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

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。

Dosimetric comparison of the helical tomotherapy, volumetricmodulated arc therapy and intensity modulated radiotherapyfor cervical cancer with retroperitoneal lymph node metastasis

Objective To compare the dosimetric parameters between HT, VMAT and 7F-IMRT for cervicalcancer with retroperitoneal lymph node metastasis. Methods Twenty-five patients with cervical cancer whounderwent radiotherapy between June 2017 and December 2019 were enrolled in this study. Three radiation treatmentplans 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.