| 李小波,邓小武,徐本华,林智星,陈远贵,黄妙云.组织不均匀条件对调强计划系统计算模型精度的影响[J].中华放射医学与防护杂志,2015,35(8):628-631 |
| 组织不均匀条件对调强计划系统计算模型精度的影响 |
| Effect of inhomogeneity on accuracy of various IMRT dose calculation models |
| 投稿时间：2014-10-16 |
| DOI：10.3760/cma.j.issn.0254-5098.2015.08.017 |
| 中文关键词: 调强放射治疗 蒙特卡罗 笔形束 剂量 |
| 英文关键词:IMRT Monte Carlo Pencil beam Dosimetry |
| 基金项目:福建省卫生厅青年课题基金(2008-1-22) |
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| 中文摘要: |
| 目的 探讨在组织不均匀条件下,治疗计划系统(MONACO)中的有限笔形束算法(FSPB)与快速X射线体积元蒙特卡罗算法(XVMC)的调强放射治疗计划计算精度差别,以及对临床治疗的影响和各自的应用范围。方法 在非均匀仿真人体模型中,对两种算法模型计算的规则照射野及调强照射野的剂量精度,利用经过刻度的放射性铬胶片(EBT2胶片),进行剂量测量以及二维平面剂量的分析比对。结果 在非均匀仿真人体模型中,不同能量的X射线规则照射野,XVMC算法在不同介质中的剂量计算与胶片测量的结果偏差均在±2.00%范围内,而FSPB计算的结果与测量结果的偏差除了15 MV射野为10 cm×2 cm情况下肺中的剂量偏差高达6.51%以外,其他条件下的结果偏差都在±3%范围内。调强放疗计划(IMRT)的胶片验证测量结果中,3%/3 mm γ通过率XVMC算法组>90%;FSPB算法组为80%~90%,且4%/4 mm γ通过率>90%。结论 当临床治疗病例的组织密度不均匀性较大、子野数较多时,XVMC算法的剂量计算精度优于FSPB算法,采用XVMC治疗设计胸腹部IMRT治疗计划可以将算法所引起的误差控制在±3%以内,而且可以避免由于算法原因所致的计划靶区剂量缺失。 |
| 英文摘要: |
| Objective To investigate the dosimetric performance of two algorithms for correcting the presence of tissue inhomogeneities, the finite site pencil beam (FSPB) and X-ray voxel Monte Carlo (XVMC) plans were implemented in the MONACO system, with the accuracy of application to clinic treatment of two algorithms were evaluated. Methods In a non-uniform artificial anthropomorphic phantom, regular open fields and intensity modulation radiated therapy (IMRT) plans of the MONACO were measured by using calibrated EBT2 films, and the dose accuracy of the two kinds of plans was analyzed by comparing the planned and measured plane dose. Results In an anthropomorphic phantom, the deviations between the calculated values by XVMC and the measured values by films were less than ±2%. While the deviations of FSPB values between calculation and measurements was within ±3%, except at the condition of 15 MV, 10 cm×2 cm field, the dose error in lung was up to 6.51%. The verification of individual IMRT beams based on films showed that the pass rates of calculation by XVMC and FSPB were larger than 90% with γ criterion of 3%/3 mm and 4%/4 mm, respectively. At 3%/3 mm, the pass rates of FSPB were in the range of 80%-90%. At the same time, the pass rates of all individual fields were higher than 90%. Conclusions The accuracy of dose calculation of XVMC is better than that of FSPB when being in multi-segments and non-uniform media. The error of algorithm can be controlled within ±3%, for the calculation by XVMC. And the dose deficiency of PTV arising from algorithm can be avoided. |
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