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[目的]比较Monaco治疗计划系统中两种不同算法在非小细胞肺癌静态调强放疗中的剂量学差异。[方法]选取12例经临床及病理确诊为非小细胞肺癌的患者,采用Monaco计划系统分别为每例患者设计XVMC算法和PB算法两组静态调强放疗计划,优化条件相同,分析比较两组计划的靶区均匀性指数(HI)和适形度指数(CI)以及正常组织的剂量分布。[结果 ]无论是靶区还是危及器官各项指标,XVMC算法结果均高于PB算法。其中,XVMC算法和PB算法的靶区HI和CI差异分别为1.11%和1.08%,且差异具有统计学意义(P<0.05);脊髓的最大量以及心脏的各项指标(V_(10)、V_(20)、V_(30)、V_(40)、Dmean)差异均小于2%,差异无统计学意义(P>0.05);但双肺的各项指标(V_5、V_(10)、V_(20)、V_(30)、Dmean)以及食管的V30、V50、Dmean差值均大于2%,且差异具有统计学意义(P<0.05)。XVMC组MU较低,优于PB组(P<0.05)。[结论]分析XVMC算法和PB算法的差异原因在于相比于XVMC算法,PB算法未考虑次级电子的输运和能量沉积以及侧向电子失衡,导致计算不精确。因此,在实际的临床计划设计时,对于组织结构密度差异较大、且低密度组织范围较大的部位,建议使用XVMC算法进行剂量计算。
[Objective] To compare the dosimetry differences between two different algorithms in the Monaco treatment planning system for static IMRT of non-small cell lung cancer. [Methods] Twelve patients clinically and pathologically diagnosed as non-small cell lung cancer (NSCLC) were enrolled in this study. Two sets of static intensity modulated radiotherapy (IMRT) plans of XVMC algorithm and PB algorithm were designed for each patient with Monaco planning system. The optimization conditions were the same. The planned target area homogeneity index (HI) and conformability index (CI) as well as the normal tissue dose distribution. [Results] The results of XVMC algorithm were higher than that of PB algorithm in both target and endangered organs. Among them, the differences of HI and CI in target volume between the XVMC algorithm and the PB algorithm were 1.11% and 1.08%, respectively, and the difference was statistically significant (P <0.05); the maximum amount of spinal cord and the indexes of heart (V 10, V_ (20), V_ (30), V_ (40), Dmean) were all less than 2%, there was no significant difference between the two groups (P> 0.05) (20), V 30, Dmean) and esophageal V30, V50 and Dmean were all higher than 2%, and the differences were statistically significant (P <0.05). Mucus was lower in the XVMC group than in the PB group (P <0.05). [Conclusion] The difference between XVMC algorithm and PB algorithm is analyzed. Compared with XVMC algorithm, PB algorithm does not consider the transport and energy deposition of secondary electrons and the lateral electron imbalance, which leads to inaccurate calculation. Therefore, in the actual design of clinical plans, for the large differences in the density of tissue structure, and a large area of low-density tissue, it is recommended to use the XVMC algorithm for dose calculation.