蒙特卡罗系统验证PBC和CCC算法精确度的临床研究

目的 运用蒙特卡罗系统验证PBC、CCC算法在肺癌放疗计划时的精确度。方法 使用Oncentra Masterplan TPS对本院2012—2013年间收治的24例肺癌患者分别进行PBC、CCC计算。设计2个IMRT计划和2个3DCRT计划,将计划的DICOM-RT文件导入蒙特卡罗系统进行剂量重建。配对t检验差异。结果 4个计划中无论是IMRT还是3DCRT计划CCC、PBC计算的靶区平均剂量与蒙特卡罗计算值的差别均随靶体积减小而增大(P=0.00、0.00、0.00、0.00),且IMRT计划比3DCRT的大(P=0.00、0.01)。IMRT计划中CCC计算的D_98%、D_95%、D_90%、D_50%、D_2%与蒙特卡罗计算值差别逐渐减小(P=0.00、0.00、0.00、0.00、0.00),上述现象同样出现在PBC算法中,但CCC计算的3DCRT计划中的不显著(P=0.18、0.08、0.62、0.08,0.97)。IMRT和3DCRT计划中,CCC算法高估了整个患侧肺剂量;PBC算法高估了患侧肺V₂₀(P=0.00、0.00),低估了患侧肺V₅(P=0.00、0.00),但3DCRT计划中V₁₀值相近(P=0.47)。结论 建议在肺癌放疗计划计算时使用精确度更高的算法而不使用PBC算法。蒙特卡罗比其他算法精度更高。

A clinical study of lung cancer dose calculation accuracy by using Monte Carlo simulation

Objective To study the evaluate the PBC and CCC algorithms for lung cancer radiotherapy with the Monte Carlo (MC).Methods From 2012 to 2013 years,24 patients with lung cancer were studied.For each patient was designed four plans wiht Oncentra Masterplan TPS.Two IMRT plans and two 3DCRT plans were developed with the PBC and CCC algorithms.Then the DICOM-RT files of the plans were exported to the MC system for recalculate.The differences of results were analyzed by paired-t test.Results For 3DCRT and IMRT plans,the mean dose differences for GTV between CCC and MC,PBC and MC increased with the GTV volume decreasing (P =0.00,0.00,0.00,0.00),for IMRT plans the mean dose differences were found to be higher than that of 3DCRT plans (P=0.00,0.01).Comparison of DVHs,the differences became smaller gradually from Dgs,D95,D90,D50 to D2 (P=0.00,0.00,0.00,0.00,0.00),but the effect is not obvious in 3DCRT plans (P =0.18,0.08,0.62,0.08,0.97),similarly,the same effect was found in the differences between PBC and MC for IMRT plans,and the differences of dose volume are lager than that of CCC and MC.For the dose of ipsilateral lung,CCC algorithm overestimated dose for all lung,PBC algorithm overestimated V20(P=0.00,0.00),but underestimated V5(P=0.00,0.00),the difference of V10 have no statistical significant (P=0.47).Conclusions It is recommended that the treatment plan of lung cancer should be calculated by an advanced algorithm other than PBC.MC can calculate dose distribution of lung cancer accurately and can provide a very good tool for benchmarking the performance of other dose calculation algorithms.