晚期鼻咽癌RapidArc与固定野调强放疗的比较研究

  目的  近年RapidArc的临床应用已引起越来越多的关注, 本研究比较RapidArc与固定野调强放射治疗(IMRT)两种放疗技术在晚期鼻咽癌治疗计划中的差异。  方法  随机选取10例晚期鼻咽癌患者, 采用RapidArc与IMRT两种技术进行计划设计与剂量验证, 比较计划的靶区剂量、危及器官与正常组织剂量、机器跳数、治疗时间与剂量验证结果。  结果  两种计划的剂量分布基本一致, 均能提供足够的靶区剂量。RapidArc的PTVnx最小剂量, PTVnd、PTV60、喉、腮腺的平均剂量低于IMRT, PTV60的HI值高于IMRT, 机器跳数比IMRT减少约58%, 治疗时间减少约70%。以3%/3mm为界, RapidArc验证的γ指数通过率为(98.75±0.50)%, IMRT的通过率为(98.86±0.67)%。  结论  两种放疗技术均能够满足临床治疗需要, 剂量验证结果能够较好的符合计划计算结果。RapidArc比IMRT有着更多的优势, 不仅可以减少机器跳数, 缩短治疗时间, 而且可以减少喉、腮腺的受照剂量。 

Comparison of rapidArc and fixed field intensity-modulated radiation therapies for advanced nasopharyngeal carcinoma

  Objective  This study compares volumetric-modulated arc therapy(RapidArc) and fixed field intensity-modulated radiation therapy(IMRT) for advanced nasopharyngeal carcinoma.  Methods  Ten advanced nasopharyngeal carcinoma patients were randomly selected for this study.Two treatment plans were completed for each patient, i.e., the RapidArc and IMRT schemes.Dosimetric verification was conducted for each scheme.The doses for the planning target volumes(PTVs), organs at risk(OARs), and normal tissues were compared.The technical delivery parameters, including monitor units(MUs), time of therapy, and results of dosimetric verification, were analyzed.  Results  No significant differences were found in dose distribution between the two schemes.Both techniques delivered adequate doses for the PTVs.For RapidArc planning, the minimal dose of PTVnx, mean dose of PTVnd, PTV60, larynx, and parotid were lower compared with those of IMRT schemes, whereas the homogeneity index of PTV60 was higher.Compared with IMRT plans, the MUs and treatment time in RapidArc plans were reduced by approximately 58% and 70%, respectively.Gamma analysis produced an average pass rate of 98.75%± 0.50% and 98.86%±0.67% at the 3%/3 mm levels for RapidArc and IMRT, respectively.  Conclusion  Both RapidArc and IMRT plans satisfied the requirements for advanced nasopharyngeal carcinoma therapy.The dose measurements showed good agreement with the computed doses.The RapidArc technique has much more superiority compared with the IMRT technique.The former decreases not only the MUs and treatment time, but also the dose to the larynx and parotid glands.