator.According to CT imaging of patient obtained by the CT simulator,IMRT treatment plans were designed by TPS and planted in phantom.Dose distribution of phantom central points was gotten;Dose in the center axis was measured by the Capintec 0.65cc PR-06C Farmer ionization chamber,which was compared with the predicted dose by the model and treatment planning system prediction.Results The average difference between model＇s prediction and treatment planning system prediction was found to be less than 3.0%,which agreed with a target dose uniformity lower than 5% recommended by ICRU Report No.24.Conclusion The model is shown to provide a reliable independent check of planning system monitor units of IMRT.