宫颈癌术后容积旋转调强放疗与5野调强放疗计划的剂量学比较

Dosimetric comparison between volumetric modulated arc radiotherapy and five fields intensity-modulated radiation therapy for postoperative cervical carcinoma

    摘要
  • 摘要:
    目的比较宫颈癌术后容积旋转调强放疗（VMAT）与5野调强放疗（5F-IMRT）计划的剂量学差异，并在危及器官保护方面进行分析。
    方法选择10例宫颈癌术后放疗的5F-IMRT计划，按相同的剂量限制对每例患者行单弧VMAT和双弧VMAT计划设计，比较3种计划的靶区剂量、适形度指数、均匀性指数、危及器官剂量及加速器跳数。组间比较采用单因素方差分析检验，组间两两比较采用LSD检验。
    结果单弧VMAT和双弧VMAT均能满足靶区处方剂量的要求，在靶区最大剂量、平均剂量、适形度指数和均匀性指数上，双弧VMAT与5F-IMRT计划相当，单弧VMAT计划最差，差异有统计学意义（F=24.102、13.710、5.919、11.045，均P < 0.05）；靶区最小剂量比较，3种计划差异无统计学意义（F=3.323，P>0.05）。单弧VMAT和双弧VMAT计划的加速器跳数明显少于5F-IMRT计划，差异有统计学意义（F=295.138，P < 0.05）。对于小肠、直肠和膀胱的参数最大剂量，双弧VMAT与5F-IMRT计划相当，单弧VMAT计划最差，差异有统计学意义（F=16.069、7.521、13.966，均P < 0.05）。对于膀胱的参数V20、V30和V40（V表示受照剂量体积百分比），5F-IMRT优于单弧VMAT和双弧VMAT，差异有统计学意义（F=5.142、20.095、7.387，均P < 0.05）。对于左股骨头参数V20和V30，单弧和双弧VMAT优于5F-IMRT，差异有统计学意义（F=3.717、16.040，均P < 0.05）。对于右股骨头参数V30和V40，单弧和双弧VMAT优于5F-IMRT，差异有统计学意义（F=10.873、7.791，均P < 0.05）。
    结论宫颈癌术后放疗，双弧VMAT计划在靶区剂量学参数上与5F-IMRT计划相当，单弧VMAT计划较差。在危及器官保护方面，3种计划各有优势，但VMAT计划的加速器跳数明显减少，可以提高治疗效率，值得进一步研究。

     

    Abstract:
    ObjectiveTo determine the dosimetric differences between volumetric modulated arc radiotherapy(VMAT) an five fields intensity-modulated radiation therapy(5F-IMRT) for postoperative cervical cancer.
    MethodsTen patients with postoperative cervical carcinoma were enrolled in this study. Single arc VMAT, double arc VMAT, and 5F-IMRT plans were generated for these patients. Dose of target, conformal index (CI), homogeneity index (HI), organs at risk and monitor units (MU) were analyzed. The measurement data were analyzed by single factor analysis of variance, and an LSD test was performed in both two groups.
    ResultsSingle arc and double arc VMAT plans both satisfied the clinical dosimetriy requirements. No significant difference was observed between the VMAT and 5F-IMRT plans with respect to the maximum dose(Dmax) of the target, mean dose(Dmean), CI, and HI. Compared with these plans, the single arc VMAT was weaker and significantly different with respect to the above-mentioned variables (F=24.102, 13.710, 5.919, 11.045, all P < 0.05). There is no significant difference between the 3 plans of the minimum dose of the target (F=3.323, P>0.05). The MU values o f the single arc and double arc VMAT plans were significantly lower than that of 5F-IMRT(F=295.138, P>0.05). Meanwhile, significant difference was observed between the Dmax values of the small intestine, rectum, and bladder for double arc VMAT plan, single arc VMAT plan and those of the 5F-IMRT plan(F=16.069, 7.521, 13.966, all P < 0.05). The bladder V20, V30 and V40 for 5F-IMRT were better than those of the single arc and double arc VMAT, and the differences were significant(F=5.142, 20.095, 7.387, all P < 0.05). The left femoral head V20 and V30 for single arc and double arc VMAT plan was superior to that of 5F-IMRT, and the differences were statistically significant (F=3.717, 16.040, both P < 0.05). The right femoral head V30 and V40 for single arc and double arc VMAT plan was superior to that of 5F-IMRT, and the differences were statistically significant (F=10.873, 7.791, both P < 0.05).
    ConclusionsCompared with 5F-IMRT, the double arc VMAT achieved equal dosimetric parameters with fewer MU. In terms of organ at risk protection, the three plans have their own advantages, but the MU of the VMAT plan is significantly reduced, which can improve the treatment efficiency and worth further study.

     

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