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    各向异性算法在宫颈癌调强放射治疗剂量学上的应用研究

    Dosimetric study of AAA algorithm inintensity modulated radiotherapy for cervical cancer

    • 摘要: 目的 研究各向异性算法(AAA算法)对宫颈癌调强放射治疗(IMRT)计划的影响,为计划优化提供参考。方法 选取宫颈癌放疗患者10例,使用瓦里安Eclipse13.5计划系统,保持计划的射野数目、角度和优化目标参数相同,将优化算法分别选择为AAA算法和笔形束卷积算法(PBC算法),为每个患者设计7野IMRT计划。比较不同算法计划的靶区和危及器官的剂量学指标、机器跳数(MU)和调强验证通过率。结果 靶区方面,AAA算法的适形度指数和均匀性指数都优于PBC算法,PBC算法的临床靶区(CTV)Dmax偏大(P<0.05);危及器官方面,除了左侧股骨头PBC算法的剂量与AAA算法各有高低以外,其他危及器官AAA算法的剂量均大于PBC算法(P<0.05);关于MU方面,AAA算法低于PBC算法,且平均差异较大(P<0.05);调强验证方面,3%/3 mm标准下的gamma通过率并无太大差别(P>0.05),都符合治疗标准。结论 Eclipse计划系统中PBC算法高估了靶区中的剂量,而又低估了危及器官在实际中的剂量沉积。治疗中,PBC算法与AAA算法都可以应用于宫颈癌临床放疗,但应该优先使用大多数方面都有更佳表现的AAA算法进行宫颈癌IMRT计划的剂量计算。

       

      Abstract: Objective To investigate the effects of AAA algorithm on cervical cancer IMRT plan and to provide reference for program optimization. Methods A total of 10 patients with cervical cancer undergoing radiotherapy were selected. The Varian Eclipse13.5 planning system was used to keep the number, angle and optimization target parameters of the plan the same. The optimization algorithm was AAA algorithm and PBC algorithm, respectively, and 7-field IMRT plan was designed for each patient. The dosimetric indexes of target area and endangered organs, machine units (MU) and intensity modulation verification pass rate of different algorithm plans were compared. Results In terms of target area, the conformal index and uniformity index of AAA algorithm were superior to PBC algorithm, and the CTV Dmax of PBC algorithm was larger (P<0.05). In terms of endangered organs, except for the left femoral head, the dose of AAA algorithm in other endangered organs was higher than that in the PBC algorithm (P<0.05). AAA algorithm presented lower MU than PBC algorithm, with larger average difference was larger (P<0.05). In terms of IMRT verification, there was no significant difference in gamma pass rate under the standard of 3%/3 mm (P>0.05), which were met the treatment standard. Conclusions In the Eclipse planning system, PBC algorithm overestimates the dose in the target area, while underestimates the actual dose deposition of endangered organs. In the treatment, both PBC algorithm and AAA algorithm can be applied for clinical radiotherapy of cervical cancer, but the priority should be given to AAA algorithm with better performance in most aspects to calculate the dose of cervical cancer planning.

       

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