腹膜后淋巴结转移宫颈癌螺旋断层、容积旋转 调强和静态调强放疗的剂量学比较

Dosimetric comparison of the helical tomotherapy, volumetric modulated arc therapy and intensity modulated radiotherapy for cervical cancer with retroperitoneal lymph node metastasis

摘要:

目的 比较螺旋断层放疗、容积旋转调强放疗（IMRT）和7 野- 静态IMRT 在伴腹膜后淋巴 结转移宫颈癌治疗中的剂量学差异及其优缺点，为临床放疗方式的选择提供依据。方法 选取2017 年6 月— 2019 年12 月中国科学技术大学附属第一医院接受放疗的26 例伴腹膜后淋巴结转移宫颈癌患者，分别进行螺 旋断层放疗、容积旋转IMRT 和7 野- 静态IMRT，所有计划处方剂量：肿瘤区的计划靶区（PTV-G）总剂 量6 020 cGy，分28 次照射，共6 周完成；临床靶区的计划靶区（PTV-C）总剂量5 040 cGy，分28 次照射，共 6 周完成。比较3 种计划模式之间靶区和危及器官之间的剂量学参数。结果 7 野- 静态IMRT 组和容积旋 转IMRT 组PTV-G 的适形指数（CI）较螺旋断层放疗组低，均匀指数（HI）较螺旋断层放疗组高（P <0.05）。 7 野- 静态IMRT 组和容积旋转IMRT 组PTV-C 的CI 较螺旋断层放疗组低，靶区平均照射剂量（Dmean）较 螺旋断层放疗组高（P <0.05）。7 野- 静态IMRT 组直肠及膀胱40 Gy 剂量受照射的体积（V40）和Dmean、脊髓 Dmean 和靶区接受最大剂量（Dmax）值较螺旋断层放疗组高（P <0.05），肾脏V20、胃V30 和Dmean 较螺旋断层放疗 组低（P <0.05）；容积旋转IMRT 组直肠及膀胱V40 和Dmean、脊髓Dmax 较螺旋断层放疗组高（P <0.05）；7 野- 静态IMRT 组膀胱V40 较容积旋转IMRT 组高，而直肠V40、膀胱Dmean、肾脏V20、胃V30 和Dmean 较容积旋转 IMRT 组低（P <0.05）。7 野- 静态IMRT 组骨盆V20、V30、V40 和Dmean 较螺旋断层放疗组、容积旋转IMRT 组高（P <0.05）。7 野- 静态IMRT 组、容积旋转IMRT 组的机器输出量较螺旋断层放疗组低（P <0.05）。 结论 螺旋断层放疗技术在靶区适形度、均匀性及周围正常组织保护上优于容积旋转IMRT 和7 野- 静态 IMRT 技术，但其机器输出量高于容积旋转IMRT 和7 野- 静态IMRT 技术，对射束利用率较低。

Abstract:

Objective To compare the dosimetric parameters between HT, VMAT and 7F-IMRT for cervical cancer with retroperitoneal lymph node metastasis. Methods Twenty-five patients with cervical cancer who underwent radiotherapy between June 2017 and December 2019 were enrolled in this study. Three radiation treatment plans for HT, VMAT and 7F-IMRT were designed respectively for each patient. Radiotherapy dose for each patient: 95% PTV-G 6020cGy/28f, 95% PTV-C 5040cGy/28f. The dosimetric parameters of target areas and organs-at risk were compared among three planning modes by paired samples t-test. Results HT was better than 7F-IMRT and VMAT in conformity index and homogeneity index of PTV-G (P < 0.05), and HT was better than 7F-IMRT and VMAT in conformity index and Dmean of PTV-C (P < 0.05). The V40 and Dmean of rectum and bladder in HT group were significantly lower than those in 7F-IMRT group (P < 0.05) and VMAT group (P < 0.05). The Dmean and Dmax of spinal cord and the V20, V30, V40 and Dmean of pelvic bone in HT group were significantly lower than those in 7F-IMRT group (P < 0.05). However, HT group showed much higher MU (5475 MU±1013) than VMAT group (683 MU±332, P < 0.05) and 7F-IMRT group (798 MU±126, P < 0.05). Conclusions HT is superior to 7F-IMRT in conformity index, homogeneity index and organs-at-risk sparing. However, the MU of HT is higher than that of 7F-IMRT and VMAT, which indicates a lower utilization rate of beams in HT.