腮腺癌术后5放射野调强放射治疗的临床观察

Postoperative Intensity Modulated Radiotherapy with 5-Fields for Parotid Cancer

目的：对5、7、9、11野的腮腺癌调强放射治疗进行剂量学评估，优选达到良好剂量分布和治疗效率的放射野数目。方法：用容积剂量图（dose-volume-histgram，DVH）对5例不同放射野数调强放疗患者，分别行剂量学研究，比较不同数量放射野放疗计划靶区（planningl target volume，PTV）的以下指标。I〉95％处方剂量的体积百分比（V95）、〉110％处方剂量的体积百分比（V110）、适形指数（conformal index，CI）和均匀指数（homogeneous index HI）；脑干和脊髓的最大剂量（D maximum）、对侧腮腺和同侧中耳的平均剂量（D mean）、跳数（monitorunits，MU）和治疗时间均值，并行统计学分析。结果：5野调强放疗与更多野（7、9、11野）技术相比，靶区V95、V110、CI、HI和同侧中耳平均剂量均未见明显统计学差异（P〉0．05）；脊髓最大剂量以5野调强放疗最低（P〈0．05）；脑干最大剂量以11野调强放疗最低（P〈0．05），但5。11野调强均在安全剂量范围内；对侧腮腺平均剂量、MU和总治疗时间均以5野调强放疗明显优于更多野技术（P〈0．05）。结论：腮腺癌术后5野调强放疗，具有良好的剂量分布和治疗效率，采用更多野调强技术对剂量分布未见明显改善．但会增加MU和总治疗时间。

Objective： The study was designed to clarify the appropriate field number for better dosimetric results and delivery efficiency of RT for postoperative patients with parotid glands cancer. Methods： The efficiency of dosimetry of intensity-modulated radiotherapy （IMRT） with 5-fields IMRT versus 7-fields, 9-fields and 11-fields IMRT were compared. The dose-volume-histgram （DVH）were used to evaluate different fields IMRT plans in 5 postoperative patients with parotid cancer. The percent volumes with 995% prescribed radiation dose （V95）, 〉110% prescription dose （V110）, conformity index （CI） and homogeneous index （HI） in the planning target volume （PTV）, maximum dose in brain stem and spinal cord, mean dose in contralateral parotid glands and ipsilateral middle ears, monitor units （MU） and times of RT of 5-fields and more than 5-fields IMRT were compared statistically. Results： There were no differences for V95,V110,C1, HI in PTV and the mean dose in ipsilateral middle ears （P〉0.05）, for the comparison between 5-fields IMRT and 7-, 9-, and 11-fields. The maximum dose in brain stem of 11-fields IMRT was the lowest （P〈0.05）, and the maximum dose in spinal cord of 5-fields IMRT was the lowest （P〈0.05）, but all doses of the groups were safety. The maximum dose in contralateral parotid glands, MU and times of RT of 5-fields IMRT were superior than that of 7-, 9-, and ll-fields IMRT （P〈0.05）. Conclusion： The 5-fields IMRT for postoperative patients with parotid glands cancer can offer good dosimetric results and lower MU and total treatment time. The more than 5-fields IMRT can not provide better dosimetric results, but will increase MU and total treatment time.